question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I'm working on my dissertation which is a multiple case study examining the use of performance information. My dissertation chair states that I need to use confirmatory factor analysis; however, after months of learning SPSS and completing other analyses through the system, I am just learning the CFA cannot be compl... | g22360 | [
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<p>I'm trying to compare my model results with an experiment. I want to overlap the model curve with experiment curve from a paper. </p>
<p>What are my options for digitizing the graph from an image in the pdf paper to excel data? </p> | g49693 | [
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<p>Lets say we have hypothetical participant that is presented with 3 stimuli conditions: a flashing dot ($C_x$), a sound blip ($C_y$) and combination of both ($C_z$). We ask this participant to respond as quickly as possible to the onset of the stimuli and we measure the reaction time (RT). It's been observed that res... | g22362 | [
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<p>I am working in a genomics project and I ended up having a huge table with around 800 measurements (cases/rows), around 200 channels (columns/continuous variables) and 5 categories (one categorical column)</p>
<p>I would like to do two things: </p>
<ul>
<li>Try to find sub-groups in the different levels of the cat... | g64298 | [
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<p>I have been given the following data and am supposed to build a multiple regression model to be able to predict the price of a car:</p>
<ol>
<li><p>Price of Car - SPSS Measurement = Scale</p></li>
<li><p>Mileage of Car - SPSS Measurement = Scale</p></li>
<li><p>Age of Car - SPSS Measurement = Scale</p></li>
<li><p>... | g64299 | [
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<p>I have a time series which is discreet and bounded (between 0 and 100). It’s actually also increasing over time, from low to high. When I test for a unit root, I find it. </p>
<p>And yet I wonder if unit root tests on bounded variables even make sense? </p>
<p>And if unit-root testing doesn’t make sense in that ca... | g10561 | [
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<p>I know that sample standard deviation and population standard deviation are different, and are used in different cases (first when N>>n, second when N=n). But what when N>n, although not by much? For example, n=7 and N=30. I guess none of these two would be appropriate, but is there another formula for such cases? O... | g33484 | [
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<p>This should be fairly easy, but for some reason i'm having hard time getting it to work and I've spent a long time trying to figure it out myself. </p>
<p>In the last paragraph of page 4 of the original <a href="http://homes.cs.washington.edu/~pedrod/papers/uai11a.pdf" rel="nofollow">Sum-Product Networks paper</a> ... | g64300 | [
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<p>In a comment recently posted <a href="http://stats.stackexchange.com/questions/40769/are-all-values-within-a-95-confidence-interval-equally-likely">here</a> one commenter pointed to a blog by <a href="http://normaldeviate.wordpress.com/2012/07/28/statistical-principles/">Larry Wasserman</a> who points out (without a... | g64301 | [
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<p>I'm looking for some advice about a problem I've been assigned to solve. This is the problem. Suppose a car has to travel from P1 to P4, with intermediate points P2, P3. Say $X1$ is a r.v. that defines the travel time from P1 to P2 is normally distributed with $\mu$ = 25, $\sigma^2$ = 3, similarly $X2$ is a r.v. for... | g41902 | [
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<p>When analyzing a dataset based on percentages, I have on occasions worked with data as "full" value (i.e. "50") or "reduced" value (i.e. ".50").</p>
<p>However, it just occurred to me that this could have a serious impact on how standard deviation and variance.</p>
<p>If my standard deviation and variance are abov... | g64302 | [
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<p>Can somebody give the definition of cross section in "cross section of stock return"?</p>
<p>Thanks</p> | g64303 | [
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<p>In R, I am using the <code>bc</code> function to do a box-cox transformation. What factors do I need to consider when setting <code>p</code> (the power argument)?</p> | g22369 | [
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<p>After an interesting lecture on Bayesian statistics (research master), all 4 males went immediately to the (female) teacher to ask questions. The 8 females did not.</p>
<p>I am interested in how to test a two-tailed significance null hypothesis with this, in <code>R</code>.</p>
<p>H0: no difference between males a... | g45289 | [
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<p>I was just about to ask a question concerning a certain 3D data-set (each point in space has a value associated), but couldn't figure out how to visualize it for you. I can understand it myself by rotating the point set in a Matlab figure, but it would be difficult to grasp from just seeing a screenshot:</p>
<p><a ... | g64304 | [
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<p>Consider drawing stones from an urn with replacement.</p>
<p>Suppose the urn contains a large number of stones, and each stone has a color, and the set of possible colors is large.</p>
<p>Suppose $N$ stones are drawn one at a time from the urn, and replaced each time.
