question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I know that people generally say that procedures which select a model based on information criterion lead to inconsistent model selections.</p>
<p>I read a paper by Leeb and Potscher (2005), MODEL SELECTION AND INFERENCE: FACTS AND FICTION which supports this theory.</p>
<p>Regardless of the kind of information cr... | g42419 | [
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<p>could you explain how to determine a the mean and standard deviation of the following: demand size, demand interval and demand per period, with respect to minimum, 25%ile, median, 75%ile and maximum from the data below:<br>
Weeks: Orders: Inventory</p>
<pre><code>0 : : 112224
04/08/2009: 2000 ... | g64575 | [
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<p>I'm modeling hospital inpatient stays with a logistic regression model, and have encountered a number of predictor variables measuring # of outpatient care episodes which have an inflated number of observations at $x=0$ (sometimes over 90%). In addition, there's a discontinuous "jump" in observed y values comparing ... | g22788 | [
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<p>Let us say that we have an experiment where people are shown images of tyres from car/bike and have to tell what it really belongs to.</p>
<p>The objective of the experiment is to validate the hypothesis that people from age group 25-35 are much better at recognizing that the tyre images are from car or bikes.</p>
... | g64576 | [
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<p><em><strong>or:</em></strong> <em>Does selecting a domain when entering a job narrows your future options for domains and hence jobs ?</em></p>
<p>To make this question as broadly applicable as possible ...</p>
<ul>
<li>profession refers to all kinds of data analysts, from statisticians
over machine learner progra... | g48510 | [
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<p>I apologise, this isn't a single question. It is more of a general problem on which I am working and am seeking guidance for how to proceed.</p>
<p>I have been provided with an inventory dataset of plot measurements (tree height, diameters etc) within a non-random selection of n forest stands (from a total N in the... | g64577 | [
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<p>I have built a prototype Naïve Bayes Classifier in an Excel spreadsheet. My data is a transaction (an order) with 13 parameters. This translates directly to a feature vector of (feature_1, feature_2, …, feature_13). Each parameter of an order, if it is incorrectly set, can be the cause of an error in the order. I am... | g64578 | [
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<p>Given that $N = n$, the conditional distr. of $Y$ is $\chi ^2(2n)$. $N$ has marginal distr. of Poisson($\theta$), $\theta$ is a positive constant.</p>
<p>Show that, as $\theta \rightarrow \infty$, $\space \space (Y - E(Y))/ \sqrt{\operatorname{Var}(Y)} \rightarrow N(0,1)$ in distribution.</p>
<p>Could anyone sugge... | g22793 | [
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<p>Let's say I have the following equation:</p>
<pre><code>Won = B0 + B1*(Bid)
</code></pre>
<p>Once I know B0 and B1, I can generate the probability curve and find the probability of "won" for each "bid." </p>
<p>However, let's say I add a variable zipcode, and add it to the logit model. In R, I save it as a factor... | g64579 | [
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<p>I am practicing MA and AR modelling by using autocorrelation and partial autocorrelation values. My data is in the image below; I can see that only at lag 12 there is a value that might be considered but I have a dilemma: what model is this if any? </p>
<ol>
<li>To be a MA of higher order the autocorr should be 0 A... | g42424 | [
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<p>The randomForest implementation does not allow sampling beyond the number of observations, even when sampling with replacement. Why is this?</p>
<p>Works fine:</p>
<pre><code>rf <- randomForest(Species ~ ., iris, sampsize=c(1, 1, 1), replace=TRUE)
rf <- randomForest(Species ~ ., iris, sampsize=3, replace=TR... | g22797 | [
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<p>This is part of problem 5.23 in A First Course in Linear Model Theory, Dey and Ravishanker. It was on a previous midterm and I didn't know how to do it, but now I am studying for the final and would like to figure it out. </p>
<p>Suppose $\mathbf{x} \sim N_{m}(\mu, \Sigma)$ and $A$ is a symmetric idempotent matrix ... | g37441 | [
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<p>I have data from an experiment that evaluated 3 methods for recommendation of news articles based on their content.
