question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>We analyze blood vessel samples of patients in an organ bath which gives us force values. Each subject (patient) donates two types of blood vessels (pulmonary vein and pulmonary artery). The organ bath measurements include dose-response curves with a pharmaceutical, i.e. different concentrations are applied. From wh... | g65902 | [
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<p>I have an income distribution dataset which I am attempting to manipulate in Stata (or SAS).</p>
<p>I need to come up with a table listing the number of households earning between one income level and another. The income levels are regularly spaced, say at $10,000 intervals for example.</p>
<p>In other words, for ... | g65903 | [
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<p>I am evaluating and combining a few binary classification models. I am using the ROC and PR curves to evaluate their performance. The problem I am having is that as I try to improve the method, I am improving the AUC-ROC but the PR curve suffers. For example:
<img src="http://i.stack.imgur.com/yH47K.png" alt="ROC cu... | g24736 | [
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<p>I'm trying to deeply understand the <a href="http://cs.brown.edu/~th/papers/Hofmann-SIGIR99.pdf" rel="nofollow">Probabilistic Latent Semantic Indexing (PLSI)</a> algorithm.</p>
<p>The generative model underlying the algorithm is the folowing:</p>
<ol>
<li>Select a document $d \in D$ with a probability $P(d)$</li>
... | g65904 | [
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<p>In a simple classification, we have two classes: class-0 and class-1.
In some data I only have values for class-1, so none for class-0. Now I am thinking about making a model to model the data for class-1. So, when new data come, this model is applied to the new data and finds a probability saying how probable that ... | g65905 | [
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<p>I was referring to <a href="http://www.inference.phy.cam.ac.uk/hmw26/papers/crf_intro.pdf" rel="nofollow">this paper</a> related to CRF.</p>
<p>However, I didn't get the part related to dynamic programming. Further I have question related to feature function selection. In this paper they have given this feature fun... | g65906 | [
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<p>When doing the feature construction for text mining, does Lucene has a better performance in terms of classification/clustering result than the traditional bag-of-word approach?</p> | g65907 | [
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<p>I got the model for the logistic regression for multiclass which is given by </p>
<p>$$
P(Y=j|X^{(i)}) = \frac{\exp(\theta_j^TX^{(i)})}{1+ \sum_{m=1}^{k}\exp(\theta_m^T X^{(i)})}
$$</p>
<p>where k is the number of classes
theta is the parameter to be estimated
j is the jth class
Xi is the training data</p>
<p>Wel... | g65908 | [
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<p>Let $Z = X + Y$ where $X \sim N\left(\mu, \sigma^2 \right)$ and $Y \sim \Gamma\left(k, \theta \right)$ using <a href="http://en.wikipedia.org/wiki/Gamma_distribution#Characterization_using_shape_k_and_scale_.CE.B8">this</a> parametrization of the Gamma distribution. Also assume $X$ and $Y$ are independent. Then what... | g24748 | [
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<p>I am wondering how to perform PCA on data with unequal lengths. In the simplest case you could split up the data matrix so that one block would be $T_{1}Xn$ and the rest is $T_{2}Xn$. The second block has effectively missing data in the first $T_{1}-T_{2}Xn$ block.</p>
<p>Many of the applications of PCA on missing ... | g65909 | [
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<p>If $X$ is a random variable and also let $X\ge 0$. </p>
<p>I want to show $E(X)\le \sum_{n=0}^{\infty}P(X>n)$.</p> | g65910 | [
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<p>I have been working on a research theme entitled,"Service Quality and Shareholders Value in select Commercial Banks of India". I have collected the data from the sampled 1200 customers from all the banks, under study and I am using time series data of 7 years for my dependent variable i.e. shareholders value. The pr... | g65911 | [
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<p>I want to try fitting an ARMA/GARCH model but want a methodological approach rather than fitting different models and picking the best one. However, I'm not sure how to choose my AR and MA terms for my mean equation, same thing for my variance equation. Hence I have the following queries:</p>
<ol>
<li><p>Are there ... | g24750 | [
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<p>I am trying to implement the ARIMA model using statsmodels. I get really unusual results for my predictions, and was hoping for advice on fixing this.</p>
<pre><code>arima = tsa.ARIMA(train[endogenous], exog=train.drop(endogenous,axis=1), order=(2,2,0),freq='B')
results = arima.fit()
prediction = results.predict(st... | g65912 | [
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<p>Suppose $y_1$, $y_2$, $\cdots$, $y_n$ are sampled from a normal distribution with expected value $\mu$ and variance $\sigma$. Then how to obtain the expectations and variances of the following expressions of $\mathcal{F}$ and $\mathcal{G}$?
<img src="http://i.stack.imgur.com/JAelX.jpg" alt="enter image description h... | g65913 | [
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<p>I have a sample which is a vector with 220 numbers. <a href="http://www.part.lt/img/26e05ba85b95211f7fe3bc171dc6286e217.jpg" rel="nofollow">Here is a link to a histogram of my data.</a>.
And I wish to check if my data fits a Pareto distribution, but I don't want to see QQ plots with that distribution, but I need an... | g65914 | [
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<p>I am reading the book "<a href="http://rads.stackoverflow.com/amzn/click/0262194759" rel="nofollow">Learning with Kernels: Support Vector Machines, Regularization, Optimization, and Beyond (Adaptive Computation and Machine Learning)</a>". I finished the first chapter and didn't notice any approach taken by the autho... | g65915 | [
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<p>I am doing a study into attentional bias (as measured by the Stroop test) and insomnia (as measured by the Insomnia Severity Index - ISI).</p>
<p>I will be comparing the mean reaction times of the Stroop test to the mean ISI scores at 4 different time points (Baseline, 3 month follow up, 6 month follow up and 9 mon... | g65916 | [
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<p>I have two questions in Energy function of expectation propagation.
