question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have been struggling with this question all day, reading everything I could find, but still do not have a clear answer.</p>
<p>A part of my research was that: 30 students tried a new educational instrument (virtual patient). Before the interaction with the patient they filled in 18 Likert items, from 1 to 5 (1=hi... | g62427 | [
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<p>I have a dataset (vector) to which I would like to fit a gamma distribution (x), which given the shape seems reasonable. The charts below show the histograms of the two dataset: vector and x. </p>
<p><img src="http://i.stack.imgur.com/MZsil.jpg" alt="enter image description here"></p>
<p>The left is my sample set,... | g41700 | [
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<p>I have some variables and I want to reduce their number for further analysis. I initially thought of combining them using factor analysis. But since the variables are of all kinds (rating, count, ordinal, continuous dollar amount) I am thinking about using CATPCA for it. However, I have some questions about the tech... | g62428 | [
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<p>I don't find a textbook presenting prediction intervals for mixed models. Moreover I'm only looking for a prediction interval for the balanced one-way random effect ANOVA model. Do you know a formula for this interval ?</p> | g62429 | [
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<p>Do you know any datasets other then Google's Google Book n-gram dataset? Especially some datasets about scientific papers would be great.</p> | g19518 | [
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<p>I used the MATLAB code written below to create the following probability density function. It creates the familiar hill-shaped distribution.</p>
<p><img src="http://i.stack.imgur.com/AqcD4.png" alt="bivariate normal distribution"></p>
<p>I'm interested to see (whether via MATLAB code or just an linked image) a PDF... | g19519 | [
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<p>It is well known that it is problematic to choose a statistical test based on the outcome of another statistical test, as the p-values are difficult to impossible to interpret (e.g. <a href="http://stats.stackexchange.com/questions/61715/choosing-a-statistical-test-based-on-the-outcome-of-another-e-g-normality/">Cho... | g62430 | [
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<p>$\Sigma(X-\bar{X})$</p>
<p>Could someone please clarify: does the sum of deviations (not squared) of a variable from its mean have to equal anything special, like 0, or is it just any number? </p>
<p>Also, do I understand correctly that in a regression, the sum of squared deviations of y from the mean is minimized... | g19522 | [
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<p>How do I test for Lack Of Fit (F-test) using R? I've seen a similar question, but that was for SPSS and it was just said that is can be easily done in R, but not how. </p>
<p>I know in simple linear regression I would use <code>anova(fm1,fm2)</code>, <code>fm1</code> being my model, <code>fm2</code> being the same ... | g19523 | [
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<p>I have another question about distributions as I am going through an exercise. I apologize for posting on the other site by mistake.</p>
<p>Millions of birds are released, 100 of them have tags and 7 of the tagged birds are found to have returned to the release site. How do you sketch the sampling distribution of P... | g62431 | [
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<p>Assume I have two feature selection algorithms, A and B, which are developed based on SVM. I applied these two algorithms on the same dataset, a Liver Cancer dataset (400 features & 150 samples), and they selected two small subsets A(30 features) and B(50 features). The classifier used is the same and is a binar... | g62432 | [
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<p>As a part of my <em>exploratory data analysis (EDA)</em> prior to further analysis, I'm trying to determine a <em>probability distribution</em> of my pilot dataset's variables. A particular feature of this dataset is a significant share of <strong>missing values</strong>. I partially alleviated this problem by perfo... | g62433 | [
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<p>Suppose I approximate a variable (events of certain type) by a Poisson distribution and I would like to write a program and measure the mean experimentally. The idea is that I have an algorithm which outputs an event which is either of our interest or not. </p>
<p>I m measuring the mean as follows. Start a counter ... | g62434 | [
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<p>This code outputs the eta-squared from an ANOVA:</p>
