question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I am trying to analyze data to predict the effect of 8 predictors on a response variable. I ant to do it using R.
There are 8 predictor variables (x1, x2, ..., x8) and one response variable (y).</p>
<p>I would like to find out which predictors have the largest influence on the response variable.</p>
<p>I have alre... | g15628 | [
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<p>I think that for the following two point boundary value problem (TPBVP), one could use the r package <code>bvpSolve</code> to come up with a numerical value, but am unsure how. </p>
<p>I am using similar notation to the following paper (<a href="http://arxiv.org/pdf/1312.7360.pdf" rel="nofollow">http://arxiv.org/p... | g59848 | [
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<p>Suppose two time series (of light flux). The goal is to determine whether the series are from the same distribution. It is usual to use the Kolmogorov-Smirnov (KS) test in this situation.</p>
<p>However, the times intervals are not necessarily even between the measurements, as some data may be missing. Is it correc... | g481 | [
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<p>Could you recommend some examples of published articles that used general mixed-models or glmer() function with only crossed random effects and no random slopes.</p>
<p>Using glmer function, the model will be like this:</p>
<pre><code>model <- glmer(response ~ V1 + V2 + (1|SITE) + (1|TIME), family = binomial, d... | g59849 | [
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<p>What does it mean intuitively to say that a time series process is causal ? </p>
<p>And what is the relationship between causality and stationary and invertibility ? </p>
<p>If I understand correctly, these 3 conditions all require the roots of the polynomial to be greater than 1. However, I have no idea how to in... | g667 | [
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<p>Consider a problem like this
You have a customer profiling application(say classic telecoms data)
You have customer transactions(lots of them)
you want to find rules
There is a data element which is sparsely populated
ex
Pets
you are interested in it because you want to explore a hypothesis
'Are cat owners wealthi... | g59850 | [
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<p>Let a~$\mathcal{N}(\mu_a,{\sigma_a}^2)$,b~$\mathcal{N}(\mu_b,{\sigma_b}^2)$ and c~$\mathcal{N}(\mu_c,{\sigma_c}^2)$. </p>
<p>We construct two normal variables x~$a-b$ and y~$a-c$.</p>
<p>Can we find the covariance between these two random variables i.e. $\textrm{cov}(x,y)$ by hand? Sorry if my question is trivial.... | g59851 | [
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<p>I am not a statistics specialist : I had to take over the internship subject of another student to include it in mine. He was working with $SARIMAX$ models and I would like to import them in an <code>Excel</code> worksheet. From the internet and <a href="http://stats.stackexchange.com/questions/82197/how-to-write-se... | g15634 | [
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<p>In my Google Analytics data a lot of traffic gets mis-labelled as "Direct" because Google doesn't know the original traffic source.</p>
<p>I've taken 6 months worth of our "Direct" traffic data and calculated the correlation of that to other traffic channels, such as Organic and Social. There is a moderate correlat... | g15637 | [
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<p>I have the following graph, which I then normalise and attempt to fit to. The data is
a histogram of counts at a given time.</p>
<p><img src="http://i.imgur.com/XpBbkab.png" alt="data"></p>
<p>The fit then looks like:</p>
<p><img src="http://i.imgur.com/TGTp2GW.png" alt="fit"></p>
<p>The issue is that the param... | g15639 | [
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<p>I have one five point Likert scale variable (importance levels) for accessibility to a certain facility, and another three-level categorical variable (preferred distance). </p>
<p>I want to combine these two variables into one variable so I could relate it to the current distance of that facility. </p>
<p>How do I... | g59852 | [
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<p>How does the relative size of a p value change at different sample sizes?
