question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I generate this data in R: </p>
<pre><code>set.seed(111)
ds=rnorm(1000)
</code></pre>
<p>When I perform Box-Ljung test to test the independency:</p>
<pre><code>Box.test(ds,type='Ljung',lag=log(length(ds)))
</code></pre>
<p>it gave me p-value=0.5957, which is reasonable. However, when I perform this:</p>
<pre><c... | g58344 | [
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<p>For example, warning casual drawings when recognizing hand-written digits.</p>
<p>Some quick thoughts:</p>
<ul>
<li>A bad input may be an outlier for the training data</li>
<li>A bad input may cause noticeable ties across different labels</li>
</ul> | g58345 | [
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<p>I have done multiple regression analysis (MLR) of my data and find out $R^2$ and $r$, and then to remove multicollinearity problem I used PCA. This analysis generated PC equal to my variables, I selected only those factors having eigen value greater than 1 after rotation (varimax rotation). Now I'm confused that if ... | g13381 | [
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<p>This is not basically a research question rather an ask for help to provide me with some useful references on Path Analysis. This seems to be a trendy technique, but looks a little bit complicated. Is there any downloadable complete free book or PDF where I can find details on its theory and usage? </p>
<p>I need t... | g42263 | [
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<p>This question was originally posted on SO and Qnan suggested me to post it here :)</p>
<p>My question: let you have a correlation matrix; you would like correlations which are next to 1 and -1 go towards 1, while those next to 0 stay there.</p>
<p>The simplest way is to use absolute values, e.g. if <code>Rho</code... | g58346 | [
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<p>I am attempting to do a icc using the <code>quickicc</code> command following the use of <code>xtmixed</code>. I'm attempting to check repeatability in a sample of 24 individuals with QT measures (a measure of ventricular depolarization). Each individual has various readings of QT; some have 31 whilst others have 5... | g48072 | [
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... |
<p>I'm working with a Gaussian random field, which can be described by joint pdf as follows:</p>
<p>$$X\mid \sim N\left ( \mu, \sigma^{2} \left ( I-C \right )^{-1}\right )$$</p>
<p>where $C$ is a structured matrix, $c_{ij}=0$ if $i$ and $j$ is not neightbours. I'm working with the Bayesian inference on such fields. S... | g13386 | [
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<p>I just graduated in engineering where I have a very strong background in pure maths, but unfortunately I didnt study any statistics in my course. I know calculus, probability theory, measure theory, analysis etc. But I have not done any courses on regression etc.</p>
<p>I am planning to apply for several "analyst" ... | g40540 | [
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<p>Consider the time series to be estimated with OLS:</p>
<p>$Y_t = a + \bf{X}_t\bf{b} + e_t$</p>
<p>where $Y_t$ is skewed, $\bf{X}_t$ is a vector of regressor values at time $t$, $\bf{b}$ is a vector of coefficient estimates.</p>
<p>Scenario (1): The design matrix is such that the skewness in the response is perfec... | g58347 | [
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<p>I am a complete stranger to statistics (apart from mandatory courses in college), but lately I ran into an interesting real-world scenario.</p>
<p>Recently I started jogging. I take my GPS phone with me to measure time and distance. I picked a route (about 4km, but I don't know exactly) and started running. I have ... | g13389 | [
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<p>Hello fellow StackExchange users,</p>
<p><strong>Preamble:</strong> I have been tasked with performing a <a href="http://en.wikipedia.org/wiki/Cluster_analysis" rel="nofollow">cluster analysis</a> (or possibly a <a href="http://www.statisticalinnovations.com/articles/lcmodels2.pdf" rel="nofollow">latent class analy... | g58348 | [
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<p>I have a logistic model that I've built with the <code>nls</code> function in R. I want to use Bayesian model averaging for variable selection, but I can't find a package for that in R. Are there any suitable packages? If not, is it possible to make a not too complicated script for it? </p>
<p>Data example:</p>
<p... | g58349 | [
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<p>I have run a regressions relating metal revenue to a metal index in each of 25 different factories. In 24 of the factorias $R^2$ is greater than .75. In one factory the $R^2$ is .061.</p>
<p>Why is that $R^2$ is so low in one factory?</p> | g42271 | [
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<p>I am performing the hierarchical clustering analysis on a dataset of 25 viral populations using 3 viral components (variables) to construct a dendrogram with average method and correlation distance calculation. We firstly used the <code>hclust()</code> method generate a plot, but we still need to support the dendrog... | g58350 | [
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0... |
<p>I have been using this method to reduce the number of variables for a model but i have just had a bad thought.</p>
<p>Due to the nature of bootstrap is it possible that by randomly using variables you are actually promoting correlated and collinear variables?</p>
<p>I have 2 very dominant X variables that demote o... | g58351 | [
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0.... |
<p>I'm trying to estimate a joint probability density function in a quite high dimensional space (around 15 or even more). </p>
<p>I've heard about Dirichlet process methods to do this kind of things. Do you know a good paper/phd thesis/book to learn about this ?</p>
<p>Thank You for your help</p> | g58352 | [
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<p>There's no package available on CRAN, so I was hoping someone in the community had written their own function/package. I see it's been done in MATLAB, so I may just have to start with that and write the code myself... </p>
<p><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=... | g58353 | [
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<p>Trying to create a list of significant variables for a regression model. I have 82 variables, so in order to only include the significant ones, I created a list of the correlations and sorted them. I want to include the variables with correlations > 0.5 and <-0.5. I created a for loop, but am having difficulty ge... | g58354 | [
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<p>I'm trying to understand the Kolmogorov-Smirnov test using a very simple example. I generate a set of random, uniform values between 0 and 1.0. I then test that these values are from a uniform distribution by using the <a href="http://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.stats.kstest.html#scipy.... | g49527 | [
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<p>I’am trying to get a new perspective on some data on sleep deprivation and counter measures and thanks in advance everybody for investing some brain power in my problem.</p>
<p>Here comes a brief description of my research I hope it helps to understand my question.</p>
<p>I investigated how different counter tacti... | g58355 | [
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<p>I've used exponential distributions to estimate maximum-entropy probability distributions before.</p>
<p>Is there an analogue to the exponential that is restricted to integers? If so, does anyone have pointers to closed-form estimators for that distribution?</p> | g58356 | [
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<p>I am trying to detect automated visits to a website. A typical data set for an automated client is of the form:</p>
<pre><code>userid: visit_time1, visit_time2, ...