1. Seeing the video of [1] (slide 24 of the second part), Minka says that, the evidence is the following:
$$
Z = \left( \int q(\mathbf{x}) d\mathbf{x} \right) ^{1-n} \prod_{i=1}^{n} \int \frac{f_i (\mathbf{x})}{\tilde{f}_i(\mathbf{x}) } q(\mathbf... | g65917 | [
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<p>I'm new to MDS, but I found some good starter code here (<a href="http://mhermans.net/static/postdata/r-examples/neighbours-mds/neighbours-mds-example.html" rel="nofollow">http://mhermans.net/static/postdata/r-examples/neighbours-mds/neighbours-mds-example.html</a>) and which I borrowed for below. The code works fin... | g65918 | [
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<p>I have two continuous predictor variables to predict a dichotomous variable. In addition i have constructed two (interaction) models, based on domain knowledge which use both variables to predict the third.</p>
<p>So now i want to compare these predictors, using R. I get these result on the wilcox test:
W = 36655, ... | g38128 | [
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<p>If I have a data set with many values repeated (example below) how would it be divided into quartiles? I assumed at first that the quartiles would be uneven, but every single definition I've read makes it sound like they must be equal.</p>
<p>Example:</p>
<pre><code>{ 1, 1, 4, 4, 4, 4, 8, 8}
</code></pre> | g65919 | [
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<p>This might be a strange case, but I'm sure that somebody in here can help me and that I'm perhaps not the only one who wants to pool RSDs correctly. </p>
<p>Consider this:
The mean weight of a powder bed is <code>W</code> mg with a relative standard deviation (RSD) of <code>Wrsd</code> %.</p>
<p>For each weighted ... | g44868 | [
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<p>I have a timeseries dataset holding stock data for a large set of companies. Assume the following subset, where <code>obsDay</code> is the observation day (148 days in reality) and <code>weekDay</code> the day of the week (1 = monday, 2 = tuesday, ...):</p>
<pre><code>company sector obsDay weekDay stockPrice
---... | g65920 | [
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<p>Let's say I have the following data and am running a regression model:</p>
<pre><code>df=data.frame(income=c(5,3,47,8,6,5),
won=c(0,0,1,1,1,0),
age=c(18,18,23,50,19,39),
home=c(0,0,1,0,0,1))
</code></pre>
<p>On one hand, I run a linear model to predict on income:</p>
<pre... | g65921 | [
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<p>I'm struggling to extract F-values and/or p-values from an ANOVA with all random effects or an ANOVA with both mixed and random effects.</p>
<p>I would expect to be able to get F- and p-values regarding the variance of the random effects based on the expected mean squares. Maybe the <code>aov()</code> function jus... | g65922 | [
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<p>I'm trying to calculate Asymptotic Standard Error (ASE) for Somer's D measure of association for some population data.</p>
<p>The formula for variation (sd^2) I've found (in the article specified below) is:</p>
<p><img src="http://i.stack.imgur.com/oYpdw.jpg" alt="enter image description here"></p>
<p><img src="h... | g24760 | [
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<p>I am trying to integrate the following function over $x$ and $g$:</p>
<p>$f(z)= \int_{a/z}^{d} \int_{a}^{zg} \frac{e^{-(g-\mu)^2/2\sigma^2}}{x^{2/3+1}} dx~dg$</p>
<p>When I integrate over $x$ I get:</p>
<p>$f(z)= 3 \int_{a/z}^{d} {e^{-(g-\mu)^2/2\sigma^2}}((gz)^{-2/3}-a^{-2/3})dg$
After re-arrangement we get two ... | g34018 | [
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<p>I'm quite new to the area of spatial statistics, but I'm very interest in some general principles. The last two weeks I've created an example dataset, which contains three datsets.</p>
<ol>
<li>A dataset of ill persons. </li>
<li>A dataset of cities with the the overall population.</li>
<li>A dataset of points, whi... | g65923 | [
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<p>I have some data which I wish to cluster. I would like to see how these clusters compare to the categories that have already been assigned. Is there some kind of metric or visualisation that will tell me how well these line up?</p>
<ul>
<li>Any suggestions with each item assigned to just one category is fine, but e... | g65924 | [
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0.036964014172554016,
-0.03693941980600357,
-0.023484380915760994,
0.02984270080924034,
-0.019668953493237495,
-0.030709728598594666,
0.06999737024307251,
0.01814441755414009,
0.10817382484674454,
0.01... |
<p>Suppose that you have a population with $N$ units, each with a random variable $X_i \sim \text{Poisson}(\lambda)$. You observe $n = N-n_0$ values for any unit for which $X_i > 0$. We want an estimate of $\lambda$.</p>
<p>There are method of moments and conditional maximum likelihood ways of getting the answer, b... | g65925 | [
0.02225523255765438,
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0.04855913296341896,
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0.012110919691622257,
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0.034447770565748215,
0.... |
<p>I have two variables over two different years. Week by week pageview numbers in 2013 and 2014 and week by week # of posts in 2013 and 2014 (number of articles posted).</p>
<p>I'm trying to find out if posting less frequently has caused a dip in pageviews.</p>
<p>Right now I am taking the percentage difference for ... | g65926 | [
-0.015707263723015785,
-0.034408215433359146,
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0.039134882390499115,
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... |
<p>I have read through the scikit learn documentation and Googled to no avail. I have 2000 data sets, clustered as the picture shows. Some of the clusters, as shown, are wrong, here the red cluster. I need a metrics to method to validate all the 2000 cluster-sets. Almost every metric in scikit learn requires the ground... | g65927 | [
-0.03556549549102783,
0.01544810552150011,
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0.0739474818110466,
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-0.02097860537469387,
0.0481281615793705,
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0.07546965032815933,
0.0264... |
<p>I am building a high-dimensional Bayesian spike-and-slab model to study the association between several organic compounds and a continuous outcome. The goal is to select the most influential compounds that are most explanatory for the continuous outcome. A number of compounds in my data are unclassified, i.e. they d... | g24768 | [
-0.005433023441582918,
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0.002100682118907571,
0.09619089961051941,
0.00... |
<ol>
<li><p>I am trying to take three independent indicators and combine them into a single composite measure.</p></li>
