question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>It seems there are two formulas to perform a wilcoxon signed rank test - one where the sum of all the signed ranks is w and another where the minimum of the sum of the negative ranks and positive ranks is used. Could someone please explain the difference and which one is the more appropriate method?</p> | g268 | [
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<p>I am using the Mahalanobis distance to classify an unknown 64-dimensional vector into one of 75 classes. There are n samples of 64-dimensional vectors for each class, arranged into an Nx64 matrix format. Reading this into Matlab with no problem.</p>
<p>However when the 64x64 covariance matrix is calculated using th... | g22204 | [
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<p>I have an unbalanced panel dataset with N=10 firms and T=61 days. Because one variable had values outside the theoretical range I had to constrain my dataset, which left me with only 239 observations. This means on average 23.9 observations per firm and on average 3.92 observations per day.</p>
<p>I'm explicitly co... | g64191 | [
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<p>We have a population of unknown size. Each element has a class A or B. We are trying to estimate the proportion of A's in the population. We can randomly sample from the population and for each element in the sample we can apply a test which will either tell us if the sample is of class A or B but in certain cases t... | g64192 | [
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<p>I am trying to develop a Generalized Linear Model (GLM) in which the dependent data is a
proportion data with 4 categories. I want to develop this model as an
alternative method to Multinomial Logit Model for comparison of
results. Here is the sample data. </p>
<pre><code>Category SharesY x1 x2
1 0.80 7480 628
2 0.... | g22206 | [
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<p>I want to fit a multilevel GLMM with a Poisson distribution (with over-dispersion) using R. At the moment I am using <a href="http://cran.r-project.org/web/packages/lme4/index.html">lme4</a> but I noticed that recently the <code>quasipoisson</code> family was removed. </p>
<p>I've seen elsewhere that you can model ... | g64193 | [
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<p>If I have a dataset of $N$ pairs ($x_i$,$y_i$) where each $y_i$ has an individual error $\sigma_{y_i}$, I can incorporate this into regression by using the inverse of this as weights.</p>
<p>If I now do logarithmic regression $\ln y_i = b_0 + b_1\,\ln x_i + \epsilon_i$, how do I incorporate now the errors? Are the ... | g41714 | [
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<p><em>note:</em> This question was inspired by <a href="http://stats.stackexchange.com/q/30763/2750">Assessing the accuracy of a deterministic mathematical model</a>. I have tried to give a more explicit example and specific question.</p>
<hr>
<p>A meteorological model that predicts the weather is deterministic, so ... | g64194 | [
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<p>I have thought for a while about this, and I'm not entirely certain what the difference is between a deterministic model and a probabilistic model with error following a degenerate distribution (centered at 0). I'm starting to think that there is a very important difference, especially with respect to analysis and m... | g22209 | [
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<p>I have some genotyping (~half a million response variables) data that was run in 4 batches (190 total samples, spread over 4 batches). The samples are from a case-control study (95 cases, 95 controls). Unfortunately, whoever set up the batches did not randomly distribute the cases and controls (e.g. batch 4 had only... | g22210 | [
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<p>Let's say I have a year's worth of magazine issues (January, February, March, etc), and I want to visualize the differences among them. The classic example of multidimensional scaling (MDS) would have a triangular matrix of subjective difference scores between each possible pair of magazine issues. MDS is then appli... | g22211 | [
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<p>I have a large aggregate market data set on wine sales in the U.S. and I would like to estimate the demand for certain high quality wines. These market shares were basically derived from a random utility model of the form
$$U_{ijt} = X’_{jt}\beta - \alpha p_{jt} + \xi_{jt} + \epsilon_{ijt} \equiv \delta_{jt} + \epsi... | g22212 | [
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<p>What book will teach the most rigorous way the regression analysis? I read as a mathematician myself, and now I have to improve my statistical skills to get a job. I would like to learn what kind of methods there are to measure how to fit model to data and why those methods work. I'm not afraid to work through proof... | g64195 | [
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<p>I ran two benchmark suites (X and Y) on two devices (D1 and D2). Device D1 complete the benchmarks after X1 and Y1 seconds and Device D2 in X2 and Y2 seconds.</p>
<p>I can very well calculateand& compare the relative performance in terms of speed of both the devices with-in the same benchmark X, e.g. if X1 (0.5... | g22837 | [
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<p>When is it preferable to use Maximum Likelihood Estimation instead of Ordinary Least Squares? What are the strengths and limitations of each? I am trying to gather practical knowledge on where to use each in common situations.</p> | g22215 | [
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<p>I am trying to classify the presence of a car in an image.For this purpose I have downloaded a Dataset containing the images of Cars.I need to know how to split this data-set into training,cross-validation and testing set.How to select which of the images to fall into what category(i.e. Testing Set or Cross Validati... | g22216 | [
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<p>I have a dataset of genomic information which I'm going to be comparing with various biochemical markers. Unfortunately a lot of the biochemical markers have limited ranges in their assays, so I have a lot of data that looks like "40", ">45", "35", ">45" for tests that have a threshold at 45 (for example).