94562: 5, 10, 15, 25, 30
^
missed
</code></pre>
<p>So the period of visit times is <code>5</code>. </p>
<p>Occasi... | g13397 | [
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<p>Using the Bradley Terry Luce 2 model:</p>
<p>We want to rank 41 scripts by paired-comparison (package BTL2). <strong>But our dataset is incomplete</strong>. We can generate ability scores, but the scores at the end of the ranking have huge estimates (s.e). Also when we make dummy-items who are always winning, or al... | g58357 | [
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<p>I have supervised learning problem where targets are angles. If I would do simple regression then numbers 360 and 1 would be far away for my model, but actually they are close and predicting x and y coordinates doesn't feels right, since I am trying to predict just one number here. What is the proper way of doing su... | g3049 | [
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<p>When doing deep learning, in particular dnn, it's shown that pre-train each layer in a unsupervised fashion, then fine-tune the weights using the labeled data in a supervised fashion.</p>
<p>My problem is, since we're pre-trian each layer in a unsupervised fashion, so how could I pick those hyper-parameters, for ex... | g13399 | [
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<p>Suppose there is a population partitioned arbitrarily into a set of subpopulations that completely cover the original population. Assume that for some variable, we know each subpopulation's <em>quintiles only</em> (or some other fixed set of quantiles), but not its distribution. However, the entire population's perc... | g58358 | [
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<p>I'm performing a meta-analysis but I have a question: I'm evaluating three different treatment strategies (A,B,C) for each of those treatment strategies I have around 20 papers describing outcomes. Now here is my question: Each of those papers describe the mean age, however, some give a range, some give a standard d... | g58359 | [
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<p>So this has really been bothering me and I was hoping for a (simple!) explanation if possible. </p>
<p>Suppose I've specified a linear regression model:
$$
Y = \beta_0 + \beta_1 X + \epsilon
$$
And an alternative:
$$
Y = \beta_0 + \beta_1 X + \beta_2 X^2 + \epsilon
$$
And I'm trying to estimate the $\beta$s, say pe... | g58360 | [
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<p>I am trying to analyze a quite large (~25,000 rows) dataset of financial forecasts. The forecasts are usually not derived from algorithms, but come from a large number of analysts who forecast the income and expenditures for their respective entities.
The forecast starts 5 quarters in advance and is revised once per... | g58361 | [
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<p>I have a directed multigraph that is used to represent an online discussion forum, where each actor is able to contribute comments to a discussion and have their comments commented on by other actors. </p>
<p>Which centrality measures are most appropriate to use for a directed multigraph? Can I use the standard cen... | g2939 | [
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<p>I have a data set for a 2 (between) x 3 (within) x 3 (within) x 3 (within) mixed ANOVA. I need to find the sample size necessary to find a significant result for one of the 3-way interactions including the between subjects factor and two of the within subjects factors. I'm trying to figure out the easiest/best way t... | g42280 | [
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-0.026914993301033974,
-0.02982725389301777,
-0.01478267926722765,
0.03130791336297989,
0.011233114637434483,
-0.027913354337215424,
... |
<p>I've been trying to teach myself some of the fundamentals of statistics by trying to work through old qualifying exams. Here's a problem:</p>
<p>Suppose $X_1, \ldots, X_n$ are a random sample from a normal distribution with mean $\theta$ and variance $\sigma^2$, where $\sigma^2$ is fixed and $\theta>0$ is a para... | g58362 | [
-0.015394588932394981,
-0.025440426543354988,
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0.0015681411605328321,
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0.013591800816357136,
0.023667849600315094,
0.04659982770681381,
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0.01916818507015705,
-0.03122512623667717,
0.05844896659255028,
-0.0048432741314172745,
... |
<p>Suppose I have a neural network, with input variables $a, b, c, d, f, g$ and output variables$ m, n, o, p, q$.</p>
<p>Given different input values, the neural network will output corresponding $m, n, o, p, q$.</p>
<p>Now I want find out the best input values which can maxmize $m, n$, while minimize $o,p,q$ with di... | g58363 | [
0.025152524933218956,
-0.0063256761059165,
-0.017929701134562492,
0.03010392375290394,
0.016416920349001884,
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0.012153659015893936,
-0.08328618854284286,
0.01720748096704483,
0.03519079089164734,
0.055... |
<p>I'm stuck on a stats problem and am wondering if someone can point out the error in my logic.</p>
<p>Imagine you are planning for a camping trip for 50 people. Each person consumes 2.0 lb of food per day on average, with a standard deviation of 0.7 lb. What is the least amount of food you need to bring to be 97.5%... | g58364 | [
0.035844262689352036,
0.029071394354104996,
-0.0020401172805577517,
0.010718276724219322,
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0.014295883476734161,
-0.039996907114982605,
-0.012253660708665848,
0.01279396191239357,
-0.0286193136125803,
-0.015177476219832897,... |
<p>It is easy to graph effect size (r) for a correlation in the form of a scatterplot.</p>
