question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>So let's say you have a distribution where X is the 16% quantile. Then you take the log of all the values of the distribution. Would log(X) still be the 16% quantile in the log distribution?</p> | g62877 | [
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<p>I want to use the variability of the residual as a measure M and then test whether M is higher or lower after some event. However, I estimate separate regression before and after the event to obtain the residuals and the variability of the residuals. </p>
<p>Now I am wondering what the effect of including/excludin... | g62878 | [
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<p>Please could you kindly advise on the implication of testing for unit root (using the augmented dickey fuller approach) on rolling data. My feeling is that this wouldn't make much sense given the non continuous nature of this data. I will be grateful if someone could provide me with some intuition in this regard.<... | g62879 | [
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<p>I have quite a complicated data set to analyze, and I cant find a good solution for it. </p>
<p>Here is the thing: </p>
<p><strong>1.</strong> the raw data is essentially insect song recordings. Each song is made of several bursts, and each burst made of sub-units. All individuals have been recorded for 5 minutes.... | g20211 | [
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<p>I have some data and I want to build a model (say a linear regression model) out of this data. In a next step, I want to apply Leave-One-Out-Cross-Validation (LOOCV) on the model so see how good it performs.</p>
<p>If I understood LOOCV right, I build a new model for each of my samples (the test-set) using every sa... | g62880 | [
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<p>I am confronted with the exercise below. I have no given solution, so I hope someone can tell me whether my solution is right or wrong.</p>
<p>I want to show the deterministic linear model $\quad \boldsymbol y = \boldsymbol X \boldsymbol \beta + \boldsymbol u,\quad \boldsymbol u \sim N(0,\sigma^2 \boldsymbol I) \... | g62881 | [
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<p>I've been using low discrepancy sequences for a while for Uniform Distributions, as I've found their properties useful (mainly in computer graphics for their random appearance and their ability to densely cover [0,1] in an incremental fashion).</p>
<p>For example, random values above, Halton sequence values below:<... | g42570 | [
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<p>I am want to assess whether successful implementation of newly developed policies are dependent on involvement of all relevant stakeholders and middle managers.</p>
<p>I have a 5-point Likert scale with ten questions (items). I collected data on 85 respondents. I assigned values ('Strongly Agree'=1, 'Agree'=2, 'Und... | g62882 | [
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<p>Can somebody give me a understanding of what power means in a Bayesian approach?
Or how you would implement it in a Bayesian simulation. </p> | g62883 | [
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<p>Here is the problem.</p>
<p>We have list of Job orders - each job has certain state associated with it, you can think of state as a situation that job is in, for example,</p>
<ul>
<li>a job that is said to be done</li>
<li>or a job that is awaiting someone's approval</li>
<li>...</li>
</ul>
<p>We have figured out... | g62884 | [
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<p>From <a href="https://en.wikipedia.org/wiki/Multiple_comparisons#Post-hoc_testing_of_ANOVAs" rel="nofollow">Wikipedia</a></p>
<blockquote>
<p><strong>Post-hoc testing of ANOVAs</strong></p>
<p>Multiple comparison procedures are commonly used in an analysis of
variance after obtaining a significant omnibus ... | g20219 | [
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<p>I'm trying to think of an example of a consistent estimator with var=0 but I'm having a hard time.