<li><p>For discussion, let's say that this is a composite measure for 'economic performance', and that the measure contains three independent indicators: worklessness, qualifications and unemployment... | g65928 | [
0.010254652239382267,
0.02739580348134041,
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0.011286012828350067,
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0.0029020330403000116,
-0.015627382323145866,
0.025801662355661392,
-0.042427074164152145,
0.0051812175661325455,
-... |
<p>I am working on a few algorithms where I have a list of $N$ samples. Currently I have plotted these into a histogram and have a view of how uniform the values are distributed within an interval, which is quite good as a visualization, although I need a comparable value of how uniform the dataset is, in order to meas... | g49139 | [
-0.007044500671327114,
0.021062886342406273,
-0.019251160323619843,
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0.010311949998140335,
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0.021674182265996933,
0.06358340382575989,
0... |
<p>I have a general question about the <a href="http://cran.r-project.org/web/packages/Amelia/index.html" rel="nofollow">Amelia</a> package. I'm no mathematician or statistician, but I had to use R and impute and analyze some data, and Amelia showed results that fitted my expectations. I'll have to defend my choice soo... | g44470 | [
0.06420803815126419,
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0.048970725387334824,
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0.001206194399856031,
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0.02756507880985737,
0.08638713508844376,
0.059... |
<p>Suppose we have a regression model. If we get estimated of some of the coefficients and the standard errors are high, does this mean that the model is wrong/bad? How exactly do statistical packages choose regression models (in particular ordinal regression)?</p> | g65929 | [
0.006768268067389727,
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0.059262655675411224,
... |
<p>First, I would like to apology if my vocabulary is not correct. I am not statistician (and not mother tongue English speaker either).
So here is my problem :</p>
<p>For n subjects I got 8 values (human pressure at 8 different times). I would like to know if my n subjects are presenting the "same pattern" ( i don't ... | g65930 | [
0.022315802052617073,
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0.007718536537140608,
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... |
<p>I am doing a segmentation project and am struggling with cluster analysis in spss right now. Could you please help me get this answered:</p>
<p>How do I determine the <em>quality</em> of the clustering in spss?</p>
<p>In many articles/ tutorials I've read it's advisable to run a hierarchical clustering to determin... | g65931 | [
0.03938639536499977,
0.028227055445313454,
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0.010219612158834934,
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0.08234938234090805,
0.... |
<p>I run a fixed effect model with <code>Stata</code> and because my dependent variable is a large number
(max of 12 million and min of - 4 million), I got large coefficients for all independent variables, although most variables are significant </p>
<p>for example </p>
<p>coefficients </p>
<ul>
<li>122896.... | g65932 | [
-0.03391803801059723,
0.018819350749254227,
0.00641328189522028,
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0.005747747141867876,
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0.020484229549765587,
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-0.026476433500647545,
-0.04920266568660736,
0.055849313735961914,
0.02958904393017292,
0.0161... |
<p>Simplified version of our problem. Assume each person can be one of three categories. </p>
<ul>
<li>The true distribution of the entire population, as a whole, of being in the i'th category is (10%, 20%, 30%, 40%)</li>
<li>Your prior belief of Person A of which category he/she belongs to is (25%, 35%, 15%, 25%)</li... | g65933 | [
0.023012777790427208,
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-0.0036943398881703615,
0.029878918081521988,
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0.015407167375087738,
... |
<p>I am trying to fit a structural equations model, which looks like this:</p>
<p>{model<- 'ambition=~NA*imprich+ipshabt+ipsuces+iprspot+0*ipeqopt+0*iphlppl
altruism = ~0*imprich+0*ipshabt+0*ipsuces+0*iprspot+ipeqopt+iphlppl
ambition ~~ 1*ambition
altruism ~~ 1*altruism
ipshabt ~~ iprspot
imprich ~~ ipsuces
ambitio... | g24778 | [
0.005368224810808897,
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0.03792731091380119,
0.021690867841243744,
0.0015526983188465238,
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0.02466168813407421,
0.01905478909611702,
0.030739836394786835,
0.023511605337262154,
0.... |
<p>An analysis was implemented in SPSS 22 that uses the "Generalized Linear Mixed Models" feature of the program. Now I am looking for a way to port this to R. I use the glmmPQL() function of the MASS package and got the same results as in SPSS when using "model-based covariances". But, the data requires to use the "ro... | g24779 | [
0.03605769947171211,
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0.00575997494161129,
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0.020866738632321358,
0.03528460115194321,
0.02428886853158474,
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0.033127352595329285,
0.02653646282851696,
-0.0033521519508212805,
0.04023498296737671,
0.02922... |
<p>I'm working with conditional a conditional logit model to avoid bias that comes with FE logit models, when it comes to generating some hypothetical substantive effects, however, I run into trouble. </p>
<p>My normal process (following methods employed by <a href="https://github.com/chrisadolph/tile-simcf" rel="nofo... | g24780 | [
-0.008605215698480606,
-0.006590396165847778,
0.0008693118579685688,
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0.029031280428171158,
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0.034294504672288895,
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-0.0704430565237999,
-0.02055547758936882,
0.004297168925404549,
0.06619410216808319,
0... |
<p>I want to compare reaction time in four groups but I have three measures (pretest,post test and delayed post test) only in one of the groups. it was impossible to give post test and delayed post test in the other two groups and in the last group just possible to give pretest and post test, and only the first group r... | g65934 | [
-0.01121474988758564,
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0.0183859895914793,
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0.01274471078068018,
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0.006966516841202974,
-0.015103793703019619,
0.005072919651865959,
-0.07143872231245041,
0.019526... |
<p>All,</p>
<p>(I'm a beginner so my question could be really dumb...)
