question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>When comparing two effect sizes with a statistical test, does it matter for the test's power whether these effect sizes themselves are large or small?</p>
<p>Imagine you are planning an experiment in which you compute an effect (difference between two conditions) for two groups (A,B). You want to show that the effe... | g63657 | [
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<p>I'm using CUSUM to check structural breaks. The plot you see below pass the <strong>CUSUM test</strong>. How is that possible?</p>
<pre><code>> cs <- sctest(pair.res ~ 1)
> cs
Recursive CUSUM test
data: pair.res ~ 1
S = 0.9448, p-value = 0.05118
</code></pre>
<p><img src="http://i.stack.imgur.com/... | g63658 | [
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<p>I am analyzing spatial patterns in vegetation structure across vegetation transects. I broke transects up into 3-m intervals that move across the transect (a moving window) 1-m at a time. So, the intervals in the analysis overlap in space. I think this is somewhat comparable to a time-series analysis as phenomena ar... | g63659 | [
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<p>I have been asked to help a colleague with analysing the following experimental design.</p>
<p>2 treatments (fixed), 5 time points (fixed) with 4 animals (random) at each time point. The animals within each time point are not the same. </p>
<p>Each animal had two samples taken, one from a treated limb and one from... | g21440 | [
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<p>I'd like to have your opinion about my case study. I'm analyzing a dataset of 9 experiments and 15 variables with the aim to highlight the variables that can majorly explain the variance between the experiments. This is an example with only 3 rows and 5 variables: </p>
<pre><code> var1 var2 var3 ... | g21441 | [
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<p>Imagine that </p>
<ul>
<li>responses were collected on a 20 item scale which was designed to measure 4 factors with 5 items on each scale. </li>
<li>participants were drawn from two groups (Group 1) and (Group 2) with sample size $n_1 = 150$ and $n_2 = 150$.</li>
<li>a researcher wanted to assess the factor structu... | g63660 | [
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<p>Given a function mapping between two sample spaces $S_1$ and $S_2$, if $S_2$,$F_2$ is measurable how do I show that preimage of $S_2$,$F_2$ in $S_1$ is measurable set?</p> | g63661 | [
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<p>Assuming to have $k$ 2x2 tables which count successes and failures for two different treatments, which is the exact formula to give the chi square test for heterogeneity?</p> | g63662 | [
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<p>I have a dataset forwhich i have performed an mds and visualized the results using scatterplot3d library. However i would like to see the names of the points on the 3d plot. How do i accomplish that? Each column belongs to a certain group i would like to see which points belong to which groups on the 3dplot.</p>
<p... | g21444 | [
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<p>i want to use an ARIMA model in R for predicting an electrical load on a minutely basis. By examining the ACF I figured out which model could suit. The ACF has shown that the value one day ahead has a periodic autocorrelation. Therefore I'd like to implement a seasonal difference with a lag of 1440 (min/day).</p>
<... | g63663 | [
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<p>I'm looking for implementations of online learners. I guess that is possible with AdaBoost. Where you train the model and then you modify it by adding later more training data. However you don't have to re-train the entire model. Are you aware of this online implementation of AdaBoost in java?</p> | g63664 | [
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<p>I need to classify objects based on a set of features - typical classification settings. The additional information is that I know the number of individual which fall in a certain class.</p>
<p>In the sample I need to classify, I have N individuals that I need to classify in k classes. I do not know which individua... | g21448 | [
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<p>What is expressed by the terms zeroth-, first-, second-, third-, etc. order of correlation?
Thanks!</p> | g40847 | [
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<p>I have a set of data points in a N-dimensional space. In addition, I also have a centroid in this same N-dimensional space. Are there any approaches that can allow me to project these data points into a two-dimensional space while keeping their relative distance information in the original space. Is PCA the correct ... | g63665 | [
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<p>Say I have 5 binary variables and 2 normal variables. I want to get the probability of success, say one of the variable 1 or 0, 1 for success. How can I do that?</p>
<p>I tried <code>glm(A~B+C+D+E, binomial, data)</code> in R.</p>
<p>$A$ is a binary variable for which I want to know the probability of success.