<pre><code>y <- c(rnorm(30, 3), rnorm(30, 4), rnorm(30, 5))
x <- sort(rep(paste("treatment", 1:3), 30))
xy <- data.frame(x,y)
xyaov <- aov(y ~ x, xy)
library(heplots)
etasq(xyaov)
Partial eta^2
x 0.4807356
Residuals ... | g62435 | [
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<p>I'm trying to prove
$$ \mathrm{Var}\left(\sum\limits_{i=1}^n{g(X_i)}\right) = n(Var(g(X_1))) $$
where $X_1...X_n$ are IID variables.</p>
<p>I have been trying to use proof for a similar question - <a href="http://stats.stackexchange.com/a/31181">http://stats.stackexchange.com/a/31181</a> - but then I'm stuck when t... | g62436 | [
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<p>Find the least squares estimator of the parameter B (beta) in the following regression model: y= B + u<br>
What is the variance of the estimator?</p> | g49645 | [
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<h2>Background</h2>
<p>I have a survival object in R called <code>km</code>.</p>
<pre><code>> km
Call: survfit(formula = Surv(Surv_day, Survive) ~ 1, data = study_data)
records n.max n.start events median 0.95LCL 0.95UCL
440 440 440 88 3964 3595 NA
> summary(km)
Call: survfit... | g62437 | [
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<p>Is there any way to perform bivariate regression using pairwise deletion of missing values in R? na.action options in lm() do not offer such a possibility – the default na.action is na.omit, which is equivalent to listwise deletion. I already tried estimating the covariance matrix using pairwise deletion and then us... | g62438 | [
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<p>With my data (Y and X variables) I have $R^2$ = 0.3736.</p>
<p>I used the data from an article that did the same type of experiment, and made a graph and found their $R^2$ = 0.3706.</p>
<p>I know that the values are very low, but that is all I think I can do with the data. Because both graphs have very similar $R^... | g62439 | [
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<p>Suppose we have a bunch of a sampled pairs $(x_1,y_1)...(x_n,y_n)$ with the $y_i =\pm1$. </p>
<p>Then consider the decision function $h(x) = -1$ if $p(x)=\frac{1}{1+e^{-x}}\leq0.5$, and $h(x) = 1$ if $p(x) > 0.5$. Where $p$ is interpreted, as per logistic regression, as the probability that $x\rightarrow +1$. ... | g62440 | [
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<p>There was already <a href="http://stats.stackexchange.com/questions/485/mathematical-statistics-videos">a request for Mathematical Statistics Videos</a>, but it explicitly asked from people for</p>
<blockquote>
<p>videos that provide a rigorous
mathematical presentation of
statistics. i.e., videos that might... | g62441 | [
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<p>Users are often tempted to break axis values to present data of different orders of magnitude on the same graph (see <a href="http://peltiertech.com/Excel/Charts/BrokenYAxis.html">here</a>). While this may be convenient it's not always the preferred way of displaying the data (can be misleading at best). What are al... | g62442 | [
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<p>I have a question regarding some time series concepts:</p>
<p>Suppose I have some "time series" data with cross correlation. Suppose I am able to fit a copula, say to capture dependencies between data of $\{t,t-1,...,t-n\}$ - i.e. for some time-lag. Now, if I want to draw some random numbers of this time series, I ... | g62443 | [
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<p>Various software for performing inference on graphical models support logical(a.k.a deterministic) nodes. PyMc, Winbugs, Smile are the ones I'm aware of. </p>
<p>Based on the different inference methods used by these software (PyMc and Winbugs use MCMC, Smile uses message passing etc), this extension to graphical m... | g62444 | [
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<p>Given a data frame in R is there a way to export it in <em>R syntax</em> such that executing this code would re-create the data frame? I would find this useful to store results in R files along with calculations without depending on external files.</p> | g62445 | [
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<p>I am using ANOVA with repeated measures to test significance between males and females results of an experiment during which participants had to evaluate 7 stimuli in 2 conditions (EXP1 and EXP2).</p>
<p>The problem is that even if from results it is clear that there are significant differences between males and fe... | g49851 | [
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<p>I have some data acquired by an acoustic sensor with 1 Hz sampling rate. Due to some inevitable issues, I have some noise in my signal, saying 10% pollution.