Like if you got $p=0.20$ at $n=45$ for a correlation and then at $n=120$ you got the same p value of 0.20, what would be the relative size of the p value for the second test, compared to the original p value when $n=45$?</p> | g59853 | [
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<p>Firstly I am very very new to stats...</p>
<p>I am trying to find a relationship between a dependent numeric factor and have 6 nominal, 1 ordinal and 4 numeric independents.</p>
<p>I have been using the category regression or optimal scaling on spss
have been using group discretization for nominal varaibles with t... | g59854 | [
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<p>In R I'm setting up a dataset to run a logistic regression on. I have two question regarding the selection of independent variables.</p>
<p>I will first briefly explain the dataset: The dataset contains of visits to a website. Some of these visits will eventually lead to a sale. Some will not. Each visit shows the ... | g59855 | [
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<p>I have two time series S, and T. they have the same frequency and the same length.</p>
<p>I would like to calculate (using R), the correlation between this pair (i.e. S and T), and also be able to calculate the significance of the correlation), so I can determine whether the correlation is due to chance or not.</p>... | g38092 | [
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<p>For some of us, refereeing papers is part of the job. When refereeing statistical methodology papers, I think advice from other subject areas is fairly useful, i.e. <a href="http://cstheory.stackexchange.com/questions/1893/how-do-i-referee-a-paper">computer science</a> and <a href="http://mathoverflow.net/questions/... | g59856 | [
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<p>I am trying to use the package <a href="http://cran.r-project.org/web/packages/BradleyTerry2/index.html" rel="nofollow">BradleyTerry2</a> in R to assess sports teams. I am using the paper "<a href="http://www.jstatsoft.org/v48/i09/" rel="nofollow">Bradley-Terry Models in R: The BradleyTerry2 Package</a>" written by... | g15647 | [
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<p>Currently, I´m analyzing data from seven regression curves. I´d like to know if there are significant differences between these lines. Although I thought the procedure was simple, I´ve found that there are not well-defined tests to solve this, recently I found <a href="http://www3.stat.sinica.edu.tw/statistica/old... | g42835 | [
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<p>I've heard/seen in several places that you can transform the data set into something that is normal-distributed by taking the logarithm of each sample, calculate the confidence interval for the transformed data, and transform the confidence interval back using the inverse operation (e.g. raise 10 to the power of the... | g49432 | [
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<p>I am modeling stock exchange according to the present value model as defined by Gregory Chow in <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.197.511&rep=rep1&type=pdf" rel="nofollow">this</a> paper. Model operates on natural logarithms of stock prices and dividends in order to "eliminate... | g59857 | [
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<p>I have a set of sports data with a date and corresponding fitness result. Dates are not uniformly separated. What would be the best way to determine current athlete's progress? I was thinking somewhere in line of fitting a line through last 3-5 measurements (data is 7-10 days apart) and checking the tangens to see w... | g59858 | [
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<p>We can write Bayes' theorem as</p>
<p>$$p(\theta|x) = \frac{f(X|\theta)p(\theta)}{\int_{\theta} f(X|\theta)p(\theta)d\theta}$$</p>
<p>where $p(\theta|x)$ is the posterior, $f(X|\theta)$ is the conditional distribution, and $p(\theta)$ is the prior.</p>
<p>or</p>
<p>$$p(\theta|x) = \frac{L(\theta|x)p(\theta)}{\in... | g45921 | [
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<p>In which cases can't I perform a Pearson's chi squared test because the outcome will be meaningless?
<strong>Edit:</strong> Is it still valid even in the case the distribution does not allow mean and variance?</p> | g16421 | [
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<p>I'm working on a 2D physical simulation and I am collecting data in time at several points. These discrete points are along vertical lines, with multiple lines in the axial direction. This makes the dataset effectively 4D. </p>
<p>For instance, let's assume I have collection points at (X,Y) coordinates of: </p>
<u... | g15657 | [
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<p>How can be proven that the entropy of a dice with equal probability for all its faces is at its maximum?
It's clear that the entropy will be smaller if there are more chances for a particular face, but how can be this proven? </p> | g59859 | [
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<p>My goal is to find out where a user would cut a curve. During training, whenever a point on a curve is chosen by the user to be a cutting point, we record some features and use the label '+1' to indicate these features correspond to a cutting point. In order to reduce the training efforts, we would like to avoid rec... | g15658 | [
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<p>I have a dichotomous variable $A$, which does not have an <em>a priori</em> determined proportion of 0's and 1's, and a continuous variable $b$.</p>
<p>In scenario 1, I decide to designate $A$ as the <strong><em>independent</em></strong> variable $X$, and $b$ as the <strong><em>dependent</em></strong> variable $y$... | g15660 | [
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<p>If the prior and the likelihood are very different from each other, then sometimes a situation occurs where the posterior is similar to neither of them. See for example this picture, which uses normal distributions.</p>
<p><img src="http://i.stack.imgur.com/07YsT.png" alt="Posterior Behaviour"></p>
<p>Although thi... | g59860 | [
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<p>Popular topic models like LDA usually cluster words that tend to co-occur together into the same topic (cluster). </p>
<p>What is the main difference between such topic models, and other simple co-occurrence based clustering approaches like PMI ? (PMI stands for Pointwise Mutual Information, and it is used to ident... | g3434 | [
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<p>I´m trying to visualize a <code>glm</code> model with a binomial response variable, I want to put a line in the plots, but neither <code>lines</code> or <code>abline</code> work and I don´t know why when I have significant responses according to the model I used. Any idea why plotting a line does not work?</p>
<pr... | g59861 | [
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<p>So I'm taking N bootstrap samples and training N logistic regression classifiers on these samples. Each classifier gives me some probability of being in a binary class and then I average these N probabilities to get a final prediction.</p>
<p>My question is if I took the N sets of regression coefficients and averag... | g59862 | [
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0.03103622794151306,
0.037114549428224564,
0.00... |
<p>3 cards are drawn from a deck of 52 cards. Let $X$ and $Y$ represent the number of hearts and number of diamonds respectively. Find the correlation of $(X,Y)$.</p>
<p>I know that correlation is defined as $\frac{\mathrm{COV}(X,Y)}{\sigma_{X}\sigma_{Y}}$.