The experiment showed an article that the user read and 6 recommendations presented in random order below it (screenshot: <a href="http://cl.ly/image/2R10073Z0i39" rel="nofollow">http://cl.ly/image/2R1... | g64580 | [
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<p><strong>Direct Question:</strong> Are there any measures of auto-correlation for a sequence of observations of an (unordered) categorical variable?</p>
<p><strong>Background:</strong> I'm using MCMC to sample from a categorical variable and I'd like a measure of how well the sampling method I've developed is mixin... | g22800 | [
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<p>I'm trying to use the prefmod package to analyzed paired comparisons, but unfortunately the documentation is a bit poor and the author is no longer with us. </p>
<p>I have a survey with 32 questions, split into two blocks (16 questions per respondent). Here's a sample of the first 10 observations:</p>
<pre><code... | g791 | [
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<p>I was wondering whether anyone could point me to some references that discuss the interpretation of the elements of the inverse covariance matrix, also known as the concentration matrix or the precision matrix.</p>
<p>I have access to Cox and Wermuth's <em>Multivariate Dependencies</em>, but what I'm looking for is... | g42428 | [
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<p>We have three years of data for online visits at a daily level. We want to forecast the daily visits for the next 90 days. What would be the best method to capture weekday seasonality , holiday seasons, and also the drift.</p>
<p>Can this be successfully done in R? We are currently using R. We have considered ARIMA... | g49484 | [
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<p>I would like to test a proprietary method of financial time series prediction that says, in effect, that on a certain day/week in the future, to an accuracy of +/- 2 to 3 days/weeks, a financial time series will make a relative high or low on this predicted date, and furthermore, within a defined period in the futur... | g64581 | [
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<p>I am trying to get to grips with Clustering and Visualisation.</p>
<p>I have a set of data (a matrix) that I want to cluster (using R) and then visualise (HTML5 Canvas). </p>
<p>So, I can use MDS to get the coordinates of a matrix, for example:</p>
<pre><code>cells <- c(1, 1, 2, 1, 4, 3, 5, 4)
rnames <- c(... | g42433 | [
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<p>I am having some trouble understanding the relationship between the weight provided from a multiple linear regression and calculating probabilities. The weights given create an equation whose values are not part of a probability distribution. Rather, they predict the y value.</p>
<p>How can this be transformed into... | g22806 | [
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<p>In a multivariate linear model</p>
<p>$Y = XB + U$,</p>
<p>where within-subject (or repeated-measures) factors are coded as simultaneous response variables in $Y$, a general linear hypothesis can be formulated as</p>
<p>$H_0: L B M = 0$,</p>
<p>where $L$ specifies the contrasts among the levels of a between-subj... | g22807 | [
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<p>I was trying to find out whether an oversampling can really make a model better.
On <a href="http://blog.data-miners.com/2009/11/oversampling-in-general.html" rel="nofollow">this blog page</a>, it says that it can improve a decision tree, but it shouldn't improve a logistic regression. Quotation below:</p>
<blockqu... | g22808 | [
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<p>I'm just getting into data science from a qualitative background, and I want to be able to do the most stuff with least amount of overhead. (mostly machine learning and agent based modeling).</p>
<p>I'm currently learning python, and would hate to switch languages in the middle of my coursera class mitx 6.00x. Also... | g22809 | [
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<p>I'm comparing performance of different classifiers on the data sets derived from financial markets, getting different accuracy and precision measures but Matthews correlation coefficient and Kappa statistic seldom exceeds 0.2. My data sets are quite big like 20000x170
so it should not be a problem with not enough of... | g22810 | [
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<p>To investigate the difference between three tasks I tested 30 individuals on each of the three tasks and ran the linear model as follows:</p>
<pre><code>model <- lme(behaviour ~ task, random = ~ 1|subject, data=dat, method="ML")
</code></pre>
<p>With contrasts using <code>glht</code> to investigate if task 1 wa... | g22811 | [
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<p>Is it necessary to have mean of residuals which is equal to 0 in Quantile regression? </p> | g64582 | [
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<p>I have a data consists of three independent variables and dependent variable, I want to fit a model to these data, p=f(x1,x2,x3), how can I find the best fit for these data?
it might be linear, quadratic,...
could you please guide me to find the optimum way to find the model.</p> | g64583 | [
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<p>I am examining rodent captures on six permanent rodent trapping grids measuring 150 x 150 meters and consisting of 121 trap stations evenly spaced 15 meters apart. There are six such trapping grids on the study site that is < 1000 hectares in size. I would like to interpolate the capture data to create a Kriged... | g64584 | [
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<p>I have a list of genes identified using algorithm_A, then using algorithm_B and finally using algorithm_C; then a second list of genes identified using algorithm_A, then using algorithm_B and then algorithm_C, and so on for a total of 100 gene lists. </p>
<p>To compare the overlap of the identified gene list using... | g22813 | [
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<p>Does anyone know how to compute (or extract) leverage and Cook's distances for a <code>mer</code> class object (obtained through <code>lme4</code> package)?