$B... | g40849 | [
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<p>I've been reading on how to calculate confidence levels from A/B tests, as I'm running some ads on Facebook and want to better understand the results. The clearest explanations I've found seem to offer two alternatives: Chi-Square and Binomial Random Variables. I'm hoping someone can explain which is more appropria... | g39624 | [
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<p>Given a population to be divided between treatment / control, if I believe a variable is distributed lognormal in the population, how do I know what the necessary control size is in order to guarantee a difference in means is significant at some arbitrary level for a specific effect size? </p>
<p>(Reference to R or... | g63666 | [
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<p>I would like to use the predict function (or something similar) in R to generate expected values from a Cox proportional hazards model with time-dependent covariates. The model takes the form</p>
<pre><code>model <- coxph(Surv(start,stop,event.time)~covars..., data=data)
</code></pre>
<p>Normally, it's pretty s... | g42610 | [
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<p>Let $X_1, \dots, X_n$ be random variables, for some integer $n > 2$. Then, $$\text{Var}\left(\sum_{i=1}^nX_i\right) = \sum_{i=1}^n \text{Var}(X_i) + \sum_{i \neq j} \text{Cov}(X_i, X_j) $$</p>
<p>There is a natural interest in the special case when the $X_i$ are such that $$\sum_{i \neq j} \text{Cov}(X_i, X_j) ... | g63667 | [
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<p>Hi I have a quick question about the details of running a model in JAGS and BUGS.</p>
<p>Say I run a model with n.burnin=5000, n.iter=5000 and thin=2. Does this mean that the program will </p>
<ul>
<li>run 5,000 iterations, and discard results, </li>
</ul>
<p>and then </p>
<ul>
<li>run another 10,000 iterations,... | g63668 | [
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<p>Suppose I draw a sample from one of the two possible random variables $X$ or $Y$ where $X\sim\text{Binomial}(p,N)$ and $Y=A+B$ with $A\sim\text{Binomial}(p,M)$ and $B\sim\text{Binomial}(q,N-M)$. Assume unknown $q\geq p$, with $p$, $M$ and $N$ known. My objective is to distinguish which random variable my sample cam... | g63669 | [
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<p>Consider the linear model $Y = B_{0} + B_{1}X_{1} + B_{2}X_{2} + e$,
where the columns $X_{1}$ and $X_{2}$ of the design matrix have mean $0$ and length $1$. That is $X_{i}'X_{i} = 1$ and $X_{i}'J = 0$ where $J$ is a column entirely of ones. Let $\rho$ be the correlation between $X_{1}$ and $X_{2}$.</p>
<p><strong>... | g63670 | [
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<p>My data set has the following variables:</p>
<ul>
<li>Treatment (4 types- fixed) </li>
<li>Location (8 locations- fixed)</li>
<li>Position in Location (3 positions per location- fixed)</li>
<li>Samples are taken in each position (3 samples per position-random)
<ul>
<li>Time (two sampling times - fixed)</li>
<li>Min... | g63671 | [
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<p>I have this linear equation</p>
<pre><code> [A] = [C]x
[B] [D]
</code></pre>
<p>where A=Cx and B=Dx. I have combined these two to form the above equation.</p>
<p>I was reading a paper where it was mentioned that if I place a weight w on D i.e, multiply D by a constant w, then depending on the value of w, the... | g63672 | [
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<p>I am Computer Science major, and new to stats, so please bear with me and point me to the right direction if what I'm asking is pretty obvious.</p>
<p>I have a dataset, where each data point consists of <code>M</code> features (e.g. <code>name</code>, <code>age</code> etc. both continuous and categorical - I might ... | g63673 | [
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<p>I have been given a data points $x_i,y_i,1\leq i\leq n$. I was asked to compute the standard error of regression coefficients estimates. As in the formula, I have to compute
$\sum_{i=1}^n (y_i-\hat{y}_i)^2.$ But how one defines $\hat{y}_i$?</p> | g63674 | [
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<p>In a dataset with 3 related measurements for each case, I ran a Friedman test, and found no significant effect. </p>
<p>Is it appropriate to now run (and report) pairwise tests, as I had planned initially? </p>
<p>On one hand, the existence of these pairwise effects may convey important information (e.g. there's a... | g63675 | [
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<p>This is basically a data generation problem.</p>
<p>Say, $t$ is an exponential lifetime with mean two years. $tr$ is the remission time and $ts$ is the after remission time. So, $t=tr+ts$. I need to simulate these quantities for $100$ patients. Now in real life, usually when $tr$ is smaller, that is when the patien... | g63676 | [
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<p>I am not sure if this question is very naive, but I was wondering if there is a relationship between sample mean and sample survival probability. For an exponential distribution with mean $\mu$,
$$S(t)=1-\exp(-\dfrac{t}{\mu})$$
Now if I generate data from an exponential distribution, can the sample mean $\bar{x}$ b... | g63677 | [
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<p>I'm confused about how interactions are treated in multiple regressions. When doing a factorial ANOVA, I'd just look at the graphs, say they're not parallel so there's an interaction, run my ANOVA with the interaction term, and determine if it's significant.</p>
<p>However, in multiple regression, I add in my inte... | g21458 | [
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<p>I have this density, I want to find a density "larger" than this</p>
<p>$f(x)=\frac{1}{c}g(x)(1-\sin (20x)/4))$
, where $g(x)$ is N(0,1). </p>