So, I have a set of data that contains 30 schools' variable A and variable B. These two variables were measured repeatedly each year for 10 years. I'm interested in knowing whether these two variables are correlated, but was confused by the repeate... | g65935 | [
0.020907972007989883,
-0.032960765063762665,
-0.005656197667121887,
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0.005661786999553442,
0.01650148816406727,
0.016358142718672752,
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-0.007829247042536736,
-0.037805989384651184,
0.025793712586164474,
-0.04957520589232445,
... |
<p>For a set A, I'm running 8 independent random samples, each with a probability of 1/8=12.5% and is without replacement. I know that the set formed by the union of these 8 samples will be of a size between 12.5% and 100%.</p>
<p>Is there an expected value for the size of this union?</p> | g65936 | [
-0.001813856652006507,
0.019042717292904854,
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-0.03548194840550423,
-0.020648213103413582,
0.001985994167625904,
-0.009554332122206688,
... |
<p>I have the following data frame:</p>
<pre><code>df=structure(list(S = structure(c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L,
3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 6L,
7L, 7L, 7L, 7L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L, 10L, 10L, 10L,
10L, 11L, 11L, 11L, 11L, 12L, 12L, 12L, 12L, 13L, 13L, 13L, 13L,
14L, 1... | g65937 | [
-0.014752030372619629,
-0.04582218825817108,
-0.0100694689899683,
-0.048324089497327805,
0.07077723741531372,
-0.010799896903336048,
0.07207996398210526,
-0.029064008966088295,
0.016301143914461136,
-0.021446360275149345,
-0.0030263399239629507,
0.06054740026593208,
-0.0005481375264935195,
... |
<p>I'm looking for some book recommendations, video lectures, tutorials or anything that can help me learn SAS.</p> | g44902 | [
0.023296797648072243,
-0.014250964857637882,
0.010505546815693378,
0.023968743160367012,
-0.016473200172185898,
0.010628321208059788,
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0.04934469610452652,
-0.05117536708712578,
0.05587412416934967,
0.018254505470395088,
0.0570535771548748,
0.017... |
<p>I am studying US public company financial performance for the last 2 decades. I am searching for evidence of "sustainable superior performance", thus to isolate those companies that display such characteristics. I will use the Compustat database.
Questions:
1) Is the total population the universe of US public compan... | g65938 | [
0.012388041242957115,
0.02164769545197487,
-0.00021882659348193556,
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0.02294507995247841,
0.01336214691400528,
0.039110247045755386,
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-0.0036675813607871532,
0.03919034078717232,
0.03817129135131836,
0.015003438107669353,
-... |
<p>I am interested in the relationship between weight Y_i at mating and the number Z_i of lambs born in a flock of n=25 female sheep.Assume Z_i can be 0(no lambs born) 1 and 2, then I know that Y_i* will be linked to Z_i by the following threshold model:</p>
<ol>
<li><strong>Z_i</strong> = 0 if Y_i* < a </li>
<li>... | g65939 | [
-0.024120613932609558,
-0.005987471900880337,
-0.019074594601988792,
-0.010717093013226986,
-0.02764502912759781,
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0.01163120474666357,
0.027096755802631378,
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-0.039586521685123444,
-0.09384746849536896,
0.0077813249081373215,
0.03886391222476959,
... |
<p>Hi I am working with a multivariate time series data consisting of 1) Demand Data 2)Sales Data 3) Rainfall Data , all available from 2010-2013,at monthly level.</p>
<p>Approach: I am trying to estimate the effect of rainfall on demand and sales of the product using VAR( Vector Autoregression) model. </p>
<p>Questi... | g24786 | [
-0.019617024809122086,
-0.06833099573850632,
0.0016639968380331993,
-0.022530198097229004,
-0.03476148098707199,
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0.07051684707403183,
-0.02330971322953701,
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0.05637124180793762,
0.022887669503688812,
0.00013784605835098773,
0.013794293627142906,
... |
<p>I have a questionnaire of 18 questions with Likert-type answers, going from 1-5. One of them was administered to parents, one to their children. I need to test 2 thing:</p>
<p>a) within each group, are the answers between each combination of two questions statistically significant? I know this sounds a bit strange,... | g65940 | [
0.01137703936547041,
-0.03059236705303192,
-0.002081401413306594,
-0.024963831529021263,
0.018717842176556587,
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0.08989167958498001,
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-0.018097829073667526,