<p>However, how do I graph the variance (r-squared)? Any thoughts on best practice?</p> | g58365 | [
0.03965441510081291,
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-0.03260799124836922,
0.06413699686527252,
0.0285860076546669,
0.024600666016340256,
0.022... |
<p>Let's say I want to count the number of people in 10 different counties that have $x$ characteristic. As each of the 10 counties have different population sizes and areas, I want to scale the count data by population size and area. </p>
<p>Is this the correct formula to use:</p>
<p>$$\frac{\text{count of people in... | g58366 | [
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0.044210560619831085,
0.00031081773340702057,
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0.0035379885230213404,
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0.010626545175909996,
0.024994300678372383,
0.05536196008324623,
... |
<p>Along the same lines as <a href="http://stats.stackexchange.com/questions/6856/aggregating-results-from-linear-model-runs-r">this question</a>, is there a nice way to display regression results in MATLAB from a single or many regressions in table or graph form?</p> | g42284 | [
0.013615898787975311,
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0.04295502230525017,
0.02452961541712284,
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0.... |
<p>I am looking for a test for circular data that is equivalent to linear repeated measures ANOVA (I have an experiment using human participants where the same sample of participants perform multiple experimental conditions and the dependent variable is an angle). </p>
<p>I have noticed 3 tests for performing ANOVA o... | g13408 | [
0.006334328558295965,
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0.0005568488850258291,
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0.016183676198124886,
-0.0057160216383636,
0.01207021065056324,
-0.03296756371855736,
-0.018... |
<p>I have a question on testing the hypothesis that a particular regression coefficient in a simple OLS scheme with all the good assumptions is zero or not.</p>
<p>In particular eq 3.12, in the book by Tibshirani and coll., <a href="http://www-stat.stanford.edu/~tibs/ElemStatLearn/" rel="nofollow"><em>Elements of Stat... | g13409 | [
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0.0043660374358296394,
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0.06328386068344116,
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0.04139036312699318,
0.0241229385137558,
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-0.014274540357291698,
0.038465071469545364,
0.036586944013834,
0.0158469... |
<p>I've read:</p>
<ul>
<li><a href="http://stats.stackexchange.com/questions/64991/model-selection-and-cross-validation-the-right-way">Model selection and cross-validation: The right way</a></li>
<li><a href="http://stats.stackexchange.com/questions/99108/crossvalidation-and-or-testdata-always-use-both-or-can-one-excl... | g13411 | [
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0.0042356643825769424,
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0.005654206499457359,
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0.05239177867770195,
0.04296209663152695,
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0.02377045713365078,
-0.0071791079826653,
0.002281182212755084,
0.06850045174360275,
0.... |
<p>I have two jointly normally distributed variables $s_1$ and $s_2$. I am now searching for the conditional expectation
$$
E(s_1|s_1>r_1,\ s_2>r_2)
$$
where $r_1$ and $r_2$ are constants. An idea of how to arrive at this and sources where it can be read up would also be greatly appreciated.</p> | g2341 | [
0.021725410595536232,
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0.025267986580729485,
0.05245032161474228,
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0.020184922963380814,
0.03499458357691765,
0.01697610877454281,
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0.024... |
<p>I have a numpy array with <em>m</em> columns and <em>n</em> rows, the columns being dimensions and the rows datapoints.</p>
<p>I now need to calculate kernel values for each combination of data points.</p>
<p>For a linear kernel $K(\mathbf{x}_i,\mathbf{x}_j) = \langle \mathbf{x}_i,\mathbf{x}_j \rangle$ I can simp... | g13413 | [
-0.0006288892473094165,
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0.01408320851624012,
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0.020375605672597885,
0.08041367679834366,
... |
<p>Can someone give a good rundown of the differences between the Bayesian and the frequentist approach to probability?</p>
<p>From what I understand:</p>
<p>The frequentists view is that the data is a repeatable random sample (random variable) with a specific frequency/probability (which is defined as the relative f... | g58367 | [
0.03188057988882065,
0.007356186397373676,
0.010355905629694462,
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0.007509150542318821,
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0.05163987725973129,
0.014965817332267761,
0.040136780589818954,
0.04... |
<p>I have a database with tests that are either a pass or fail and around 25 description fields. Each description field is either a boolean or has between 3 and 10 options.</p>
<p>I'd like to hook into my Postgres database using R and extract a subset of data that's hopefully representative of the entire database. The... | g58368 | [
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0.015594976022839546,
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<p>In a cross table, if the adjusted residual value for a cell is less than -1.96 or greater than 1.96 then we could say that this cell is determinant in the dependency (suppose pearson is 0.03). However, is this sign really important? I mean, if I get -2.5 can I say that the variables are negatively correlated?