I pretty sure it exists but I'm unable to find one.</p>
<p>Any help\hints would be much appreciated.</p> | g62885 | [
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<p>Suppose $X_1,X_2,\ldots,X_n$ is a random sample of $\operatorname{Beta}(\theta,1)$. How can I find UMVUE of parameter $\displaystyle a^{\theta}$, $(0<a<1)$?</p> | g16292 | [
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<p>We are looking at a data set and try to use garchSpect o define the Garch parameters and garchSim to simulate the garch model.</p>
<p>The original data are as shown in the pic below, have a high sd (around 30000) and a high autocorrelation until lag 5 (not seen)</p>
<p>When we now simulate with:</p>
<pre><code>aa... | g62886 | [
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<p>I'm a programmer, not a mathematician.</p>
<p>I have tried to use real math terms and notation here, but I may be misusing them.</p>
<p>I am doing split-testing, and I want a test to compare different click-through rates between two groups, A and B.</p>
<p>Existing tutorials and samples suggest a z-test or a t-te... | g62887 | [
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<p>I have the following model that I am running in JAGS from R:</p>
<pre><code> model {
for( i in 1:nData){
y[i] ~ dnorm(mu[i], tau)
mu[i] <- b0 + inprod(b[],x[i,])
}
tau ~ dgamma(.01,.01)
b0 ~ dnorm(0,.0001)
for (j in 1:nPredictors){
... | g62888 | [
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<p>In order to analyze data obtained from a repeated measure study, I used the following SAS code:</p>
<pre><code>proc mixed;
class id trial_type trial_seq condition;
model decision_quality = condition|trial_seq;
repeated / subject = user_id type=cs;
lsmeans condition / pdiff CL ADJUST=SIMULATE(SEED=18713 NSAM... | g20228 | [
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<p>I am using ARMA over a dataset with missing samples. How do I treat them? Would you suggest to make linear/nonlinear interpolation or just keep them out and consider two samples with missing data in between as consecutive samples?</p> | g62889 | [
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<p>Under which conditions would a researcher choose optimally when there is a trade-off between the variance and bias of an estimator? I hope this question is not too broad...</p>
<p>Any help would be appreciated.</p>
<p>As an example, what criteria would I use, if we're referring to Linear Models?</p> | g20229 | [
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<p>I ran a Generalized Linear Mixed Model in R and included an interaction effect between two predictors. The interaction was not significant, but the main effects (the two predictors) both were.
Now many textbook examples tell me that if there is a significant effect of the interaction, the main effects cannot be int... | g62890 | [
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<p>Below I have performed forecasting of volatility, in my simple case of 6 days:</p>
<pre><code> Date WIG r Forecast
61 2014-03-03 51984.88 -0.003157046 0.255080969
62 2014-03-04 54823.49 -0.007566441 0.011048830
63 2014-03-05 50947.86 -0.003180499 0.012665863
64 2014-03-06 49995.55 0.0011... | g20230 | [
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<p>Take an event to be a set $E \subseteq {\mathbb R}^{\ge 0}$. We want to estimate the duration of the event (the measure of $E$) by sampling using a Poisson process $N$. That is, for some experiment duration $D$, at each time $t\leq D$ such that $\forall t'>t\colon N(t')>N(t)$, we check whether $t\in E$. See <a... | g62891 | [
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<p>Purpose: pragmatic data mining and prediction, NOT for publication or science
Data: observations from nature, so a high degree of stability is expected in the relationships
N: approx. 15 k</p>
<p>I am working on a dataset where some of the independent observations have measurement issues (i.e. mixed feet and metri... | g20438 | [
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<p>I am testing the test-reliability of a newly developed questionnaire over two time points. The study involves parents answering about their child over the two occasions.</p>
<p>Would intraclass correlation be suitable? Most explanations of ICC seem to use a group of raters who rate something else, while the each ch... | g49655 | [
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<p>I have a data set of 1,100 observations, I have two continuious variables (counts of different things) that were positively skewed, so I first log transformed each of them.
