question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have a dataset structured as follows:</p>
<pre><code>Variable1 Variable2 Variable3 Variable4 Variable5 Variable6 Variable7 Variable8
60 70 75 73 57 69 85 90
55 66 47 79 63 76 82 97
</code></p... | g110 | [
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<p>Suppose I flip a coin 584,369 times and observe 5,257 heads and 579,112 tails. I wish to know the lower edge of the 90% credible interval for the probability that the next flip will come up heads.</p>
<p>I believe:</p>
<ul>
<li>I could use a <a href="http://en.wikipedia.org/wiki/Beta_distribution" rel="nofollow">b... | g66320 | [
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<p>When an observation $x$ is generated by $P(x|\theta)$ for a parameter $\theta$ the Bayesian optimal estimator for the value of $\theta$ is $\hat\theta_{BEST}=\mathbb{E}[\theta|x]=\frac{1}{P(x)}\int d\theta P(\theta)P(x|\theta)$. </p>
<p>Now assume that instead of using $P(x|\theta)$ in the above formula we have $Q(... | g27274 | [
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<p>From <a href="http://en.wikipedia.org/wiki/Dynamic_Bayesian_network">Wikipedia</a></p>
<blockquote>
<p>A Dynamic Bayesian Network (DBN) is a Bayesian Network which relates
variables to each other over adjacent time steps. This is often called
a Two-Timeslice BN because it says that <strong>at any point in tim... | g66321 | [
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<p>I'm using a time-series model to do weekly forecasts on the number of <strong>incoming calls</strong> to a company. This variable has a weekly 'in-month' pattern and a monthly 'in year' pattern, and i have data from 2008-01-01 to 2012-08-31.</p>
<p>To explain it better: Mondays show peaks along weeks, and rainy mon... | g25286 | [
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<p>I am programmer developing a Software that features the display of a probability plot. As far as I know there are 2 different ways to display a probability plot (please correct me if I say something wrong):</p>
<ul>
<li>A Percent / Percent Chart</li>
<li>A Quantile / Quantile Chart</li>
</ul>
<p>My customers want ... | g66322 | [
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<p>I have a question regarding my dat. It appears that i have extremely large values of the F statistics, ranging from 20 to 20,000. How is this possible?
I should mention that it is panel data, controlled for fixed effects as well as clustering.
thanx in advance,
Luisa</p> | g38003 | [
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<p>I have an experiment with 44 subjects and two within-subject factors, condition (3 levels) and round (6 levels). It is fully crossed such that each person completes one of each task condition in each round. I have done the analysis (and ANOVA) in R using the lmer function. My lmer model is:</p>
<pre><code>lmer(dist... | g66323 | [
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<p>I'm running a series of permutation tests inside 2 for loops (2 for loops will calculate some new data and then this data will be shuffled and then i apply a linear regression based on the shuffled data). Here is my code:</p>
<pre><code>for(i in seq(1,12000,200))
{
for j in seq(1, 12000, 200))
{
... | g66324 | [
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<p>I have a 2x3 factorial design for my experiment: 3 levels of information given to participants (None, Moderate, Extreme), and 2 levels of time that the information focuses on (2050 or 2100), for those who received information.</p>
<p>I'm curious about how to deal with the fact that my control group, receiving no in... | g66325 | [
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<p>I need to calculate MR but my data consists of many dummy variables. I had a question in my survey that asked for the budget/month. But instead of giving the option to fill in a value, I offered ranges (steps of 250, so I have like 0-250; 250.01-500 and so on)</p>
<p>I created dummy variables for these different st... | g25294 | [
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... |
<p>According to <a href="http://www.itl.nist.gov/div898/handbook/prc/section2/prc241.htm" rel="nofollow">http://www.itl.nist.gov/div898/handbook/prc/section2/prc241.htm</a>
Agresti-Coull intervals cannot be negative; however using the formula from Wikipedia as well as the binom.confint function in R with x = 0 and n = ... | g25296 | [
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<p>I'm trying to determine statistical significance of inputs on the dependent variable using neural networks. I'm trying to test the null hypothesis that the partial derivatives are equal to zero. I found a method called Bootstraping but it requires to retrain the neural network a 1000 times. Is there any alternative ... | g66326 | [
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<p>I am using three categorical predictor variables $X_1$, $X_2$, $X_3$ and one continuous dependent variable $Y$, and I want to treat $X_3$ as a random effect.</p>
<p>The simplest model I could come with:<br/></p>
<pre><code>M1<-lme(Y~X1*X2, random=~1|X3,method="ML")
</code></pre>
<p>Here are some more complex m... | g66327 | [
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... |
<p>I have a questionnaire with one "open" text box, and 20,000 responses. I'm not planning to read all of them, but I'm thinking of interesting things to do with them. A general tag cloud would not be very interesting (I can predict which words would be the biggest), but it would be fun to split it along another catego... | g25298 | [