I also understand that the two random variables are not inde... | g15662 | [
0.03151099383831024,
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<p><strong>Summary:</strong>
Consider a scenario where you observe the inputs ($X$) to and outputs ($Y$) from a process ($B$). If I have a model describing how $X$ evolves over time, and a similar model for $Y$, how do I combine the two?</p>
<p><strong>Example + Details</strong>
To make this concrete, consider the cou... | g59863 | [
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0.022981565445661545,
0.07778207957744598,
... |
<p>I'm working on analyzing some data that need to use lme model, but I'm not sure about interpreting the output.</p>
<p>Data looks like this:</p>
<pre><code>> head(data)
Mouse.Number Mouse.Number.Unique Overall.Mouse Batch Day Drug Tumor.Volume X
1 1 1 1 10 -35 ... | g59864 | [
-0.029201045632362366,
-0.0828198492527008,
-0.02726287581026554,
-0.06664755940437317,
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0.036029234528541565,
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-0.00972049217671156,
0.023454610258340836,
0.013401488773524761,
0.08858593553304672,
-0.... |
<p>When do I need to normalize the data?</p>
<p>What's the problem if I always normalize the data?</p>
<p>For example, I am given a set of multivariate gaussian data. I use max. likelihood to estimate the estimate the mean and co-variance matrix. And then, I want to use Bayes classifier to classify new data point. In... | g49325 | [
0.04674613103270531,
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0.005673273000866175,
0.017340272665023804,
0.0002159762370865792,
0.03899868205189705,
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0.064146488904953,
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-0.008128980174660683,
0.03150798752903938,
0.038531698286533356,
0.005639720242470503,
0.0303... |
<p><img src="http://i.stack.imgur.com/o5e0M.png" alt="enter image description here"></p>
<p>I got this plot when I plotted a clustering object in R. If I run <code>km <- clara(data, 2)</code>, then <code>plot(km)</code>, I get a similar plot. How do we interpret this plot with respect to the clustering? How useful ... | g59865 | [
0.0214385986328125,
0.015216956846415997,
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0.01402709074318409,
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0.03572116792201996,
0.07181428372859955,
-0.0... |
<p><strong>Description</strong></p>
<p>I have to find number of clusters for <strong>1D data</strong>. All clusters are assumed to have a gaussian distribution (so there is a big number of same points). I have a robust "aglomerative clustering + EM" based algorithm which is able to find cluster centers.</p>
<p><stron... | g59866 | [
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0.04142754524946213,
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0.05546562746167183,
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0.02849947288632393,
0.08967062085866928,
0.04... |
<p>Suppose that two groups, comprising $n_1$ and $n_2$ each rank a set of 25 items from most to least important. What are the best ways to compare these rankings?</p>
<p>Clearly, it is possible to do 25 Mann-Whitney U tests, but this would result in 25 test results to interpret, which may be too much (and, in strict u... | g87 | [
-0.013435053639113903,
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0.020886380225419998,
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<p>Consider a Poisson process with unknown parameter $\lambda$.<br>
We perform a sequence of $n$ observations at intervals $\overline{t}=t_1,\,t_2,\,\dots,\,t_n$. Each observation is a binary variable $x_i$ equal to zero if no changes occurred during interval $t_i$ or equal to one if one or more changes occurred:<br>
$... | g59867 | [
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0.04566187411546707,
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0... |
<p>If the Hosmer-Lemeshow indicates a lack of fit but the AIC is the lowest among all the models....should you still use the model?</p>
<p>If I delete a variable, the Hosmer-Lemeshow statistic is not significant (which means there is no gross lack of fit). But the AIC increases.</p>
<p><strong>Edit</strong>: I think ... | g49827 | [
0.04165264591574669,
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0.0251... |
<p>Say I have a sequence of yes-no trials where the probability of winning decays over time <strong>as the supply of wins is gradually exhausted</strong>. Assume that for every trial the probability of replacement is <strong>not 1 nor 0</strong>, but some other value.</p>
<p>Are there any known distributions that mode... | g15668 | [
0.009862788021564484,
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0.006045904476195574,
0.006852169521152973,
... |
<p>I have several Pearson correlation coefficients with their corresponding p-values. But I need an Average Correlation Coefficient. To calculate it, I've used the Fisher z transformation mentioned <a href="http://stats.stackexchange.com/questions/8019/averaging-correlation-values">here</a> and <a href="http://stats.st... | g59868 | [