<p>I am looking for a proposal distribution for f(x), basically find a density that is "larger" everywhere than the one above? </p>
<p>I was told to use g(x), but g(x) is... | g37528 | [
0.04063687473535538,
0.027327654883265495,
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0.05427613854408264,
... |
<p>AMOS, like other SEM packages offers standardized and unstandardized estimates of the parameters. What is the difference? Are unstandardized estimates based on the covariance matrix and standarized on the correlation matrix? Or is it something else?</p> | g14012 | [
0.05310739204287529,
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<p>I am using Weka 3.6 to do Association Rule mining. In our data set, each transaction is a word, and each letter in the word is an item. The rules that we are mining would be in the format of <code>{a set of letters} -> {another set of letters}</code>.</p>
<p>So far, I have formatted six transactions by represe... | g63678 | [
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0.021... |
<p>I have a time series of measurements (heights-one dimensional series). In the observation period, the measurement process went down for some time points. So the resulting data is a vector with NaNs where there were gaps in the data. Using MATLAB, this is causing me a problem when computing the autocorrelation (<code... | g63679 | [
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0.036120... |
<p>Let's say we have 7 samples of data and we wish to test whether there is a significant difference between the means of each sample. We could use t-tests, which would require 21 different t-tests. However, I've read that this isn't advisable as the risk of drawing the wrong conclusion (1 in 20) is increased. Instead... | g63680 | [
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<p>I'am getting familiar with the statistical notion of Divergence. The word "divergence" is also used in physics (or vector analysis, see here <a href="http://en.wikipedia.org/wiki/Divergence" rel="nofollow">http://en.wikipedia.org/wiki/Divergence</a>). As I was more familiar with the second use, I wonder If there is ... | g40864 | [
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0.0383... |
<p>I have a regularized logistic regression model using scikit-learn and would like to share it with others, however the data it is trained on is confidential and must remain protected. The model uses bag-of-words style features to automatically classify texts describing injuries, and would be useful for a broad variet... | g63681 | [
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-... |
<p>What does having a seasonality of 1 mean? </p>
<p>Suppose I have hourly data and I define the seasonality to be 1, does that mean the data will be dealt with as if there is no seasonality?</p> | g63682 | [
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<p>I am training a 4-class neural network classifier.
The details of my data are:</p>
<p>featurelength = 280</p>
<pre><code> training testing
---------------------------------------------
no. samples 438 250
samples class1 203 135
samples class2 19 10
samples... | g43797 | [
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<p>What is the easiest way to understand boosting?</p>
<p>Why doesn't it boost very weak classifiers "to infinity" (perfection)?</p> | g63683 | [
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<p>I'm new to data mining and currently doing mining project on telecom customer segmentation (based on profile and call details record). I have gender, age, call time and call duration and have to perform k-mean clustering. My question is:- How to normalize data to perform clustering. Any reference or suggestion are w... | g21466 | [
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<p>Say a study aims to see if two variables A and B are correlated in the general population. It isn't clear to me how extraneous variables like gender should be treated when the sample is selected. Each of the two methods of "controlling" for gender that I am aware of (see below) seems non-ideal, so is it a case of se... | g21467 | [
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<p>I hope you all won't mind a basic question. </p>
<p>We are examining the effects of a compound at various concentration on the behaviour of an organism. The compound is administered once at the beginning of the time course. Observations are made every minute for a period of 2 hours. Each concentration is applied ... | g40868 | [
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<p>I am seeking advice on programming a new random effects variance-covariance matrix/structure (pdmat) in R for use in lme()? I've checked out the lme source code (as suggested if you want to program your own pdmat), but remain confused. Does anyone have a good reference? Thanks in advance!</p> | g63684 | [
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<p>I am conducting multinomial log. regression, my DV has three categories, therefore my output gives me the comparison between the reference category and the other two. I would also like to compare those two which are not reference with each other. I know I can do this by changing the reference category in a second an... | g40528 | [
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0.02112921141088009,
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0.00029062264366075397,
0.03936222940683365,
0.02... |
<p>I'm trying to fit two equations with nls() function in R. The two functions are:</p>
<p>$f(x) = c_{1} \exp\left(-\left(\frac{x-\mu}{\sigma_{(x)}}\right)^2\right)$</p>
<p>where $\sigma_{(x)} = \sigma_{11}$ if $x \le \mu$ and $\sigma_{(x)} = \sigma_{12}$ if $x > \mu$</p>
<p>and</p>
<p>$f(x) = a K \exp\left(... | g21472 | [
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0... |
<p>I'm wondering how to test the significance of factor(s) and/or covariate(s) along with modeling the causal relationship among responses.