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<p>I have been wading through the many discussions on outliers on this site but I am still unfortunately having difficulty determining what to do with my data set.</p>
<p>My study consists of a simple pre-post test setup whereby i conduct 6 tests prior to and 6 tests following my treatment. The purpose of the repeated... | g25299 | [
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<p>I have been using the fPortfolio package and have found some inconsistency in the usage of terminology in the package. </p>
<p>What does a "covariance risk budget" in the result returned by mean variance portfolio optimization- mean?</p> | g45103 | [
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<p>Suppose you have a casino with <em>n</em> poker players. Each player has a win rate - the amount of money he wins or loses per hand. We assume that these win rates are normally distributed with a mean of 0. (We also assume that the players don't pay the casino any money.) Our goal is to estimate the variance <em>V</... | g66328 | [
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<p>I have the following dataset (triplicate values of 5 independent measurements and duplicate values of a control):</p>
<pre><code>Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 C
181.8 58.2 288.9 273.2 290.9 53.9
120.3 116.8 108.9 281.3 446 39.6
8... | g45605 | [
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<p>I want to perform an ANOVA using R. I have three populations, represented by their respective means and SD:
Pop.1: 5.5 +- 0.4 (n=100)
Pop.2: 5.9 +- 0.3 (n=150)
Pop.3: 6.2 +- 0.5 (n=200)</p>
<p>Which is the exact code using R to perform the ANOVA using exclusively these data?</p>
<p>Moreover, how can I perfom subse... | g32825 | [
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<p>I have been reading a number of papers where researchers have created risk scores based on logistic regression models. Often they refer to "<a href="http://www.ncbi.nlm.nih.gov/pubmed/15122742" rel="nofollow">Sullivan's method</a>" but I have no access to this paper and the explanations provided are far from clear. ... | g66329 | [
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<p>I have been investigating the possibility of using the interval between uncommon events to test for changes in the frequency of such events over time.<br>
As an example, say that the event is breaking a record in some sporting competition. This might occur at most a few times a year, and the data segmentation proble... | g25312 | [
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<p>This is the Jensen's inequality I saw in my textbook: </p>
<p>$$E{ f(X) } \geq f( E(X) ),$$</p>
<p>where $f$ is a convex function.</p>
<p>Is this also applicable for two random variables--independent or otherwise--like this:</p>
<p>$$E{ f(X,Y) } \geq f( E(X,Y) )?$$</p> | g45612 | [
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<p>Can I use the t-test to compare means between groups (N=300) if data is not normally distributed? </p> | g49749 | [
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<p>I have been looking at unit root testing. Specifically 2 tests:</p>
<ol>
<li><p><strong>The ADF test.</strong>
The ADF (augmented Dickey Fuller) test has the null hypothesis that "the time series has a unit root" (meaning that the time series is not weakly stationary) </p></li>
<li><p><strong>The KPSS test.</stron... | g66330 | [
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0.03743... |
<p>For instance, I have a bar chart - in which I have 4 samples/bars. for these 4 bars, I want to check statistical significance for all combinations.</p>
<ol>
<li><p>How can I do it? Can unpaired t-test be used - to compare 2 samples at a time? or this is not correct. What is then the appropriate way in which all the... | g66331 | [
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<p>How to test for simultaneous equality of choosen coefficients in logit or probit model ? What is the standard approach and what is the state of art approach ?</p> | g47847 | [
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<p>I've got a set of (continuous) values from a measurement, where each object should be either positive or negative, and I know that the values of the "negative" objects should be approximately normally distributed.</p>
<p>I've been using a <code>k-means</code>-based algorithm in <code>R</code> to cluster the data an... | g66332 | [
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<p>I have been reading a <a href="https://media.readthedocs.org/pdf/a-little-book-of-r-for-time-series/latest/a-little-book-of-r-for-time-series.pdf" rel="nofollow">tutorial</a> for an introduction to time series.</p>
<p>It contains a dataset, with an $Arima(2,0,0)$ forecast along with a 80% and 95% prediction interva... | g10649 | [
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<p>I have a set of Inspection Time data that consists of two variables: SOA (stimulus onset asynchrony) and Accuracy. This data refers to how accurately you can perform on a simple stimuli discrimination task at a given duration of exposure. The accuracy data is binary (0,1) and the SOA data is in increments of .01 (... | g66333 | [
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0.00510826... |
<p>The problem is:</p>
<blockquote>