Suppose $S$ of them have the same color, $C$.<... | g64305 | [
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<p>I'd appreciate some pointers for the following question: Given 3 random variables $X_i$, $i = 1, 2, 3$ such that none of them have a pairwise correlation of $+1$ or $−1$. Can we find a combination of $X_1$ and $X_2$ that has a correlation of $+1$ with $X_3$?</p> | g19384 | [
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<p>With data from two centres I want to account for potential heterogeneity or confounders between two centers. So the analysis will initially be stratified by clinical center and a chi square test performed with one degree of freedom. Is this appropriate with just two centres? Or is there an alternative?</p> | g41906 | [
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<p>I am using the LASSO with multiple imputed datasets and I am not sure how should I combine the coefficients obtained on the different imputed datasets. I could simply average them (as I would do had I computed the coefficients using ordinary least squares), but then since the set of variables with non-zero coefficie... | g64306 | [
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<p>Is it possible to specify that one parameter must be larger than another parameter in an nls call in my R script?</p>
<p>Here's my nls call:</p>
<pre><code>fit <- nls(y ~ ifelse(g, m1 * (x - x0) + y0, m2 * (x - x0) + y0),
start = c(m1 = -1, m2 = 1, y0 = 0, x0 = split),
algorithm = "port"... | g42488 | [
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<p>I came across this nice illustration of the "Coefficient of determination" (<a href="http://en.wikipedia.org/wiki/File%3aCoefficient_of_Determination.svg" rel="nofollow">source</a>):</p>
<p><img src="http://i.stack.imgur.com/ukljW.png" alt="enter image description here"></p>
<p>Which leads me to ask two questions:... | g22377 | [
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<p>I've heard a bit about using neural networks to forecast time series. </p>
<p>How can I compare, which method for forecasting my time-series (daily retail data) is better: auto.arima(x), ets(x) or nnetar(x).</p>
<p>I can compare auto.arima with ets by AIC or BIC. But how I can compare them with neural networks?</p... | g16038 | [
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<p>I am doing some web page clustering work and I'm going to use cosine similarity as my distance measure. Even though cosine similarity is a clustering technique, I have to give training data in order to build the query vector. Clustering algorithm doesn't need training data in the sense of with labeled classes, but h... | g22379 | [
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<p>I have a regression problem for multi-dimensional response, say like 1000 dimension response, without using PCA to the response, my mean square error for regression is like ~80.
Then, I apply PCA to these 1000 dimensions, and use 3 of them which represent 90% variation of the response, and perform the regression a... | g64307 | [
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<p>I have data collected from a survey administered on a subset of the population. I also have the population proportions of variables such as gender, race and housing type. I would like to combine the weights from each separate cross tab (of gender, race and housing type) such that the weighted proportions of my surve... | g22381 | [
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<p>I have been attempting to do an ARIMA modelling in SAS. The series is not stationary but when I estimate the ACF and PACF p-values I don't get appropriate answers to find out if my model is adequate or not.Can anyone help me as may be I have been choosing the wrong p and q values. year age-group members.For stationa... | g64308 | [
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<p>The assignment is to run a simulation on excel to figure out the probabilities on obtaining a certain goal:</p>
<p>John and Jane Doe are planning to save money to pay a house for their 6-month-old son, Patrick. They have decided that they would like to have $500,000 saved by the time Patrick is ready for college 1... | g64309 | [
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<p>I recently submitted a paper, in which I used quantile regression, to a psychology journal. Although I thought I had already put enough thought in a clear exposition of quantile regression, the reviewers asked for better explanations of the quantile regression technique being only familiar with standard OLS regressi... | g64310 | [
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<p>Recently, I have got some 'strange' comments from the reviewer of my paper. In my paper, I discussed a novel feature extraction method, and then I compared three classification methods for my binary classification task. I applied kNN, Neural Networks, and Support Vector Machine classifiers. Simply speaking I have go... | g64311 | [
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<p>I am actually reviewing a manuscript where the authors compare 5-6 logit regression models with AIC. However, some of the models have interaction terms without including the individual covariate terms. Does it ever make sense to do this?</p>
<p>For example (not specific to logit models):</p>
<pre><code>M1: Y = X1 ... | g49556 | [
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<p>I understand that there are degrees of trust one can have in the output of ANOVA. However, naturally I want to maximize the amount I can trust my results.</p>