My intend... | g41722 | [
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<p>I have some experience with both FLD and LR for classification. </p>
<p>On most data sets, I get very similar results, which raises the question - are FLD and LR related in some why? </p>
<p>An idea, for example, if I assume a normal distribution on the likelihood function instead a of a logistic function, does th... | g22217 | [
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<p>I am trying to compute inter-rater reliability for ranking multiple objects across multiple scenarios.</p>
<p>For example suppose for scenario A we had multiple objects and multiple raters like in the table below. </p>
<pre>
Object V W X Y Z
Rater1 2 1 3 4 5
Rater2 1 3 5 2 4
Rater3 ... | g64196 | [
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<p>First of all, my apologies if I mess up the terminology. I've been out of math for several years, so I'm certain I'm going to use terms incorrectly. Also, though I concentrated mathematics in college, I have lost those legs; I'm particularly braindead when it comes to remembering what means what with mathematical no... | g22219 | [
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<p>I have two independent sets of gene expression data (biological replicates) that were generated at the same time. Each gene is sampled dozens of times on the machine (technical replicates). Data are filtered for transcripts having expression values above background (p-values less that 0.05). I then export everything... | g22221 | [
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<p>I was reading <a href="http://en.wikipedia.org/wiki/Equicontinuity" rel="nofollow">this</a> wikipedia article. The article is about equicontinuity. And my first thought was the regression line. THis question is to more help me understand and to check my understanding. Please note, I am not very knowledgeable; how... | g64197 | [
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<p>Assume that we know the model of physical experience (for example - the pendulum is moving forward - then the position $s = vt + b\sin(t)$, where $t$ is time and $v$ and $b$ do not matter). </p>
<p>We have measured some points. We can predict (forecast) next points, but how to measure the confidence interval of pre... | g41730 | [
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<p>I have a problem, where I need to learn a classifier (such as SVM) such that all the learned weights to be non-negative due a constraint on the classifier function. </p>
<p>I found out that "SVM Struct" is able to do as mentioned in the comments inside some of their source codes. But, I'm still unable to find any r... | g22223 | [
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<p>Here, I am using RBF function of SVM for fingerprint verification and matching. Please tell me What is the approximate range of sigma and gamma values in RFB for fingerprint recognition.</p> | g41735 | [
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<p>I've read in the library manual for test <code>ks.test</code> that</p>
<blockquote>
<p>The possible values "two.sided", "less" and "greater" of alternative specify the null hypothesis that the true distribution function of x is equal to, not less than or not greater than the hypothesized distribution function (on... | g64198 | [
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<p>I have some spatially autocorrelated vegetation data, and would like to know the how well tree size measured at one location can predict tree size in plots 100m away. </p>
<p>I've made a semivariogram of the data, but am wondering if I can calculate an R squared value from this? From my (basic) understanding, I'm t... | g64199 | [
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<p>I want to use the time a user spends viewing an article as an implicit rating of how much the user likes the article. My question is how do I normalize this information across all users. At the moment, I'm subtracting the time spent by the user-specific mean, and dividing by the standard deviation.
Is this the right... | g64200 | [
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<p>Given a set of points <code>(x,y)</code>, I would like to create K clusters of these points similar to the k-means algorithm. The difference is that I would like to define the number of points contained in a cluster, in my situation I would like them to all be equal. For example, take 30 points and put them into 3 s... | g37820 | [
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<p>I am currently carrying out an investigation to find if certain factors such as playing home or away or position of a footballer affects overall pass completion using logistic regression. I am using R to compute my data. In my current section in which I am trying to analyse uses the data of every player to convey a ... | g22225 | [
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<p>I have an estimator $t$, whose variance depends on the dimension of
my sample $x_{1:n}$:</p>
<p>$$
\text{Var}(t(x_{1:n})) = f(n).