Now I need to make a composite variable, per literature, that measures a construct.</p>
<p>My question, per observation/row, should I now add ... | g62892 | [
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<p>Below is the output from a model of novel object test scores fit with the <code>nbinom1</code> (quasi-Poisson) option in <code>glmmADMB</code>. I used this package/method because: </p>
<ol>
<li>the Poisson mean is < 5, so according to Bolker et al. 2009 I should not use <code>glmmPQL</code></li>
<li>there was ov... | g62893 | [
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... |
<p>Given the following data:</p>
<pre><code>X
X =
332 428 354 1437 526 247 427
293 559 388 1527 567 239 258
372 767 562 1948 927 235 433
406... | g20237 | [
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<p>Hello I would like to draw samples from two binomial distributions, say B1 ~ binomial(100,p1) and B2 ~ binomial(100,p2) and I want them to be dependent. Any suggestions on how to do it? I am using R.</p> | g62894 | [
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<p>I wish to do topic modeling on text corpus some of which are about company earnings which has lots of numbers in it. It has no sentence structure. I think tagging numbers using nltk.pos_tagging can help me find out if the number is CD (numeral/cardinal). Using numeral feature as one of the many features in the BOW c... | g62895 | [
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<p>I have a list of 20 QTL from an experiment involving a certain phenotype related to bone development. Of all the candidate genes within the 20 QTL intervals, 5 are associated with a certain disease in humans. I tested the set of 20 QTL to see if they are enriched for the disease-associating genes. Each of the 20... | g62896 | [
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<p>I need some advice. I have a stratified sampling design by season and area. However, within any stratum the statistic I'm interested in $\hat{R} = \sum y/\sum x$ is also affected by other factors. To overcome this, I basically take a weighted average across both factors to obtain a single estimate $\hat{R}$ for e... | g62897 | [
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0.02815471775829792,
0.0330114066600799... |
<p>I am estimating a logistic model for a binary $Y$ (0=controls, 1=cases), and a set of covariates ($x_1, x_2, x_3, \ldots$) including sex (male, female). I know from the data that risk of $y$ is quite different for males and females with certain covariates. </p>
<p>What I was trying to do, with no success so far, wa... | g62898 | [
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<p>Basically I have a repeated measures experiment with two reward levels and two speed levels. Every trial participant can be randomly presented with highReward*slowSpeed or lowReward*fastSpeed etc., resulting in a 2 x 2 design. I am not completely sure when it is appropriate to use either of the models below:</p>
<p... | g62899 | [
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0.02622485719621181... |
<p>MAD (Median Absolute Deviation) is:</p>
<p>$\text{MAD} = M_i(|x_i-M_j(x_j)|)$</p>
<p>where $M()$ is the median operator ($M_i(x_i) = \text{median}(x_1,...,x_n)$).</p>
<p>I'd like to scale the MAD in such a way as to include (say) 95% of a distribution around the median, the way that that 95% of a normal distribu... | g62900 | [
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0.020116101950407028,
0.034557949751615524,
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<p>This is the most widely used method for outlier detection in econometrics and statistical problems. <code>X</code> is our data that we're searching for outliers in it (in MATLAB) :</p>
<pre><code> abs(X-mean(X)) >= n*std(X)
</code></pre>
<p>So if this inequality was true, that sample is an outlier; otherwise we... | g6730 | [
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<p>I have read about the fact that, there is dependency of variance on mean of count data.In most of cases they do variance stabilization transfomration as preprocessing step of data modeling.</p>
<p>I wonder, why variance depends on mean in count based data ? in other word, which properties of count data make this ha... | g62901 | [
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<p>Assume $x_1, x_2, ..., x_n$ are realizations from a normal distribution with mean $0$ and standard deviation $1$ and assume they are ordered from small to large. Let $y_i=x_i-x_{i-1}$ be the difference of the two adjacent numbers (so $y_i$ is always larger than $0$). My questions are:</p>
<p>1) What is the distribu... | g62902 | [
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<p>I want to calculate the mean and standard error of the mean for the amount spent per person visiting a store. Most people don't buy anything, so the distribution looks like this </p>
<p>${\rm P}({\rm purchased},{\rm spend}) = {\rm P}({\rm purchased}) {\space} {\rm P}({\rm spend} | {\rm purchased})$</p>
<p>where p... | g62903 | [
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<p>I'm conducting a meta-analysis using water-quality data collected from multiple lakes in multiple regions. Due to the differences in the sampling programs, each waterbody has been sampled an unequal number of times. I would like to describe the distribution of concentrations at the regional level (rather than the w... | g20246 | [