I'd like to plot these for a residuals analysis.</p> | g64585 | [
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<p>I read from <a href="http://www.mathworks.com/help/stats/copulafit.html" rel="nofollow">this</a> link and thought that kernel density functions are used for solving the unrealistic normal distributions or specification errors. But when I read the description of kernel density in MATLAB, the estimate is based on a no... | g22815 | [
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0.0... |
<p>Suppose that $x \sim U(0, 255)$ and and $y \sim U(0, 255)$, and that $x$ and $y$ are independent.</p>
<p>What is the distribution of $x - y$?</p>
<p>If I were to draw 1,000 samples from this distribution, how many times should I expect to see each possible value?</p>
<p>NB. These are all <em>discrete</em> random ... | g64586 | [
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... |
<p>I'm having trouble modeling the following scenario:</p>
<blockquote>
<p>Roll two dice and take the best
result.</p>
</blockquote>
<p>What is the proper way to model the average result from this? I understand intuitively that the average should go up, but I'm having trouble understanding exactly what plays into... | g22817 | [
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<p>I have this confusion related to PCA. PCA assumes that the variables given have corresponding latent variables which are uncorrelated. What PCA does it project the data into the eigen space which preserves maximum variance and decorrelates the dimensions. </p>
<p>Why does PCA makes such assumption that the underlyi... | g64587 | [
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<p>Suppose I want to compare the difference between means of samples selected from two populations (the treatment and control). Assume both groups have normally distributed observations. Then $$Z = \frac{(\bar{X}_{t}- \bar{X}_{c})-(\mu_{t}-\mu_{c})}{\sqrt{\left(\frac{\sigma^{2}_{t}}{n_t}+ \frac{\sigma^{2}_{c}}{n_c} \ri... | g22819 | [
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<p>I'm relatively new to statistics and I'm a little confused about which test I should be using for this problem. Let’s say I am collecting data about responses to a book under two different conditions (C1 and C2). In each condition, I am looking at several attributes about the book and asking for ratings using a 5 po... | g22144 | [
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<p>I've followed guidelines for comparing models in Chapter 6 of Bolker's <em>Ecological Models and Data in R</em>, applying code used in this section to cancer count data. The models include parameters for age group (a) and birth cohort (c), and are as follows:</p>
<pre><code># Value of lambda is the same for all age... | g64588 | [
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0.031006500124931335,
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0.0576033741235733,
0.03... |
<p>I have some qualitative data and having trouble preparing the data before I perform the analysis in SPSS. My understanding of Friedman's anova is that the data must be ranked from lowest to highest. </p>
<p>My experimental design was repeated measures using a single variable (interaction technique) with three level... | g64589 | [
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0... |
<p>I have two questions regarding the R script.</p>
<p>If I want to know the size of the sampling when I do a t-test with R, I can use this R script :</p>
<pre><code>power.t.test(delta=1,sd=1.5,sig.level=0.05,power=0.8)
</code></pre>
<p>If I want to know the size of the sampling when I do the test of Pearson correla... | g64590 | [
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<p>I take two simultaneous measurements from two different regions of a biological system, where both signals can be modelled by simple exponential rise and decay:
$$
I(t)=(1-e^{-t/\tau_{rise}})(e^{-t/\tau_{decay}})
$$
First, by kernel matching to get initial coefficients, and later by nonlinear regression (<code>nlinf... | g22825 | [
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0.009518872946500778,
0.029982011765241623,
0.057... |
<p>For example, I have a set of numbers (say 0 to 10) that are presented to 100 subjects.