$$</p>
<p>Suppose that the form of $f(n)$ is known. I would like to determine
what is the optimal sample size $n$, given that every sample has a cost $c$. </p>
<p>I was considering:</p... | g22227 | [
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... |
<p>What does the ridge parameter change in a Logistic Regression classifier as for example implemented in <a href="http://weka.sourceforge.net/doc.dev/weka/classifiers/functions/Logistic.html" rel="nofollow">Weka Logistic classifier</a> "Parameter -R ridge". The paper describing the underlying theory: <a href="http://s... | g22228 | [
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<p>Using the following code, I tried to draw four plots on a graph in <code>R</code>. I am not happy with the figure because there is a lot of space between the plots, therefore the width of the plots are not sufficient enough to analyze the plots. </p>
<ol>
<li><p>Could someone help me to produce a nice graph having... | g22229 | [
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<p>I am currently working with a data set that contains about 26 IVs of almost all sorts of scale of measurement (binary, nominal, ordinal and interval scale variables). There are strong reasons to suspect that some variables are probably highly correlated, while some may not be related to any other IVs to a great exte... | g37697 | [
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<p>Let's say I'm polling for a binary election in different states with known biases. Furthermore, let's say I only manage to poll only a small sample of people in each of these states. How would you combine the results to come up with the best estimate for the election? </p>
<p>My best guess is the normalized vote is... | g22231 | [
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<p>I have several exercises to solve that deal with sample space of PMF.</p>
<p>One is:</p>
<p>Let $X_1,\dots , X_n$ be independent random variables with pmf $p(x;\pi) = (1-\pi)^x \pi$</p>
<p>What is the sample space of $X_1?$ Try to give a probabalistic interpretation of such a sample space. Hint: for example. a Be... | g22232 | [
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<p>Is it possible for a binary classifier to have a recall of <code>0.0</code> for one of the classes and
at the same time an area under the ROC curve (AUC) of <code>1.0</code> for the same class?</p> | g22233 | [
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<p>I am trying to perform some logistic regressions (and I am a neophyte user of R). Initially I used "glm" to compute coefficients, AIC and p-values; this worked great until I ran across a data set suffering from <a href="http://en.wikipedia.org/wiki/Separation_%28statistics%29" rel="nofollow">complete separation</a>... | g22234 | [
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<p><strong>Question:</strong> Assume a bivariate GARCH process as follows:
\begin{align} r_{mt} &= \sigma_{mt}\epsilon_{mt} \ \ \ \cdots \ \ \ \text{(1)} \\ r_{it}&=\sigma_{it}\rho_{it}\epsilon_{mt}+\sigma_{it}\sqrt{1-\rho_{it}^2}\xi_{it} \ \ \ \cdots \ \ \ \text{(2)} \\ (\epsilon_{mt}, \xi_{it}) & \sim S ... | g64201 | [
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<p>A person from group A has 20% chance of having some characteristic</p>
<p>A person from group B has 30% chance of having the same characteristic</p>
<p>How can I calculate the probability of a person belonging to both groups having the given characteristic?</p>
<p><strong>edit</strong></p>
<p>Since a number of p... | g22236 | [
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<p>I have a case and control group, both of which had a blood sugar level tested multiple times over 48 hours. I took the mean of the levels for each person and then calculated the mean of the means (with an SD etc) to compare the two groups. I am not sure if this is a valid method for comparison and whether another me... | g64202 | [
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<p>I am trying to understand the concept of conditional likelihood in the context of logistic regression. </p>
<p>One paper I am reading defines $L(\theta; y|x) = f(y|x; \theta)$, then goes on to point out that there may be different distributions $f(y|x; \theta)$ for every different $x$, and also that these different... | g64203 | [
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<p>I'm trying to apply a <code>polynomial approximation</code> for a given function (via Genetic Algorithms), and so far the results are not so good:</p>
<pre><code> # or any other GA package
require(gaoptim)
# for polyval
require(pracma)
# polynomial of degree 10
ndeg = 10
ndim = ndeg + 1
# search... | g64204 | [
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<p>The summary of my GLM shows day 12 of factor Date to be significant, but anova(model, test="Chisq") shows Date to be not significant overall. I know how to report the statistics from the Chisq table, but as I have z values in the summary table I am unsure how to report, or if I should report, that day 12 is signific... | g22237 | [
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<p>I need to perform stepwise binary logistic regression (The horror! The horror!) on 1.5 million observations. This takes far too long in SAS, so I'm wondering if I can use R to process it in a multicore environment. Apparently package gmulti (<a href="http://www.jstatsoft.org/v34/i12/paper" rel="nofollow">http://ww... | g64205 | [