I'm looking for a reliable method for replacing the outliers.</p>
<p>In order to find a suitable approach I manipulated a clean record such that it contains 9... | g19541 | [
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<p>Does anybody know how to plot all AIC values for different size models, when using the command <code>regsubsets</code> from the package <code>leaps</code>?</p>
<p>Assume you have the following variables:</p>
<pre><code>treatment <- factor(rep(c(1, 2), c(43, 41)), levels = c(1, 2),labels = c("placebo", "treated"... | g19542 | [
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<p>I have 2 alternative methods to solve a problem, and I was just wondering what people who know the math better than I think, and if there is a better method to use for this type of problem.</p>
<p>The problem: I have a list of lat/lon positions and a value for the time interval between position updates and wish to ... | g62446 | [
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<p>Does any standard statistical software like R, SAS or SPSS have procedures or codes to analyze log-linear models for missing data in contingency tables using maximum likelihood estimation (or EM algorithm or other iterative procedures), not multiple imputation techniques ? </p> | g62447 | [
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<p>I want to explain the relation between getting a reply and posting in a e-commerce. I want to know how much a reply increases postings.</p>
<p>I know I could do a regression of postings=f(replies) but the issue is that I have most of the postings getting only one reply. The distribution is skewed. </p>
<p>So, I co... | g62448 | [
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-0.03552093729376793,
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... |
<p>I am using a MANOVA test to compare nine different dependent variables (from neuropsychological and neuropsychiatric assessment) between three groups. The output shows a significant influence from GROUP on my variables (<em>p</em> < .001). </p>
<p>Ofcourse, I am interested in how the three groups influence every... | g2797 | [
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<p>Is it possible to perform logarithmic regression on multiple variables with Excel? If I just have a single independent variable than it's very easy to do this using the best-fit line option (it lets me switch from linear to logarithmic). But this feature does not work for multiple variable regression and the regress... | g19548 | [
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<p>I have a basket of time series (stock prices). I want to find the N (fixed or not) time series that will best replicate the basket in the sense that combination of them will be best cointegrated with the basket.<br>
Beside using the N series that have the best cointegration scores (ADF test) and regressing these var... | g38606 | [
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<p>Let $X_1, X_2, ..., X_n$ be a random sample from a distribution with p.d.f.,
$$f(x;\theta)=\theta^2xe^{-x\theta} ; 0<x<\infty, \theta>0$$ Obtain minimum variance unbiased estimator of $\theta$ and examine whether it is attained?</p>
<p>MY WORK:</p>
<p>Using MLE i have found the estimator for $\theta=\frac... | g62449 | [
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... |
<p>I've developed a logit model to be applied to six different sets of cross-sectional data. What I'm trying to uncover is whether there are changes in the substantive effect of a given independent variable (IV) on the dependent variable (DV) controlling for other explanations at different times and across time. </p>
... | g62450 | [
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<p>I'm optimizing 5 parameters for an option pricing model. Now I want to asses whether these parameters are stable over time (i.e., a year). For this I create about 12 subsamples and estimate the optimal parameters for each subsample (I do this by minimizing a cost function, i.e., chi-squared, under a certain threshol... | g62451 | [
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<p>I'm trying to find the most similar sample between a candidate and a bag of samples.</p>
<p>Consider you have a knowledge corpus as follows:</p>
<pre><code>corpus = data.frame(region = factor(), time = numeric(), observation = numeric())
corpus = rbind(corpus, data.frame(region = 'america', time = 1:20, observatio... | g62452 | [
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<p>I am trying to find the area with thickest density. I have newborn numbers by day for which I am trying to find the series of 7 consecutive days that would produce the highest frequency. So the start and end dates are not tied to any particular day of the week the period can start on any day but would end in 7 days... | g62453 | [
0.03832247108221054,
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<p>Why doesn't the scatter plot change when I perform multidimensional scaling on distance or similarity matrix?</p>
<p>This figure uses similarity matrix</p>
<p><img src="http://i.stack.imgur.com/ZKWYA.png" alt="enter image description here"></p>
<p>And this figure use distance matrix (sqrt(1-similarity))</p>
<p><... | g62454 | [
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... |
<p>There is a statistical property - and I only know the name in German and cannot find any proper translation - that is defined as: variance explained of a specific regressor x1 in addition to the variance explained by all other regressors. </p>
<p>That is, the shared variance is <em>not</em> included in the explaine... | g62455 | [
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<p>I am trying to implement singular value decomposition in C. I am using routines svdfit and svdvar from Numerical Recipes.
The results from svdfit seem to be correct, but the results from svdvar are not. I am struggling with this problem for some time now, and I don't know how to solve it.
For example, take the follo... | g62456 | [
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<p>how do i interpret the results of the Johansen cointegration test if the result from my STATA output fails to accept both null hypotheses of r=0 and r<=1 ?</p>
<p>for example:</p>
<p><a href="http://s4.postimage.org/61l9i9pwt/Stata_PRT_SCRN.png" rel="nofollow">STATA Screenshot</a></p>
<p>can i conclude whether... | g62457 | [
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<p>Given an i.i.d. sample $X = (x_{1}, \dots, x_{n}) \sim N(\mu, 1)$. I have been asked to show that the likelihood of $\mu$ based on the whole sample is proportional to the likelihood based on $\bar{x}$ (the sample mean) alone. I'm a little confused by the phrasing of this question.