Each subject is asked whether the number is a small or a large number. </p>
<p>The results are that 100 people think zero is a small number, 70 people think one is a small number, etc. </p>
<p>Now I use a certain distribution, s... | g64591 | [
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... |
<p>I am working out a book on Lebesgue measure by Bartle, and would like to see the steps that go into the construction of a proof for the following:</p>
<blockquote>
<p>Show that any $\sigma$-algebra of subsets of $\mathbb{R}$ which
contains all open intervals also contains all closed intervals.</p>
</blockquote>... | g64592 | [
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... |
<p>Is there any agreement on when to reduce data dimension before clustering in order to avoid curse of dimensionality?</p>
<p>My intuition is that if I have say 1000 points and data dimension is 10 then it is OK to cluster. But if dimension is 50 then it is not OK because data points become sparse and hard to cluster... | g64593 | [
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0.017586350440979004,
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<p>I'm trying to wrap my head around dynamic factor analysis. So far, my understanding is that DFA is just factor analysis plus a time series model on the scores (the loadings remain fixed). However, in the cases that I've seen, the model on the scores is just a random walk with a diagonal correlation matrix. This seem... | g37970 | [
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... |
<p>I'm running mixed design ANOVA using R. Somehow, I got incorrect values for the Df. There are two factors: <code>time</code> (within subjects), and <code>task</code> (between subjects). <code>Time</code> has four levels and <code>task</code> has three levels. I expected to find Df 3 for <code>time</code> and Df... | g64594 | [
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... |
<p>I am trying to understand how to apply the <a href="http://en.wikipedia.org/wiki/Intraclass_correlation_coefficient" rel="nofollow">intraclass correlation coefficient</a>.</p>
<p>The situation we have is the following: we have $k$ judges who can assign numerical ratings to targets, and we want to test the reliabili... | g64595 | [
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0... |
<p>When preforming Johansen Cointegration test for 2 time series (the simple case) you need to decide the lag you want to use. Doing the test for different lags return different results: for some lag levels the null hypothesis can be rejected but for others it can't.</p>
<p>My question is what is the right method base... | g22832 | [
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0.0... |
<p>I have a set of data about the incidence of certain types of infections that occur in hospitals. The analysis has looked at the incidence trend for all aggregated results in a time series. This uses a GAM fitted spline to identify the incidence trend for aggregated data.</p>
<p>Over the past year the incidence tren... | g22201 | [
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<p>I have to find the similarity between two documents. The two documents are simple text documents and i have to report a score. I was using cosine similarity initially. But I was told that LSA is a better means. But when I got to read a few tutorials i always noticed that they used more than two documents. </p>
<p>S... | g64596 | [
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0.039090346544981,
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0.03973083943128586,
0.039304859936237335,
-0.02... |
<p>I would like to fit a multivariate regression model of an ordinal random vector using ordinal variables as covariates. I am wondering if there is anything implemented in R or other software that could do that. Or, alternatively using a Bayesian approach. </p> | g22835 | [
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<p>I think this is a straightforward question, although the reasoning behind why or why not may not be. The reason I ask is that I have recently written my own implementation of a RF and although it performs well it is not performing quite as well as I had expected (based on the <a href="http://www.kaggle.com/c/PhotoQu... | g64597 | [
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0.05085313692688942,
0.015... |
<p>At a given node, random forests sample <code>k</code> (aka <code>mtry</code>) variables (predictors). Then they pick the variable for which they get the best split.</p>
<p>How is this specifically determined? From what I understand RF do something like this:</p>
<pre><code>for variable in variables_sampled:
for t... | g489 | [
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0.015121099539101124,
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0.016899723559617996,
0.03182613477110863,
-0... |
<p>The number of breakdowns Y per day for a certain machine is a Poisson random variable with mean $\lambda$. The daily cost of repairing these break downs is given by $C=3Y^2$ If $Y_1, Y_2, ..., Y_n$ denote the observed number of breakdowns for $n$ independently selected days find an MVUE for $E(C)$.</p>
<p>We can us... | g64598 | [
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0.01931479573249817,
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0.... |
<p>So I am trying to figure out if there is a nice decomposition for sampling from the multivariate Student's t-distribution like there is for sampling from the multivariate normal distribution: <a href="http://en.wikipedia.org/wiki/Multivariate_normal_distribution#Drawing_values_from_the_distribution" rel="nofollow">... | g22842 | [
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0.011657102964818478,
0.017242195084691048,
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0.017333567142486572,
... |
<p>I'm trying to run discriminant function analysis on 27 acoustic, temporal and descriptive variables I obtained from animal calls. However, a number of these variables are collinear because they were calculated from other variables. For example: f0 range = f0 high - f0 low. </p>
<p>Previous work using the same varia... | g64599 | [
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0.06672897189855576,
0.01328131090849638,
0.0347... |
<p>Say I have predictor array <code>x:(n,px)</code> and a predicted array <code>y:(n, py)</code>. What would be the best way in Python to calculate all regression coefficients (linear) from <code>x</code> to each dimension of <code>y</code> (<code>1...py</code>)? The output of the whole thing would be a matrix <code>(p... | g64600 | [