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<p>I have done a data analysis trying to cluster longitudinal data using R and the <a href="http://cran.r-project.org/web/packages/kml/">kml</a> package. My data contains of around 400 individual trajectories (as it is called in the paper). You can see my results in the following picture:</p>
<p><img src="http://i.sta... | g64206 | [
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<p>This is probably a pretty simple question, but I have been having some trouble interpreting the documentation for the <code>predict</code> function.</p>
<p>I am generating a simple linear model from a data frame containing (X, Y) pairs, which I would then like to use to predict Y given new X. My code looks somethin... | g64207 | [
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<p>I want to jointly estimate a very simple MV-Normal two-dimensional AR[1] process,
$[x_t,y_t]=[x_{t-1},y_{t-1}]+\text{[Bivariate Gaussian error]}$, in BUGS. But the syntax has been impossible to figure out. Here's the problem part of the code:</p>
<pre><code> ## transition model (aka random walk prior)
for(i in 2:... | g22238 | [
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<p>Is there a way to give (in R or Minitab or Statgraphics) a fractional factorial design like that and inspect the generators and the complete defining relation ($2^4 - 1$ relations)? </p>
<pre><code>A B C D E F G H
-1 1 1 1 -1 -1 1 -1
-1 -1 -1 1 1 1 1 -1
-1 1 1 -1 1 1 ... | g41749 | [
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<p>You are likely all familiar with Polya Urn process. I initially start with an urn containing $b$ black balls and $w$ white balls. At each step, I sample a black ball with probability $\frac{b}{b+w}$ (alternatively, a white ball with probability $\frac{w}{b+w}$), then put back the same ball and another of the same ... | g43214 | [
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<p>$\DeclareMathOperator{\E}{\mathrm{E}}$</p>
<p>An investor has $\$100,000$. When the current interest rate is $i$% (compounded continously so that the growth per year is $e^{i/100}$) she invests her money in an $i$ year CD, takes the profits, and then immediately reinvests the $\$100,000$. Suppose that the $k$th inv... | g22241 | [
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<p>This is one necessary part of a slightly larger problem, but this part has me stumped.</p>
<p>We have that $X_1, X_2, ..., X_n\stackrel{iid}{\sim} U(0,\theta)$. What is the joint density of the first observation and the maximum order statistic: $f_{X_1,X_{(n)}}(s,t)$?</p>
<p>Is this doable, any ideas? Many thanks ... | g64208 | [
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<p>I'm trying to do some percentage based comparisons across different groups in a criminal sentencing data set (http://dl.dropbox.com/u/1156404/wightCrimRecords.csv)</p>
<p>I have a data in an array of the form:</p>
<pre><code> $Female
x
Burglary Criminal Damage an... | g41755 | [
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<p>I have a dataset with the following variables:</p>
<ul>
<li>Treatment : (fixed,3 levels) </li>
<li>Location : (fixed, 4 levels) </li>
<li>Sample (random, 5 levels): 5 samples are taken in each location (randomly) </li>
<li>Subsample (random - 3 levels): 3 subsamples are taken in each sample. One treatment is assig... | g64209 | [
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<p>The Ubuntu Software Center uses a 1 to 5 star rating system for its App Reviews. However, it's current ratings sorting algorithm <a href="https://bugs.launchpad.net/ubuntu/+source/software-center/+bug/894468" rel="nofollow">looks very fishy</a>. I believe this is a different question from <a href="http://stats.sta... | g64210 | [
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<p>I need to compute the estimate the variance component for my data.</p>
<p>I have the following model, y = gene, cell line, gene*cell line, DNA extract[cell line]</p>
<p>How do I write this for the lme function? I am confused on how to indicate that "DNA extract" is nested within "cell line" and also have it marke... | g64211 | [
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<p>Can you calculate the Standard Error of the Mean (SEM) for a set of data given the SEM from two subsets of the data? How would you do this?</p>
<p>(The two subsets are mutually exclusive and exhaustive.)</p>
<p>Let's say I have the mean and SEM for both men and women on some test, but I do not have access to the ... | g64212 | [
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<p>I am working with an ANOVA model. I want to run a fixed effects ANOVA in which I have a ratio dependent variable and three independent variables with two and three levels. Obviously, before analyzing the results, I want to check the assumptions of factorial ANOVA. Reviewing some handbooks, I found some divergences i... | g64213 | [
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<p>In a questionnaire, I have asked some Likert scale questions. These questions were asked to the same population 6 years ago in another study. I only have the mean scores and standard deviation of the old study. Is there a way to compare the answers of my study to that of the old one statistically? </p>
<p>I have li... | g18523 | [