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<p>Assume that I want to predict the value of a variable that has three different states: a, b, and c.</p>
<p>The chance that these variables have the 3 states is not equally distributed. Out of 10 trials, the distribution is like this:</p>
<p>a: 2
b: 3
c: 5</p>
<p>If I have a random predictor that randomly predicts... | g62904 | [
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0... |
<p>Like the title says, does dimension reduction always lose some information? Consider for example PCA. If the data I have is very sparse, I would assume a "better encoding" could be found (is this somehow related to the rank of the data?), and nothing would be lost.</p> | g62905 | [
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<p>My question is the following:
How to test for a root larger than 1 in AR(p) process from its observations.</p>
<p>Thanks in advance.</p> | g62906 | [
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<p>I was wondering if it is possible to apply the method of hypothesis testing to real life. For example if someone can use it for decision making. I have always used this method for homework problems but maybe we can use this method as an aid in decision making. Therefore we could somehow know for example the probabil... | g49656 | [
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<p>Chapter 13 of Kevin Murphy's book <a href="http://rads.stackoverflow.com/amzn/click/0262018020" rel="nofollow">Machine Learning: A Probabilistic Perspective</a> discusses Sparse Linear Models. After a short introduction on the benefits of sparse models, he introduces the following problem:</p>
<p><img src="http://i... | g62907 | [
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<p>I'm considering using R for my master thesis in order to do some analyses with the mvpart package. The problem is that I only have limited time to learn the program and to do the analyses. I already read through some information concerning R and I'm starting to get the feeling that it is impossible to get the know t... | g62908 | [
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<p><strong><a href="http://en.wikipedia.org/wiki/Mantel_test">Mantel's test</a> is widely used in biological studies</strong> to
examine the correlation between the spatial distribution of animals (position in space) with, for example, their genetic relatedness, rate of aggression or some other attribute. Plenty of goo... | g62909 | [
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<p>Let say, I have 2 continuous random variables X1 & X2. Both have same location parameters. Other parameters may be same or may not.</p>
<p>Now say, the q1-th quantile of X1 is less than the q1-th quantile of x2. But the q2-th quantile of x1 is more than the q2th quantile of x2.</p>
<p>My question is, is that p... | g62910 | [
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<p>What is the difference between sample variance and sampling variance? They seem same. Aren't they?</p> | g62911 | [
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<p>I am a bit confused about the namings in the SVM. I am using this library LibSVM. There are so many parameters that can be set. Does anyone know which of these is the slack variable? thx</p> | g20256 | [
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<p>In my system I have users rating objects (e.g. films) from <strong>1 to 5 stars</strong>.
The mean rating clearly tells something about the overall opinion on an object, but I'd like to use a more precise measure of variability.
For example, if the stars are set randomly, if half of the users give 1 and the other ha... | g37523 | [
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<p>I've got a problem. I need to create network graph where avatars are nodes (different sizes). Similar to this one:</p>
<p><img src="http://i.stack.imgur.com/d6o6k.jpg" alt="enter image description here"></p>
<p>Furthermore on this image every avatar has the same size, what I need to do is different size of avatar ... | g62912 | [
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<p>I have a significant 2x2 interaction in a between-subjects design. I would normally report omega-squared as my effect-size measure, but I've been asked to provide Cohen's d instead? Can Cohen's d be computed for an interaction? If so, how?</p> | g20257 | [
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<p>I have written a computer program that can detect coins in a static image (.jpeg, .png, etc.) using some standard techniques for computer vision (Gaussian Blur, thresholding, Hough-Transform etc.). Using the ratios of the coins picked up from a given image, I can establish with good certainty which coins are which. ... | g20258 | [
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<p>I'm really confused about measuring the accuracy of Holt-Winters fitted models applying different transformations.</p>
<p>How do i compare the accuracy between models when i apply no transformation to the data, the BoxCox power transformation and, for instance, log transformation?</p>
<p>Say i have a time series x... | g62913 | [
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<p>What are the proper assumptions of Multinomial Logistic Regression? And what are the best tests to satisfy these assumptions using SPSS 18?</p> | g20261 | [
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<p>I have data in an excel spreadsheet of around 500 participants in a taste experiment. The data includes the age of the participant, in addition to one of five locations on their tongue in which they tasted five separate flavours, e.g. (Sweet, Middle), (Salt, Back) - The image below shows the first 20 entries to demo... | g62914 | [