0.03358835726976395,
-0.009900884702801704,
0.01895502209663391,
-0.0... |
<p>(A) In this book "Introduction to Neural Network using Matlab 6.0 - S. N. Sivanandam, S. N Deepa" <a href="http://books.google.ca/books?id=jJTN8RPgyXgC&printsec=frontcover#v=onepage&q=genetic&f=false" rel="nofollow">http://books.google.ca/books?id=jJTN8RPgyXgC&printsec=frontcover#v=onepage&q=gene... | g65941 | [
0.023143013939261436,
-0.010049775242805481,
0.011749271303415298,
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0.07828712463378906,
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0.04339607059955597,
0.06310882419347763,
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0.02154196985065937,
-0.025997528806328773,
0.0490105003118515,
0.05111653357744217,
0.041230... |
<p>I'm a guy who is interested in computer science and algorithms. I've spent a bit of time recently developing my own ranking system based on PageRank.</p>
<p>I'd like to compare it to the Elo system, in particular, the chess Elo ratings of the top 50 chess grandmasters.</p>
<p>I've got 2 datasets. All games played ... | g24787 | [
-0.008425549603998661,
-0.026384782046079636,
-0.028431054204702377,
-0.03331689536571503,
-0.014041932299733162,
-0.013788132928311825,
-0.058137815445661545,
0.017789997160434723,
0.003653027582913637,
-0.011805426329374313,
0.011574024334549904,
0.01734340563416481,
0.08094469457864761,
... |
<p>Where can I find a good proof that CRF based models and logistic regression based models are convex? Is there a general trick to test/prove that a model or objective function is convex?</p> | g24788 | [
0.05794684961438179,
-0.06364116072654724,
0.02305774576961994,
0.013079727068543434,
0.08730600774288177,
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0.017681913450360298,
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-0.023754127323627472,
-0.011032314039766788,
0.03929056227207184,
0.06636356562376022,
0.00225... |
<p>To me, the two are similar in the sense that <a href="http://.wikipedia.org/wiki/Slice_sampling" rel="nofollow">slice sampling</a> is just <a href="http://en.wikipedia.org/wiki/Gibbs_sampling" rel="nofollow">Gibbs sampling</a> for the uniform distribution over the area under the plot of the density function. Is that... | g44915 | [
0.03962016478180885,
-0.0015082604950293899,
-0.004901638254523277,
-0.04797426238656044,
-0.020236272364854813,
-0.04094346985220909,
0.010777811519801617,
0.016672493889927864,
-0.03086850605905056,
-0.010836741887032986,
0.05085141956806183,
-0.012453547678887844,
0.06864042580127716,
-... |
<p>In other words, does the independent components form a vector basis? </p>
<p>EDIT:Let'me try to clarify the question</p>
<p>If I calculate $n$ independent components for a given set of $n$ dimensional observations, are those components also linearly independent (property required to form a vector basis)?</p> | g65942 | [
-0.012956267222762108,
-0.005872038193047047,
0.02033950760960579,
-0.02647421881556511,
-0.03000442311167717,
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0.02672245167195797,
0.014673631638288498,
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-0.014611875638365746,
-0.005172133445739746,
-0.015171167440712452,
-0.04253794252872467,
... |
<p>I have a data set $\mathcal{S}$, which is univariate. I would like to discover the data points which can be thought of as outliers of $\mathcal{S}$. I use $\bar{\mathcal{S}}+2*\sigma(\mathcal{S})$ and $\bar{\mathcal{S}}-2*\sigma(\mathcal{S})$ to compute the upper and lower threshold in terms of 95% confidence inte... | g24790 | [
-0.017657894641160965,
0.009767516516149044,
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0.005200550891458988,
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0.06294950097799301,
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-0.00877689104527235,
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0.09252488613128662,
0.024144290015101433,
-... |
<p>Let's say I have some sample of people with a measure of interest for each one, let's call it <code>v</code>. Let's say I measure <code>v</code> twice for the same set of people, one in January and one in December. Now I want to assess whether a person's <code>v</code> value improved from January to December. Let's ... | g65943 | [
0.019847650080919266,
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0.01... |
<p>I am trying to figure out the relationship between $\text{Cov}(x_i^2, e_i^2), V$ and $V_0$, where:</p>
<p>$V=$ asymptotic variance of $\sqrt{n(\hat{\beta}-β)}$ under heteroskedasticity, and<br>
$V_0=$ asymptotic variance of $\sqrt{n(\hat{\beta}-β)}$ under homoscedasticity</p>
<p>Also, I am given that that the expe... | g65944 | [
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0.0... |
<p>I would like to perform a Fixed effect logit estimation in R.