<p><strong>Question:</strong> If I have data that violate the assumption of normality (of residuals), how robust is a factorial ANOVA when cell sizes are une... | g64312 | [
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<p>I want to whiten a vector $X$ by transforming the variance-covariance matrix so the variance-covariance matrix of the transformed series will be the identity matrix $I$.</p>
<p>$X$ is a time-series column vector with variance-covariance matrix $M$ and mean $0$.</p>
<p>If $X$ was a set of correlated data, then the ... | g22636 | [
-0.024658216163516045,
-0.05112728476524353,
-0.000002265694320158218,
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0.07245197892189026,
0.012017005123198032,
0.09197212755680084,
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0.... |
<p>According to M. Katz in his book <a href="http://books.google.be/books?id=-X4G4dHsARQC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false" rel="nofollow">Multivariable analysis</a> (Section 1.2, page 6), "<em>A confounder is associated with the risk factor and causally related ... | g64313 | [
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0... |
<p>Please help me prove the following:</p>
<p>n-Box is defined as $B=[a_1,b_1]\times[a_2,b_2]\times[a_3,b_3]\times...\times[a_n,b_n]$ Cartesian product of $n$ closed intervals, where $a_i$ and $b_i$ are all from $R$ and $a_i\le b_i$ for $i=1,...,n$. Vertices of the box are $c=(c_1,...,c_n)$ where $c_k=a_k$ or $c_k=b_k... | g64314 | [
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0.001431656302884221,
-0.03356677293777466,
0.018741371110081673,
0.004459934309124947,
0.026055... |
<p>Some distributions have conjugate priors and some do not. Is this distinction just an accident? That is, you do the math, and it works out one way or the other, but it does not really tell you anything important about the distribution except for the fact itself?</p>
<p>Or does the presence or absence of a conjugat... | g22393 | [
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... |
<p>I have a bunch of independent p-values and now I want to combine them using the Fisher's method. Each of the individual p-values is coming from a one-sided test. I am just a little bit confused about the "side" of the Fisher's method test, i.e. when I calculate the Fisher's method p-value in R, I use:</p>
<pre><cod... | g64315 | [
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... |
<p>For a classification task, I have developed two methods and FScore(harmonic mean of precision and recall) of both the classes serves as the performance criteria. How can I check whether the difference between the performance of the two systems is statistically significant or not.</p>
<p>For eg. I was reading <a hre... | g64316 | [
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0.07816088199615479,
... |
<p>I have built a logistic regression model with two or more highly correlated factors. I did this by doing a bagging procedure. </p>
<p>In my understanding having highly correlated factors in a <em>prediction</em> model is not an issue (especially after bagging). But in a model where you are trying to <em>explain</em... | g64317 | [
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<p>I have data from a two-factor within-subjects experiment design where the conditions are not orthogonal. Factor one (Location) has three levels; factor two (Stimulus) has three levels, one of which is "no stimulus".</p>
<p>When multiplying these factors I get nine conditions, three of which are equivalent. All thre... | g64318 | [
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<p>this is my first post to stackexchange, I have read many solutions, especially to programming questions in R and have appreciated their helpfulness.</p>
<p>Currently I find myself stuck with a time series analysis problem. I am an aspiring dendrochronologist, measuring the annual tree-rings from a particularly diff... | g64319 | [
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<p>Just ordered this textbook, and Wow, the complete omission of this subject from an otherwise excellent reference on logistic regression is a bit surprising. The 2nd edition was published in 2000 - there's been a lot of research into penalized regression techniques since then: for example, the lasso and elastic net.<... | g64320 | [
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<p>Suppose I have one sample of frequencies of 4 possible events:</p>
<pre><code>Event1 - 5
E2 - 1
E3 - 0
E4 - 12
</code></pre>
<p>and I have the expected probabilities of my events to occur:</p>
<pre><code>p1 - 0.2
p2 - 0.1
p3 - 0.1
p4 - 0.6
</code></pre>
<p>With the sum of the observed frequencies of my four even... | g22397 | [
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<p>What proportion of shoppers at a large appliance store actually make a large ticket purchase? To estimate this proportion within 10% and be 95% confident of the results, how large a sample should you take? Assume that you have no idea what proportion of all shoppers actually make a large ticket purchase</p>
<p>A) 6... | g22402 | [
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0.0061... |
<p>I am a beginner on calculating correlations and I would like to ask possibly a very simple question.</p>
<p>If I have two variables that I want to perform correlation on, and those variable are of unequal size, does this affect my correlation result?</p>
<p>Thanks</p> | g49694 | [
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<p>I have a question that I have difficulties in answering:
I have two groups of patients tested twice at the same continuous variable.