Let me explain this with a concrete example.</p>
<h3>Example:</h3>
<p>Suppose a researcher observed four responses <strong>Y1</strong>, <strong>Y2</strong>, <strong>Y3</strong>, ... | g63685 | [
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<p>I am performing a generalized linear model, where I have to specify a family different from the normal one.</p>
<ul>
<li>What is the expected distribution of residuals? </li>
<li>For example, should the residuals be distributed normally?</li>
</ul> | g49474 | [
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<p>Suppose I sample and perform tests from two <strong>small</strong> populations, <strong>without replacement</strong>, and I want to test for a significant difference in the proportions of positives in each population. How can I perform this test? </p>
<p>I know how to do this if the populations were large, or I wa... | g63686 | [
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0... |
<p>Is it always a good idea to <strong>train with the full dataset after k-fold cross-validation</strong>? Or is it better instead to stick with one of the models learned <strong>in one of the cross-validation splits</strong> for $\alpha_{best}$? Is there any way to tell?</p>
<p>Perhaps most importantly, how can I tra... | g49893 | [
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<p>I have a count of sickness absences before and after an accident,
and I want to find out whether an accident increases the sickness
absences differently in different groups.</p>
<p>I'm trying to formulate a Poisson model for this, but I'm not
sure if I'm doing it correctly, or if I should be doing something
complet... | g40872 | [
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<p>My current understanding of the notion "confidence interval with confidence level $1 - \alpha$" is that if we tried to calculate the confidence interval many times (each time with a fresh sample), it would contain the correct
parameter $1 - \alpha$ of the time.</p>
<p>Though I realize that this is not the same as ... | g49534 | [
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<p>Suppose I have a model of stock prices developed using Brownian motion. I have a second time series derived from the first. At each price point in the first time series, I take the arithmetic mean up to that point and that is the data point for my second time series. The volatility of the second time series is lo... | g690 | [
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<p>In my design I have 48 permanent plots in 3 summits (16 plots for each summit). Plots are grouped in clusters arranged in the cardinal direction (4 plots for cardinal direction = 16 plots) and grouped into summits (16 plots for summit x 3 summits = 48 plots). I have two observations of the response variable for each... | g40874 | [
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<p>I am working on a data which contain nearly 80% of zeros and positive counts as large as 7. The dataset is very large, nearly 16,000 cases. It is a health related data. I have fitted ZIP, ZINB and Hurdle models on it with five covariates, same for zero and positive counts. Later I have fitted negative binomial and P... | g4351 | [
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... |
<p>I am using neural net package in R. While I understand the basic neural network concepts, the details and back end is still a tough nut for me. </p>
<p>Currently all I can do is use brute force to change the parameters one at a time(changing neuron layers, adjusting hidden neurons, threshold,etc)</p>
<p>I tried te... | g63687 | [
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<p>Suppose that I want to study the relationship between two variables $Y$ and $X$ using the linear model $Y \sim X$. Unfortunately, both $Y$ and $X$ are not normally distributed, say they are both skewed and have long right tails. So I'd do the trick of log-transforming both of them to make them look more like bell-sh... | g21478 | [
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0.02565078064799308... |
<p>I am wondering how to best approximate the <strong>information value</strong> of a word $x$ in <strong>general human speech</strong>. By information value I literally mean its entropy:</p>
<p>$H(X) = \mathbb{E}_{X} [I(x)] = -\sum_{x \in \mathbb{X}} p(x) \log p(x).$</p>
<p>with $p(x)$ the probability of the word $... | g21479 | [
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... |
<p>We are interested in determining whether there's an association between frequency of screening visits and cancer outcomes and whether that differs by race. We have Medicare data to analyze this. Typically, the knee jerk reflex for modeling survival times is that of Cox proportional hazards models, but the problem is... | g37649 | [
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<p><strong>Background:</strong> I am building a count data model with an abundancy of zeros. More precesely, I am trying to estimate the number of competitors that will enter a certain market. 70% of my data consists of zeros (no entries). So, I am trying to model using a Zero-Inflated Poisson (or Neg. Binomial) mod... | g63688 | [
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<p>I recently started reading Gelman and Hill's, "Data Analysis Using Regression and Multilevel/Hierarchical Models" and the question is based on that:</p>
<p>The sample contains 6 observations on proportions: $p_{1}, p_{2}, \dots, p_{6}$</p>