I was hoping the perhaps somebody c... | g62458 | [
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<p>I am attempting to update the design of an annual survey which measures the percent-deficient of 26 different asset inventories. Most of these assets don't occur on every sampling unit and some of them are quite rare (occur on around 5% of sampling units). The asset deficiency rates can be estimated by either a sim... | g62459 | [
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<p>I was looking at the Poisson regression. Here I find that the canonical parameter is taken to be the logarithm of the rate of the Poisson. I was wondering if there is any reason for considering this as the canonical parameter, rather than the rate of the poisson itself (with the restriction that the parameter is pos... | g19559 | [
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<p>A conjecture that I have heard is this: </p>
<p><em>When you add a quadratic or a cubic term to a linear latent growth curve model, the fit will always improve</em>. </p>
<p>Is this correct? Why/why not?</p>
<p>As I have had the idea explained to me, adding additional terms will capture a additional portion of th... | g38614 | [
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<p>Let $f$ be a function such that:</p>
<p>$$f~:~(x,~\theta)\in\mathbb{R}^{3}\times\mathbb{R}^{12} \rightarrow f(x,~\theta)\in\mathbb{R}^3$$</p>
<p>My observations $y$ are noisy values taken by the function $f(\cdot ,~\theta)$ for known values of $x$. I would like to estimate the conditional distribution of $\theta \... | g62460 | [
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<p>I have a problem with the <code>forecast</code> function for ARIMA models in R. It calls <code>predict</code> that calls <code>KalmanForecast</code>. Ok...here's the deal.</p>
<p>the mean one-step forecast of the Arima object produced by this call</p>
<pre><code>forecast(Arima, h=1)$mean[[1]]
</code></pre>
<p>is ... | g62461 | [
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<p>Are there any <strong>analytic approaches</strong> to using <em>mixture distribution fitting</em> for <em>latent variable analysis</em>? I'm specifically interested in existing approaches to determining whether mixture components indicate a presence of <em>sub-populations</em> OR <em>effect(s)</em> from underlying <... | g19560 | [
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<p>Is Student's t test a Wald test?</p>
<p>I've read the description of Wald tests from Wasserman's <em>All of Statistics</em>.</p>
<p>It seems to me that the Wald test includes t-tests. Is that correct? If not, what makes a t-test not a Wald test?</p> | g62462 | [
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<p>I have a question about cluster analysis. There are 3000 companies, which have to be clustered according to their power usage over 5 years. Each company has values for every hour during 5 years. I would like to find out if some companies have the same pattern in usage power over the time period. The results should b... | g19563 | [
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<p><img src="http://i.stack.imgur.com/nGx8c.png" alt="Question for interpretation"></p>
<p>The way I interpreted this question was that $H_0: \mu \ge 10, H_a: \mu < 10$. But the answer for this question set up a hypothesis of $H_0: \mu = 10,H_a: \mu>10$. Shouldn't it be the first way?</p> | g62463 | [
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<p>I'm trying to re-create an analysis done using <code>Stata</code> function <code>xtreg</code> (though I don't have the code) with <code>R</code> package <code>plm</code>, and I'm having trouble translating between the two. A minimal example of the model I'm trying to estimate would be as follows:</p>
<p>$$
\text{De... | g62464 | [
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<p>I would like to know how can I explain PCA to someone not familiar with statistics. I have categorical/binary data and when I apply PCA the representation actually makes sense. So, if I put PCA in context what is the intuition behind it? Say, you have variables x,y,z and row 1= 0 0 1 row 2= 0 1 0 (i.e. for 1st obser... | g49447 | [
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<p>In several analyes I performed, I occasionally observed that when dealing with lagged variables, including contemporaneous values of the same variables in the regression increases the signficance of the lagged variables. The contemporaneous values are insignificant themselves nevertheless.</p>
<p>For example, I reg... | g62465 | [
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<p>I am trying to train a random forest classifier. As predictors, I keep both discrete features and continuous features (the discrete ones including booleans, counters, etc., and the continuous contains floats).</p>
<p>Training the model both in <code>R</code> and in Python's <code>scikit.learn</code>, I get that the... | g62466 | [
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<p>I have a basic question - how to I set up a loss matrix to weigh the cost of a false positive higher than a false negative? I am trying to produce a tree in rpart to classify a disease with high specificity.</p>
<p>Any advice would be appreciated, thanks</p> | g610 | [
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<p>I have a set of means and standard deviations. For each mean I can calculate a 95% confidence interval. I plot these means and confidence intervals against an independent variable and I fit a best sigmoidal curve through this data. </p>
<p>I want to calculate the region of 95% confidence above and below this curve... | g62467 | [