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<p>Suppose I have a fleet of two-car trains riding around, and that each car is equipped with a data recording device. Unfortunately, some of the recording devices aren't working. I don't know either the exact size of the fleet or the percentage of failed recording devices. I'd like to make a reasonable guess about how... | g41760 | [
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<p>Greetings,</p>
<p>I'm performing research that will help determine the size of observed space and the time elapsed since the big bang. Hopefully you can help!</p>
<p>I have data conforming to a piecewise linear function on which I want to perform two linear regressions. There is a point at which the slope and inte... | g64214 | [
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<p>If I search for "HOTT homotopy type theory" on youtube, I find numerous (advanced/state-of-the art) academic lectures on the topic.</p>
<p>For instance the following lectures are found on youtube:<br>
<a href="http://www.youtube.com/watch?v=O45LaFsaqMA" rel="nofollow">http://www.youtube.com/watch?v=O45LaFsaqMA</a><... | g64215 | [
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0.0059394268319010735,
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0.0198910403996706,
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0.08960814028978348,
0.0... |
<p>Given $n$-vectors $x, y_1, y_2$ such that the Spearman correlation coefficient of $x$ and $y_i$ is $\rho_i = \rho(x,y_i)$, are there known bounds on the Spearman coefficient of $x$ with $y_1 + y_2$, in terms of the $\rho_i$ (and $n$, presumably)? That is, can one find (non-trivial) functions $l(\rho_1,\rho_2,n), u(\... | g22251 | [
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0.01758314110338688,
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0.08301632851362228,
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0.... |
<p>I am trying to do time series modeling and forecasting using R based on weekly data like below -</p>
<pre><code>biz week Amount Count
2006-12-27 973710.7 816570
2007-01-03 4503493.2 3223259
2007-01-10 2593355.9 1659136
2007-01-17 2897670.9 2127792
2007-01-24 3590427.5 2919482
2007-0... | g22252 | [
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0.0728883296251297,
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0.05883965268731117,
-0.0145... |
<p>I want to set up a simple JAGS model using matrix multiplication, but I am not sure how to set up the matrices. My overall equation is $c=yx$ where $c$ is a 2x1 matrix defined in R of observed data values, $y$ is a 2x2 matrix of prior distributions, and $x$ is a 2x1 matrix of values to be estimated with the prior of... | g64216 | [
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0.07100095599889755... |
<p>We collected data from 40 animals in which we recorded the total time the animal spent in each of the 3 possible chambers. Thus, for each animal, we have three times (one for each chamber) and those 3 times add up to 10 minutes. Does anyone have any recommendations on statistical test that incorporates the magnitu... | g22254 | [
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0.03876598924398422,
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... |
<p>I inherited some old programming code for a scoring mechanism and I am trying to understand it.</p>
<p>The premise is that every user $u$ has receives many ratings from other users, all in the range $[0, 1]$. We store all of user's ratings in a list $L$.</p>
<p>The code then computes this "score" for the user $u$:... | g22256 | [
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0.009777288883924484,
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0.023646803572773933,
0.0328398235142231,
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<p>Suppose I have two datasets $y1$ and $y2$ sampled equally on $x$. I would like to bring $y2$ in register with $y1$ in a least-squares sense, and referenced to one point at $x_{ref}$ in $y1$ (i.e. the point $y2$ at $x_{ref}$ should be the same as $y1$ at $x_{ref}$.</p>
<p>How would go I about doing that? </p> | g64217 | [
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0.05931759253144264,
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0.0... |
<p>I was doing one of the Papoulis problems and got a bit confused if I got it right, because as you will see in the end, the conditions given in the problem can be relaxed and still be obtained.</p>
<p>The problem is to calculate $P(A\overline{B}+B\overline{A})$ given that $P(A) = P(B) = P(AB)$.</p>
<p>The Papoulis ... | g22258 | [
0.0028745748568326235,
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0.039... |
<p>I have a series of observations that fall into bins (or "scores"); that is, the data can be 0, 1, 2, 3 or 4. There are two groups of such data, control and treated. I know the number of individuals with each score for each group. </p>
<p><strong>What is the best way to determine whether these groups are differen... | g46149 | [
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0.024130135774612427,
0.0040919603779911995,
0.... |
<p>I have a problem with the normality of some data I have:
I've done a Kolmogorov test which says it isn't normal with p=.0000,
I don't understand: the skewness of my distribution =-.497, and the kurtosis =-0,024</p>
<p>Here is the plot of my distribution which looks very much normal ...</p>
<p>(I have three score... | g49695 | [
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0.02109166793525219,