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<p>Both my independent and dependent variables are binary. My result for classification table is 72% for predicted, and my ROC curve area is 0.389. Since <0.5 for ROC area is the worst for accuracy model, what should I do?</p> | g20263 | [
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<p>What I am trying to do is to fit a log-normal distribution to a data-set, and then determine confidence and prediction intervals for the fitted distribution - not just for the mean and sd estimates.</p>
<p>My final goal is to be able to say that if we repeated a set of measurements, then 95 % of the values would fa... | g62915 | [
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<p>I am using randomForest in R for regression, I have many categorical predictors (all of them have the same 3 categories (0,1,2)) and I want to see which of them can predict the response (continuous). I am trying this with many different response variables (one at the time) and all the models have a very low explaine... | g6790 | [
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<p>Could you please give me some hints for the exercise below?</p>
<p>Suppose we toss a coin once and let $p$ be the probability of heads. Let $X$ denote the number of heads and let $Y$ denote the number of tails. I have to first show that </p>
<ul>
<li><p>$X$ and $Y$ are dependent </p></li>
<li><p>and afterwards if ... | g62916 | [
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<p>I have a data set that includes a list of zip codes. Is there a way in R to convert these zip codes to latitude and longitude coordinates?</p>
<p>Thanks!</p> | g62917 | [
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<p>I want to generate survival time from a Cox proportional hazards model that contains time dependent covariate. The model is</p>
<p>$h(t|X_i) =h_0(t) \exp(\gamma X_i + \alpha m_{i}(t))$</p>
<p>where $X_i$ is generated from Binomial(1,0.5) and $m_{i}(t)=\beta_0 + \beta_1 X_{i} + \beta_2 X_{i} t$.</p>
<p>The true pa... | g62918 | [
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0.04833126440644264,
... |
<p>I am trying to assess a 20-item multliple choice test. I want to perform an item analysis such as can be found in <a href="http://www.utexas.edu/academic/ctl/assessment/iar/students/report/itemanalysis-example.php" rel="nofollow">this example</a>. So for each question I want the P-value and the correlation with th... | g62919 | [
-0.00027581152971833944,
-0.04862411320209503,
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0.01450076699256897,
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0.016324292868375778,
0.011203758418560028,
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-0.04232460632920265,
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0.08238966763019562,
... |
<p>If I understand correctly a confidence interval of a parameter is an interval constructed by a <em>method</em> which yields intervals containing the true value for a specified proportion of samples. So the 'confidence' is about the method rather than the interval I compute from a particular sample. </p>
<p>As a use... | g20270 | [
0.03380928561091423,
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0.0019857517909258604,
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-0.03672338277101517,
0.0297259371727705,
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0.07644011080265045,
-0.0077... |
<p>I have a design matrix of p regressors, n observations, and I am trying to compute the sample variance-covariance matrix of the parameters. I am trying to directly calculate it using svd.</p>
<p>I am using R, when I take svd of the design matrix, I get three components: a matrix $U$ which is $n \times p$, a matrix... | g20271 | [
0.0057066441513597965,
-0.016108397394418716,
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0.00834010262042284,
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0.024571947753429413,
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0.004388771485537291,
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0... |
<p>I would like to generate data with "Model 1" and fit them with "Model 2". The underlying idea is to investigate robustness properties of "Model 2". I am particularly interested in the coverage rate of the 95% confidence interval (based on the normal approximation).</p>
<ul>
<li>How do I set the number of iteration ... | g20272 | [
0.019110439345240593,
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0.00478448998183012,
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0.004069255664944649,
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0.0... |
<p>I have been reading the description of ridge regression in <em><a href="http://rads.stackoverflow.com/amzn/click/007310874X" rel="nofollow">Applied Linear Statistical Models</em>, 5th Ed</a> chapter 11. The ridge regression is done on body fat data available <a href="http://www.cst.cmich.edu/users/lee1c/spss/V16_mat... | g62920 | [
0.028989970684051514,
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<p>Suppose I have constant <code>x=0.1</code> in the language <code>R</code> and I have a vector <code>vec = rnorm(200)</code>. Is there a pre-packaged function to find the quantile of <code>vec</code> that corresponds the closest to <code>x</code>? </p>