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0.02258635126054287,
... |
<p>I am attempting to construct a contrast matrix that I can run in R, using the limma bioconductor package, but I am not sure that I have coded the contrast matrix correctly. A previous <a href="https://stats.stackexchange.com/questions/64249/creating-contrast-matrix-for-linear-regression-in-r?newreg=add2674ca9d04b7eb... | g33829 | [
0.008703144267201424,
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0.025364534929394722,
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0.06268341839313507,
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0.08658744394779205,
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<p>I am trying to learn how Neural Network works on image recognition.I am confused that how neural network that how i will give input.My defination is find(track) object in squence of images(particular that image come from aircraft travelling & capturing images from camera.so in that most of objects are same so ho... | g59869 | [
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0.023025348782539368,
0.07000850141048431,
0.0008... |
<p>I'm taking a course in Statistical Quality Control as an elective in my masters program. We're using Montgomery's <em>Introduction to Statistical Quality Control</em>, 6th Edition.</p>
<p>The book uses minitab throughout and the professor would like us to use minitab to follow along with the examples. He did howeve... | g15672 | [
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<p>There is a system containing $N$ clusters and in each cluster there are some elements. The clusters' sizes varies dramatically and most of the clusters are singletons. </p>
<p>I need to know the precision and recall of this system, but since I need to check it manually it is impossible to check too many units. </p... | g59870 | [
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<p>I am confused by different terms of logistic regression. What are the differences between stepwise, kernel, forward, and backward?</p> | g22344 | [
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<p>An old-fashioned way of generating normally distributed random numbers entailed setting each normally distributed random number equal to the average of a set of uniformly distributed random numbers, rescaled and shifted by a constant. Let x be a uniformly distributed random variable, i.e. p(x) = 0 if x < 0 and x... | g15674 | [
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... |
<p>I have a continuous monotonically increasing function, $f(x)$, whose $x$-intercept, $x^*$, I am trying to estimate. I have a dataset of $(x_i,y_i)$ pairs, with each $y_i=f(x_i)+\varepsilon_i$, where $\varepsilon_{i} \sim \text{Normal}(0, \sigma)$. The value of $\sigma$ is relatively large. The dataset includes a hea... | g59871 | [
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0.05556999146938324,
0.009129255078732967,
... |
<p>My research topic is based on comparison of the effects of traditional and modern teaching techniques on students’ attitude and achievement in science.</p>
<p>I followed a pretest-posttest experimental design, in which one control group and one experimental group were involved.</p>
<p>Pretest and posttest used are... | g59872 | [
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<p>I need to learn about Matrix Factorization for recommender systems, so I downloaded this paper <a href="https://datajobs.com/data-science-repo/Recommender-Systems-%5bNetflix%5d.pdf" rel="nofollow">https://datajobs.com/data-science-repo/Recommender-Systems-[Netflix].pdf</a> but I found it too shallow. It didn't expla... | g59873 | [
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<p>Let's say I have two databases, in the first (DB1) there is individual data on how much people trust in the government ($X_{j,r}$), and on the second (DB2) there is individual data on how much people donate $Y_{i,r}$ (I use $j$ instead of $i$ to make clear the individuals observed in both databases are not the same... | g59874 | [
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0.03949151188135147,
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0.05141700059175491,
0.008983699604868889,
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<p>As I understand it, one of the main goal of the chi-squared test on a contingency table is to determine if the link between lines and columns of the table is "more" than the sampling bias and the random fluctuations it can generate.</p>
<p>So my question is : if a contingency table contains the whole surveyed popul... | g59875 | [
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0.029561130329966545,
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0.029431... |
<p>I created an Arima (3,1,1) model using the steps below. I was able to create a nonparametric model, but now I would like bootstrap for the created model (model 3). Also I'd like to plot the paths of the various simulations. Any help would be greatly appreciated. I'm new to R and this is my first question, so apologi... | g15679 | [
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0.024973778054118156,