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<p>I am learning about AB testing using the G-test. In my example, I have a 2x2 contingency table.</p>
<pre><code>>print(T)
response
AB no yes Sum
A 29 7 36
B 23 16 39
Sum 52 23 75
</code></pre>
<p>Event A is the red background of a website. Event B is the blue background of a website. I... | g22260 | [
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<p>I am trying to use Random Forest to accurately predict forested land cover classes using Landsat 7, climatic and geographical data. I have 23 predictor variables and 1 response variable. When I drop the least important predictor variables as reported by the Random Forest variable of importance list, I get what seems... | g22261 | [
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<p>I have a question about SAS and R. For a research, I used a longitudinal data and I initially used SAS (<code>GLIMMIX</code>) and then I analyzed the data with R (<code>glmer</code>) programming. There are differences between p-values of SAS and R. I expected that regression coefficient and standard error could be d... | g22262 | [
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-... |
<p>Due to an assignment I need to implement a algorithm based on <em>KDE</em> to schedule an input data in different servers.</p>
<p>So far, I studied statistics in my bachelor but we did not go that far and they did not explain me about estimation functions and Kernel. So my questions are the next:</p>
<p>Assuming t... | g64218 | [
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0.03303544223308563,
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0.04441111907362938,
0.07171949744224548,
0.0464... |
<p>In my book (<em>Introduction to data mining</em> by Tan, Steinbach and Kumar - chapter 3), in the section about visualization, it's written:</p>
<blockquote>
<p>Another general motivation for visualization is to make use of the domain knowledge that is "locked up in people's heads." While the use of domain knowle... | g22263 | [
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<p>I was just thinking how ML techniques can be applied in the retail industry. Suppose we have data from a retailer who deals with apparel and cloth in this format
and for each item there are pre-defined features, for example a shirt will have features like color, half/full sleeves etc.. I want to understand how to e... | g64219 | [
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<p>I will defend my Master's thesis on Thursday, and I have a doubt about an analysis that I have to present. In my experiment, I had two independent variables: </p>
<ol>
<li>Age category (SU = senior unemployed subjects and YU = young unemployed subjects) </li>
<li>Experimental condition (ST = stereotype threat; NST... | g64220 | [
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<p>I have a question connected with this exercise. In question a) I am supposed to calculate the probability using this formula $P(A \text{ and } B)=P(A) \times P(B|A)$. I think there is not enough data. Can anybody please help me?</p>
<p>In March 2005, the Australian government announced that an extra 450 troops woul... | g64221 | [
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<p>Imagine a regression model where there is a continuous-valued response variable and three continuous-valued explanatory variables. For concreteness, imagine that we are interested in the effects of "Predictability," "Length," and "Frequenty," on the reading times "RT" of words. </p>
<p>Suppose further that we know ... | g64222 | [
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<p>Causal diagrams are extremely good tools for discussing research plans for multivariate modeling between statisticians and non-statisticians. It's easy after some deliberation to decide which variables should go into a model based on their classification as confounders, precision variables. At least this applies ins... | g16604 | [
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<p>I have a sample of 2000 projects randomly extracted from a population of 10,000,000 following an exponential distribution. From this sample I would like to check if a statistical dependency exists between the number of lines of code and the number of users.</p>
<p>Instead of comparing these two features with Spearm... | g64223 | [
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0.013571569696068764,
... |
<p>How can I summarize the confidence intervals for several levels of factors?</p>
<p>This is what I got:</p>
<pre><code>interest rate (1.280393e+01 16.1980844628);
fico range 645-649 (-3.581231e+00 1.9591171919);
fico range 650-654 (-4.533451e+00 3.7764777115);
fico range 655-659 (-2.797205e+00 2.291494709... | g64224 | [
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0.06267894059419632,
0.05046743154525757,
... |
<p>Hi I have experimental observations that look like this.</p>
<p><img src="http://i.stack.imgur.com/XF2dM.png" alt="enter image description here"></p>
<p>The output is not a function of concentration, so I thought within each experiment they could just be considered repeated observations. However the machine figure... | g64225 | [
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0.008261268958449364,
0.08859491348266602,
0.036... |
<p>I adopt a within-group experiment, such that the same participant uses 3 devices to perform a task, which has a result "pass" or fail.