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0.0025580700021237135,
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0.08092246949672699,
0.03650248423218727,
0.0... |
<p>i am learning data mining through <a href="http://stats.stackexchange.com/questions/51416/k-fold-vs-monte-carlo-cross-validation">book</a> . During classification chapters about Neural Networks the authors have below code. I have below questions:</p>
<pre><code>## pre2008 <- 1:nrow(training) ## training is a dat... | g64601 | [
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0.008306498639285564,
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0.0788150355219841,
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0.... |
<p>We are a financial institution which falls under this ‘Big Bank’ category. As a part of our routine analysis on input variables that feed several of our risk models, we would like to setup an input monitoring system that can trigger any drastic changes in the trend/pattern in our input variables over different perio... | g34991 | [
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0.0038197780959308147,
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0.04870739206671715,
0.017991928383708,
-0.0000333... |
<p>I'm trying to understand the idea behind the Topic Models in document clustering. In Latent Dirichlet Allocation, it is necessary to approximate the posterior distribution of topics over the document. One of the methods is Gibbs sampling - I'm not sure if I understand how it works - I'm basing my understanding on th... | g64602 | [
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0.006150797940790653,
... |
<p>I have scoured around, reading posts on Cross Validated (<a href="http://stats.stackexchange.com/questions/20523/difference-between-logit-and-probit-models#30909">Difference between logit and probit models</a>) and also looking at references including Dobson and McCullagh and Nelder, e.g. <a href="http://www.statsci... | g64603 | [
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<p>Imagine you are receiving a message over and over via a lossy data path. The path causes bit errors but does not affect the length of the message (or shift any bits). You don't know the <em>actual</em> message but you will get many copies of it so you can reconstruct it (e.g. with a median filter). You want to es... | g64604 | [
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0.0382976... |
<p>I'm using particle filters for inference in a hidden markov model with an infinite state-space.
My current state-variable is multidimensional and there are interdependencies between some dimensions. I thought therefore, that it would be beneficial, if I split it up into sub-states and model ther dependences in a sma... | g64605 | [
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0.007988156750798225,
-0.03274079039692879,
-0.003461096901446581,... |
<p><a href="http://stats.stackexchange.com/questions/10856/what-is-the-distribution-of-the-difference-of-two-t-distributions">What is the distribution of the difference of two-t-distributions</a> suggests that the sum of two t-distributions is never t distributed. </p>
<p>With t distribution I mean the (non-standardiz... | g64606 | [
0.025397036224603653,
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0.00030847490415908396,
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0.0237054359167814... |
<p>I'm implementing the k-means algorithm (in R Map-Reduce) and I wanted to verify if the output I'm getting is close enough to the true centroids of the cluster. This is how I'm verifying with a 2D dataset currently:
I plot both the dataset and the centroids I've got as output and see if the centroids are close to the... | g64607 | [
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0.0491330511868,
0.012842... |
<p>I'm playing with a randomForest and have found that generally increasing the sampSize leads to better performance. Is there a rule / formula / etc that suggests what the optimal sampSize should be or is it a trial and error thing? I guess another way of phrasing it; what are my risks of too small of a sampSize or ... | g64608 | [
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0.03079509176313877,
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<p>I am working on a project on gesture recognition(in c# language). In some part I had to use neural networks using the sigmoid activation function. I am using the aforge.net(http://www.aforgenet.com/) library for the same.
The system developed gets trained when I use a certain part of the training data. However when... | g42466 | [
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0.044... |
<p>It has been a few years since I fit a mixed model, so I have gone on a massive review session on old notes, books (Pinheiro and Bates, Faraway, etc) and going through the posts on SO and CV about mixed models. It has been great, but I am left with a few questions that are likely so basic they are missed in most of t... | g22268 | [
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<p>I'm wondering if someone could suggest what are good starting points when it comes to performing community detection/graph partitioning/clustering on a graph that has <strong>weighted</strong>, <strong>undirected</strong> edges. The graph in question has approximately 3 million edges and each edge expresses the degr... | g42467 | [
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<p>I need to automatically identify if a time series is intermittent or not. Depending on the result I'll use one or another method for forecasting it.</p>
<p>Is there any test to detect intermittent time series?</p> | g64609 | [
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<p>I'm running a glmm with the lme4 package in R that looks like the following:</p>
<pre><code>glmer(y ~ factor1 + factor2 + (1 | RE), data=data, poisson)
</code></pre>
<p>And I get the following warning message:</p>
<pre><code>Warning message:
In mer_finalize(ans) : gr cannot be computed at initial par (65)
</code>... | g22853 | [
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<p>I have MLE curve parameter estimates for 3 populations (2 per population), and am looking for a clever way to compare them.
At the moment, I am non-parametrically bootstrapping my datasets in order to create <em>n</em> datasets, which I then compare using a standard MANOVA procedure.