<p>Each $p_{i}$ has mean $\pi_{i}$ and variance $\frac{\pi_{i}(1-\pi_{i})}{... | g63689 | [
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... |
<p>For variables A (product research) and B (product purchase), I am proposing to do three levels of analysis as follows:</p>
<ul>
<li><p><strong>Test 1: Overall:</strong>
The goal here is to see if there is a relationship between A and B. My data is at the interval level and the scatter plot shows a linear relations... | g21481 | [
0.03202512487769127,
-0.06708698719739914,
0.0021453280933201313,
-0.0043142205104231834,
-0.007891375571489334,
0.021169306710362434,
0.023929044604301453,
0.012796932831406593,
0.022035183385014534,
0.05182676017284393,
0.039491746574640274,
-0.0024609710089862347,
0.006427794229239225,
... |
<p>I need to determine if a single number "fits" with a group of numbers. All the numbers will be percentages, so we'll use decimals.</p>
<p>For example:</p>
<p>The group is: <code>0.1, 0.25, 0.3, 0.4, 0.9</code> and we'll test against two single numbers: $y_1$ = 0.2 and $y_2$ = 0.8</p>
<p>The group is all low numbe... | g63690 | [
0.006072062533348799,
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0.05918404459953308,
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-0.00... |
<p>I am trying to write a Monte Carlo simulation in R and I am really stuck! I want to know the probability distribution of a random person in the UK becoming ill from eating a cooked 100g piece of chicken. </p>
<p>I have the following information: out of 1000 pieces of chicken tested 20 had bacteria in question and I... | g37650 | [
0.052270159125328064,
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0.045358918607234955,
0.04555404558777809,
0.009... |
<p>Can the percentages in a pie chart add up to more than $100\%$ and the data or analyses will still make sense (or be logical)? Let's say the percentage in a pie chart adds up to $100\%$ . Does this make statistical sense?</p> | g63691 | [
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0.032264359295368195,
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0.045849982649087906,
... |
<p>Allright, so I have a dataset for around 40k firms over fiscal years 1950-2011 with about 430k firm-years. If I'm not mistaken I have panel data. </p>
<p>I created a unique identifier <code>ticn</code> for each firm. Years are indicated by <code>fyear</code>. For now my variables of interest are yearly sales <code>... | g63692 | [
-0.010930505581200123,
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0.059904564172029495,
0.04411043971776962,
0.014776072464883327,
0... |
<p>I collected a data-sets which tested for many users (>100.000) which out of ten features in a software-product they use. They can use multiple features but for each feature there is only "use" or "don't use". So in terms of software-development, I have many sets of features in a length of zero to ten.</p>
<p>I want... | g37437 | [
0.004598837345838547,
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0.019610263407230377,
0.015316511504352093,
0.06356664001941681,
0.051... |
<p>I am studying the paper by Efron: <a href="http://www-stat.stanford.edu/~ckirby/brad/papers/2003PredictionError_July.pdf" rel="nofollow">The Estimation of Prediction Error: Covariance Penalties and Cross-Validation</a>.
To estimate prediction error in the Gaussian case by Mallows' $C_p$ or other methods studied in... | g21488 | [
0.05701654031872749,
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0.007123845629394054,
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0.06683391332626343,
0.013016955927014351,
0.007574236951768398,
0.017807612195611,
0.0130... |
<p>I have a question about how I can calculate true and false positive rate in a simulation study?</p>
<p>I have seen some articles and thesis by different definitions. One of them is the following one:</p>
<blockquote>
<p>TPR=the ratio of the truly selected covariates relative to the number of active covariates</p... | g14109 | [
0.007739657536149025,
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0.07775500416755676,
0.007501929998397827,
0.04201065003871918,
0.016437746584415436,
-0.00381... |
<p>What is the correct way (if there is one) to think about when authors claim that stocks have produced some percentage annual return X over every 20 year period of time? They might calculate this by using the monthly starting price of the S&P500 and compare it to the monthly ending price of the S&P500 20 year... | g63693 | [
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0.0034666156861931086,
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... |
<p>I'm completing scientific analysis of chemical compounds in consumer products. As a non-statistician, I would really appreciate any thoughts from the experts here. </p>
<p>My data is non-normal so I've used non-parametric tests like MW and KW for hypothesis testing between samples so far. However I now have to cond... | g63694 | [
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0.02... |
<p>I have a categorical fixed effect with 3 levels that I'm trying to enter into an LME.</p>
<pre><code>a = lmer(Reaction ~ ContinuousEffect * CategoricalEffect + (1|Subject) + (1|StrengthOfStimulus))
</code></pre>
<p><code>StrengthOfStimulus</code> is a numerical variable that's being used as a random effect, along ... | g40883 | [
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0.04... |
<p>I'm wondering if I can call the following procedure “cross validation”.</p>