My data looks like this:</p>
<pre><code> Pass Fail
deviceA 21 13
deviceB 15 20
deviceC 9 25
</code></pre>
<p>My questions are:</p>
<ol>
<li>Is McNemar's te... | g64226 | [
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0.0... |
<blockquote>
<p>Derive $IF(x;T,F)$ when
$$\displaystyle T(F)=\int_{F^{-1}(\alpha)}^{F^{-1}(1-\alpha)}x ~dF(x)$$
Here $IF$ stands for Influence function.</p>
</blockquote>
<p>Trial: Here $$\begin{align}IF(x;T,F) &=\lim_{t\to 0}\frac{T((1-t)F+t\Delta_x)-T(F)}t \\ &=\lim_{t\to 0}\frac{g(t)-g(0)}t=\frac{d}{... | g64227 | [
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0.056368228048086166,
0.055099934339523315,
0.01617... |
<p>There are two methods which produce different ranking of a group of hypotheses.
I want to compare the two methods showing that one method generally produces
lower ranking than the other method for a specific subset of the considered group of
hypotheses. I was thinking of comparing the quantiles of the two rankings ... | g22266 | [
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0.018991371616721153,
0.04462425410747528,
0.015636160969734192,
0.059126853942871094,
0.06... |
<p><strong>Question:</strong> What is a quadravariate distribution?</p>
<p><strong>Motivation:</strong> I found a reference to quadravariate distributions in <a href="http://books.google.com.au/books/about/Spectral_analysis_and_time_series.html?id=olYZAQAAIAAJ" rel="nofollow">Priestley (1981) <em>Spectral Analysis and... | g64228 | [
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0.005028436426073313,
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... |
<p>I am performing K means clustering on a gene expression dataset.
I am aware of the fact that the Pearson correlation metric allows to group trends or patterns irrespective of their overall level of expression. I was wondering if the same concept stands for Covariance metric (I believe that the only difference betwee... | g22267 | [
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0.008387114852666855,
0.05490913242101669,
0.... |
<p>I have been working in R for a bit and have been faced with things like PCA, SVD, QR decompositions and many such linear algebra results (when inspecting estimating weighted regressions and such) so I wanted to know if anyone has a recommendation on a good comprehensive linear algebra book which is not too theoretic... | g22269 | [
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-... |
<p>I have a set of $N$ high-dimensional vectors. I use some approximation routine to make my output faster. Now I would like to evaluate the error of the approximation.
Typically I use the RMSE to compute errors, but I'm getting stuck here on how to do it right.</p>
<p>For each vector $\vec x_i \in \mathbb R^D$ I have... | g64229 | [
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0.09460607171058655,
0... |
<p>How does one choose between the two? How do you decide which one is more appropriate for your data? </p>
<p>I have a numeric data and I would like to discretize it using one of these. I know what they do but I have no idea which one I should pick and why.</p> | g64230 | [
0.08405912667512894,
-0.008334560319781303,
0.010641812346875668,
-0.010662988759577274,
0.0228433795273304,
-0.04536572843790054,
-0.013662981800734997,
-0.017046047374606133,
-0.06320607662200928,
-0.04927673563361168,
-0.006240046117454767,
0.02363964542746544,
0.02682875469326973,
-0.0... |
<p>tldr version: What's an algorithm I can use to classify different series with very different standard deviations across a single variable?</p>
<p>I'm working with data that follows changes of stock prices through non-sequential, uncorrelated, instances of time. I would like to group stocks together that tend to ch... | g22270 | [
0.02147809788584709,
-0.012673411518335342,
-0.008426194079220295,
-0.042075056582689285,
-0.021684342995285988,
-0.0648093894124031,
-0.005741667002439499,
-0.0012394499499350786,
-0.020043358206748962,
0.02091602049767971,
0.042386092245578766,
0.04720818251371384,
0.027982138097286224,
... |