I have a number of issues with t... | g64610 | [
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0.025424476712942123,
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0.03677954897284508,
... |
<p>I was wondering if it is OK to use one-way ANOVA after normalisation to the untreated controls? This is in an animal model of wound healing where there are 4 wounds per animal, one untreated and 3 treated with different drugs. I have noticed that the healing rate differs between animals so in order to reduce the sta... | g64611 | [
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0.01056367252022028,
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<ul>
<li>Is the sample semi-partial correlation a biased estimate of the population semi-partial correlation?</li>
<li>If it is biased, what is an unbiased estimator of the population semi-partial correlation?</li>
<li>Are there are any references in the statistical literature that discuss this? </li>
</ul> | g64612 | [
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<p>I am having a hard time to understand how one derives the jackknife bias for the variance and mean. </p>
<p>1) Why do we need an inflation factor of $(n-1)$ when calculating the jackknife bias of the mean?</p>
<p>2) How does one derive the jackknife bias for the variance? </p> | g64613 | [
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<p>I am attempting to analyze my (experimental psych) data in SPSS, and I have a few questions regarding the kind of analysis I should be using (GEE or GLMM), how I should be interpreting the output, and how I should be selecting the best fitting model. </p>
<p>(Disclaimer: Regression analyses in general are fairly ne... | g42472 | [
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<p>I have a binary classification problem and I experiment different classifiers on it:
I want to compare the classifiers. which one is a better measure AUC or accuracy? And why?</p>
<pre><code>Raondom Forest: AUC: 0.828 Accuracy: 79.6667 %
SVM: AUC: 0.542 Accuracy: 85.6667 %
</code></pre> | g64614 | [
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0.05705555900931358,
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<p>After performing a factor analysis on a set of variables, I have one variable that loads equally on two factors.</p>
<ul>
<li>What should I do with this variable that loads equally on two factors?</li>
<li>Should I remove this variable from the factor analysis, and rerun the factor analysis?</li>
</ul> | g41826 | [
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<p>I have estimated a model with many interactions of both continuous and factor explanatory variables. The model is to be used for prediction.</p>
<p>My model has performed reasonably in out-of-sample testing. </p>
<p>However, I have found that my errors are correlated. </p>
<p>I took my fitted values of y and ran ... | g64615 | [
0.06535454839468002,
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<p>I learnt about PCA a few lectures ago in class and by digging more about this fascinating concept, I got to know about sparse PCA.</p>
<p>I wanted to ask, if I'm not wrong this is what sparse PCA is:
In PCA, if you have n data points with p variables, you can represent each data point in p dimensional space before ... | g64616 | [
0.037709321826696396,
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<p>A psychiatrist hires you to study whether her clients self-disclosed more while sitting in an easy chair or lying down on a couch. All clients had previously agreed to allow the sessions to be videotaped for research purposes. You randomly assigned 10 clients to each condition. The third session for each client was ... | g22856 | [
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-0.02098177932202816,
0.0485... |
<p>I am trying to map slowness of underwater sound velocity in a river using some tomographic device. The location of each acoustic receiver/transmitter is shown in the picture below</p>
<p><img src="http://i.stack.imgur.com/dM7wr.png" alt="enter image description here"></p>
<p>To find the slowness m={S11,S12,S13, ..... | g64617 | [
0.011236341670155525,
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0.010114656761288643,
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0.07345253974199295,
0.01195484958589077,
0.024... |
<p>I'm brand new to SAS programming, and I'm having difficulty figuring out this issue:</p>
<p>I have two sets of data</p>
<p>1st set has 4 columns (income is a continous range of numbers, sex is 0 for male - 1 for female, and employed is 0 for yes - 1 for no.</p>
<pre><code>id | income | sex | employed
</code></pre... | g64618 | [
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0.07959382236003876,
-... |
<p>I have exponentially distributed probability of event $E$ </p>
<p>$$P(E|a) = a \exp(-aE),$$ </p>
<p>where $a$ is the rate parameter of the exponential distribution.</p>
<p>Now the probability distribution for $a$ is a Gamma distribution with parameters $d$ and $b$</p>