I'm c... | g58369 | [
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0.07269341498613358,
0.01450317446142435,
0.... |
<p>I am involved in a nested Case-Control study that involves cohorts of cases and controls entering a program, with the outcome of failure by six months. Cases and controls are individually matched on month / year of entry. I have a lot (>10,000) of both.</p>
<p>A primary risk factor of interest is receiving a medi... | g40717 | [
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0.00916878692805767,
0.005124710500240326,
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0.048048168420791626,
0.025988643988966942,
0.08377830684185028,
0.... |
<p>The question title doesn't help, but i'll try to explain it:</p>
<p>I have historical data (weekly points) from 2001/01/01 to yesterday and
my variable has a strong seasonal pattern of 12 months (weather data).</p>
<p>I'm using the stlf() function (from the R 'forecast' package) to make weekly forecasts - and gett... | g58370 | [
0.0014469652669504285,
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0.001389128272421658,
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0.015363426879048347,
0.06336706131696701,
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<p>I have 3 observers, who each perform multiple observations in which they count a phenomenon. I'm trying to quantify both inter- and intra- observer error for this study. I'm new to this and am finding the analysis options quite confusing. Someone recommended using the ICC. I've mocked up some data below with "number... | g58371 | [
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<p>I am looking for a short course (1 week or less) that teaches the theoretical and applied aspects of principal components analysis in a mathematically rigorous way. I've seen university courses on multivariate statistics in general or the linear model, but not just PCA. Travel is not an issue, so good international ... | g58372 | [
0.03289712592959404,
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0.06589962542057037,
0.013856437057256699,
0.045026745647192,
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<p><strong>Short Introduction</strong></p>
<p>In a classification problem, the objective is to identify to which of a set of categories a new observation belongs, on the basis of a set of examples whose category membership is known.</p>
<p>The bottom-line of any solution to this problem is to find a set of features t... | g58373 | [
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0.026187973096966743,
0.00726659270003438,
0.06833938509225845,
0.05159... |
<p>If I had a response variable that was square-root transformed, and an explanatory variable that is log transformed, and I wished to back transform the model using the summary statistics below, such that Y ~ (X)^2, how would I interpret the meaning of the relationship between X and Y using the estimated Beta coeffici... | g58374 | [
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0.017418548464775085,
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0.08350375294685364,
0.05387641862034798,
-... |
<p>Say I have a bag with 10 balls (either red or blue), and I know that there are 8 balls that are red. How do I calculate the probability of drawing a a red ball $>75\%$ of the time if the first ball I picked without replacements is red? Hope this is clear. Thanks! </p> | g58375 | [
0.006128584500402212,
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0.01832481473684311,
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0.013660186901688576,
-0.08427096158266068,
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0.0563998706638813,
0.0292388... |
<p>We do a monthly fundraising letter at my nonprofit. I know how to set up tests in R to compare whether the proportion of response and amount received between two mailings is significantly different, but I would like to compare all twelve for the last year. I figure there is a test to do that, but I don't know what i... | g13416 | [
-0.006377662997692823,
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0.015894079580903053,
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0.03761444240808487,
-0.0007157057989388704,
0.06632789224386215,
0.00201860792003572,
0.02502824366092682,
... |
<p>When doing a multiple binomial regression, is it possible to do the regression with a categorical variable as x at the same time as y is categorical? Most of my x-variables are continuous except for two, while my y-variables is all categorical.</p> | g13417 | [
0.0006944391061551869,
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0.04355556517839432,
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-0.014840022660791874,
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-0.01263874489814043,
0... |
<p>I have 100,000 random binary sequences like this</p>
<pre><code>01011101101001100111001100100001010...
11110111001110000110001100001010101...
00110010100011111000100010101010101...
10001001110101000111000101010011110...
11100100111100010100010010100001010...
...
</code></pre>
<p>and so on. I also have a master bin... | g13418 | [
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0.05222581699490547,
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0.06225372850894928,
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-0.06926604360342026,
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0.03537091240286827,
0.017263276502490044,
0... |
<p>I recently finished reading <a href="http://rads.stackoverflow.com/amzn/click/0805071342">The Lady Tasting Tea</a>, a fun book about the history of statistics. At the end of the book, the author, <a href="http://en.wikipedia.org/wiki/David_Salsburg">David Salsburg</a>, proposes three open philosophical problems in ... | g58376 | [
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0.02701660804450512,
-0.03196898102760315,
0.037878889590501785,
-0.07788383215665817,
0.07322666794061661,
0.04... |
<p>How do you determine if the percent growth between two time periods is statistically significant? For example, the total population in 2000 was 180,000. It grew to 220,000 ten years later. How do you determine if this 22% growth was significant? Similarly, group A (6,000 people) earned £50,000 last year. Group B (9,... | g37750 | [
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0.03675694018602371,
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0.06448952108621597,
0.02090855874121189,
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-0.027014102786779404,
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-0.002444629091769457,
0.03980607911944389,
-0.0... |
<p>There is an abundance of literature about VAR-models, which teaches how to test preconditions, specify and estimate VAR-models for stationary and also cointegrated time-series.</p>
<p>However, I'm still a bit puzzled by the meaning of the model's parameters. Namely the coefficients $\phi_{ijk}$ of the phi-matrices ... | g58377 | [
0.009608249180018902,
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0.054829031229019165,
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0.09358097612857819,
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0.032889317721128464,
0.028739184141159058,
-0.06055055558681488,
0.044662024825811386,
0.020430581644177437,
0.... |
<p>I have performed an experiment to study the response of a yeast (that contains 5000 genes) to stress caused by heat shock. I have one list of 48 genes that are overexpressed at 37ºC and another list of 145 genes that are overexpressed at 42ºC. There are 38 genes that are overexpressed in both of them.</p>
<p>By cha... | g58378 | [
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0.016220640391111374,
0.0021214846055954695,