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<p>I have a question about Monte Carlo integration. As I understand it the method takes a region S of known volume V which contains the region T specified in the definite integral. $T \in S$.</p>
<p>Then random points in S are selected and it is checked if they belong to the volume that is the volume under the graph.<... | g62468 | [
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<p>Over the past few weeks I have been trying to understand MCMC and the Metropolis-Hastings algorithm(s). Every time I think I understand it I realise that I am wrong. Most of the code examples I find on-line implement something that is not consistent with the description. i.e.: They say they implement Metropolis-Hast... | g1090 | [
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<p>I am looking at several dependant variables for which I created LMMs of the following kind:</p>
<pre><code>DV ~ Group + (1|Subject) + (1|Time)
</code></pre>
<p>Now I am struggling with how to interpret the output concerning the random effects, e.g. for DV1:</p>
<pre><code>Random effects:
Groups Name Var... | g19574 | [
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<p>Is there a way of performing HAC robust standard errors in SPSS?</p> | g62469 | [
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<p>I want to use analysis of covariance in R. The model is</p>
<p>$y_{ij} = \mu + t_i + r_j + b(x_{ij} - \bar{x}) + e_{ij} $ </p>
<p>In R it is possible to get Ryy, Tyy, Eyy, SSE as well as b and adjusted treatment or block with using 'lm' and 'anova'.</p>
<p>However I need Rxx, Txx, Exx, Rxy, Txy and Exy (SSCP).
SA... | g62470 | [
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<p>I want to construct a path analysis model that can account for measurement error in totally aggregated parcels, which refer to parcels where all of the items in a scale are summed or averaged. If I am not mistaken, Bollen (1989) advocates the following formula for computing the error variance of each parcel:</p>
<p... | g19575 | [
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<p>I've heard a couple of definitions of a Bayesian plot, but I am not 100% sure what it is and whether it is possible to plot this in an R.</p>
<p>An example of the plot is here: <a href="http://www.springerimages.com/Images/MedicineAndPublicHealth/1-10.1007_s11307-008-0154-3-1" rel="nofollow">http://www.springerimag... | g38639 | [
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<p>I am trying to classify texts using a bag of words algorithm. My feature vector is thus a large array of words. In order to build my feature vector, I parse the sample and put a one in the index corresponding to the word found. I use sparse format to represent the feature vectors. A little example to clarify:</p>
<... | g19576 | [
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<p>It is fairly easy to figure out what is the average number of rolls it would take to roll all faces of a die [$1 + 6/4 + 6/4 + 6/3 + 6/2 + 6/1 = 14.7$], but that got me thinking of a seemingly more complicated problem.</p>
<p>If you roll a die 1-5 times, the odds of <em>all</em> faces showing is obviously 0.
If you... | g62471 | [
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<p>I am working on a project where I need to chart statistical data and related, skewed distributions a la <a href="http://en.wikipedia.org/wiki/Skew_normal_distribution" rel="nofollow">http://en.wikipedia.org/wiki/Skew_normal_distribution</a>.</p>
<p>Unlike with normal distributions, in these charts, when there is sk... | g62472 | [
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<p>I need to reproduce this code using all of these variables.</p>
<pre><code>composite <- read.csv("file.csv", header = T, stringsAsFactors = FALSE)
composite <- subset(composite, select = -Date)
model1 <- lm(indepvariable ~., data = composite, na.action = na.exclude)
composite is a data frame with 82 variab... | g62473 | [
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<p>My original data has many more columns (features) than rows (users). I'm trying to reduce the features of my SVD (I need all of the rows). I found one method of doing so in a book called "Machine Learning in Action" but I don't think it will work for the data I am using.</p>
<p>The method is as follows. Define SVD ... | g62474 | [
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<p>I want to test the hypothesis that IV 2 (post-test value) is a better predictor for the criteria (no success vs. success) than IV 1 (pre-test value). Those IVs are indicators for static vs. dynamic learning. I conducted a logistic regression analysis for both IVs seperately and it seems that IV 2 is indeed the bette... | g5378 | [
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<p>I was hoping somebody could help with determining the correct statistical test to use.</p>
<p>Basically a teaching session was done which assessed confidence and perceptions of handling a situation using 3 questions. Each question had a Likert Scale (1-5). The same 3 questions on the pre and post questionnaire.</... | g19578 | [
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<p>I need to test my data to see if it follows a normal distribution with specific mean and std like N~(mu, std) I know that this can be done by Kolmogorov-Smirnov test which has a function in both MATLAB and R but the default for these function is standard normal and I do not know how should I specify my mu and std i... | g19580 | [
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<p>Just a quick introduction, I'm rubbish at stats.