<p>$$P(a|d,b) = b^d a^{d-1} \exp(-ba) / \... | g64619 | [
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0.023208554834127426,
0.010739350691437721,
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-0.... |
<p>How would I go about checking for autocorrelation if I had a few thousand observations for each time period and had about 15 different time periods? The data set I am working with has a lag variable which is obviously very influential but I am concerned about the bias in my other predictors when I use this lag vari... | g64620 | [
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0.06367368251085281,
0.0665096715092659,
0.050105880945920944,
... |
<p>I have some data on serving sizes of a particular food (raw oysters), and I am trying to determine what probability distribution I should select to model these data for a risk assessment (RA). The R package I am planning to use for the RA (mc2d) uses a gamma distribution for serving size in its example, although the... | g64621 | [
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0.0016739715356379747,
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0.014951491728425026,
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0.0035476640332490206,
0.03611000254750252,
0.016843466088175774,
0.01948961801826954,
0.... |
<p>I have trouble finding the following sufficient statistics.<br>
How do you do this?<br>
$$X\sim \Gamma(\alpha, \beta)$$
$$f(x;\alpha, \beta)=\frac{e^{-x/\beta}x^{\alpha-1}}{\Gamma(\alpha)\beta^\alpha}$$ </p>
<p><strong>Question</strong>:
Is $log(X_1+X_2)$ a sufficient statistic for beta? </p>
<p>I am using the f... | g64622 | [
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0.05855758115649223,
0.0029251002706587315,
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0.04099704697728157,
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-0.03681382164359093,
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-0.009541759267449379,
-0.012783437967300415,
... |
<p>I'm currently trying to implement a model along the lines of <a href="https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/8928/1/UPhDIMA_June_2009owen.pdf" rel="nofollow">Owen (2009)</a> and <a href="http://wilson.engr.wisc.edu/rsfc/oth_sites/rate/papers/knorr-held99dynamic.pdf" rel="nofollow">Knorr-Held (2000)</... | g3785 | [
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0.0258535984903574,
0.041775740683078766,
... |
<p>I have two signals <em>s1</em> and <em>s2</em>, sampled 170 times each.</p>
<pre><code>x = 0.2:0.2:34;
s1 = rand(size(x));
s2 = randn(size(x));
</code></pre>
<p>The calculation of the MI (mutual information) between two discrete variables requires knowledge of their marginal probability distribution functions and ... | g64623 | [
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0.0019513799343258142,
0.045472439378499985,
0.019019415602087975,
0.03284445032477379,
-0... |
<p>Let's say I have a questionnaire about a toy and I ask:</p>
<ol>
<li>The person to rate the toy on a scale of "bad, medium, good"</li>
<li>How much the person thinks it cost to make the toy</li>
</ol>
<p>I want to test whether there's a (monotonic) relationship between the two variables. What's the best way of doi... | g64624 | [
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0.02399047464132309,
0.05087579786777496,
0.035142... |
<p>I was given the returns of a cross-asset class portfolio of ETFs and I conducted PCA to obtain factors on dates from T-n, T-3, T-2,..., T. What I would like to do is decompose the market moves from T+1, T+2, ... onwards into combinations of the PCs.</p>
<p>My questions is, what sort of algorithm or optimization met... | g64625 | [
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0.009360551834106445,
0.00... |
<p>i'm trying to compute the variance of the random variable </p>
<p>$$X = \frac{1}{N}\sum_{i=1}^N x_i$$</p>
<p>where $x_i$ are correlated identical random variables (mean and variance defined) obtained from a stationary stochastic process.</p>
<p>I've reached the point where, with algebra only, I obtain </p>
<p>$$... | g64626 | [
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-0.01478754635900259,
0.0011789754498749971,
0.05806950107216835,
0.0010925556998699903,
0... |
<p>Can anyone give a definition for Geometric Autoregressive Process? Any specific properties? And, in what fields is this mostly applied?</p>
<p>To add some context to the question, here is a section of the original Mathematica code that mentions the process:</p>
<pre><code> n = 1000;
\[Lambda] = n \[Gamma];
\[Cap... | g64627 | [
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0.019140981137752533,
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0.0743992030620575,
0.07425639033317566,
-0.0222... |
<p>I am trying fit an ARIMA model to stock returns.</p>
<p>I have reached a decent model using the AIC criterion. </p>
<p>However, the ljung-box p value under a diagnostic plots are pretty weird.
The null hypothesis get rejected at higher lags.