Can someone point out a package that can do the job?</p>
<p>Note: For the time being I'm not really interested in the random effect.</p>
<p>Update;</p>
<p>Essentially I wonder if there is the plm package for a binary response model.</p>
<p>Here is so... | g65945 | [
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... |
<p>Is anyone aware of code for a wild bootstrap F-test? Namely, testing joint significance of several coefficients where the standard errors of each coefficient are computed using a wild bootstrap. </p>
<p>The following paper exposits the theory, but I wanted to see if anyone has implemented this in practice?</p>
<p>... | g65946 | [
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<p><strong>Note:</strong></p>
<p>There is another post with very similar title, but it is really on the author's specific problem with submarines. Mine is more general.</p>
<p>I have asked a <a href="http://stats.stackexchange.com/questions/82316/forecast-model-developed-now-but-only-used-later-is-it-still-valid">sim... | g65947 | [
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<p>I'm reviewing a multiple regression time series analysis, and I'm concerned about the (possibly insufficient) sample size. The goal of the analysis is to determine whether an event during the time period had an effect on the dependent variable. The event is dummy coded (0 before the event, 1 for every period thereaf... | g65948 | [
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<p>In case you suspect your time series has a linear trend, what is the best way to prove it? If you just regress it against time, you ignore the auto correlation of the time series so I assume that is a bit foolish.</p>
<p>We learned to do unit root tests, and in those test you remove the auto correlation by includin... | g65949 | [
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<p>I have always used PCA as a preprocessing techniques.
There are some people that use it for pattern recognition. </p>
<p>Once I used pca to project my data in a 2 dimensional space and then I observed that the samples where divided in 2 groups. </p>
<p>What other kind of analysis can be done using PCA?
Or at leas... | g65950 | [
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<p>I'm looking to join the field of statistics and more exactly to forecasting. I'm a software developer and I just started playing with R.</p>
<p>Can you recommend me some tutorials related to forecasting, but something which beginners can handle. It will be great also to read and try some forecasting related problem... | g49599 | [
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<p>I'm trying to test some data for the best distribution fit, and am looking to try the t-dist (all theoretically, no R computations)
I think the best way to do this is to assume the distribution is true, use MLE or MoM to estimate parameters and then conduct a goodness-of-fit test.
Firstly, is this an appropriate way... | g49740 | [
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<p>Suppose you want to compare survival of males and females within three groups. What is the difference between performing a log-rank test for each group (stratification) vs adjusting for it? Does the stratification allow for the survival curves in each group to differ?</p> | g65951 | [
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<p>So I've fit an ANOVA model to 32 predictors and 32 data points. The summary output simply gives me the SS for each predictor and no F-stat or p-value. Is there any way to still make some sort of discussion as to the validity or effectiveness of the model?</p> | g23236 | [
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0.0091... |
<p>I'm quite new on this with binomial data tests, but needed to do one and now I´m not sure how to interpret the outcome. The y-variable, the response variable, is binomial and the explanatory factors are continuous. This is what I got when summarizing the outcome:</p>
<pre><code>glm(formula = leaves.presence ~ Area,... | g65952 | [
0.007330972235649824,
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0.09547225385904312,
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-0.04301665350794792,
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0.057012658566236496,
0.043701305985450745,
-0.... |
<p>This is continuing the discussion about the posterior probability densities and conjugate priors.</p>
<p>So, my posterior distribution over the parameters is defined as:</p>
<p>$$
P(w, \phi, \lambda | y) \propto P(\phi) P(w|\lambda) P(\lambda) \prod_{i}P(y|w, \phi, \lambda)
$$</p>
<p>Now, $\phi$ is the parameter ... | g65953 | [
0.06269349157810211,
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0.02605711854994297,
0.006098942365497351,
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0... |
<pre><code>All Drugs CASE CONTROL
AVG 11.07 7.88
ST DEV 3.58 2.95
# SUBJECTS 7399 3537
NM DRUGS
AVG 5.49 3
ST DEV 4.33 2.51
# SUBJECTS 6831 2507
</code></pre>
<p>Ho - Cases and controls are prescribed the same numbers of medication
alpha =.05</p>
<p>I've got ... | g65954 | [
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0.005891943350434303,
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0.043707188218832016,
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0.0005480285617522895,
0.05944487825036049,
-0.004655550699681044,
0.05109918862581253,
... |
<p>I have a time series, which is produced from a sensor. This sensor detect sound in the real World. My aim is to separate sounds with different frequencies from this time series.</p>
<p>With which technique can I do this job? </p> | g65955 | [
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-0.013284137472510338,
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-0.00485136453062295... |
<p>I have a set of data which consists of one independent variable (2 groups) and one dependent variable. I successfully checked for normality (each group separately) and conducted a t-test.</p>
<p>Now I want to check for robustness by changing the cut-off between groups.</p>
<p>Do I have to also do another normality... | g24805 | [
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0.006821234244853258,
0.03604455292224884,
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... |