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0.023580869659781456,
0.017323141917586327,
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0.01071922853589058,
-0.04368530213832855,
0.057531364262104034,
-0.015914112329483032... |
<p>I have a list of teams in a local soccer league, ranked from 1 to 10, where the top (1st) ranked team has the most wins (and hence "points").</p>
<p>I'm trying to create a "power" list, so that if the 10th ranked team wins against the 1st ranked team, the game is more important that if the 1st ranked team wins agai... | g58379 | [
-0.017934218049049377,
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0.02600318007171154,
-0.012347052805125713,
-0.012201841920614243,
0.0729871317744255,
... |
<p>So I've been trying to algebraically prove that overfitting a model leads to greater variance values for the parameter estimates. I've gotten close (reduced the problem to showing a certain matrix is positive definite) but I don't really like the approaches I've taken and I'd like to see if there's a simpler way. </... | g58380 | [
0.03103385493159294,
0.01942768134176731,
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0.000057574157835915685,
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0.058057479560375214,
-0.014039857313036919,
0.010566573590040207,
0.025841614231467247,
... |
<p>Im currently attacking SPSS, and I'm just testing for normality... In the Shapiro-Wilk<br>
Statistic test, my dependent variables have a wide range of significance levels. Obviously, I know that the sig. should be >0.05, which most the variables are...apart from 1 variable. </p>
<p><strong>Does this mean all of my ... | g58381 | [
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0.003042027587071061,
-0.008444484323263168,
-0.0005435760249383748,
0.023401912301778793,
0.0533975251019001,
0.014702956192195415,
-0.05497166886925697,
-0.03613346070051193,
0.04134509712457657,
0.0007103352108970284,
0.0... |
<p>I'm trying to use the bootstrapping method to essentially do what an $F$-test does - determining if the restricted or unrestricted model is better. My two models are below:</p>
<pre><code>lm3 <- lm(gamble ~ sex + status + income + verbal, data=teengamb)
lm4 <- lm(gamble ~ income, data=teengamb)
</code></pre>
... | g58382 | [
-0.06429112702608109,
0.03116869553923607,
0.01529874186962843,
0.029312163591384888,
0.04556640237569809,
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0.04516309127211571,
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-0.04894242435693741,
-0.012981187552213669,
0.021679623052477837,
0.049843356013298035,
0.0296... |
<p>I'm facing a challenge: writing my own general equilibrium model in MATLAB. I would like to ask for:</p>
<ol>
<li>the basic needed knowledge in mathematics</li>
<li>the basic needed knowledge in programming</li>
</ol>
<p>with references if possible.</p>
<p>I'm a master's degree student in economics, but I'm willi... | g58383 | [
-0.025095900520682335,
0.050345271825790405,
0.031144995242357254,
0.04964000731706619,
0.008442454971373081,
0.028626274317502975,
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0.023727882653474808,
-0.02020045928657055,
-0.0032097571529448032,
0.05730234086513519,
-... |
<p>I want to fit a GAM in R. My data are negative binomial. Plus they have a temporal autocorrelation.</p>
<pre><code>m1 <- gam(Y~s(X,Day), s(fDate, bs="re"), family=negbin(c(1,10), link = log), data=data)
Resid <- resid(m1)
acf(Resid)
</code></pre>
<p>With the <code>acf()</code> function I have detected a... | g13430 | [
0.03602194786071777,
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0.010484759695827961,
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0.045621104538440704,
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-0.053233977407217026,
0.023428326472640038,
0.026861460879445076,
0.025130124762654305,
... |
<p>Would data in two columns such as Shoe Size (variate x) and Number of Pairs (frequency f) be considered grouped or ungrouped data? Does grouped data necessarily imply the existence or classification via class intervals? </p> | g58384 | [
-0.023474249988794327,
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0.01781034842133522,
0.014317859895527363,
0.04663560912013054,
0.00... |
<p>I have a question about clusters that I am contemplating to treat with a nonparametric mixture approach (I think).
I am working on the explanation of human comportment.<br>
Each row of my database contains:</p>
<ol>
<li>the ID of someone </li>
<li>some parameters of the environment <em>X</em> (example: the temperat... | g58385 | [
0.0032885754480957985,
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0.007890915498137474,
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0.05054913088679314,
0.025622017681598663,
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-0.0437910370528698,
0.03475240617990494,
-0.012104719877243042,
0.046560946851968765,
0... |
<p>I have some problems in finding the outliers using clustering. </p>
<p>The data.frame is ~20000 observations and each row has mixed types of variables(numeric, nominal and binary). What I want to do is to detect the outliers by clustering.</p>
<p>I have calculated the dissimilarity matrix using daisy() function in... | g58386 | [
0.05418557673692703,
-0.05947517603635788,
0.004904348868876696,
-0.022537728771567345,
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0.020891092717647552,
0.030330020934343338,
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-0.035451773554086685,
-0.03622285649180412,
0.03423609212040901,
0.04427377134561539,
0.01... |
<blockquote>
<p>regression analysis helps one understand how the typical value of the dependent variable changes...
-- <a href="http://en.wikipedia.org/wiki/Regression_analysis" rel="nofollow">http://en.wikipedia.org/wiki/Regression_analysis</a></p>
</blockquote>
<p>What does this mean? What "typical value" is it... | g13433 | [
-0.0248105488717556,
-0.010587984696030617,
-0.02035144902765751,
-0.011825869791209698,
0.04075101763010025,
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0.04739787429571152,
0.03306073695421219,
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-0.02681058645248413,
0.009339994750916958,
0.06944406032562256,
0.06775256991386414,
0.0097... |
<p>I read from my lecture notes that Pearson correlation can be computed as $\frac{s_{xy}}{s_xs_y}$. If I have been given a finite amount of data points $(x_i,y_i),i=1,\ldots,n$, how can I compute the Pearson correlation using formula $\tfrac{s_{xy}}{s_xs_y}$? I managed to find that $s_{xy}=\dfrac{\sum_{i=1}^n (x_i-\ba... | g58387 | [
0.006324870511889458,
0.021738186478614807,
-0.024198690429329872,
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0.013106288388371468,
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0.024893660098314285,
0.003968214616179466,
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-0.03338530659675598,
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0.0319613516330719,
0.023674121126532555,
0.00... |
<p>Please give a clean, simple, explanatory answer that any 7 yr old can understand. </p>
<p>You can also link to a regression guide that is very good and simple. Should be fully explanatory all the way through. That's what makes a good, not bad, writing to learn from.</p>
<p>Some sub-questions within my main questio... | g13435 | [
0.008500657044351101,
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0.004507941659539938,
0.004738026298582554,
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0.04558996483683586,
0.031087545678019524,
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-0.06137639284133911,
-0.05775810778141022,
0.020396452397108078,
0.09588222950696945,
0.0... |
<p>Let $g(x)=1$ if $x \leq c$ and $g(x)=(1-x)/(1-c)$, where $0 \leq x \leq 1$ and $0 <c <1$.