<p>A solution is as follows:</p>
<pre><code>x = 0.1
vec = rnorm... | g20274 | [
0.03190464898943901,
-0.0784350261092186,
0.0065847765654325485,
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0.0013332768576219678,
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0.010285775177180767,
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0.03792259842157364,
0.009566299617290497,
0.039... |
<p>What properties do these measures have and how can I determine which one is better for a given purpose? What are extreme cases where they differ a lot?</p> | g39434 | [
0.0034640254452824593,
0.017922211438417435,
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0.01013131532818079,
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0.012100283056497574,
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-0.0... |
<p>I found a question that is related <a href="http://stats.stackexchange.com/questions/34510/how-to-measure-agreement-between-a-set-of-raters">here</a>, but it doesn't really goes on what I want to know.</p>
<p>I found a couple of papers using Kappa Statistic from 2006, and 2010, but afterwards I found other authors ... | g20275 | [
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0.003310716012492776,
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0.0... |
<p>I need to check if two ergodic distributions statistically differ. I know about the Kolmogorov - Smirnov test. However, being the ergodics computed as in Feyrer (2003), <em>Convergence by parts</em>, I do not have two vectors of observations on which performing the test. Is there any way to do this ? Moreover, is th... | g62921 | [
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<p>One way one could state Chebyshev's inequality is </p>
<blockquote>
<p>The probability that a realization deviates from the mean more
than $k$ standard deviations is at most $\frac{1}{k^2}$.</p>
</blockquote>
<p>My question is: Can one rigorously reverse this logic and make a statement about the probability th... | g618 | [
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<p>I have developed an attrition model for clients (proc phreg) with time dependent covariates in the observation window.</p>
<p>How can I predict the future survival probabilities in this case? </p> | g20277 | [
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<p>I am using bootstrap for my simulation.</p>
<p>The number of the population is flexible for each case, and the sample size is decided by a certain percentage. For example, I have a 10,000 population, and I decide to use 10% for each iteration of bootstrap, so the sample size is 1,000.</p>
<p>In practice, I found i... | g49451 | [
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0.056... |
<p>Since standardized betas are correlation coefficients in bivariate regression, is it the case that standardized betas in multiple regression are partial correlations?</p> | g20279 | [
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<p>I have data from a survey that was (attempted to to be) administered to all children of particular grades in a certain state. I am getting it after a cleaning step by the survey designers that removed obvious invalid answers (from obnoxious teens).</p>
<p>Questions A and B have binary answers, and I'm interested in... | g62922 | [
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0.035... |
<p>If I have a regression or classification problem</p>
<pre><code>y ~ x1 + x2 + ... + xn
</code></pre>
<p>I might call the <code>xi</code> the <em>regressors</em> or the <em>predictors</em>. But what do you call <code>y</code>?</p>
<p>The terms <em>regressand</em> and <em>predictand</em> are clunky, don't seem part... | g39443 | [
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<p>Bootstrapping works well to access the uncertainty in the mean estimate, however I remember reading somewhere the bootstrap does not do a good job in assessing the uncertainty in quantile estimates (particularly the median). </p>
<p>I don't remember where I read this, and I couldn't find much with a quick Google s... | g39444 | [
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0.05438626557588577,
0.03... |
<p>When you do an OLS regression and plot the resulting residuals, how can you tell if the residuals are autocorrelated? I know there are tests for this (Durbin, Breusch-Godfrey) but I was wondering if you can just look at a plot to gauge if autocorrelation could be a problem (because for heteroskedasticity it is fairl... | g62923 | [
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<p>I am having some confusion regarding least squares method. Actually, least squares method is for minimizing the square of the $L_2$ norm of $Ax-b$ as given in this video lecture. However I am confused if we are given a set of points like $(x_1,y_1),(x_2,y_2)...(x_4,y_4)$. Then our model is something like</p>
<p>$$y... | g12579 | [
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0... |
<p>I have two questions regarding standard multiple regression: </p>
<ol>
<li><p>Why is my shared variance a negative number?</p></li>
<li><p>Should I only include the positive semipartial correlations when calculating uniquely explained variance? </p></li>
</ol>
<p>I am trying to calculate the amount of shared varia... | g62924 | [
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0.... |
<p>Im trying to apply text mining on a text document with the help of Information Extraction plugin. I dont know which operators to use and how. Please help how do I proceed further?