I asked a question before which was very well answered but I have since modified the experiment in a way that confuses me as to which test I should use.</p>
<p>So in the previous question we finished concluding that an independent t-test would be suffice as I am comp... | g62475 | [
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<p>I am doing a work to school in which I have to analyze effect of expenditure for research and development on Gini index. I have <em>Panel data</em> and when I do <em>Fixed effect model</em>, I have problem with interpreting them. If anybody can help, I am looking for some place where I can find what each of the resu... | g19581 | [
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<blockquote>
<p>Suppose a researcher was investigating gender-based wage disparities
across 10 different firms. The researcher obtained the following data
from these 10 companies employees: 1) years of experience; 2)
education; 3) gender; and 4) the employees’ company. Suppose the
researcher is interested in ... | g62476 | [
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0.0... |
<p>I have a fundamental question: is it reasonable to use a statistical test to find out if 2 datasets are similar or not? Some comments have called out the T-test as being unable to answer that question. Why is the T-test insufficient? Furthermore, what other tests are there to determine differences in distributions f... | g62477 | [
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0.0517788901925087,
0.0054... |
<p>There is a sequence of data. It might have different types of trend, i.e., increasing, decreasing, and even cycling pattern. But there is an assumption that these trends should be smooth. (maybe not mathematically strict). In other words, there should not have a spike, or a sharp changing point; or the changing rati... | g62478 | [
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0.03807223215699196,
0.01... |
<p>Let's say there's a measurement hierarchy for discrete variables, that looks like nominal (grade pass/fail) < ordinal (grade A/B/C) < interval (grade 90-100; 80-89; 70-79, etc). Hierarchy is used to refer to the possiblity that we can assign order to the discrete values.</p>
<p>I read a line that methods appl... | g19585 | [
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0.04405910521745682,
0.005074368789792061,
0... |
<p>I'm trying to build a weekly alert system to let me know when something unusual has happened in my analytics data that might require further investigation. Currently there is an outdated system in place that only looks at week over week % increase, which obviously is not working.</p>
<p>Let's think about the only m... | g62479 | [
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0.0022818611469119787,
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-0.... |
<p>I am trying to predict the time to certain type of failure given the following data on Certain Factory Equipments. The data I have are readings collected every day for sensor installed on those equipments .On Same day, an equipment can have different Repaires performed,and on some days no repairs. When a repair is p... | g62480 | [
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... |
<p>One month before the election, a poll of a large number of randomly selected voters showed 65% planning to vote for a certain candidate. The newspaper article reported a 90% conservative margin of error of 4 percentage points.</p>
<p>Use the above information to construct a 90% conservative confidence interval for ... | g19587 | [
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0.026196865364909172,
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... |
<p>This is probably a really basic question, but it's the first time I've created a model that defines Poisson as its error family. </p>
<p>In setting up my variables to make the model, should I be concerned about whether or not predictor variables are normally distributed, and if not, should I be attempting to transf... | g62481 | [
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... |
<p>I have the following study setup:</p>
<p>Three groups of people were asked a question, and the answer was ordinal (likely, somewhat likely, somewhat unlikely, unlikely). In my data set, I have a contingency table between the response and groups, and would like to know whether some of the groups of people were more ... | g38660 | [