<p>I am trying to verify the expression for Omitted Variable Bias (OVB) as given e.g. in Wooldridge: $\tilde{\beta_1} = \hat{\beta_1} + \hat{\beta_2} \cdot \tilde{\delta_1}$, where $\tilde{\delta_1}$ is the estimated slope of the regression of $x_2$ on $x_1$.</p>
<p>Choosing the housing price data (hprice1.gdt) from W... | g65956 | [
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0.006284003145992756,
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0.025199133902788162,
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0.06448961049318314,
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... |
<p>I am working on a dataset with with 100 or so X variables and the effects on a single Y.</p>
<p>As with previous threads this contains a lot of fairly significant correlations. I considered using PCA but did not really want to loose the original variables by creating linear combinations (factors).<br>
X variables a... | g65957 | [
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0.025594061240553856,
-0.002291977172717452,... |
<p>I have two data sets obtained from two different kind of chemical analysis: GC-MS and IR. Both the chemical analysis were performed using the same samples. My aim is to know if there are some relations between GC-MS data and IR data. </p>
<p>The data sets are two 'fat' matrix where: number of columns (objects) > nu... | g24806 | [
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0.07014026492834091,
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<p>I have implemented a version of "impact coding" : <a href="http://www.win-vector.com/blog/2012/07/modeling-trick-impact-coding-of-categorical-variables-with-many-levels/" rel="nofollow">http://www.win-vector.com/blog/2012/07/modeling-trick-impact-coding-of-categorical-variables-with-many-levels/</a>. I have not see ... | g65958 | [
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0.08297707885503769,
0.0... |
<p>I am very new to R and statistics as a whole so this may be a very simple question. I am trying to carry out <a href="https://climatedataguide.ucar.edu/climate-data-tools-and-analysis/empirical-orthogonal-function-eof-analysis-and-rotated-eof-analysis" rel="nofollow">empirical orthogonal function (EOF) analysis</a> ... | g65959 | [
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0.05436166375875473,
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0.09723024070262909,
... |
<p>It's quite common to normalise different feature vectors so that they have the same mean and variance (usually <code>(X-mean(X))/sd(X)</code>), so that the changes in the smaller variables aren't swamped. </p>
<p>Is the same ever done for higher moments (skewness, kurtosis, ...), for data where those moments are ex... | g65960 | [
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0.009734876453876495,
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0.03953562304377556,
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<p>Let's say I have measurements $Y$ which are all positive, and the distribution seems to be somewhat skewed. I'm modelling $Y$ in GLM framework. Now I could set my GLM using different distributional assumptions for $Y$, i.e. I could set family as normal or gamma, or I could log-transform $Y$ and use normal distributi... | g65961 | [
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0.0032314518466591835,
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0.01518551167100668,
0.04993675276637077,
-0.0... |
<p><strong>The practical POV</strong>:</p>
<p>I sample 35 matches: 15 turn out as home win, 10 as tie and 10 as home lose. I want to conduct a test for the hypothesis "A home court advantage does exist." with a significance level of say 5%. What would be a reasonable test statistic / calculation of the p-value to acce... | g65962 | [
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0.05165804922580719,
0.03225047141313553,
... |
<p>I am currently examining efficiency measurement techniques in Kenyan hospitals. We don't have a lot of resources, tutorials or courses here and hence very challenging to undertake the analysis if not an expert. Anyone please advice on any intensive short courses that concentrate on stochastic frontier analysis and d... | g24808 | [
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0.024086561053991318,
0.07281647622585297,
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0.01732093095779419,
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<p>We understand a SLR model as
$$y_i = \alpha + \beta x_i + \varepsilon_i$$
with $\varepsilon_i$ i.i.d with equal variance.</p>
<p>Suppose I have two instruments measuring a common entity, say, density of samples of different liquids, and assume that we do not know the exact density of each liquid (nor is there any w... | g65963 | [
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0.016569584608078003,
0.03415476903319359,
0.026835786178708076,
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0.02... |
<p>Let $Y_f, Y_1,..., Y_n$ denote measurements taken from a father and his n sons. It is assumed that $Y_f, Y_1,...,Y_n$ have equal variance with father-son correlation $ρ_f$ and equal correlation $ρ_S$ between sons. Transform $Y_f, Y_1,..., Y_n$ linearly to $Z_0, Z_1,..., Z_n$ to remove the correlations.</p>
<p>The h... | g65964 | [
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0.006844131276011467,
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... |
<p>I know that one can approximate this density ($p(v) \propto 1/v$) using its truncated version and implement it this way:</p>
<pre><code> B~dunif(log(BInf),log(BSup))
v<-exp(B)
</code></pre>
<p>but I would like to use the exact form (I checked that under this prior my posterior is proper).</p> | g65965 | [
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... |
<p>I am currently using a measure of the price level (CPI) from which I would like to remove the effects of food prices (also an index). Notice that food prices are included in the CPI (so that CPI is the total index).</p>
<p>First, I made sure that both were based in the same way (that is, the base value of 100 is on... | g65966 | [