Group A=104 & GroupB=21.
So two groups, one continuous variable, measured twice. Due to the uneveness of the samples I think that repeated measures ANOVA is not suitable.</p>
<p>I... | g64321 | [
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<p>I have a data set like this:</p>
<pre><code>df
Income Education_in_years
40,000 10
50,000 9
70,000 12
30,000 5
100,000 20
</code></pre>
<p>I would like to create a bivariate distribution from this and try to guess probability of income given eduction in years.</p>
<p>I can build the line... | g64322 | [
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0.008834519423544407,
0.05885068327188492,
... |
<p>I have a stunningly simple data set and, unfortunately, an equally simple mind when it comes to stats. This is how my data are set up:</p>
<p>I asked people to sit small exams on different days of the week (Friday, Saturday, Sunday and Monday) and their performances in these tests have been calculated as a percenta... | g64323 | [
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0.026874180883169174,... |
<p>Could someone give me a step-by-step example of time series prediction using ARIMAX or ARMAX model? The example doesn't need to be long or complicated. It could be for example forecasting temperature with past data of only ten values (e.g [15, 16, 17, 15, ..., 12])</p>
<p>You don't have to calculate autocorrelatio... | g64324 | [
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-... |
<p>I would have expected the correlation coefficient to be the same as a regression slope (beta), however having just compared the two, they are different. How do they differ - what different information do they give?</p> | g41936 | [
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<p>I haven't found any literature on the application of Random Forests to MNIST, CIFAR, STL-10, etc. so I thought I'd try them with the <em>permutation-invariant</em> MNIST myself.</p>
<p>In <strong>R</strong>, I tried:</p>
<pre><code>randomForest(train$x, factor(train$y), test$x, factor(test$y), ntree=500)
</code></... | g64325 | [
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0.00969... |
<p>R seems to be able to output nice summary plots from the <code>bugs</code> and <code>jags</code> objects generated by the functions <a href="http://cran.r-project.org/web/packages/rjags/index.html" rel="nofollow">R2WinBUGS::bugs</a> and <a href="http://cran.r-project.org/web/packages/R2jags/index.html" rel="nofollow... | g64326 | [
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0.022917959839105606,
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0... |
<p>Could you please point me to tutorial/notes that can help me understand "rlm" better?
Here is an example: <code>summary(rlm(stack.loss ~ ., stackloss, weights=myweights))</code></p>
<p>My questions are:</p>
<p>a. How does the iterative procedure work?<br>
b. What's the relation between the weights I supplied a... | g22408 | [
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0.05292927473783493,
0.032912105321884155,
0.05... |
<p>I have a discrete sample, numebr of passengers. when I try to find the best fit to this data set, none of the discrete distribution give the good fit according to goodness of fitness test. but the probability density function seems to be ok for example for Neg Binomial Should I rely on the plot or goodness of fitnes... | g22409 | [
0.006893295794725418,
0.016597209498286247,
0.04334961622953415,
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0.03970876336097717,
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<p>I am using <code>KFAS</code> package for <code>R</code>.</p>
<p>You can run</p>
<pre><code>install.packages("KFAS")
library(KFAS)
?regSSM
</code></pre>
<p>to see how this package allows to build a state space representation of linear regression models and many others.</p>
<p>Now let we have the following state s... | g41940 | [
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0.022209366783499718,
0.030383998528122902,
0.053516730666160583,
... |
<p>Already classified data set for the t-shirt factory problem</p>
<p>I want to calculate the accuracy of my algorithm. I have the training data without any size information and I couldn't find the classified version of the data set. Should I create artificial data or find another data set? </p> | g22411 | [
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0.0004266572941560298,
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0.04636767879128456,
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0.... |
<p>(I apologize for the length of this post. I don't know how to frame the question more succinctly.)</p>
<p>I have some experimental data, in the form of a collection of curves with fairly little noise, which I'm trying to interpret. Specifically, I'm working on the question: what does these data say about the "int... | g64327 | [
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0.013601708225905895,
0.10137122869491577,
-0.00256... |
<p>I have employee attrition model. I have reported odd ratios.My question is " can i use risk ratio?". Example : The odds of male to get attrited is 2.5 times than males. It is non-intutive for layman. It is better to say the chances of male to get attrited is more than males. I have googled and it yielded the relativ... | g22412 | [
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0.01585083082318306,
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<p>I'm looking at a multinomial logistic regression analysis of deer behavioural responses to camera traps. The levels of the response variable are <code>no reaction</code>, <code>reaction</code> and <code>strong reaction</code>. I've selected a number of models based on their AIC values. However, I've found that the <... | g64328 | [
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0.029628906399011612,