So $g$ is an non-increasing function.</p>
<p>Define $g^{-1}(y)=\inf\{0 \leq x \leq 1 \mid g(x) \leq y\}$.</p>
<p>Now $X$ is a random variable that takes on value $0, 0.1, 0.2, \ldots, 1$.</p>
<p>Is it true that </p>
... | g13436 | [
-0.017037279903888702,
0.052103083580732346,
-0.017712250351905823,
-0.05365380272269249,
0.053488295525312424,
0.019925862550735474,
-0.011007889173924923,
-0.035592611879110336,
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0.00873992033302784,
-0.05431605502963066,
0.08936066925525665,
-0.01095372624695301,
0... |
<p>Support vector machines do binary classification. If there is more than two classes, it is possible to train several classifiers instead of one. Two common approaches are training <em>one vs. one</em> (each class against each other class) and <em>one vs. all</em> classifiers (each class against all other classes).</... | g13437 | [
-0.010424409992992878,
0.01609175279736519,
0.029982373118400574,
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-0.022147929295897484,
0.016560599207878113,
0.05657881870865822,
-0.04678422585129738,
-0.04759899526834488,
0.020357944071292877,
0.0048737055622041225,
-0.0007720140856690705... |
<p>How to prove this:</p>
<p><strong>Proposition.</strong> If $F_n$ is the distribution function of a $\textrm{Bin}(n,p)$ random variable, then, for every real fixed $t$, the sequence $\{F_n(t)\}_{n=1}^\infty$ is nonincreasing. </p>
<p>P.S. There was some heavy editing here.</p> | g58388 | [
0.002470999490469694,
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0... |
<p>Are there any statistical or econometric studies before 2008 that predicted <a href="http://en.wikipedia.org/wiki/2007%E2%80%932012_global_financial_crisis" rel="nofollow">2008 financial crisis</a>?
Note that there are <a href="http://maf2012.unive.it/viewpaper.php?id=203" rel="nofollow">some publications</a> that a... | g58389 | [
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0.016273068264126778,
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-0.0009079996380023658,
0.006093522999435663,
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0.06878681480884552,
-0.02... |
<p>I have a polynomial of the form $K^2((a-i)^2 + (b-j)^2 + c^2) = (ct)^2$
where $a,b,c,t$ are unknowns.
I have multiple observation points for the values of $i,j,\&\ K$.</p>
<ul>
<li>Can I use some technique to learn the values of $a,b,c,\&\ t$ from these?</li>
<li>Could some machine learning technique help m... | g25313 | [
-0.021917926147580147,
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-0.07013795524835587,
0.029899153858423233,
-0.017997853457927704,
0.050386592745780945,
0.08375658839941025... |
<p>Letting $\Phi$ be the CDF of the standard normal, and $\Phi^{-1}$ be the quantile function of the normal, I am looking for the Taylor series expansion of
$$
\Phi^{-1}\left(\Phi\left(x\right) + \epsilon\right).
$$
Using the Taylor series expansion of the inverse error function, I believe I get something like
$$
\Phi^... | g58390 | [
-0.01603160984814167,
0.0038146108854562044,
0.005233399104326963,
-0.048975907266139984,
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0.03973769396543503,
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0.032755106687545776,
0.03394460305571556,
0.04335501044988632,
-0.011828947812318802,
0... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/1444/how-should-i-transform-non-negative-data-including-zeros">How should I transform non-negative data including zeros?</a> </p>
</blockquote>
<p>I have a question:</p>
<blockquote>
<p>Suppose we have ... | g49418 | [
0.011718286201357841,
0.022360198199748993,
0.005293172784149647,
-0.01899779587984085,
0.048369720578193665,
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-0.052469149231910706,
0.0343322716653347,
-0.07195205241441727,
-0.014787218533456326,
-0.023988649249076843,
0.06530232727527618,
0.025388576090335846,
-0.... |
<p>Good Morning,</p>
<p>By comparing the dendrograms produced by the <strong>clustergram</strong> object and the "manual" approach i.e. <strong>pdist</strong> -> <strong>linkage</strong> -> <strong>dendrogram</strong> I found they are different, but cannot find an explanation for that difference.<br><br>
Clustergram d... | g3200 | [
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0.005113308783620596,
0.060534268617630005,
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-0.038946256041526794,
0.002493793610483408,
-0.008623072877526283,
0.06697015464305878,
... |
<p>So in everything I've found, they tell you have to calculate $\rho$, or how to test for confidence interval for it. What I am trying to figure out is how to calculate the SE which would get us our critical value, i.e. if you get a $\rho$ of 0.8. To test it, you would do $(\rho-1)/(\text{SE}(\rho))$. To clarify, rho ... | g58391 | [
0.01055785734206438,
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0.032106272876262665,
0.029673807322978973,
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0.049891743808984756,
0.04220251366496086,
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0.011621467769145966,
-0.050463102757930756,
0.07643800973892212,
0.0811598151922226,
-0.0... |
<p>Is there a statistical measure for nonlinear time series data that is comparable to $R^2$ value in linear regression (giving an idea of how well the fit is)? </p>
<p>The data is not monotonic, so I cannot use Spearman's $\rho$; and it's not linear, so Pearson's $\rho$ is not valid here either. </p>
<p>Data looks l... | g58392 | [
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0.0005784056265838444,
0.04261151701211929,
0.03518948704004288,
... |
<p>I am working on a prediction problem that leverage sparse clinical datasets.