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<p>I have conducted a study of children with leukemia where I have looked at the change in BMI z score during treatment with glucocorticoids. I have done some different tests and have seen that BMI z score increases significantly during treatment, but I would like to know whether there is a correlation between the BMI ... | g65967 | [
0.017178373411297798,
0.014588998630642891,
0.018444636836647987,
-0.0025053289718925953,
-0.007639581803232431,
-0.05284331738948822,
0.04046036675572395,
0.015003371052443981,
-0.05207057297229767,
-0.005563901271671057,
-0.027470381930470467,
0.05932937562465668,
0.023033205419778824,
0... |
<p>I am building a regression model and I need to calculate the below to check for correlations</p>
<ol>
<li>Correlation between 2 Multi level categorical variables or 2 binary variables</li>
<li>Correlation between a Multi level categorical variable and
continuous variable </li>
<li>VIF(variance inflation factor) for... | g65968 | [
0.043060705065727234,
-0.08566023409366608,
0.014483178965747356,
-0.017364008352160454,
0.024212202057242393,
-0.008424117229878902,
-0.03260859102010727,
0.02132313884794712,
-0.0499984510242939,
-0.01896641030907631,
0.011293578892946243,
0.01083480753004551,
0.011328930035233498,
0.017... |
<p>I am evaluating a web search relevance feedback algorithm. The algorithm uses Bing API as source for its result sets. To evaluate the algorithm I will be conducting a user study.</p>
<p>In the end I will have binary judgements, whether the documents are a good answer to the query. Since the web as a test collection... | g24812 | [
-0.023556962609291077,
-0.008312711492180824,
-0.0015997515292838216,
-0.02403310127556324,
0.022801529616117477,
-0.019403140991926193,
-0.01280233170837164,
0.01169903576374054,
0.00091454794164747,
-0.003947307821363211,
0.007983095943927765,
0.010710299015045166,
0.02790198288857937,
0... |
<p>I have a question about model selection and model performance in logistic regression. I have three models that are based on three different hypotheses. The first two models (lets name them z and x) only have one explanatory variable in each model, and the third (lets name it w) is more complicated. I’m using AIC for... | g44967 | [
0.04283318668603897,
-0.02751946449279785,
0.02155460976064205,
-0.0064970157109200954,
0.03953835368156433,
-0.007943124510347843,
0.030495908111333847,
-0.0027849613688886166,
-0.04070466011762619,
0.04428691044449806,
0.03260059654712677,
0.0044732424430549145,
0.0524086132645607,
0.051... |
<p>Let $Y_1, Y_2, Y_3$ be <strong>i.i.d</strong> continuous random variables. For $i = 1, 2$ define $U_i$ as</p>
<p>$U_i=1$ if $Y_{i+1} > Y_i,$</p>
<p>$=0$ ,otherwise</p>
<p>Find the mean and variance of $U_1 + U_2$</p>
<p>I can't find the distribution of $U_1 + U_2$.</p> | g65969 | [
-0.004259678069502115,
-0.0007379481103271246,
-0.04197084531188011,
-0.00759673397988081,
0.0034558146726340055,
0.011453640647232533,
-0.005255317315459251,
0.022127661854028702,
-0.012233670800924301,
-0.051016516983509064,
-0.013469372875988483,
0.015105700120329857,
-0.05892478674650192... |
<p><strong>Context</strong></p>
<p>I have a set of data that was collected from several inertial measurement units (orientation and acceleration data). I want to determine to what extent an inference method degrades when the data becomes noisy (or, should I say "noisier").</p>
<p><strong>Questions</strong></p>
<p>Ho... | g24814 | [
0.07074584811925888,
0.003273752983659506,
-0.015094965696334839,
-0.017591936513781548,
0.044093068689107895,
-0.0030641609337180853,
0.058474425226449966,
0.011554528027772903,
-0.044656798243522644,
-0.03272606432437897,
-0.03558233380317688,
-0.0052236998453736305,
0.04947366192936897,
... |
<p>My girlfriend is an Actuarial Analyst at a large insurance company in the Netherlands and because we'll soon have our two year anniversary, I thought of gifts for her.</p>
<p>On <a href="http://proofmathisbeautiful.tumblr.com/post/5104877044/baseln-statistical-distribution-plushies-am" rel="nofollow">Proof: Math is... | g24815 | [
0.09007089585065842,
0.04791873320937157,
-0.0082024447619915,
-0.04926984757184982,
-0.025789638981223106,
0.0026349974796175957,
0.004347676876932383,
-0.0433373861014843,
-0.0004086690896656364,
0.02631569467484951,
-0.0030095537658780813,
-0.004082271363586187,
0.040533989667892456,
-0... |
<p>In the book “Programming Collective Intelligence” Segaran explains the Fisher method for categorizing text as an alternative to Naive Bayes classifier. The Fisher method uses inverse-chi-square-distribution, which I do not really understand.</p>
<p>I watched this video found on stats.stackexchange about chi-square-... | g12 | [
0.04319009557366371,
0.014311331324279308,
0.004967710003256798,
-0.0395267978310585,
0.029503388330340385,
-0.03987782076001167,
-0.002059745602309704,
0.07586601376533508,
-0.05252144858241081,
0.006790034007281065,
-0.042244236916303635,
0.012590578757226467,
0.05572056025266647,
0.0431... |
<p>I am solving a classification problem using Random Forests. For that I have decided to use Python library scikit-learn. But I am new to both Random Forest algorithm and this tool. My data contains many factor variables. I googled for that and found out that it's not right to give numerical values to factor variables... | g65970 | [
0.016425281763076782,
-0.04474901407957077,
0.029451239854097366,
-0.06438583880662918,
0.04281529039144516,
-0.021653980016708374,
-0.010635378770530224,
-0.005552315153181553,
-0.039944835007190704,
-0.038670286536216736,
0.013592863455414772,
-0.003543494502082467,
0.0026643199380487204,
... |
<p>What functionality should exist in a <a href="http://en.wikipedia.org/wiki/Computer_algebra_system" rel="nofollow">CAS</a> that was specifically geared toward Statistics?</p>
<p>Symbolic algebra systems like Mathematica and Maple are often used for calculus, logic, and physics problems but are rarely used for stati... | g24816 | [
0.033502936363220215,
0.04883582517504692,
-0.006836561020463705,
-0.025049595162272453,
-0.016984160989522934,
-0.0922711119055748,
0.08769137412309647,
0.031937334686517715,
-0.03216468170285225,
-0.05519793555140495,
0.0008583494345657527,
0.03921087458729744,
0.04566875845193863,
0.029... |
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