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0.03942194581031799,
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0.02793256938457489,
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<p>I am using SKLearn and Statsmodel in python to build a RF and Logistic Regression, respectively.</p>
<p>I have a feature that the RF indicates is important (feature importance of 0.202, closely behind #1 and #2 most important features). </p>
<p>However, in running the logistic regression, the coefficient associate... | g22414 | [
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0.027461927384138107,
0.02975371666252613,
0.0... |
<p>I'm trying to calculate the sample size for a repeated measures within subject experiment. </p>
<p>I'm going to test the subjects under 4 conditions and for each condition 6 measurements are taken at different time points. I want to use an alpha level of 0.05, but I'm unsure how to calculate the sample size needed.... | g64329 | [
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<p>This is a somewhat basic question, I guess. I have a sequence of random variables $X_1,\ldots,X_n$ that I believe to be i.i.d. uniform on $[0,1]$. Being i.i.d. uniform corresponds to my model predicting the correct distribution for $P(Y_k\mid Y_{1:k-1})$ for some time series $Y$. I can test that by, say, applying th... | g64330 | [
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0.046106427907943726,
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0.005517139099538326,
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0.01422814093530178,
0.021328913047909737,
0.... |
<p>I am trying to understand the steps behind the linear regression process. I already have a linear model like:</p>
<p><code>lmodel1 <- lm(y~x1+x2+x3, data=dataset)</code></p>
<p>for which R calculates several different things (<code>Coefficients, Intercept, Residuals, F-statistic</code> and <code>p-value</code>)... | g64331 | [
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<p>I am reading Stephen Taylor's Asset Dynamics book and came across something I didn't fully understand.</p>
<p>For an ARCH process, the return series is modeled as
$r_t = \mu_t + h_t^{1/2}z_t$ where is $z_t$ is $D(0,1)$ and may be normal/non-normal and $h_t$ is conditional variance (some function of subset of $\thet... | g619 | [
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<p>I'm working on a naive Bayes classifier that calculates probabilities using a normal Gaussian distribution. This works very well when I am classifying something into two mutually exclusive buckets (e.g. spam vs. not-spam), but when I am working with a factor that is not easily classified that way (when the classific... | g64332 | [
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<p>In network motif algorithms, it seems quite common to return both a <a href="http://en.wikipedia.org/wiki/P-value" rel="nofollow">p-value</a> and a <a href="http://en.wikipedia.org/wiki/Standard_score" rel="nofollow">Z-score</a> for a statistic: "Input network contains X copies of subgraph G". A subgraph is deemed ... | g22416 | [
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<p>We're developing real-time alerts for fine-grained (every 5 minutes) time series bookings data, and I'm looking for the best approach to doing this. Idea is that if over the past 10–15 minutes (say) there's a big drop in bookings volume relative to some expectation, then I want to fire an alert. We've been using his... | g64333 | [
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<p>Is it to show that MSE = 0 as $n\rightarrow\infty$? I also read in my notes something about plim. How do I find plim and use it to show that the estimator is consistent?</p> | g46192 | [
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<p>I have come up with an algorithm to cluster geospatial data points. I have quite a few volunteers (100) collecting data for me, using my app on their smart phones to check in at places. However, I'm afraid the data will be positively biased since the volunteers all receive instructions on how to use the app. The dat... | g22418 | [
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<p>In the logistic mixed model ${\rm logit}(P(Y_i=1))= α + βX_i + u_i + ε_i , i=1,...,m$, when we know $u_i\sim \mathcal N(0,σu^2)$, and $ε_i\sim\mathcal N(0,σi^2)$,
and if we know $σi^2$ in each area $i$:</p>
<ol>
<li>How do we use $σi^2$ in estimation of parameters (likelihood formula)?</li>
<li>How can we estimate ... | g22419 | [
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<p>I have a set of objects each of which has a list of traits. Data on the traits is binary: an object has a trait or does not. The number of objects that I have is moderately greater than the number of traits, and much greater if you exclude traits that are held by only a few objects. Virtually all objects have at l... | g64334 | [
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<p>I take an input <code>x</code>, based on which I do an experiment that gives me several data points. I compute the standard deviation of these data points. Then, I change <code>x</code>, and repeat the process. Finally, I ask the dependence of the standard deviation on <code>x</code>. I am observing a quadratic depe... | g64335 | [
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<p>Correlation and linear regression are sometimes distinguished in statistics books by saying that the former is symmetric and the latter is asymmetric in the following sense: in the case of correlation, no distinction is made between dependent and independent variables, whereas it makes a difference which variables a... | g64336 | [
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<p>I have a number histogram from a data source. I want to compare their distribution. For example series 2 is more to the right than series 1.</p>