<p>Suppose we fit a model Y = X<sub>A</sub> β<sub>A</sub> + ε. However, the true model is Y = X<sub>A</sub> β<sub>A</sub> + X<sub>B</sub> β<sub>B</sub> + ε. A is k<sub>A</sub> x 1 and B is k<sub>B</sub> x 1. Show that the OLS estimates of β<sub>A</sub> will still be equal if X<s... | g66334 | [
0.0179589856415987,
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0.004244024865329266,
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0.05416274443268776,
0.00925470795482397,
0.043533217161893845,
0.03540898486971855,
0.0238... |
<p>I have seen five types of estimates of kurtosis and skewness:</p>
<ul>
<li>three from <a href="http://stats.stackexchange.com/a/84057/1005">http://stats.stackexchange.com/a/84057/1005</a></li>
<li>one from <a href="http://books.google.com/books?id=OKUGARAXKMwC&lpg=PP1&dq=financial%20time%20series%20tsay&am... | g66335 | [
0.0011692879488691688,
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0.006576349027454853,
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0.008193767629563808,
0.046618279069662094,
0.00021038201521150768,
0.05022318288683891,
0... |
<p>For the likelihood associated with the mixture model </p>
<p><code>1/4*Normal(mu1,1)+3/4*Normal(mu2,1)</code></p>
<p>I would like to have a figure as like as following one for a simulated sample of 500 observation from <code>mu1=0</code> and <code>mu2=2.5</code>. My <code>R</code> code is:</p>
<pre><code>da=rbind... | g66336 | [
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0.019082114100456238,
0.05897669121623039,
0.... |
<p>I am having a hard time understanding what a sufficient statistic actually helps us do.</p>
<p>It says that</p>
<p>Given $X_1, X_2, ..., X_n$ from some distribution, a statistic $T(X)$ is sufficient for a parameter $\theta$ if</p>
<p>$P(X_1, X_2, ..., X_n|T(X), \theta) = P(X_1, X_2, ..., X_n|T(X))$.</p>
<p>Meani... | g66337 | [
-0.0016412528930231929,
0.02921740896999836,
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0.019301410764455795,
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0.0349300280213356,
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-0.024675501510500908,
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0.06627760082483292,
-0.... |
<p>I'm having trouble finding a suitable model for predicting the AVG value (revenue in cents) of a single click on a product on a large e-commerce site. (assuming a click leading directly to a purchase has value equal to its revenue)</p>
<p>Using only categorical (perhaps ordered) predictors, how do I best model a co... | g66338 | [
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0.011349959298968315,
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0.054874662309885025,
... |
<p>On page 331 of "Elements of Information Theory" (1991), author says that while entropy is related to the volume of the typical set, Fisher information is related to the surface area of the typical set, but I can't find anything more on this...can anyone explain this connection?</p> | g66339 | [
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0.00830091256648302,
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... |
<p><strong>Duplicate thread:</strong> <a href="http://stats.stackexchange.com/questions/73/what-r-packages-do-you-find-most-useful-in-your-daily-work">What R packages do you find most useful in your daily work?</a></p>
<p>Are there any R packages that are just plain good to have, regardless of the type of work you are... | g66340 | [
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0.006185460835695267,
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-0.011999080888926983,
0.028002897277474403,
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-0.037708550691604614,
... |
<p>I have seen some classes in my University labeled as an "Inference class" and others as "Machine learning" classes, but I was not sure if appreciated the core difference between these two labelings? </p>
<p>I normally think of machine learning as the study of systems/algorithms that are able tp extract information ... | g49750 | [
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0.011881961487233639,
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0.034451231360435486,
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0.08588006347417831,
0... |
<p>I'm playing around with kernel Canonical Correlation Analysis, as implemented in the R package kernlab. Is there a simple way to extract the residuals after fitting? (Is this a well-defined quantity?) Here's some sample code:</p>
<pre><code>library(kernlab)
x = as.matrix(rnorm(100))
y = as.matrix(.5 * x + rnorm(100... | g66341 | [
0.027895119041204453,
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0.0016787077765911818,
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0.0251315850764513,
0.02183002233505249,
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0.007892061956226826,
0.... |
<p>Rephrased a problem trying to solve for work in terms of people buying wine, also included progress made so far.</p>
<p><strong>Set-up:</strong>
Customers enter a winery with the option of buying bottles of wine. Those who chose not to purchase can leave through one exit while those who wish to purchase go to the c... | g66342 | [
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0.005032320041209459,
-0.00015787819575052708,
0.0071373204700648785,
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0.0226079300045967... |
<p>I am doing research on the field of functional response of mites.
I would like to do a regression to estimate the parameters (attack rate and handling time) of the Rogers type II function.
I have a dataset of measurements.