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0.07667204737663269,
0.03720315918326378,
0.0014028694713488221,
... |
<p>I want to perform a simulation study where I want to use gamma random variable
as the test statistic for some test. Does anyone know a hypothesis test whose
test statistic has a gamma distribution.</p>
<p>Thank you very much.</p> | g19589 | [
0.01786447875201702,
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0.05763833969831467,
0.03157445043325424,
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-... |
<p>Instead of this simplified-version of this <a href="http://matplotlib.sourceforge.net/plot_directive/mpl_examples/pylab_examples/histogram_demo_extended.py" rel="nofollow">file</a>:</p>
<pre><code>#!/usr/bin/env python
import numpy as np
import pylab as P
data = [x.rstrip().split("\t") for x in file(".data", "r")... | g62482 | [
-0.012120676226913929,
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-0.06291788071393967,
0.011315764859318733,
0.031483232975006104,
0.06890513002872467,
... |
<p>I fit a logistic on three numeric continuous variables, followed by a categorical factor [Y, N].</p>
<pre><code>logit2A <- glm(DisclosedDriver ~ VehDrvr_Dif+POL_SEQ_NUM+PRMTOTAL+SAFE_DRVR_PLEDGE_FLG, data = DF, family = "binomial")
</code></pre>
<p>Fit looks wonderful.</p>
<pre><code>Coefficients:
... | g133 | [
0.0047137923538684845,
-0.03363977372646332,
-0.004065013024955988,
-0.026997704058885574,
0.040865734219551086,
-0.022770432755351067,
0.05078815296292305,
0.04285081848502159,
-0.062407031655311584,
-0.06624138355255127,
-0.057516638189554214,
0.01571761816740036,
0.028178006410598755,
-... |
<p>I came across <a href="http://web.mit.edu/~wingated/www/introductions/mcmc-gibbs-intro.pdf" rel="nofollow">this article</a> where it says that in Gibbs sampling every sample is accepted. I am a bit confused. How come if every sample it accepted it converges to a stationary distribution.</p>
<p>In general Metropoli... | g62483 | [
0.06341686099767685,
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0.029643461108207703,
0.0059010679833590984,
0.0704808235168457,
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-0.02371469885110855,
-0.01008076686412096,
0.0259457528591156,
0.04211168363690376,
0.010... |
<p>Canonical correlation analysis (CCA) is a technique related to principal component analysis (PCA). While it is easy to teach PCA or linear regression using a scatter plot (see a few thousand examples on google image search), I have not seen a similar intuitive two-dimensional example for CCA. How to explain visually... | g62484 | [
0.054754838347435,
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0.09259520471096039,
0.012787104584276676,
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-0.06334929168224335,
0.0517582967877388,
0.035541120916604996,
0.056331850588321686,
0.03018... |
<p>Consider a multiple regression predicting outcome <code>Y</code> using a continuous predictor <code>P</code> and an interaction between <code>P</code> and a group variable <code>G</code> with the values 0, 1, and 2. We create two interaction variables, <code>PxG1</code> (set to P when G is 1 and 0 otherwise) and <co... | g62485 | [
-0.004550248850136995,
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0.03072955459356308,
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0.030356762930750847,
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0.012729714624583721,
0.03337616100907326,
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0... |
<p>I am looking for a fast approximation to the inverse CDF of the Beta distribution. The approximation need not be precise, but more stress is on simplicity (I'm thinking Taylor expansion of the first 1 or 2 terms). Any ideas?</p>
<p>A few more details: in my Beta distribution, $a,b$ are integers. Also the value I am... | g62486 | [
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0.007862774655222893,
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0.00852237083017826,
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-0.03947974741458893,
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0.057762786746025085,
-0.041493773460388184,
... |
<p>In some sense the multivariate normal is the "nicest" distribution that we can describe using only a vector (rank one tensor) and a symmetric positive definite matrix (rank two tensor).