<p>I extracted <em>k</em> independent sets of data with comparable size from the same population. One of them was used for model development / training and all other sets were used to validate this particular model. So there is no “rotation... | g21494 | [
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0.012248408049345016,
0.004627797286957502,
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0.017553677782416344,
-... |
<p>I am very new to stats, so I apologize for this naive question.</p>
<p>Say I have the following data</p>
<pre><code> Yi X1 X2 X3
(5,17) A C E
(8,10) A C F
(1,2) A D E
(2,4) A D F
(6,18) B C E
(9,11) B C F
(2,3) B D E
(5,9) B D F
</code></pre>
<p>where the $Y_i$'s... | g63695 | [
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0.024516500532627106,
0.010416114702820778,
-0... |
<p>I am reviewing some studies on the relationship between cognition and driving. Some studies have controlled for age and some have not (age is correlated with cognition. Can anyone please provide any good references on statistical control I can use to explain the positives and negatives of controlling for age?</p> | g63696 | [
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0.06729866564273834,
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0.07384341210126877,
0.04... |
<p>I'm running a GLM using counts as my response variable and would normally use <code>family=poisson</code>. But I'm also running SAR models, which couldn't easily handle my counts as there was such a small amount of variation between them (high number of counts at very low numbers) so my supervisor suggested I use th... | g63697 | [
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-0.0652167797088623,
0.048278845846652985,
0.0008065098081715405,
0.02975795790553093,
0.018... |
<p>I have the following data, representing the binary state of four subjects at four times, note that it is only possible for each subject to transition $0\to 1$ but not $1\to 0$:</p>
<pre><code>testdata <- data.frame(id = c(1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4),
day = c(1,1,1,1,8,8,8,8,16... | g63698 | [
-0.04682258889079094,
0.005984396208077669,
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0.02222224324941635,
0.02143576368689537,
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0.049700867384672165,
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-0.022341452538967133,
-0.07434820383787155,
0.03401836380362511,
0.001613086904399097,
-0.04... |
<p>One factor random effect model:</p>
<p>$$y_{ij}=\mu+\tau_{i}+\epsilon_{ij}\quad i=1,2,\ldots,a;
j=1,2,\ldots,n$$</p>
<p>where,</p>
<p>$y_{ij}$ is the $j$th observation of $i$th treatment effect</p>
<p>$\mu$ is the overall mean</p>
<p>$\tau_{i}$ is the $i$th treatment effect and $\tau_{i}\sim NID(0,\sigma^2_{\... | g63699 | [
0.006291764788329601,
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0.015850696712732315,
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0.0328252837061882,
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0.03975294902920723,
0.05028776824474335,
-0.025271931663155556,
0.0... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/9398/supervised-learning-with-rare-events-when-rarity-is-due-to-the-large-number-o">Supervised learning with “rare” events, when rarity is due to the large number of counter-factual events</a> </p... | g49679 | [
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-0.06422334909439087,
0.017519710585474968,
0.07124369591474533,
0.07365492731332779,
-0.00... |
<p>Let's say I have two time series, one of which updates more frequently than the other:</p>
<p>$x_0,x_1,x_2,\dots,x_t,\dots$</p>
<p>$y_0,y_{10},y_{20},\dots,y_{10t},\dots$</p>
<p>I want to fit a model to this that predicts $y$ from $x$ (and possibly from previous values of $y$) at each of the values $1,2,3,\dots$,... | g63700 | [
0.03129220008850098,
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-0.01633484475314617,
0.03422344848513603,
0.016668329015374184,
0.07370724529027939,
0.008... |
<p>I have a question about omitted variable bias in logistic and linear regression. </p>
<p>Say I omit some variables from a linear regression model. Pretend that those omitted variables are uncorrelated with the variables I included in my model. Those omitted variables do not bias the coefficients in my model.</p>
<... | g63701 | [
0.02308938466012478,
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0.004121309611946344,
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0.06530618667602539,
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0.025357674807310104,
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-0.034998875111341476,
0.008776453323662281,
0.0338803306221962,
-0.006079608108848333,
-0.0... |
<p>Could someone provide a sample interpretation for the following:</p>
<pre><code> dependent variable
Categorial variable
category 1 Beta estimate of 1.78 (-3.39,6.69).
cat 2 2.45 (-287, 9.34)
cat 3 4.49 (-3.65, 7.08... | g21505 | [
-0.022494299337267876,
-0.028991824015975,
-0.005607256665825844,
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0.04104209691286087,
0.02275075763463974,
0.05218660831451416,
0.0003262067912146449,
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-0.011206815019249916,
-0.02205180935561657,
0.07229902595281601,
-0.0063616326078772545,
0.0... |
<p>I've tried to find the answer to this on this website but haven't been able to, so apologies if this has already been resolved. I am carrying out a hierarchical multiple regression. In the first step, the model is significant, and the predictors $X_1$, $X_2$ and $X_3$ have significant coefficients. When I add $X_4$ ... | g63702 | [