<strong>How can I can best determine outliers?</strong></p>
<p>For my regression I use the fo... | g25324 | [
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0.00036570613156072795,
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0.008765154518187046,
0.057232823222875595,
0.02236447110772133,
0.0... |
<p>I'm not sure if machine learning is the best way to do this, but I'm interested in seeing if this problem is feasible. Normally you use machine learning for classification. ie.given the size of a tumor and the color(darkness) of the tumor, determine whether its lethal or benign. However, say you want to figure out h... | g66343 | [
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<p>Suppose you have a response variable, number of transactions a customer makes in the 24 hour period following acquisition, which follows a negative binomial distribution. Let's call the response <em>trans</em>. </p>
<p>Now it's easy to model the number of transactions the customer makes in this immediate 24 hour pe... | g66344 | [
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0.007518644444644451,
0.02655550092458725,
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0.08813153207302094,
-... |
<p>I have a data set (21 binned values) which I have fitted to a Gaussian with IDL ($\mu=3.825$, $\sigma =0.0377$). I have tried to find the $\chi^2$, getting $21.14$ for $20$ d.f.. Here my understanding is a little shakey; I think this means I can be 60% confident that the distribution is normal (please correct me if ... | g66345 | [
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... |
<p>I'm new to data mining and I'm trying to train a decision tree against a data set which is highly unbalanced. However, I'm having problems with poor predictive accuracy.</p>
<p>The data consists of students studying courses, and the class variable is the course status which has two values - Withdrawn or Current.</p... | g25327 | [
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0.016195423901081085,
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0.08624584227800369,
0.0... |
<p>I’m hoping to get some guidance in specifying a mixed model using the lme4 package in R.</p>
<p>The study is quite straightforward. It’s a repeated measures design with pre/post measurements on the variable of interest where half of the participants received the treatment (a physical therapy program) and the other... | g25329 | [
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0.0016482361825183034,
... |
<p>The following question might have relations to <a href="http://stats.stackexchange.com/questions/77529/correlation-of-distribution-standard-deviation-with-subtraction-of-its-mean-from" title="Correlation of distribution standard deviation with subtraction of its mean from mean of normal distribution">this question</... | g66346 | [
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0.002034020610153675,
0.00013078736083116382,
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0.0029803540091961622,
-0.053284600377082825,
0.0008935121586546302,
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0.028302995488047... |
<p>I'm looking to model land cover change using a variety of environmental predictors (e.g. elevation, rainfall, etc.) stored as raster layers. In most similar studies I've found in the literature the authors sample the raster layers at some subset of the cells before performing the regression. I'm trying to understand... | g66347 | [
0.06321007013320923,
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0.004216252360492945,
0.0492434985935688,
0.03190724924206734,
0.04246462136507034,
0.038... |
<p>I am studying classification and regression trees, and one of the measures for the split location is the GINI score. </p>
<p>Now I am used to determining best split location when the log of the likelihood ratio of the same data between two distributions is zero, meaning the likelihood of membership is equally like... | g66348 | [
0.007874655537307262,
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0.016483096405863762,
... |
<p>Bootstrap is a well known resampling method. But I want to know what is blocked weighted bootstrap sampling? Why we need this? </p> | g66349 | [
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0.020375367254018784,
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0.07814875990152359,
0.0... |
<p>I'm analysing some behavioural data using <code>lme4</code> in <code>R</code>, mostly following <a href="http://www.bodowinter.com/tutorials.html">Bodo Winter's excellent tutorials</a>, but I don't understand if I'm handling interactions properly. Worse, no-one else involved in this research uses mixed models, so I'... | g25330 | [
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0.020469864830374718,
0.00908701028674841,
0... |
<p>I m doing a quantitative analysis for my dissertation
and I m having issues with the interpretation of my results (I have little knowledge of SPSS).
I m doing a panel data analysis with multiple regression.
What, I want to understand is when I should keep or remove a control variable?
My R2 and adjusted R2 are opt... | g66350 | [
0.020915333181619644,
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0.019499661400914192,
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0.006838299799710512,
0.027065057307481766,
0... |
<p>There are more phenomena to which experimental design may be applied than there are alternative valid design strategies. This should be true, though there are many ways to properly design an experiment.</p>
<p>What are the best "problems" that truly demonstrate the value and nuance for the different types of optim... | g66351 | [
0.013812318444252014,
0.0402832068502903,
0.00939486175775528,
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0.050605881959199905,