$$\mathcal{N}(\mu_i, \Sigma_{ij}) = |2\pi\Sigma|^{-\frac{1}{2}}e^{-(x-\mu)^T\Sigma^{-1}(x-\mu)}$$</p>
<p>Is there a generalizati... | g37464 | [
0.01137822587043047,
-0.014166499488055706,
-0.020805569365620613,
-0.018734563142061234,
-0.01744842901825905,
-0.018431812524795532,
0.005526495631784201,
-0.040044866502285004,
-0.02703779563307762,
0.032084871083498,
0.012324046343564987,
0.03019379824399948,
0.02206171303987503,
-0.05... |
<p>I have 20 correlation coefficients (r) to report, for example, .34, .45, .67, .23. and so on. These are correlations between Variable A and Variable B, based on gender, age, education levels etc. </p>
<p>I am after a succient method to show all the correlations in one glance. Is there any best practice in regard to... | g62487 | [
0.04843929782509804,
0.009896847419440746,
0.00854557380080223,
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0.0023557147942483425,
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-0.025374749675393105,
0.03308409824967384,
-0.04632405564188957,
0.0530976839363575,
0.0... |
<p>I have an intuition that re-casting the <a href="http://en.wikipedia.org/wiki/Poisson_binomial_distribution" rel="nofollow">Poisson binomial distribution</a> probability mass function in the following way might lead to a more elegant closed form than the DFT approach:</p>
<p>Sum the $\log_2$'s of the probabilities ... | g62488 | [
-0.028872050344944,
0.010782686993479729,
-0.0035469753202050924,
-0.00961768813431263,
-0.018081462010741234,
-0.0542316697537899,
-0.020915964618325233,
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-0.038704726845026016,
-0.05271946266293526,
0.00022771656222175807,
0.016196217387914658,
... |
<p>I have a question on how a statistician would normally interpret an anova output. Say I have anova output from R.</p>
<pre><code>> summary(fitted_data)
Call:
lm(formula = V1 ~ V2)
Residuals:
Min 1Q Median 3Q Max
-2.74004 -0.33827 0.04062 0.44064 1.22737
Coefficients:
E... | g49562 | [
0.023196134716272354,
-0.01620413362979889,
-0.00663936510682106,
-0.001985112437978387,
-0.03427771106362343,
0.015820031985640526,
0.062291789799928665,
0.025395318865776062,
-0.015055864118039608,
-0.004922426771372557,
-0.05014656484127045,
0.043031927198171616,
0.059202488511800766,
0... |
<p>I performed two principal components analyses: in R and in SPSS - using the same dataset and the same variables. I got the same results - at least to some point. The eigenvalues are the same (I used the correlation matrix in both cases, no rotation), but the loadings are different.</p>
<p>I decided to take a look a... | g19599 | [
0.012417193502187729,
-0.047195665538311005,
-0.009119346737861633,
-0.0956088975071907,
-0.014482386410236359,
-0.0077621908858418465,
0.059857264161109924,
-0.009762316010892391,
-0.01979060471057892,
-0.012304766103625298,
0.012257437221705914,
0.023777740076184273,
0.020805973559617996,
... |
<p>The Beta distribution has the PDF:</p>
<p>$$f\left(x\right)=\frac{x^{\alpha-1}\left(1-x\right)^{\beta-1}}{\mathrm{B}\left(\alpha,\beta\right)}$$</p>
<p>for $0<x<1$, and $f(x)=0$ otherwise. The parameters $\alpha,\beta$ are positive real numbers.</p>
<p>The mean and variance are given by:</p>
<p>$$\mu=\frac... | g62489 | [
-0.027849599719047546,
-0.03871921822428703,
-0.02583879418671131,
-0.06243428587913513,
0.07683255523443222,
0.0024205625522881746,
0.0031711687333881855,
0.03802276402711868,
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-0.026177391409873962,
-0.040511444211006165,
0.07185004651546478,
-0.050697024911642075,
0... |
<p>Consider the companion papers by Clayton & Schifflers (1987) here: <a href="http://www.pauldickman.com/cancerepi/handouts/handouts_time_trends/clayton_schifflers_1987a.pdf" rel="nofollow">http://www.pauldickman.com/cancerepi/handouts/handouts_time_trends/clayton_schifflers_1987a.pdf</a>, <a href="http://www.paul... | g19601 | [
-0.0044107199646532536,
-0.05356437340378761,
-0.03223728761076927,
-0.03424469009041786,
0.021532481536269188,
0.04306066408753395,
0.07562018185853958,
0.01798447221517563,
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-0.0027661737985908985,
0.010050605051219463,
0.02135121263563633,
0.046548567712306976,
0.00... |
<p>I have a Pandas data frame as follows:</p>
<p>Event Location| Number of events | %age success</p>
<p>A | 10 | 0.5</p>
<p>B | 2 | 1</p>
<p>C | 1 | 0</p>
<p>D | 100 | 0.3</p>
<p>E | 1 | 0</p>
<p>F | 1 | 1</p>
<p>...</p>
<p>...</p>
<p>The data represent the entire population of events. I am looking for a way... | g62490 | [
-0.013463054783642292,
0.045156728476285934,
0.004981879144906998,
-0.048553358763456345,
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0.03581994026899338,
0.07560046762228012,
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-0.05575796961784363,
0.008397378958761692,
0.004414507653564215,
0.05911397933959961,
-0.... |
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