I tried modifying the parameters, but L-B p value betters only marginall... | g64628 | [
0.07567247748374939,
-0.02313210628926754,
-0.018836114555597305,
-0.05425642803311348,
0.044148195534944534,
0.011225716210901737,
0.014554250985383987,
-0.01235047634691,
-0.02015596069395542,
-0.02176201529800892,
0.07336146384477615,
0.05136270076036453,
0.09305725246667862,
0.02605236... |
<p>I have a fine <code>randomForest</code> classification model which I would like to use in an application that predicts the class of a new case. The new case has inevitably missing values. Predict won't work as such for NAs. How should I do this then?</p>
<pre><code>data(iris)
# create first the new case with missin... | g64629 | [
0.03767584636807442,
-0.05328594520688057,
0.008775722235441208,
-0.059130653738975525,
0.046679943799972534,
0.007336457259953022,
0.0011824739631265402,
-0.0013819618616253138,
-0.011579678393900394,
-0.03117106668651104,
0.009463992901146412,
0.010606620460748672,
0.07783360034227371,
0... |
<h3>Weighting in sequence analysis</h3>
<p>So far, I have scarcely found papers that address the issue of weighting for sequence analysis (using for example the optimal matching algorithm). Sequence analysis normally involves several steps: </p>
<ol>
<li>setting or calculation of substitution and insertion/deletion ... | g64630 | [
0.042850565165281296,
-0.017922883853316307,
-0.00078871805453673,
-0.008517388254404068,
0.0018997422885149717,
-0.05071390047669411,
0.019456181675195694,
0.04386712238192558,
-0.06985467672348022,
0.027564093470573425,
-0.039856452494859695,
-0.03876689448952675,
-0.0013669395120814443,
... |
<p>I am wondering about the correct statistical analysis for an experiment involving 2 independent variables (treatment A, 4 levels and treatment B, 2 levels) and one dependent variable (C, score). Because subjects undergo all levels of both treatments, I am assuming a two-way within-subject (repeated-measures) ANOVA (... | g22866 | [
-0.035697996616363525,
-0.03963908553123474,
-0.007321097422391176,
-0.01846391335129738,
-0.02400059625506401,
0.004747752100229263,
0.018133675679564476,
-0.0023027292918413877,
-0.04448777809739113,
0.007689890917390585,
0.004915308207273483,
0.012714595533907413,
-0.024142887443304062,
... |
<p>I would like to perform an A/B Test on my website. I have basic knowledge on know how to do a basic test statistics, but I'm not sure on how to choose the sample size. In particular, if I have an event with a conversion rate (before the campaign) very very low, let's say p = 1/10^6. To apply the C.L.T. on p for a gi... | g64631 | [
0.014689953997731209,
0.0005216864519752562,
-0.009903349913656712,
-0.021215157583355904,
0.001123682945035398,
-0.020786339417099953,
-0.007006980013102293,
0.07800235599279404,
0.04147240146994591,
-0.012781849130988121,
0.05510937049984932,
-0.004664221312850714,
0.015222186222672462,
... |
<p>I am reading this paper: <a href="https://dipot.ulb.ac.be/dspace/bitstream/2013/96837/1/2011-025-ARIAS_DEHON-theroads.pdf" rel="nofollow">https://dipot.ulb.ac.be/dspace/bitstream/2013/96837/1/2011-025-ARIAS_DEHON-theroads.pdf</a></p>
<p>On page 23 (of the paper, not the pdf) they have a table showing the "outcome h... | g64632 | [
-0.0005123810842633247,
0.005929737817496061,
-0.021412167698144913,
-0.047316648066043854,
0.039804983884096146,
0.008975187316536903,
0.04925249516963959,
0.025914616882801056,
0.00508468272164464,
0.011627763509750366,
-0.0427979975938797,
0.03211376070976257,
0.08191974461078644,
-0.02... |
<p>I'm not a statistician so maybe this question doesn't make sense, but here goes...</p>
<p>I'm trying to write some code that does a 2-sided Fisher's exact test on some data that looks like this:</p>
<pre><code>| GROUP | SAMPLE_NUMBER | TOTAL_RESULT | BAD_RESULT |
---------------------------------------------------... | g64633 | [
-0.05164704844355583,
-0.03207266330718994,
0.00730391638353467,
-0.0739530622959137,
0.03519285097718239,
0.005957475863397121,
-0.006757269147783518,
0.007918902672827244,
-0.09555421024560928,
0.010948546230793,
-0.01493297703564167,
0.024549659341573715,
0.00364062306471169,
0.02109080... |
<p>I am running a VAR based Granger non-causality tests. I've obtained asymptotic and bootstrap $p$ values for Wald joint test of 0 restriction on a set of lagged variables. It appears that bootstrap based models fail to reject Granger non-causality more often than the models based on asymptotic theory.</p>
<p>My ques... | g64634 | [
0.05123760923743248,
-0.015816958621144295,
-0.0027327663265168667,
-0.012997565791010857,
0.04387127235531807,
-0.028462503105401993,
0.04375765100121498,
-0.0014444617554545403,
-0.05784301832318306,
-0.002581131411716342,
0.09139490872621536,
0.03173204883933067,
0.03590598329901695,
0.... |
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