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0.042582228779792786,
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0.032549116760492325,
-0.04344635456800461,
0.015111279673874378,
0.065... |
<p>I have a homework question in which data is taken from three months of hospital admission data. It is then split into six 4-hour groups (0000–400, 0400–0800, etc.). The data are given with just the hour group and one column containing a number of admits. We are to draw a conclusion about how nurses should be schedul... | g66352 | [
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0.004080692771822214,
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0.029389843344688416,
0.012946441769599915,
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0.010862254537642002,
0.015920326113700867,
0.013913197442889214,
0.0744004175066948,
0.0... |
<p>Multilevel factor analysis seems to be the technical term for factor analysis with repeated measures, judging from <a href="http://www.ncbi.nlm.nih.gov/pubmed/15799887" rel="nofollow">this abstract</a>. To be precise, following <a href="http://en.wikipedia.org/wiki/Factor_analysis" rel="nofollow">Wikipedia's factor... | g66353 | [
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0.014728927053511143,
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0.006562313064932823,
... |
<p>Let $X_t$ be a weakly stationary process with mean $\mu$ and autocovariance function $\gamma$. </p>
<p>How do I show that
$$n^{-2}\sum_{i=1}^n \sum_{j=1}^n cov(X_i, X_j)$$ equals $$ n^{-2} \sum_{i-j=-n}^n (n- |i-j|)\gamma(i-j)$$ </p>
<p>Thanks</p> | g66354 | [
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0.02716829441487789,
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0.05794705078005791,
-0.005529394373297691,
0.03... |
<p>I have a model to achieve Bayesian estimates the population size $N$ and probability of detection $\theta$ in a binomial distribution solely based on the observed number of observed objects $y$:
$$
p(N,\theta|y)\propto \frac{ \text{Bin}(y|N,\theta)}{N}
$$
for
$
\left\{N|N\in\mathbb{Z}\land N\ge \max(y)\right\}\ti... | g66355 | [
0.0442410409450531,
0.0010362735483795404,
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0.04675137624144554,
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0.05813910439610481,
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-0.049014534801244736,
0.00022050585539545864,
0.047130897641181946,
0.02605474554002285,
0... |
<p>I have a set of samples, each depicting a (full) social network of coworkers. The questionnaire, which was used to gather the data, was exactly the same for all the samples; just the respondents and the number of respondents is different.</p>
<p>For hypothesis-testing, I use multiple regression (MRQAP). For now, I ... | g66356 | [
0.027781866490840912,
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0.013536596670746803,
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0.00970002543181181,
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0.005371663253754377,
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0.009340766817331314,
0.018807340413331985,
0.0... |
<p>I have obtained the following estimations and forecasts in R for a seasonal ARIMA(1, 0, 1)(1, 0, 1)[7]</p>
<blockquote>
<p>model1</p>
</blockquote>
<p>Series: PO </p>
<p>ARIMA(1,0,1)(1,0,1)[7] with zero mean </p>
<p>Coefficients:</p>
<pre><code> ar1 ma1 sar1 sma1
0.9895 -0.8241 0.... | g23326 | [
-0.01504986546933651,
-0.06685149669647217,
0.01044379360973835,
0.028519783169031143,
0.002423960482701659,
-0.018405364826321602,
0.06309812515974045,
0.016071533784270287,
-0.01349770650267601,
0.018968921154737473,
-0.0007239377591758966,
0.0979500263929367,
0.06582023203372955,
0.0035... |
<p>I have 2 groups (biomaker high vs. low) and I measured quality of life (QoL) score (continuous variable) on 2 time-points. I want to run interaction statistics (group*time) to assess the effect of interaction on QoL score. My question is, can I use Mixed ANOVA on SPSS for this purpose? I have done it and it looks fi... | g66357 | [
-0.017822593450546265,
-0.039192333817481995,
0.007137717679142952,
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0.043428294360637665,
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0.00023015002079773694,
0.006153095979243517,
0.003959027584642172,
0.01823846809566021,
-0.0015438343398272991... |
<p>I am getting below output from <code>coxph</code> function in R.</p>
<pre><code>Concordance= 0.581 (se = 0.024 )
Rsquare= 0.06 (max possible= 0.995 )
Likelihood ratio test= 11.52 on 3 df, p=0.009216
</code></pre>
<p>Can somebody explain what do <code>11.52</code> and <code>0.009216</code> mean in this output... | g66358 | [
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-0... |
<p>I would like to know how I can determine the appropriate amount of lags in Matlab or another statistical package. I'm getting confused with VAR models and ARMAX models all the time and I'm a little stuck to be honest.
Introduction on ADL models at wikipedia: <a href="http://en.wikipedia.org/wiki/Distributed_lag" rel... | g25338 | [
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<p>Consider the following example. Suppose I want to model <code>x</code> in <code>DF2</code> using everything else. While it makes sense to do <code>pca</code> pre-processing on variable 1 to 10, I want to keep <code>z</code> the factor variable as is and simply center and scale <code>y</code> and <code>v</code>. My f... | g25339 | [
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0.00... |
<p>I asked this previously but I failed to activate my account so I was not able to respond to comments and my question was never answered. Here is attempt 2:</p>
<p>I have two rates of compliance for two different populations:</p>
<pre><code> Group N Compliant Rate (Compliant/N)
A 696 ... | g25340 | [