Missing data rate is in the range of 80%. </p>
<p>1- I am wondering if there is any example of application of matrix completion to clinical or other datasets with such a missing rates. </p>
<p>2- Currenlty exploring glmnet, pcaMethods an... | g58393 | [
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0.06416788697242737,
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0.047515686601400375,
-0.033... |
<p>In R, usually one performs a generalized additive model like so:</p>
<pre><code>library(mgcv)
x <- gam(depvar ~ s(indvar1) + s(indvar2) + parametricvar)
</code></pre>
<p>Say I want to explore the non-parametric interaction of <code>indvar1</code> and <code>indvar2</code>.</p>
<p>Is the following kosher?</p>
<... | g49528 | [
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-0.013840672560036182,
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0.007212921977043152,
0.04065382853150368,
... |
<p>I have two variables, one with 2 categories and one with 6 categories.
To test, whether there is any relation between these variables, I performed
Fisher's exact test, which gave a significant result.</p>
<p>Now I want to know for which of the categories of the second variable respective
subjects have a differing ... | g13445 | [
-0.009161589667201042,
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0.026714803650975227,
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0.02826913259923458,
0.008174989372491837,
-0.03201640397310257,
0.039... |
<p>We have been collecting statistics on a queueing and processing system that powers part of our business. We have multiple servers processing items in a queue.</p>
<p>We recently added new servers, and we want to know whether we're processing faster. By "processing faster", I mean something like this:</p>
<blockquo... | g58394 | [
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0.05753360688686371,
0.0015912497183308005,
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0.006026130635291338,
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0.00804373063147068,
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-0.009625634178519249,
0.02633439563214779,
0.02237817458808422,
0.003472457639873028,
-0.00... |
<p>First, a bit of background: I'm currently working on a project at work that produces variable width data. During a operation qualification I collected a bunch of data at low, nominal, and high levels. The data is all independent and I have no reason to expect anything but identical distributions part to part as th... | g13446 | [
0.043096013367176056,
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0.005738871172070503,
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0.00294622965157032,
0.010508631356060505,
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-0.018611956387758255,
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0.029107240960001945,
-0.017465872690081596,
... |
<p>This might sound a bit basic and stupid, but I've been looking up all across the internet to see what IS lag length. I want to perform a EG ADF test, but for ADF, it always asks to specifiy a lag. It seems to me that whenever i look up lag length, most people just have trouble determining what it should be. I want t... | g58395 | [
0.05409764498472214,
0.06758689880371094,
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0.050066687166690826,
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0.043789349496364594,
0.03582960367202759,
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-0.027980832383036613,
-0.005800374783575535,
0.05842967331409454,
0.018967485055327415,
0.03... |
<p>In R, the eigen() returns descending sorted eigenvalues. However, the eigenvectors do not correspond to these sorted eigenvalues. How do I identify the eigenvector corresponding to the ith sorted eigenvalue? </p>
<p>One approach might be to sort by the norm of the eigenvectors (is there a procedure in R that can do... | g58396 | [
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0.005976738873869181,
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0.04152239114046097,
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0.012164270505309105,
0.02263188175857067,
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0.005201451480388641,
0.0025726293679326773,
0.015397245064377785,
0.030227769166231155,
0.0... |
<p>I am using Lasso to reduce my number of variables and I have identified which variables had been retained after running my analysis (e.g. yrseduc, age). However, I don't know which numbers I should report in a scientific paper. I have been trying to find examples, but can't quite find the answer. </p>
<p>I am wonde... | g58397 | [
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0.05708886310458183,
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0.013454342260956764,
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0.037976812571287155,
0.0846468135714531,
0.... |
<p>When developing a general purpose time-series software, is it a good idea to make it scale invariant? How would one do that?</p>
<p>I took a time series of around 40 points, and then multiplied by factors ranging from 10E-9 to 10E3 and then ran through the ARIMA functions of Forecast Pro and Minitab. In Forecast Pr... | g13454 | [
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0.014147247187793255,
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0.034610405564308167,
0.02782268449664116,
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0.002074488438665867,
0.032960209995508194,
0.00836463738232851,
0.09947403520345688,
-0.0... |
<p>I feel I'm pretty new to this, since some time passed since my last statistics assignment, so please bear with me.</p>
<p>I am analyzing results of a biological experiment. Basically, I'm looking at a some graph over a genome, where each position in the genome has a value, and I'm looking for local minima (peaks).... | g58398 | [
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0.06844271719455719,
0.... |
<p>I have two statistical tests which are inverse of each other, meaning that the null hypothesis are reversed. I want to use both the tests to take a decision. For this purpose, I am planning to do the following:</p>
<ul>
<li>If both the tests point to same result (by, say, rejecting the null hypothesis in test A and... | g58399 | [
0.01154595147818327,
0.014031658880412579,
-0.005612251348793507,
-0.03788071125745773,
0.003971732221543789,
-0.014447546564042568,
-0.03932010754942894,
0.02168773114681244,
-0.015235761180520058,
-0.00454698083922267,
0.05003633350133896,
0.03684666007757187,
0.03835051506757736,
-0.008... |
<p>I have the table below, and I want to find the degrees of freedom for these data. Will my $k$ value from the formula $n-k-1$ include the dummy variables and <code>DIST^2</code>. That is, does $k=7$ or $3$, $4$, $5$, or $6$? </p>
<pre><code>Dependent Variable: LFARE
Method: Least Squares
Date: 02/28/13 Time: 11:12
S... | g58400 | [
0.013853703625500202,
-0.006497664842754602,
0.0037852188106626272,
-0.02869301103055477,
-0.009456422179937363,
-0.04578972980380058,
0.008449751883745193,
-0.06318452209234238,
-0.011030224151909351,
-0.021409662440419197,
-0.06597844511270523,
0.06510110944509506,
-0.014900853857398033,
... |
<p>This is a question regarding the use of the 'weights' function in lmer.