<p><img src="http://i.stack.imgur.com/7yF5L.png" alt="enter image description here"></p>
<p>Is there any good way to contrast besides plotting the histogram side by side.... | g64337 | [
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<p>I have a PHP/MySQL application that stores symptoms and the appropriate drug. What machine learning algorithm should I use to predict the drug for any symptoms. Also, what would be the format of the training set?</p>
<p>Features: 2 (not numeric, string/character)
Samples: More than 100
No Missing Values</p>
<p>The... | g64338 | [
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<p>I am taking a business statistics course and I can't seem to figure out how to find the missing figures in the following problem; here's the question:</p>
<p>Using the data below, determine the trial central line and trial control limits for the Xbar chart. Subgroup size is 5. For the R chart, the trial central lin... | g64339 | [
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<p>I am interested in linking records across 2 datasets by first name, last name, and birth year. Might this be doable with the EM algorithm, and if so, how?</p>
<p>Consider the following record in the 1st as an example: Carl McCarthy,1967. I will search through all records in the 2nd dataset, and assign a jaro-wink... | g41959 | [
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<p>First, let me give some context for my question.</p>
<p>I'm working on a project in which our research team implemented a workshop intervention at a number of different departments at my university. Each department that received the intervention also had a matched control department. We obtained several different... | g64340 | [
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<p>I am trying to do some feature selection, having around 3500 variables for about 200 samples. To each sample is associated two numerical values (the expected outcome). I can't manage to make the caret work with this, or even find any information on this. Does anybody know how to do this?</p>
<p>As an example, my da... | g64341 | [
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<p>I have a data that I would like to use arima model to perform forecast. when I use auto.arima, my results does not seem right. When I change my arima order to c(1,0,1), numbers starts changing and seem more realistics. </p>
<p>How do I know which arima order to pick? Which orders set I should try to compare results... | g64342 | [
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0.03441312536597252,
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0.06126305088400841,
0.05124591290950775,
-0.03365... |
<p>I am modelling a process distributed as a 2 parameter lognormal distribution; determining the parameters by maximum likelihood.</p>
<p>I have simulated the bias in the estimators (logmean and logsd) as well as the skewness. The logmean seems unbiased and the logsd and skewness seem asymptotically biased; underesti... | g22431 | [
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<p>Suppose that I want to regress the income level of a worker with qualitative variables such as eye color and the state that they live. Obviously, if I try to create a model with these variables, I will have multiple categorical variables, such as a variable representing a person living in California or having green ... | g22432 | [
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<p>Suppose we have $10$ pairs of matched data (i.e. pre-exposure and post exposure). Call the exposure $E_1$. So the data are in the form $(\overline{x}_1, \overline{y}_1), \dots, (\overline{x}_n,\overline{y}_n)$. For example, $(\overline{x}_1, \overline{y}_1)$ is the average of measuring $E_1$ of subject $1$ 10 times ... | g64343 | [
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<p>What is wrong with the following sentence: </p>
<blockquote>
<p>The Central Limit Theorem implies that, as the sample size grows, the error distribution approaches normality.</p>
</blockquote>
<p>Am I correct by saying that it should in stead state the MEAN of the sample error approaches zero as sample size gro... | g49654 | [
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<p>I am running factor analysis on stata to reduce a few variables to a single explanatory variable which means "experience" of a manager (should be non-negative value), however, after using "predict" command I check the range of the new variable and found that there are many negative values, how do I avoid this?</p>
... | g64344 | [
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... |
<p><a href="http://stats.stackexchange.com/questions/9131/obtaining-a-formula-for-prediction-limits-in-a-linear-model">This thread</a> offers some good information on the calculation of linear regression prediction intervals and includes a <a href="http://www.weibull.com/DOEWeb/confidence_intervals_in_multiple_linear_r... | g64345 | [
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<p>I have just read a paper in which the authors carried out a multiple regression with two predictors. The overall r-squared value was 0.65. They provided a table which split the r-squared between the two predictors. The table looked like this:</p>
<pre><code> rsquared beta df pvalue
whole model 0.6... | g64346 | [
-0.024605898186564445,
-0.06360733509063721,
0.0000946649961406365,
0.00400145398452878,
0.007628253195434809,
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0.018596801906824112,
0.04613785073161125,
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-0.002774446504190564,
0.005761674139648676,
0.005858047399669886,
0.041385065764188766,
-0.... |
<p>I need to plot lognormal distribution with mean 1 and variance 0.6 in <code>R</code>.