Any good video tutorial available for this plugin? I couldn't find any.</p>
<p><img src="http://i.stack.imgur.com/YFrhW.png" alt="enter... | g62925 | [
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... |
<p>I'm reading the paper <a href="http://www.cs.princeton.edu/~blei/papers/BleiFrazier2011.pdf" rel="nofollow">"Distance Dependent Chinese Restaurant Processes"</a> by Blei and Frazier. On page 8 predictive posterior for the process is described for a new data point $x_{new}$:
$$
p(x_{new} | \mathbf{x}) = \sum_{c_{new}... | g62926 | [
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<p>I have 2 (monthly) time-series that look like this:</p>
<p><img src="http://i.stack.imgur.com/oewFd.png" alt="cross plot of 2 series"></p>
<p>Economical intuition suggests that they are positively related and I can see this on the plot but if I compute correlation between their log-returns $\ln x_t/x_{t-1}$ and $\... | g20287 | [
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<p>I have been discussing the following issue with a colleague of mine and I can't seem to wrap my head around it. I have a computer vision background, so I'm mostly familiar with 2D MRFs/CRFs for image restoration and segmentation. </p>
<p>What is clear to me is that MRFs typically have a simple 2D grid structure for... | g62927 | [
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<p>I understand theoretically (sort of) how they would work, but am not sure how to go about actually making use an ensemble method (such as voting, weighted mixtures, etc.). </p>
<ul>
<li>What are good resources for implementing ensemble methods?</li>
<li>Are there any particular resources regarding implementation in... | g62928 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/5450/what-if-interaction-wipes-out-my-direct-effects-in-regression">What if interaction wipes out my direct effects in regression?</a> </p>
</blockquote>
<p>I did hierarchical regression analysis on my dat... | g49395 | [
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0.0156... |
<p>Given a regression loss function $l(Z,\beta)=||Y-Z\beta||_2 + \lambda \beta^TD\beta + r(X,Z)$ where $X$ is the predictor matrix, I would like to estimate a $Z$ that minimizes the above loss in a regression setting. $D$ is a fixed matrix similar to the setting in ridge regression, but $r(.)$ is non-convex.</p>
<p>Ho... | g45437 | [
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0.05847013369202614,
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0.... |
<p>Can a distribution with finite mean and infinite variance have a moment generating function? What about a distribution with finite mean and finite variance but infinite higher moments? </p> | g49553 | [
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... |
<p>I'm working with a general bayesian information criteria to determine if this data exhibits a bimodal, trimodal, quadmodal etc. My existing BIC exhibits clear trimodality, but I'd like a hypothesis test of sorts.</p>
<p>How can I determine the probability that this model is true?</p> | g62929 | [
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<p>The data I have are a regression slope value of y~time, a standard error, an n value and a p value, for a particular species in two different areas. I want to check whether the the regression slope for one area is significantly different from the regression slope for the other area - is this possible with such data... | g62930 | [
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0.03294263035058975... |
<p>I have two datasets, or .dta files. One has certain variables where each value has a corresponding label. The other datafile has no value labels, but the values of the variables are similar to certain variables in the first datafile. What I want is to copy those value labels from the first file to the second file.</... | g20293 | [
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0.00... |
<p>Suppose I have constructed a prediction model for the occurrence of a particular disease in one dataset (the model building dataset) and now want to check how well the model works in a new dataset (the validation dataset). For a model built with logistic regression, I would calculate the predicted probability for ea... | g62931 | [
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0.04352864250540733,
0.11282925307750702,
-0.... |