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0.01320519670844078,
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0.02087070420384407,
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0.013085425831377506,
0.02432326227426529,
-0.0... |
<p>I wonder if the following model is a linear or nonlinear time series model:</p>
<p>$$
X_t = d(t) + \sum_{i=1}^p a_i X_{t-i} + \sum_{i=0}^q b_i e_{t-i}
$$</p>
<p>when $d(t) = ct$, $d(t) = e^t$, $d(t)=sin(t)$, and $d(t) = t^3$?</p>
<p>According to the definitons in Tsay's Financial Time Series, I guess they are lin... | g66359 | [
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0.0315462201833725,
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0.04578396677970886,
-0.0... |
<p>Im trying to make a multiple regresion in which the dependent variable and one of the factors were originally positive variables but were centered and scaled for easire interpretation of effect sizes. The other factors are principal components derived from a PCA procedure based on correlation and thus are also cente... | g66360 | [
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<p>I'm currently testing a (binary) logistic regression model, which seems to have at least some issues with multicollinearity. Now I don't really trust the data anymore and would like to also test it on heteroscedasticity. I found some information on Breusch-Pagan Test on the internet, but I could not find an answer t... | g66361 | [
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<p>I'm currently working with the method proposed by Koenker (2004) and Lamarche(2010) on fixed effects for quantile regression, for this I'm using the RQPD code in R. I would like to get the predicted values for each firm after running the RQPD code.</p>
<p>The problem is that, after the running the code is only poss... | g66362 | [
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... |
<p>I'm struggling to understand what $\phi(x_{N+1})$ is in this excerpt of an algorithm (namely Linear Bayesian Regression embedded in other algorithm):</p>
<p>$c_i = \gamma_i / \sum^L_{j} \gamma_j$</p>
<p>$V_i^{N+1} = ((V_i^N)^{-1}+\beta \phi(x_{N+1})^Tc_i \phi(x_{N+1}))^{-1}$</p>
<p>$\theta_i^{N+1} =V_i ^ {N+1} ((... | g66363 | [
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0.0... |
<p>This question is concerned with the paper <a href="http://www.jstor.org/stable/2240672" rel="nofollow">Differential Geometry of Curved Exponential Families-Curvatures and Information Loss</a> by Amari. </p>
<p>The text goes as follows.</p>
<p>Let $S^n=\{p_{\theta}\}$ be an $n$-dimensional manifold of probability d... | g66364 | [
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0... |
<p>It seems like when the assumption of homogeneity of variance is met that the results from a Welch adjusted t-test and a standard t-test are approximately the same. Why not simply always use the Welch adjusted t?</p> | g25345 | [
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... |
<p>I have been wanting to get a Monte Carlo based power calculation working for Logistic Regression cases for a little bit. I have put together a workflow with some assisstnace and I wanted to ask the community if this solution is on the right track and help to highlight any possible issues. I will list the code and ... | g66365 | [
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<p>EDIT:</p>
<p>As pointed, there is already a similar question "buried" inside a larger-scope one. I'll reproduce the relevant part here:</p>
<blockquote>
<p>If I have multiple recordings of the same routes are there any valid techniques to combine them to get closer to the real route?</p>
</blockquote>
<p>The re... | g49751 | [
0.01390008069574833,
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0.00017170060891658068,
0.0332576148211956,
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0.012106673792004585,
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0.06196289882063866,
0... |
<p>Let say I have a 2 samples from the same population that is unknown</p>
<pre><code>Sample 1: n=100 mean=50 range= 0-100
Sample 2: n=40 mean= 70 range=50-140
</code></pre>
<p>How would I combine these two data sets to create a sample that better reflects the population for calculating the probability of events. Wo... | g66366 | [
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0.022949770092964172,
0.08179043233394623,
-0.... |
<p>Hi looking for advice on how to calculate the probability of the following.</p>
<p>If someone has a 4% chance of catching a disease (so 4 people out of 100)</p>
<p>Then if they caught the disease they have a 15% chance of it not showing up with tests, so 15 out of 100 who have caught the disease won't be diagnosed... | g66367 | [
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0.003237714059650898,
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0.04559649899601936,
0.029813852161169052,
-0.014824... |
<p>I have a large (650K rows * 62 columns) matrix of binary data (0-1 entries only). The matrix is mostly sparse: about 8% is filled. </p>
<p>I would like to cluster it into 5 groups - say named from 1 to 5. I have tried hierarchical clustering and it was not able to handle the size. I have also used hamming distance ... | g66368 | [
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0.04955466836690903,
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<p>I am doing a project to estimate students' final graduation GPAs based on several variables. I have students' first year GPAs, high school GPAs, their race, where they come from, and their ACT score, and so on. </p>
<p>I have two questions:</p>
<ol>
<li><p>How to convert race into numbers, I know I can just assign... | g66369 | [
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0.03668055683374405,
0.02241220697760582,
0.047719571739435196,
0.048152126... |