I tried to do this using <code>rlnorm</code> function in <code>R</code> as</p>
<pre><code>x= rlnorm(500, log(1), log(0.6))
plot(density(x))
</code></pre>
<p><code>log(0.6)</code> is negative that might be the reason my code is ... | g22436 | [
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0.03510512411594391,
0.014063010923564434,
... |
<p>Is there any adjustment required when computing the correlation coefficient between:</p>
<ul>
<li><p>continuous and discrete variable </p></li>
<li><p>two discrete variables ? </p></li>
</ul>
<p>Thanks !</p> | g49600 | [
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<p>For 5 raters, I have calculated intra-rater Cohen's Kappa statistics for the test-retest nominal ratings, intra-rater Kendall's tau-b statistics for the test-retest ordinal ratings, and intra-rater ICCs for the test-retest scale ratings. Is it valid to calculate overall mean intra-rater reliability coefficients (Ka... | g22437 | [
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<p>The $r$-th moment of a random variable $X$ is <strong>finite</strong> if
$$
\mathbb E(|X^r|)< \infty
$$</p>
<p>I am trying to show that for any positive integer $s<r$, then the
$s$-th moment $\mathbb E[|X^s|]$ is also finite.</p> | g49775 | [
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0.... |
<p>Is it true that (and if so, how does one prove) the following.
$$E\left|\hat{Var}_{n}(X)-Var(X)\right|^{2}=O(n^{-1})$$
where:</p>
<p>• $X$ is a random variable with mean $\mu$ and variance $\sigma^{2}$</p>
<p>• $\hat{Var}_{n}(X)$ is the sample variance of $X$ from $n$
i.i.d. random variables $X_{1},\cdots,X_{... | g64347 | [
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... |
<p>It seems that through various related questions here, there is consensus that the "95%" part of what we call a "95% confidence interval" refers to the fact that if we were to exactly replicate our sampling and CI-computation procedures many times, 95% of thusly computed CIs would contain the population mean. It als... | g22439 | [
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0.014118785038590431,
-0.010202738456428051,
0.003334104549139738,
0.02825196087360382,
0.025454573333263397,
-0.035544492304325104,
-0.03920903429389,
-0.00457025459036231,
-0.01774270460009575,
0.03176845237612724,
-0.0407... |
<p>I have the data with me however I don't have any idea as to how to analyze the variables. Can anybody help me? The variables/questions are as listed:</p>
<pre><code>1. Gender
2. Age
3. Education Level
4. Occupation
5. Household monthly income (in PHP $)
6. Daily usage of the Internet
7. Have you ever used th... | g22440 | [
-0.04237370565533638,
0.008813966996967793,
-0.0038622368592768908,
0.01706061325967312,
0.008241280913352966,
0.012549923732876778,
0.08946298807859421,
-0.03485197201371193,
0.01392687950283289,
0.027008982375264168,
-0.009241176769137383,
-0.011066572740674019,
0.01999640464782715,
-0.0... |
<p>I have difficulty to derive the Hessian of the objective function, $l(\theta)$, in logistic regression where $l(\theta)$ is:
$$
l(\theta)=\sum_{i=1}^{m} \left[y_{i} \log(h_\theta(x_{i})) + (1- y_{i}) \log (1 - h_\theta(x_{i}))\right]
$$</p>
<p>$h_\theta(x)$ is a logistic function. The Hessian is $X^T D X$. I tried ... | g64348 | [
0.03728100657463074,
-0.014728307723999023,
-0.019941402599215508,
-0.05034966394305229,
0.015620258636772633,
-0.08840961009263992,
0.07123421132564545,
-0.038197703659534454,
-0.05825711414217949,
-0.012526223435997963,
0.0120855076238513,
0.06581481546163559,
0.051238127052783966,
0.023... |
<p>I am relatively new to the worlds of bioinformatics and genetics research. I have been tasked with presenting to my lab the potential value of a <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa1400382" rel="nofollow">paper</a> that uses <a href="http://en.wikipedia.org/wiki/Complex_segregation_analysis" rel="nof... | g64349 | [
-0.005740736611187458,
-0.026960929855704308,
-0.009855061769485474,
-0.020547306165099144,
0.013934974558651447,
0.014894678257405758,
0.08521457016468048,
0.04615628346800804,
-0.049422044306993484,
-0.012595572508871555,
-0.021887583658099174,
0.014848408289253712,
0.06740604341030121,
... |
<p>Does someone know what "independent p-values" or "p-values independently distributed" means?