<p>How should I prove that for a given series $x_{t}=\frac{3}{2}x_{t-1}-\frac{1}{2}x_{t-2}+w_{t}$ that is non-stationary, $y_{t}=\nabla x_{t}$ is stationary?</p>
<p>I attempted to get an equation based on the lag operator $B$, defined as $\nabla x_{t} = (1-B)x_{t}$ but I can't obtain roots greater than 1 (which is the... | g64231 | [
0.03055601380765438,
-0.0036902877036482096,
-0.014437898062169552,
0.024589210748672485,
0.013915523886680603,
-0.04765268415212631,
0.0750184953212738,
0.00419802637770772,
-0.046594470739364624,
0.05119267851114273,
-0.024092677980661392,
0.052798718214035034,
-0.01668410748243332,
0.05... |
<p>I would like to estimate a multiple linear regression model $N$ observations (with $\beta$ of length $k$):</p>
<p>$$Y = X \beta + \epsilon$$</p>
<p>subject, however, to some linear constraints on the coefficients. I.e a constraint of the form</p>
<p>$$M \beta = 0$$</p>
<p>where (at least in my case) $M$ is of di... | g64232 | [
-0.028508732095360756,
-0.011254914104938507,
-0.006016314495354891,
-0.0003870920918416232,
0.030926305800676346,
-0.03012799844145775,
-0.0030828306917101145,
-0.03534240648150444,
-0.09010612964630127,
0.005527193658053875,
-0.05322536453604698,
0.03206762671470642,
-0.018941819667816162,... |
<p>There is a doubt about the meaning of covariance and its definition. Does it change under different conditions such as primary data or statistic such as r in case of meta-analysis?</p> | g22272 | [
0.044414032250642776,
0.005802237894386053,
0.005278696306049824,
-0.03272656351327896,
0.0024148982483893633,
0.028056133538484573,
0.016343960538506508,
0.00913930032402277,
-0.03617013245820999,
-0.027247456833720207,
-0.021602962166070938,
0.023339377716183662,
-0.028060924261808395,
-... |
<p>I have non-stationary time series. It has evident trend in means and seasonality. These raw data are measured every second. On the plot of original series I see trend and seasonality about 80,81 (after each 80 second we can see new growth). It is possible that I will never obtain model with white noise? I have tried... | g64233 | [
-0.0111314682289958,
-0.04411600902676582,
0.006125099491328001,
-0.061418838798999786,
0.012112542055547237,
-0.0015164705691859126,
0.09249240905046463,
-0.05553784221410751,
-0.04644785821437836,
0.018192872405052185,
-0.03114079125225544,
0.08762961626052856,
0.02389932982623577,
0.009... |
<p>I would like to generate thousands of distributions with respect to: VaR@5%=-7% and Median=0%.</p>
<p>A first idea:</p>
<ol>
<li>Choose a family, say the Gaussian one.</li>
<li><p>Estimate its parameters. This is straightforward for the Gaussian but let's write the general algorithm (see mpiktas' answer on <a href... | g919 | [
-0.018550286069512367,
0.004719046410173178,
-0.007610819302499294,
-0.0426386222243309,
-0.013476450927555561,
-0.022265873849391937,
-0.04440361633896828,
0.019482485949993134,
-0.030781971290707588,
-0.00012853713997174054,
-0.028825484216213226,
-0.029317378997802734,
0.06593240052461624... |
<p>Is MATLAB better than R for time series analysis and forecasting or vice versa?
What other software is considered best for time series analysis?</p> | g64234 | [
0.05306674540042877,
-0.05799584090709686,
0.030506040900945663,
0.026106497272849083,
-0.05150112509727478,
-0.028325773775577545,
0.025669071823358536,
0.015174588188529015,
-0.08243691921234131,
-0.020075924694538116,
0.047545697540044785,
-0.01886592246592045,
0.03695405274629593,
0.00... |
<p>In answering <a href="http://stats.stackexchange.com/questions/1412/consequences-of-an-improper-link-function-in-n-alternative-forced-choice-procedur">this</a> question John Christie suggested that the fit of logistic regression models should be assessed by evaluating the residuals. I'm familiar with how to interpr... | g64235 | [
0.017503254115581512,
-0.03903515264391899,
-0.004475942812860012,
-0.0329943485558033,
-0.014996667392551899,
0.0031107584945857525,
0.033453598618507385,
0.005406524054706097,
-0.05143706873059273,
-0.0017673312686383724,
-0.04339157044887543,
0.0006963476189412177,
0.04438738897442818,
... |
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