0.018767768517136574,
0.011844519525766373,
0.055453527718782425,
-0... |
<p>I have questions with the following Bayesian inference problem I found in the book by Bertsekas & Tsitsiklis (Introduction to Probability 2nd ed.).</p>
<p>Problem is as follows (P.445, Problem 2):</p>
<blockquote>
<ul>
<li>A student takes a test with 10 questions, each with 3 choices.</li>
<li>For each q... | g3984 | [
0.02253161184489727,
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0.03045213595032692,
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0.007220346946269274,
0.015254736877977848,
-0.01699129119515419,
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0.04484838619828224,
0.029750395566225052,
0.0115... |
<p>I have 2 groups and 2 correlation coefficients that I would like to compare using Fisher's transformation. Unfortunately, one of these coefficents is not significant, so not different from zero. </p>
<p>Can I still perform the transformation because "not different from zero" does not mean "not different from the ot... | g59876 | [
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0.029102541506290436,
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-... |
<p>Suppose that the true model is $$Y_i = βZ_i + u_i$$
However, the researcher/analyst can only
observe $X = Z + w$, where $w$ is a measurement error with zero mean and constant variance
$\sigma^2_w$. $Z$ and $w$ are distributed independently. What is the plim of estimator of $\beta$:
$$b=\frac{\sum_{i=1}^nX_iY_i}{\sum... | g59877 | [
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0.0020792356226593256,
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0.04483204334974289,
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0.... |
<p>I have some repeated measures with 196 individuals and some of my regressions have a plateau. So I want to characterize this with an eventual breakpoint for each ID.</p>
<p>Example: subset of my personal data</p>
<pre><code> ID time y
7G009 0 9
7G009 108,33 13
7G009 185,69 16
7G009 309,22 20... | g59878 | [
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0.0025588106364011765,
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-0.03300628438591957,
-0.0016149578150361776... |
<p>I'm currently taking my first applied linear regression class at the graduate level, and am struggling with predictor variable transformations in multiple linear regression. The text I'm using, Kutner et al "Applied Linear Statistical Models" doesn't seem to cover the question I'm having. (apart from suggesting that... | g59879 | [
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... |
<p>I am searching to get a detailed development for the multivariate normal likelihood function in order to enter it to <a href="http://en.wikipedia.org/wiki/Multivariate_normal_distribution#Likelihood_function" rel="nofollow">Wikipedia</a>.</p>
<p>Can anyone suggest to me a good reference book (or if you have it hand... | g59880 | [
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0.04634728655219078,
... |
<p>This questions is in reference to equation 3.15 in the book <a href="http://www-stat.stanford.edu/~tibs/ElemStatLearn/" rel="nofollow"><em>Elements of Statistical Learning</em></a> by Tibshirani and coll.</p>
<p>I do understand the individual beta confidence interval estimation as provided in equation 3.14, but equ... | g15684 | [
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0.04274919629096985,
0.012326056137681007,
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-0.031022178009152412,
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0.08034534007310867,
0.03262839838862419,
-0.0... |
<p>I have a data frame which contains several true/false columns, some numeric and a class (target) variable which has true/false values.</p>
<p>Now, how can I produce with R multiple barplots for all numerical and factor columns without having to specify each data frame's column name and imposing the class attribute'... | g46143 | [
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<p>I've found myself in a situation where I have been given a model that has been developed from what I believe to be the "this seems right" approach. The model in question is very complex but it has no associated error margins or tests of correctness. I.e., there is nothing supporting this model to be good.</p>
<p>To... | g59881 | [
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<p>Why would I get 0 estimates of coefficients in logistic regression? And the coefficients are exactly 0. These are for variables of different levels of a categorical variable.</p> | g45044 | [
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<p>my supervisor has asked me a few questions that I'm not entirely sure how to answer.</p>
<p>For a quick summary, my study includes a small sample of 16. To describe the sample, I compared the scores of the 16 participants (n=6 of Age 3, n=8 of Age 4, and n=2 of Age 5) to the normative information (n=107 of Age 4 an... | g33835 | [
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<p>We are given a probability distribution $p_1 \ge$ $p_2 \ge$ $p_3 \ge \cdots p_n$ on $n$ items. We sample from this distribution without replacement (re-scaling probabilities after each sample to account for the removed item). We discard the first $n-k$ sampled items and keep the last $k$ sampled items. What is the e... | g59882 | [