Similar to the "weighted" approach discussed here for use in linear regressions:
<a href="http://www.stat.cmu.edu/~cshalizi/uADA/13/lectures/ch07.pdf" rel="nofollow">http://www.stat.cmu.edu/~cshalizi/uADA/13/lectures/ch07.pdf</a></p>
<p>I wante... | g58401 | [
0.0036052835639566183,
-0.027924705296754837,
-0.02696153335273266,
-0.05140744149684906,
-0.0044044977985322475,
0.026130853220820427,
0.06025946885347366,
0.014357244595885277,
-0.1217072457075119,
-0.00920954905450344,
0.011349990032613277,
0.003971574362367392,
0.009729631245136261,
0.... |
<p>Let $A$, $B$ and $C$ be events in the same probability space. Does
$$\begin{align}
\mathbb P(A\,|\,B\cup C) \ge \mathbb P(A\,|\,B)
\end{align}$$
hold?</p> | g58402 | [
0.04951512813568115,
-0.009327120147645473,
0.017762133851647377,
0.0007065786048769951,
0.060958415269851685,
0.02297363430261612,
0.010491875000298023,
-0.008885092101991177,
-0.04305349662899971,
-0.02609897218644619,
-0.03525485843420029,
0.031109562143683434,
-0.06324703246355057,
-0.... |
<p>Let $S$ be the set of all probability distributions on $\mathbb{R}$ and $S_n=\{p_\theta\}$ be an $n$ dimensional submanifold of parameterized family of probability distributions on $\mathbb{R}$ where $\theta=(\theta_1,\dots, \theta_n)\in \Theta$ are called parameters of the probability density $p_\theta(x)$ and $\Th... | g27416 | [
0.061850741505622864,
0.006693541072309017,
-0.033280421048402786,
-0.00841638445854187,
0.010973097756505013,
0.02794240415096283,
0.045942965894937515,
-0.022357968613505363,
-0.0667155459523201,
0.019430220127105713,
0.009048336185514927,
0.012248008511960506,
0.061630476266145706,
-0.0... |
<p>I'm looking for recomendations of books on credit scoring. I'm interested in all aspects of this problem, but mostly in:
1) Good features. How to build them? Which have been proved to be good?
2) Neural networks. Their application to credit scoring problem.
3) I've chosen neural networks, but I'm interested in othe... | g27417 | [
0.05341508984565735,
0.007562647573649883,
0.02523217350244522,
-0.020134279504418373,
0.035222191363573074,
-0.02087428607046604,
-0.027044516056776047,
0.005125106777995825,
-0.05551726371049881,
0.04553147777915001,
0.027150418609380722,
0.01645311899483204,
0.07998239248991013,
-0.0124... |
<p>Using PCA analysis, I was able to reduce the initial 23 variables into 10 principal components. But I do not understand what to do with this insight. I mean, how do I validate this information on, say, another set of data? Is there any way to identify which of the original set of 23 variables are more important, so ... | g3063 | [
0.015133204869925976,
-0.01656227931380272,
-0.009778995998203754,
-0.09362007677555084,
0.016017451882362366,
-0.03915053978562355,
0.09050099551677704,
-0.006322826258838177,
-0.0407702699303627,
-0.05515260994434357,
0.008536705747246742,
0.01819623075425625,
-0.008869287557899952,
0.02... |
<p>I understand that once we plot the values as a chart, we can identify a bimodal distribution by observing the twin-peaks, but how does one find it programmatically? (I am looking for an algorithm.)</p> | g58403 | [
0.03531771898269653,
0.03844645619392395,
-0.038132671266794205,
-0.08074749261140823,
-0.02958524227142334,
-0.10816816985607147,
0.026807058602571487,
-0.002600978361442685,
-0.023939715698361397,
-0.02450942061841488,
-0.0447348952293396,
0.014789124019443989,
0.12702925503253937,
0.009... |
<p>Based on the answer to a previous question, <a href="http://stats.stackexchange.com/questions/5543/for-which-distributions-are-the-parameterizations-in-bugs-and-r-different/5564#5564">For which distributions are the parameterizations in BUGS and R different?</a></p>
<p>I have been transforming R parameterizations t... | g37538 | [
0.006499194074422121,
-0.03876795619726181,
-0.016396187245845795,
-0.055722884833812714,
0.019895238801836967,
-0.060578688979148865,
-0.008131977170705795,
-0.009365005418658257,
-0.014570320956408978,
0.006117973476648331,
-0.0069933095946908,
-0.018353385850787163,
0.028039682656526566,
... |
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