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0.0020735685247927904,
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0.0024980311281979084,
0.056006722152233124,
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0.03591877594590187,
0.04559406638145447,
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-0.013619598932564259,
-0.05341174826025963,
0.017404790967702866,
0.000653460796456784,
... |
<p>Assume that we have two multivariate normal distributions $\mathcal{N}_1 = \mathcal{N}(\mu_1, \Sigma_1)$ and $\mathcal{N}_2 = \mathcal{N}(\mu_2, \Sigma_2)$. We do these two steps: </p>
<ol>
<li>Pick a point, say $x$, from $\mathcal{N}_1$. </li>
<li>compute $\mathcal{N}_2(x)$ (probability density of x in $\mathcal{N... | g63703 | [
0.027271179482340813,
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0.023907674476504326,
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0.037071675062179565,
0.05329281464219093,
0.03690073639154434,
0.06563983857631683,
-0.... |
<p>I have built a model which basically does the following:</p>
<pre><code>run regressions on single time period
print results
</code></pre>
<p>The regressions output two numbers that I am interested in storing. However, I intend to extend the single time period to rolling through a large timeframe, in essence:</p>
... | g21506 | [
0.019607311114668846,
0.02175614982843399,
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0.06292413920164108,
0.02141132950782776,
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-0.03588472306728363,
0.012393087148666382,
0.038232650607824326,
0.018071085214614868,
-0.004... |
<p>If we have a standard model in the setting of a $2^3$ design with factors $A$, $B$, and $C$:
$$
y_{ijkl} = \mu + \alpha_j + \beta_k + \delta_l + \alpha\beta_{jk} + \alpha\delta_{jl} + \beta\delta_{kl} + \alpha\beta\delta_{jkl} + e_{ijkl}
$$
where $j = 1, 2;~k = 1, 2;$ and $l = 1, 2$. Assuming that $j = 1$ correspon... | g63704 | [
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0.11079737544059753,
0.008244816213846207,
0.014497267082333565,
0.0129458699375391,
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-0.03649095445871353,
-0.02540668472647667,
0.058233678340911865,
0.01839534565806389,
0.0416... |
<p><img src="http://i.stack.imgur.com/WxrrY.png" alt="enter image description here"></p>
<p>Here I have two time series (ACF, PACF), one on the left and one on the right. I have difficulties interpreting the results. Both PACF/ACF couples look the same and I can't distinguish any geometric decay or cutoff points. Woul... | g21507 | [
0.05671624094247818,
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0.08549747616052628,
0.01035405695438385,
0.060268111526966095,
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0.012322276830673218,
-0.002178153023123741,
0.04064282029867172,
0.03680000454187393,
0.05244496464729309,
-0.03763... |
<p>I am an absolute beginner in field of machine learning, I started doing <a href="https://www.kaggle.com/c/titanic-gettingStarted/" rel="nofollow">titanic assignment</a> in Kaggle and found(read some where) Random Forest is the best fit. I started reading about random forest and found the Explanation by Edwin Chen in... | g63705 | [
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0.0013552589807659388,
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0.023575549945235252,
0.059416763484478,
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0.012695078738033772,
-0.030806461349129677,
0.06012241914868355,
0.006... |
<p>I'm intending to do a bayesian zero-inflated regression, where some of my regressors are categorical variables, like this one, the country regions:</p>
<pre><code>>table(db$region)
REGIAO1 REGIAO2 REGIAO3 REGIAO4 REGIAO5 REGIAO6 REGIAO7 REGIAO8
4851 2293 5471 410 1157 626 36... | g63706 | [
-0.02904932200908661,
0.027676671743392944,
0.0031886775977909565,
-0.04148641973733902,
0.046540435403585434,
-0.03065258078277111,
0.025393689051270485,
0.058195289224386215,
0.0028193711768835783,
-0.0470900796353817,
-0.004591632168740034,
-0.0014819951029494405,
0.051451802253723145,
... |
<p>I want to plot the results of a regression model, but allowing two variable to vary simultaneously. I guess I could do that using predict() function in R, but I am running a model that does not have such function developed yet.</p>
<p>Let's suppose we have a data set</p>
<pre><code>x1 <- rnorm(100)
x2 <- rno... | g42054 | [
-0.013786256313323975,
-0.02404879219830036,
-0.012029636651277542,
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0.015968408435583115,
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0.021813170984387398,
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-0.04506464675068855,
0.002946191933006048,
0.043290670961141586,
0.06906642764806747,
0.... |
<p>Supposing that I have an interval n units long with m arrivals, and I model arrival using a poisson distribution with lambda = m/n, it's pretty easy to show that the distance between successive arrivals has an exponential distribution lambda * exp(-lambda * x).</p>
<p>However, I'm having a hard time generalizing th... | g21511 | [
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0.04443703964352608,
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-0.020213529467582703,
0.02900821343064308,
0.047133419662714005,
0.... |