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0.00456... |
<p>I've been trying to read up on Poisson regression models, and it looks like it is possible to estimate such a model with a binary outcome. This has come up before on this site <a href="http://stats.stackexchange.com/questions/18595/poisson-regression-to-estimate-relative-risk-for-binary-outcomes">here</a> (and somew... | g15689 | [
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<p>Sorry for my long question but I'm sure it will be interesting for some of you:</p>
<p>My research is in the construction area. The dependent variable is time required to finish a construction task and several independent variables has been collected (crew size, job size, etc.). However the main dependent variable ... | g59883 | [
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... |
<p>I would like to test for a difference between 3 groups for a binomial variable. There are around 400 in one group, 900 in the other group and 100,000 in the third group. I am wondering if this huge difference would have an impact (if any) on the result of the chi-square test. Or is there another strategy? Also, what... | g59884 | [
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<p>I have a doubt regarding confirmatory factor analysis (CFA). I have three different constructs, each one with its corresponding scale:
1) resilience (3 dimensions, 4 items each)
2) humour (3 dimensions, 4-5 items each)
3) coping (2 dimensions, 8 items each)
My question is: do I have to perform a different CFA for e... | g59885 | [
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<p>Following my question <a href="http://stats.stackexchange.com/questions/37865/detecting-outliers">here</a>, I am wondering if there are strong views for or against the use of standard deviation to detect outliers (e.g. any datapoint that is more than 2 standard deviation is an outlier).</p>
<p>I know this is depend... | g59886 | [
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<p>I have measurements of a set of socio-economic variables on italian municipalities; the aim is to run a series of clustering algorithms on them, in order to see if any significant pattern of local association emerge. I'd like your input on the correct way to standardize the variables, since most of my data is some s... | g59887 | [
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<p>I was reading <a href="http://www.agu.org/pubs/crossref/2006/2005JD006898.shtml" rel="nofollow">this information related to aerosol</a>, especially aerosol optical depth of the MISR and MODIS instruments. I didn't actually get what bias means in the context of the AOT retrievals of these instruments.</p> | g45051 | [
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<p>I'm trying to replicate results of <a href="http://www.cs.toronto.edu/~fritz/absps/esann-deep-final.pdf" rel="nofollow">this paper</a> using Theano. The problem at the moment is, all Theano-related tutorials are only for MNIST classifiers, which isn't much use in unsupervised image retrieval.</p>
<p>I have followin... | g59888 | [
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<p>One of the demerits for my research is have not compared with gold standard data, can someone help me how to compare my data with available gold standard data for face recognition.
Would like to know what is gold standard data and is there any data available for face recognition.</p> | g59889 | [
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<p>I have received a text containing medical terms, and I want to use text mining on it to get a word count. I would like to know if R has a medical corpus that I can use so that I can compare my text document to the medical corpus.</p> | g59890 | [
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<p>I have data from an experiment where I measured the $CO_2$ from: </p>
<ul>
<li>4 different dissolved organic carbon (DOC) solutions </li>
<li>each at 4 different concentrations </li>
<li>each in light and in dark. </li>
</ul>
<p>Each combination of DOC source, concentration, and light occurred only once (e.g., onl... | g59891 | [
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<p>I have conducted a pre-post test study with a set of 20 participants. There were two independent variables and therefore 4 groups of 5 participants each. The experiment took place in a classroom and one group did significantly better than the rest in the pre-test. </p>
<p>I'm trying to find a classification for thi... | g21785 | [
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<p>I understand how linear regression is used on a sample to produce a model of how each independent variable affects the dependent variable. What I would like to do is something similar, except where the model can also represent interactions between the independent variables. Also, I would like the model to be nonline... | g15697 | [
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<p>My end goal is a C++ implementation of</p>