<p>I am trying to find out the degrees of freedom in a glmer model in R. I know that their calculation can be tricky, but I can't find any package or clear explanation on how to obtain them. </p>
<p>My model is: </p>
<p>glmer(Response~A+B+C+(1|D)+(1|E), family="poisson")</p>
<p>Where A is a factorial vairable with t... | g20297 | [
0.030898043885827065,
0.012105217203497887,
-0.002354554831981659,
0.013736131601035595,
0.05693267285823822,
-0.031320665031671524,
0.05712182819843292,
-0.013594829477369785,
-0.015719778835773468,
0.01569254696369171,
-0.08365033566951752,
-0.04870443418622017,
-0.028558889403939247,
-0... |
<p>If $N_1$ and $N_2$ are independent Poisson processes then the superposition is a Poisson process. Is it possible to construct two dependent Poisson processes such that the superposition is a Poisson process again? How can I do that? Can I use some copula directly?</p>
<p>An article that suggests this is possible is... | g62932 | [
0.021707462146878242,
-0.016340291127562523,
-0.008655769750475883,
-0.04998619481921196,
-0.008316844701766968,
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0.008872969076037407,
0.022986289113759995,
-0.05929659679532051,
-0.029057156294584274,
-0.06086522340774536,
-0.024775633588433266,
0.01468025241047144,
... |
<p>I'm trying to fit the GAMLSS library's Sichel distribution to some zero-truncated data, but the only way to get the function to work is to include the zero-class anyway but give it a frequency of 0, which doesn't take into account the zero-truncated nature of my data. Can anyone suggest a way to properly "redistribu... | g62933 | [
0.003202384104952216,
-0.011327777057886124,
0.005477179307490587,
-0.04414108768105507,
0.003970400430262089,
0.006720616016536951,
0.014071165584027767,
0.03721950948238373,
-0.008015214465558529,
-0.025800654664635658,
-0.016130009666085243,
-0.02359096333384514,
0.057577937841415405,
-... |
<p>So assuming that there is a point in testing the normality assumption for anova (see <a href="http://stats.stackexchange.com/questions/2492/normality-testing-essentially-useless">1</a> and <a href="http://stats.stackexchange.com/questions/2824/checking-anova-assumptions">2</a>)</p>
<p>How can it be tested in R?</p>... | g38018 | [
0.011144843883812428,
-0.07032281160354614,
0.003984392154961824,
0.016537807881832123,
-0.07239583879709244,
0.019908465445041656,
0.0021794920321553946,
0.005431589670479298,
-0.024166973307728767,
0.021527355536818504,
-0.03844873234629631,
0.024503810331225395,
-0.012975731864571571,
-... |
<p>I am having some confusion with year fixed effects. If I would like to estimate the effect of Policy A on Outcome Y, will the year fixed effects capture the effect of Policy B (also occurring in this time period and affecting Y, but not specifically controlled for in the equation) on Y?</p> | g62934 | [
0.024681581184267998,
-0.04158513993024826,
0.008575549349188805,
0.015724139288067818,
-0.004648090340197086,
0.03287274017930031,
0.04907242953777313,
0.06241235136985779,
0.027802949771285057,
-0.01809791661798954,
-0.038864728063344955,
0.05489056929945946,
0.006918083410710096,
0.0164... |
<p>Please help me out to determine of those are representative samples, not, or either:</p>
<p>First example: A conservative talk radio host conducts a poll among his listeners. He asks his listeners to phone in whether they support the President’s policies or not. Will this poll be a representative sample of the... | g62935 | [
0.012002015486359596,
0.009888336062431335,
0.011439522728323936,
-0.0242446418851614,
0.03710344433784485,
0.04114407300949097,
-0.033182013779878616,
-0.023451218381524086,
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0.01598484441637993,
-0.012807696126401424,
-0.0028539688792079687,
-0.02471822313964367,
0.02... |
<p>I've got a problem with CV on feature selection. I've used a method, but I don't know it's correct...</p>
<ol>
<li>I split my data into 70% training set and 30% test set </li>
<li>I work now with my training set. I do on my training set a 10-fold CV </li>
<li>On each fold, I use the training part to search for the ... | g62936 | [
0.0159026850014925,
-0.02284078858792782,
0.017895743250846863,
-0.019078204408288002,
0.02294841967523098,
-0.03537283465266228,
0.031420398503541946,
-0.0035205581225454807,
-0.029164889827370644,
-0.015232132747769356,
0.0357331782579422,
0.043901458382606506,
0.008614764548838139,
-0.0... |
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