And the "dependence structure among test statistics"?</p>
<p>Thanks in advance</p> | g64350 | [
0.0052153873257339,
0.04824381321668625,
-0.04136071354150772,
0.01639643684029579,
-0.014481249265372753,
0.02688010036945343,
0.013782195746898651,
0.017179308459162712,
-0.003942847717553377,
-0.03985090181231499,
-0.04729364812374115,
0.0019864579662680626,
-0.02409788966178894,
0.0093... |
<p>I am trying to run a power calculation for a randomized control trial. For this I need a mean and standard deviation for our 'baseline'. There are papers out there which would have a mean and standard deviation, but what we would want would be to use their final outcomes as our baseline. In other words, these papers... | g22447 | [
-0.0029950777534395456,
-0.05029413476586342,
-0.022090107202529907,
-0.05570586025714874,
-0.030119551345705986,
-0.026149578392505646,
-0.06059136241674423,
-0.002015909878537059,
-0.02827366068959236,
-0.008989487774670124,
0.015284119173884392,
0.04249320551753044,
0.0072472416795790195,... |
<p>There does not seem to be a standard way to deal with missing data in the context of the exponential smoothing family of models. In particular, the R implementation called <em>ets</em> in the <em>forecast</em> package seems to just take the longest subsequence without missing data, and the book "Forecasting with Exp... | g64351 | [
0.019763443619012833,
-0.08497514575719833,
-0.0043848175555467606,
-0.018776074051856995,
-0.007928135804831982,
0.015873325988650322,
0.045074403285980225,
-0.012416607700288296,
-0.02151837758719921,
0.036519501358270645,
0.024499958381056786,
-0.03177574276924133,
0.08777819573879242,
... |
<p>I'm looking into the Itakura Parallelogram global constraint for Dynamic Time Warping. </p>
<p>I am confused about the maximum width of the parallelogram, is it solely based on the length of the two time series being compared, or can it be varied to achieve a bigger or smaller warping window?</p> | g64352 | [
0.04159370809793472,
0.07105506211519241,
-0.01034441776573658,
-0.0318186990916729,
-0.030292998999357224,
-0.039896026253700256,
0.06491386145353317,
-0.008305227383971214,
-0.056644078344106674,
0.0033363199327141047,
0.04724185913801193,
0.01771964132785797,
-0.012903818860650063,
0.01... |
<p>I want to estimate the parameters (mean , variance ) $e(t)$ for the random walk model<br>
$X (t) = X (t-1) + e(t)$. </p>
<p>(where $e(t)$ is the white noise with a Normal distribution).</p>
<p>By using the fact that the $E(X(t)) = E (X(t-1))$ mean can be easily proven to be zero. Can someone help me to come up wi... | g22449 | [
-0.0009174429578706622,
0.027564525604248047,
-0.013879643753170967,
-0.012626164592802525,
0.041250381618738174,
-0.004347916692495346,
0.07009642571210861,
0.021330492570996284,
-0.024974746629595757,
0.022815998643636703,
-0.05594591051340103,
0.02430945821106434,
-0.005891364999115467,
... |
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