<p>Not sure if dealing with repeated measures analysis...? Measuring X at 3 seasons (summer, winter, spring/fall) during a year – might be high summer/low winter, high winter/low summer, consistently high, consistently low, etc. Y (health outcome) measured at same 3 times. Time between measures not fully equal between ... | g66370 | [
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0.038317516446113586,
0.0066612642258405685,
... |
<p>I'm expanding a question I posed earlier because I think it was lacking detail. </p>
<p>I'm attempting to forecast daily demand for a restaurant that sells take away food, primarily to office workers on their lunch breaks. They are located in the downtown core of a major city.</p>
<p>They are only open on workdays... | g66371 | [
-0.030239935964345932,
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0.010891355574131012,
0.04432664066553116,
0.07376690208911896,
0.01... |
<p>Suppose that you are have a response variable $Y$ and explanatory variables $X_1$, $X_2$ and $X_3$. If we want to use a quadratic transformation for $X_1$, would we still include $X_1$? In other words, would we have:</p>
<p>$$E[Y|X] = \beta_0+\beta_{1}X_{1}^{2} + \beta_{2}X_{2} + \beta_{3}X_{3}$$ or $$E[Y|X] = \bet... | g66372 | [
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-0... |
<p>How do I calculate the constant coefficient in logistic regression manually, i.e without having to use a calculator?</p>
<p>My model is</p>
<p>$g(Y) = X \beta + \alpha$</p>
<p>is it possible to calculate just the constant parameter $\alpha$ without performing the full regression fit?</p> | g66373 | [
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0.03520... |
<p>I'm working on a problem, I was wondering if there are any methods available to do the following.</p>
<p>I have a data set with information on people (continuous and categorical data). I have 3 categories to assign to these people {A, B, C}, and I want to try and develop some rules of how to assign each person a ca... | g25354 | [
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0... |
<p>When using the sign test, we assume, that:</p>
<p>$\textrm{test statistic} \sim Bi(n_+ + n_-, 0.5)$</p>
<p>ie. that the probablity of $+$ or $-$ to occur is $0.5$. But how about the case of values being the same (resulting in $0$). The probablity of $0$s increases when dealing with ordinal variables.</p>
<p>How c... | g66374 | [
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0.... |
<p>I am regressing monthly data that I know has significant seasonality. I have about 50 monthly observations. I was thinking of using 12 variables and for each row of my data turn on one variable depending on the month. I was then going to see what monthly variables were significant and then rerun for the these possib... | g66375 | [
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0.... |
<p>I am trying to better understand the conditions under which the application of continuity correction is appropriate for the normal approximation to the binomial distribution. </p>
<p>Everything I have found says "this is something you should do" or gives an intuitive explanation, but I would like to see a formal pr... | g66376 | [
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0.034061647951602936,
0.011938171461224556,
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... |
<p>I need to run multiple regression with 2 IVs and 1 DV and include a control variables. The control variable is "Type of House" and has 4 categories: 1=bungalow, 2=apartment, 3=penthouse and 4=condominium. </p>
<p>How do I enter the control variables into the model? Is it just the way it is (i.e., nominal) or do I h... | g66377 | [
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... |
<p>Are studies in epidemiology all observational and not controlled? My impression comes from <a href="http://en.wikipedia.org/wiki/Epidemiology#Types_of_studies" rel="nofollow">Wikipedia</a>, which lists:</p>
<ul>
<li>Case Series</li>
<li>Case Control Studies</li>
<li>Cohort Studies</li>
<li>Outbreak Investigations</... | g66378 | [
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0.0183... |
<p>In <a href="http://en.wikipedia.org/wiki/Bradford_Hill_criteria" rel="nofollow">Bradford Hill criteria</a> for causality</p>
<blockquote>
<p>Plausibility: A plausible mechanism between cause and effect is helpful (but Hill noted that knowledge of the mechanism is limited by current knowledge).</p>
</blockquote>
... | g66379 | [
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0.04... |
<p>I have been attempting to set up a <code>lme</code> and have looked at numerous posts including '<code>R</code>'s <code>lmer</code> cheat-sheet' as well as reading a number of papers and other resources including <code>R</code> help, but I am still a little confused on how to write my model (I thought I had it). I h... | g66380 | [
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0.... |
<p>I've worked the slope all the way down to $\sum [x_i(y_i - \bar{y})] = \hat\beta_1 \sum[x_i(x_i - \bar{x})]$</p>
<p>But I can not figure out how to show the steps for:</p>
<p>$\sum[x_i(y_i - \bar{y})] = \sum(x_i - \bar{x})(y_i - \bar{y})$</p>
<p>and</p>
<p>$\hat \beta_1 \sum[x_i(x_i - \bar{x})] = \hat \beta_1 \s... | g45693 | [
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0.07238666713237762,
-0.015775641426444054,
-0.028333930298686028,
-0.0042113373056054115,
-0.06883566826581955,
0.057958122342824936,
0.02258593589067459,
0.0... |
<p>I have something like this:</p>
<pre><code>Case I
A
|-----------------|
|------------------|B
Case II
A
|-----------------|
|---------------------|
B
</code></pre>
<p>And the following numbers:</p>
<pre><code> Total generated by A Total... | g66381 | [
0.0002855307830031961,
0.059325218200683594,
0.014025775715708733,
-0.013738241977989674,
0.00667840801179409,
0.016747286543250084,