<ul>
<li>a Profile HMM (a profile hidden markov model is a model which contains information about a multiple sequence alignment of proteins; just providing some background as the type of model is not necessarily important for what I want to ask).</li>
<li>Baum Welch train... | g59892 | [
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... |
<p>I want to calculate the $AIC_c$ (corrected $AIC$) for k-means to decide on the number of clusters, but there is an overfitting problem that I don't know how to solve. Let's say that I have $n$ data points of $d$ dimensions each, and I want to cluster those $n$ points into $c$ clusters. The Akaike Information Criteri... | g59893 | [
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<p>I am using a RandomForest on features (pixels) of images, and I am considering adding cost for "similarity to already other included features" to the cost function.</p>
<p>Imagine you have a current RF model, which is using 400 features. Consider adding another 400 features. Since it becomes again tricky to figure ... | g59894 | [
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<p>Suppose in group 1 there are $n$ people and in group 2 there are $n$ people. If we conduct a 2 sample t test versus a paired t test, would we use $2n$ for power calculations in the two sample t test and $n$ as the sample size for the paired t test?</p> | g46268 | [
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<p>I'm working on a concept for a game that requires some statistical inference and I'm not sure how to go about it. My issue is I'm trying to come up with a way to calculate if a city (in the game) could evolve into a thriving city. </p>
<p>I have a bunch of rules that rate different factors of the city like health q... | g59895 | [
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<p>I tried to train a deep belief network to recognize digits from the MNIST dataset. Everything works OK, I can train even quite a large network. The problem is that the best DBN is worse than a simple multilayer perceptron with less neurons (trained to the moment of stabilization). Is this normal behaviour or did I m... | g59896 | [
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0... |
<p>I am fitting a conditional logistic regression model with 1:4 controls using <code>R</code>. I wish to obtain <code>AIC</code> from the model. How can I extract the appropriate parameters based on the object <code>m</code>?</p>
<pre><code>library(survival)
m<-clogit(cc~exp+ factor1+ factor2 + strata(stratum),dat... | g59897 | [
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0.017414433881640434,
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-0.0017192468512803316,
0.06081189960241318,
-... |
<p>Let's assume I have a simple cointegrating regression of the type </p>
<p>$$y_t=\beta_0+\beta_1x_t+\varepsilon_t$$</p>
<p>$y,x$ are $I(1)$.</p>
<p>If testing the OLS residuals I find that $y$ and $x$ are cointegrated, how can I perform tests on the coefficients? Are the two estimators distributed as a usual t-stu... | g59898 | [
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0.03834301233291626,
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0.056634820997714996,
0.016268419101834297,
-0.0... |
<p>I have <a href="http://en.wikipedia.org/wiki/Least-angle_regression" rel="nofollow">read</a> that least angle regression is good for high dimensional data. I didn't actually understand the meaning of high dimensional data, so does this mean $p>>n$ case?</p>
<p>And does anyone know any good dataset with such p... | g59899 | [
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<p>This question has also been asked on stackoverflow.com. Yet my aim is to ask for efficiency gains on the aforementioned platform. My aim here is the correctness of my approach.</p>
<p>I am trying to cluster 365 multivariate (2 to 4 dimensions) time series, each consisting of 24 entries. That means that I try to gro... | g59900 | [
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<p>I have simulation data from 1000 runs, plotting some measurable (in this case convergence of the algorithm) as a function of simulation time. Each run produces a discrete set of points <code>(t, f(t))</code> and the superimposed image of all the runs looks like:</p>
<p><img src="http://i.stack.imgur.com/UyZ44.png" ... | g15707 | [
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<p>I'm looking for advice/resources/recommendations on how to best format graphs for presentations. From experience, I know that a graph produced for print publication doesn't "scale" very well when one displays it with a beamer. The text is often too small, the lines not thick enough etc. It is almost always a bad ide... | g59901 | [
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0.00866623967885971,
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0.0546598844230175,
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<p>I try to compute the standard error of the mean for a demeaned AR(1) process $x_{t+1} = \rho x_t + \varepsilon_{t+1} =\sum\limits_{i=0}^{\infty} \rho^i \varepsilon_{t+1-i}$</p>
<p>Here is what I did:</p>
<p>$$
\begin{align*}