<p>I have a number of predictors to use for a binary (Classes 0 and 1) classification task. Let us call them $x_1, x_2, x_3, ... x_n$. The way these are calculated, my naive heuristic assumption is that $S = \sum_{k=1}^n x_k$ should predict Class 1. That is higher $S$ means it is more likely that it is Class 1.</p>
<p... | g21513 | [
-0.00900264736264944,
-0.0007490242714993656,
0.013605184853076935,
-0.021901333704590797,
-0.0015373179921880364,
-0.05929751321673393,
0.026054488494992256,
0.04184810444712639,
-0.0215323306620121,
-0.054718293249607086,
0.025938233360648155,
-0.0017789764096960425,
0.046289749443531036,
... |
<p>In the Bayesian version of (binary) hypothesis testing one has to decide which of two hypotheses $A$ and $B$ holds true. The two hypotheses are given prior probability $p(A)$ and $p(B)$, summing up to 1. $A$ and $B$ induce two probability distributions on a set of possible <em>observations</em> $X$, say $p(x|A)$ and... | g21514 | [
0.004074719734489918,
-0.017294583842158318,
-0.0024895314127206802,
0.05117806792259216,
-0.0005359422648325562,
-0.025105973705649376,
0.03801857680082321,
0.006844229530543089,
-0.0775209590792656,
-0.010737819597125053,
0.008139919489622116,
0.010754570364952087,
0.01172693632543087,
-... |
<p>Several posts (<a href="http://stats.stackexchange.com/questions/29038/regression-for-an-outcome-ratio-between-0-and-1">here</a> and <a href="http://stats.stackexchange.com/questions/43366/extending-logistic-regression-for-outcomes-in-the-range-between-0-and-1?lq=1">here</a>) suggest that beta regression is more app... | g63707 | [
0.06440499424934387,
-0.0270402729511261,
0.021408705040812492,
-0.010708712972700596,
0.013461646623909473,
0.03473827615380287,
-0.01890941523015499,
-0.003996591549366713,
-0.09700576961040497,
-0.05676203966140747,
0.05898008123040199,
0.0019415969727560878,
-0.0009132302366197109,
0.0... |
<p>I have done a simple test using R, take a look at the code below:</p>
<p>First of all I have created three samples:</p>
<pre><code>> a = rnorm(10)
> b = rnorm(10)
> c = rnorm(10)
> a
[1] -0.2485833 -1.3077108 0.4019243 0.4453618 0.3024991 -0.4228684
[7] -0.3817301 0.2195161 1.3693408 -1.1030199
... | g63708 | [
0.006335603538900614,
-0.10301733762025833,
-0.009695050306618214,
-0.04026264324784279,
0.0189750287681818,
-0.010289578698575497,
0.06456846743822098,
0.05435573309659958,
-0.05618276819586754,
-0.021554477512836456,
-0.05724230781197548,
0.0656825378537178,
-0.011508466675877571,
-0.022... |
<p>I have a question about the proper way to describe the results I get to a prediction (both of which have statistical errors). I get a result with 1-sigma, let's say: </p>
<pre><code>-1 +/- 2
</code></pre>
<p>There is a published prediction (and 1-sigma error) for this measured value, let's say: </p>
<pre><code>4... | g43268 | [
0.023054203018546104,
-0.04990669712424278,
-0.015527044422924519,
-0.025881731882691383,
0.01053665205836296,
-0.03890509903430939,
0.03981134667992592,
0.016214929521083832,
-0.0306942630559206,
-0.006589197553694248,
0.02728014439344406,
0.019662940874695778,
0.010789429768919945,
0.047... |
<p>I want to compute the value of $\frac{1}{\sqrt{a + b + c}}$. Say I can observe a and b, but not c. Instead, I can observe d which is a good approximation for c in the sense that $P( |c-d| \leq 0.001 )$ is large (say 95%), and both c and d are known to have $|c| \leq 1, |d| \leq 1$ so a difference of 0.001 is actua... | g63709 | [
0.004489406943321228,
-0.011021562851965427,
-0.009868872351944447,
-0.06777133047580719,
0.0032238278072327375,
-0.007724652998149395,
0.015247371047735214,
-0.00992870144546032,
-0.04490593448281288,
-0.025775287300348282,
0.05116857960820198,
0.05246778205037117,
0.03464936837553978,
0.... |
<p>I have used <code>glm()</code> to model some data I have. The code looks like the following:</p>
<pre><code>for(ddm_idx in 1:90) {
for(ppm_idx in 1:90) {
mdfit <- glm(cuse[[4]] ~ cuse_ddm[[3 + ddm_idx]] + cuse_ddm[[3 + ddm_idx]]^2 +
cuse_ppm[[3 + ppm_idx]] + cuse_ppm... | g5395 | [
0.028085431084036827,
0.008190912194550037,
-0.01563315838575363,
-0.025762928649783134,
0.025563174858689308,
-0.010364498011767864,
-0.028830232098698616,
0.02660638839006424,
-0.06736227124929428,
-0.03890913724899292,
-0.019012760370969772,
0.0014854364562779665,
0.0526743158698082,
-0... |
<p><a href="http://en.wikipedia.org/wiki/Deviance_%28statistics%29" rel="nofollow">Deviance</a></p>
<blockquote>
<p>is a generalization of the idea of using the sum of squares of
residuals in ordinary least squares to cases where model-fitting is
achieved by maximum likelihood.</p>
</blockquote>
<p>As I underst... | g49680 | [
0.024257851764559746,
-0.025212083011865616,
0.0007288228953257203,
-0.0018189611146226525,
-0.006297883111983538,
-0.08597330003976822,
0.040649138391017914,
0.10515553504228592,
0.01609162613749504,
-0.04250979796051979,
-0.019787877798080444,
0.04009963572025299,
0.08840867877006531,
-0... |
<p>In principal component analysis (PCA), one can choose either the covariance matrix or the correlation matrix to find the components (from their respective eigenvectors). These give different results (PC loadings and scores), because the eigenvectors between both matrices are not equal. My understanding is that this ... | g63710 | [
0.03639039397239685,
-0.06103053689002991,
0.015846479684114456,
-0.029581008478999138,
0.01291430089622736,
0.01213628426194191,
0.032550737261772156,
0.016338398680090904,
-0.013035189360380173,
-0.01162745151668787,
0.043201059103012085,
-0.03527701646089554,
0.03174972906708717,
0.0247... |
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