0.08099000155925751,
0.04491228610277176,
0.000007813108823029324,
-0.04753483086824417,
-0.01342996209859848,
-0.034488506615161896,
0.003613813314586878,
0... |
<p>Suppose $x_i$ are drawn <em>i.i.d.</em> from a $p$-variate Gaussian, $\mathcal{N}\left(\mu,\Sigma\right)$. Suppose one observes $x_1,x_2,\ldots,x_n$. One also observes $s_{n+1},s_{n+2},\ldots,s_{n+m},$ where $s_i = \mbox{sign}\left(x_i\right)$ is a $p$-vector consisting of -1 and +1's. (Well, in principle, it could ... | g45695 | [
-0.021114755421876907,
-0.002867849776521325,
-0.01358325406908989,
-0.06949379295110703,
-0.038953181356191635,
-0.029568182304501534,
0.01713949628174305,
-0.02172314189374447,
-0.02096436731517315,
-0.0015990848187357187,
0.004974606912583113,
0.05101415514945984,
0.06736385822296143,
0... |
<p>I am new to statistics.</p>
<p>After an MCMC sampler warmed up, the posterior is better estimated as the mean of several samples. (e.g. related question: <a href="http://stats.stackexchange.com//questions/56077">http://stats.stackexchange.com//questions/56077</a>)</p>
<p>However, in my MCMC sampler, after it reach... | g25361 | [
0.00931027065962553,
-0.0315207913517952,
-0.014588935300707817,
-0.09408532083034515,
-0.03654587268829346,
-0.03825649246573448,
-0.0005671395920217037,
-0.015899736434221268,
-0.04313026741147041,
0.005815199110656977,
-0.042066577821969986,
0.01972566731274128,
0.00004960084334015846,
... |
<p>My name is Abhi and I am trying to teach myself regression by solving some practice problems available on the internet. I am using RStudio as my development environment.</p>
<p><strong><em>Problem Statement</em></strong>
<br>
Given the age, sex, class(first,second,third), ticket_id for each passenger can you predic... | g66382 | [
-0.013767188414931297,
-0.07959846407175064,
-0.006714557763189077,
-0.0052329543977975845,
0.02870984748005867,
0.04129253700375557,
0.08260013163089752,
0.04557497799396515,
-0.05672033876180649,
-0.025461526587605476,
-0.03681306168437004,
0.009590702131390572,
0.07276309281587601,
-0.0... |
<p>I am interested in quantifying the similarity between 2 time-series. Can I simply sum the squared values of their differences, ie compare the sum of square residuals? </p>
<p>More specifically, I have some observed data that can be represented as a time series. I am able to simulated this data and would like to fin... | g66383 | [
0.007100917864590883,
-0.03296841308474541,
-0.017294304445385933,
-0.03152421489357948,
-0.018790924921631813,
-0.029283566400408745,
-0.017557742074131966,
-0.038276273757219315,
-0.04118354618549347,
0.034687552601099014,
0.008795496076345444,
0.030933741480112076,
0.0059957318007946014,
... |
<p>I am asking myself how cointegration and causality are related in a VAR/VECM model.</p>
<p>Suppose you have two $I(1)$ variables in your 2 dim VAR process which are cointegrated, so there is one cointegration relationship.
In my opinion this should imply that the two variables are granger causal to each other?!</p... | g66384 | [
0.10046270489692688,
-0.08928646147251129,
0.0071136304177343845,
-0.010790937580168247,
0.07592174410820007,
-0.015855856239795685,
0.06257792562246323,
0.04456087574362755,
-0.02724255993962288,
0.03361242637038231,
-0.060212552547454834,
0.008288946002721786,
0.010991965420544147,
-0.00... |
<p>I'm trying to use R's <a href="http://cran.r-project.org/web/packages/neuralnet/index.html" rel="nofollow"><code>neuralnet</code></a> package (documentation <a href="http://cran.r-project.org/web/packages/neuralnet/neuralnet.pdf" rel="nofollow">here</a>) for prediction.</p>
<p>Here what I'm trying to do:</p>
<pre>... | g66385 | [
-0.006602348294109106,
0.015830419957637787,
-0.017411261796951294,
0.0009045782499015331,
0.03505342826247215,
-0.05421029403805733,
0.07312511652708054,
0.04828241840004921,
-0.07851041853427887,
0.0035248498897999525,
-0.033191390335559845,
0.029481301084160805,
0.038520801812410355,
0.... |
<p>With respect to the change point detection for data stream, there is a concept of "average run length", which is discussed in the <a href="http://cran.r-project.org/web/packages/cpm/vignettes/cpm.pdf" rel="nofollow">CPM package manual</a>: </p>
<p><img src="http://i.stack.imgur.com/056Cl.png" alt="enter image descr... | g66386 | [
0.012104924768209457,
-0.02221553958952427,
-0.03961382061243057,
-0.024341031908988953,
0.028765778988599777,
-0.06118789687752724,
0.058256130665540695,
0.02139488235116005,
-0.10157684981822968,
-0.02016499638557434,
0.03015926666557789,
0.047675929963588715,
0.044642653316259384,
0.087... |
<p>I am learning elementary statistics.</p>
<p>I found an exercise, which asks to compute the desired sample size for some interval for standard error.</p>
<p>The solution, in class slides, first assumes the sample size to be computed is big enough to be approximated by a normal distribution (central limit theorem), ... | g66387 | [
0.012657695449888706,
0.015328455716371536,
0.007272630929946899,
-0.0461980439722538,
-0.025600310415029526,
-0.0028322115540504456,
0.009152577258646488,
0.01906214840710163,
-0.05132395029067993,
-0.026322292163968086,
0.024563001468777657,
0.026024727150797844,
0.007303754799067974,
0.... |
<p>I wonder how can I test if a data sequence is really random?</p>
<p>Of course I can randomly cut it into equal pieces, and check if the correlation coefficient between different pieces on average is zero.</p>
<p>But is that sufficient? Or if that is the best way to do it?</p>
<p>Thank you</p> | g49380 | [
-0.011840135790407658,
0.0033212981652468443,
0.007792899385094643,
-0.055669136345386505,
0.0024219646584242582,
-0.025352582335472107,
0.01896250806748867,
0.028380153700709343,
-0.0004646906163543463,
-0.007738546933978796,
-0.009083486162126064,
-0.012701154686510563,
-0.0125710498541593... |
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