Var(\overline{x}) &= Var\left(\frac{1}{N} \sum\limits_{t=0}^{N-1} x_t\right) \\
... | g46320 | [
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0.05920279026031494,
0.0026190215721726418,
... |
<p>have a question regarding mean square distortion returned by MATLAB's quantiz function. </p>
<p>Here is my code:</p>
<pre><code>dataset = rand(1,1000)*2-1;
M1 = 128;
qlevels1=-1+(2/M1):2/M1:1-(2/M1);
codebook1 =-1+(1/M1/2):2/M1:1-(1/M1/2);
[index1, quants1, dist1] = quantiz(dataset, qlevels1, codebook1);
Qnoi... | g45061 | [
0.013857907615602016,
-0.032603442668914795,
0.014001262374222279,
-0.02319975383579731,
0.008596600964665413,
0.010673400945961475,
-0.007157903164625168,
-0.010799438692629337,
-0.048234425485134125,
0.023047959432005882,
0.009433391503989697,
0.040940746665000916,
0.07995419949293137,
0... |
<p>Any good places to start getting into Bayesian statistics? I'm a graduate student in social sciences, with a decent amount of stats classes under my belt, but I'm far from fluent. Any references would be much appreciated.</p>
<p>Thanks!</p> | g49573 | [
0.045158952474594116,
0.0029988985043019056,
0.021430401131510735,
0.001503162900917232,
-0.023088837042450905,
0.00021023297449573874,
-0.027366258203983307,
0.0029865633696317673,
-0.007911995984613895,
-0.028957391157746315,
0.020872170105576515,
0.0029011021833866835,
0.06615923345088959... |
<p>I have 3 lists of significant hits (p-value < 0.05). I also adjusted for multiple comparison problem and added q-values to each list. These 3 lists (hits) also partially overlap. For the hits that overlap I was wondering if it makes sense to average the q-value? So, for instance, </p>
<p>Hit X (List1): pval=0.00... | g59902 | [
-0.04239499196410179,
-0.016510920599102974,
0.003755057929083705,
-0.011452201753854752,
0.013789849355816841,
0.03465703874826431,
-0.002562536159530282,
-0.020154140889644623,
-0.05000338330864906,
0.01796085573732853,
0.04738616570830345,
-0.014369889162480831,
0.05987218767404556,
0.0... |
<p>I understand how the simulation at <a href="http://stats.stackexchange.com/questions/10574/power-calculation-for-likelihood-ratio-test">Power calculation for likelihood ratio test</a> can compute the alpha, using prop.test, and the power from a direct count of simulation values, for two Poisson distributed variables... | g59903 | [
-0.010089345276355743,
-0.006893059238791466,
-0.03632045537233353,
-0.05134187266230583,
-0.03987901657819748,
-0.042310066521167755,
-0.02850210666656494,
0.05485207960009575,
-0.06998320668935776,
0.006263087969273329,
0.016926677897572517,
-0.03601977601647377,
-0.002321995794773102,
0... |
<p>This question is about a paper I am reviewing, so I cannot give a lot of detail, but I can say it involves patients clustered in hospitals and a Cox proportional hazards model.</p>
<p>My instinct for such data would be to use multilevel modeling, since hospitals may vary on ways that are not accounted for. The auth... | g59904 | [
0.044097788631916046,
-0.005411219317466021,
0.012543885037302971,
0.016780858859419823,
0.006130086723715067,
-0.02515367791056633,
-0.04361389949917793,
0.024618426337838173,
0.007892892695963383,
-0.0007014254224486649,
0.011577964760363102,
-0.03823242709040642,
0.08963700383901596,
-0... |
<p>I was just involved in a <a href="http://stats.stackexchange.com/questions/83173/use-of-t-test-to-compare-performance-of-algorithms">Q/A</a> were a poor guy was requested to run a statistical test to <em>prove</em> that algorithm A is better than two other algorithms. However, he has only 4 data points. Does it real... | g59905 | [
0.05526997148990631,
0.02084188163280487,
-0.006987334229052067,
-0.017975272610783577,
-0.011760145425796509,
-0.00647247489541769,
0.023462163284420967,
0.008439474739134312,
-0.07488582283258438,
-0.039401207119226456,
0.014826812781393528,
0.012918034568428993,
0.046788644045591354,
-0... |
<p>I started learning ridge regression in R. I applied the linear ridge regression to my full data set and got the following results. </p>
<pre><code>gridge<-lm.ridge(divorce ~., data=divusa, lambda=seq(0,35,0.02))
select(gridge)
modified HKB estimator is 0.07693804
modified L-W estimator is 0.3088377
smallest ... | g59906 | [
0.0064645749516785145,
-0.09232504665851593,
-0.01132778637111187,
-0.04517710953950882,
0.042280614376068115,
0.007309853099286556,
0.0016646271105855703,
0.015614903531968594,
-0.03229965642094612,
-0.041131630539894104,
-0.023236460983753204,
0.003635142697021365,
0.04476604610681534,
0... |
<p>I am reading a book that in one page it talks about cdf of a random vector. This is from the book:</p>
<blockquote>
<p>Given $X=(X_1,...,X_n)$, each of the random variables $X_1, ... ,X_n$ can be characterized from a probabilistic point of view by its cdf.</p>
</blockquote>
<p>However the cdf of each coordinate ... | g59907 | [
0.012322480790317059,
-0.028660988435149193,
-0.012951171025633812,
0.009694263339042664,
0.02149626612663269,
-0.003779677441343665,
0.03977052867412567,
0.003963934723287821,
-0.06991396844387054,
-0.04609395191073418,
-0.022166196256875992,
0.0443640761077404,
0.016250936314463615,
0.01... |
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