question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>This question is a bit embarrassing, but I do not have much experience of statistical analysis. The problem I have is that the analysis I do of the results in my paper is so meager. My results from a fixed effects regression basically consist in the effect of one or two central explanatory variables. I can comment o... | 73,267 |
<p>I have a dataset for cell-phone accounts and I am trying to predict whether or not an account will cancel given some input features. One such feature is the number of devices an account owns. I am trying to figure out if this is a predictive feature. </p>
<p>I was thinking that one way to do this is to calculate... | 231 |
<p>I've recently started experimenting with Genetic Programming as an optimization tool. I'm still a little confused as to how to reduce overfitting in this framework. </p>
<p>A couple of techniques I've read about </p>
<ol>
<li>Limiting the number of generations</li>
<li>Limiting the tree (genome) size</li>
<li>Addi... | 73,268 |
<p>I am trying to understand the Fellegi-Sunter Probability Model for Record Linkage problem. I am following the thesis at: <a href="http://www.inf.ed.ac.uk/publications/thesis/online/IM080663.pdf" rel="nofollow">http://www.inf.ed.ac.uk/publications/thesis/online/IM080663.pdf</a> in order to learn about the model. Acco... | 73,269 |
<p>OK. I've just read that a breakpoints object with "NA" means no significant structural breakpoint was found, which is fair enough. But then if you call summary() on that breakpoint object, it will report a breakpoint. Who to believe?!</p>
<p>Also, my independent variable is not time. I'm searching for a change ... | 73,270 |
<p>I have a large dataset that is weighted due to: </p>
<ol>
<li>probability proportional to size sampling, & </li>
<li>disproportionate stratification. </li>
</ol>
<p>I would like to compare the means for two different domains within the same sample, using the weighted means and variance estimates. I believe ... | 73,271 |
<p>I need help trying to figure out what data-structure I'm dealing with, and what estimation & inference models I can therefore use.</p>
<ul>
<li>There are multiple units and periods.</li>
<li>No unit identifiers, so there's no way to match observations over time to create your traditional panel dataset.</li>
<li... | 49,512 |
<p>This question is a follow-up to a <a href="http://stats.stackexchange.com/questions/33038/do-these-residual-plots-indicate-that-my-least-squares-regression-coefficient-es">prior question</a>.</p>
<hr>
<p>Basically, I wanted to study under what conditions when we regress the residuals to $x_1$, we will get $\small ... | 73,272 |
<p>I am looking for applied references to data augmentation (preferably with some written code). Either online references are books would be great.</p>
<p>I found this book online:</p>
<p><a href="http://rads.stackoverflow.com/amzn/click/142007749X" rel="nofollow">http://www.amazon.com/Bayesian-Missing-Data-Problems... | 35,563 |
<p>This seems to be so straightforward that I can't believe I haven't found the answer in the SPSS help or online - I must be missing something.</p>
<p>I have two scale variables, let's call them $X$ and $Y$. They are likert scale variables measuring agreement with attitude statements for two items that are thought to... | 35,566 |
<p>Is there any GUI for R that makes it easier for a beginner to start learning and programming in that language?</p> | 73,273 |
<p>My name is Tuhin.
I came up with a couple of questions when I was doing an
analysis in R.</p>
<p>I did a logistic regression analysis in R and tried to check
how good the model fits the data.</p>
<p>But, I got stuck as I could not get the pseudo R square value
for the model which could give me some idea about the ... | 73,274 |
<p>I have a time series with an exponential moving average and I want to calculate a moving return of the EMA over the last m periods (something like a smoothed moving return).</p>
<p>Let's say:</p>
<p>Y(t) is the value of the time series at time period t</p>
<p>S(t) is the value of an EMA of Y at time period t</p>
... | 73,275 |
<p>I've dealt with <strong>Naive Bayes</strong> classifier before. I've been reading about <strong>Multinomial Naive Bayes</strong> lately.</p>
<p>Also <strong>Posterior Probability = (Prior * Likelihood)/(Evidence)</strong>.</p>
<p>The only prime difference (while programming these classifiers) I found between Naive... | 73,276 |
<p>I know that there is a way to "redistribute the frequencies of a variable" as stated here: </p>
<p><a href="http://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CC8QFjAB&url=http%3A%2F%2Fwww.cis.hut.fi%2FOpinnot%2FT-61.181%2Fs99%2Fpresentations%2Foct27_MK.ppt&am... | 73,277 |
<p>Suppose I have a mixture of finitely many Gaussians with known weights, means, and standard deviations. The means are not equal. The mean and standard deviation of the mixture can be calculated, of course, since the moments are weighted averages of the moments of the components. The mixture is not a normal distribut... | 35,572 |
<p>Often I have heard the data miners here use this term. As a statistician who has worked on classification problems I am familiar with the term "train a classifier" and I assume "learn a model" means the same thing. I don't mind the term "train a classifier". That seems to portray the idea of fitting a model as th... | 35,573 |
<p>This is from <em>Probability and Measure</em> by Billingsley, 3rd Edition.</p>
<p><strong>27.21 (p. 370)</strong> Let $X_1, X_2,...$ be independent and identically distributed, and suppose that the distribution common to the $X_n$ is supported by $[0,2\pi]$ and is not a lattice distribution. Let $S_n=X_1+\cdots+X_... | 73,278 |
<p>Using Excel's correlation function I get a correlation of -7% between data sets A & B. Data set C has a 92% correlation to A and an 84% correlation to B. How can C be strongly correlated to A and B, but A and B are slightly negatively correlated to one another?</p>
<p>What other tests can I perform to help me... | 49,697 |
<p>Assume a one-sample t-test, where the null hypothesis is $\mu=\mu_0$. The statistic is then $t=\frac{\overline{x}-\mu_0}{s/\sqrt{n}}$ using the sample standard deviation $s$. In estimating $s$, one compares the observations to the sample mean $\overline{x}$:</p>
<p>$s=\sqrt{\frac{1}{n-1}\sum_{i=1}^n (x_i-\overline{... | 73,279 |
<p>I am developing a multiple regression model. Recently I came across a statement that for the calibration set it's "better" to select samples which are uniformly distributed in a response variable space -Y as opposed to "normally" distributed samples.</p>
<p>I am trying to understand this. If for the calibration set... | 73,280 |
<p>What is the formula (if it exists) for the sample variance / confidence interval of a quantile / percentile of the normal distribution?</p>
<p>For example, the 5th percentile for a standard normal population distribution is -1.64, but what is the 95% one-sided confidence interval if I have a sample of n=1,000? I.e.... | 35,575 |
<p>I have been reading <a href="http://faculty.sites.uci.edu/mdlee/bgm/" rel="nofollow">a book</a> that cites an example where a uniform distribution is the initial prior, and then a person scores 9/10 on a test. Then the resulting posterior becomes the prior distribution. </p>
<p>The book provides the following expla... | 35,576 |
<p>I have 70,000 observations for my depentant variable. I have 12 independant variables. After removing zero value and error and missing value form my data set, my data reduced to 4000. Can I still do the multiple linear regression with this data set? I think 4000 data is more than enough for 12 indepndant variables, ... | 35,577 |
<p>I'm studying neural networks, and I'm trying to decide why the default choice of cost function for a single neuron seems to be quadratic loss:
$$\sum_i(y_i-f_i)^2,$$</p>
<p>instead of:</p>
<p>$$-\prod_ip_i^{y_i}(1-p_i)^{1-y_i},$$</p>
<p>as per logistic regression. Where both $f_i$ and $p_i$ are the sigmoid (acti... | 73,281 |
<p>An excel program runs a Monte Carlo coin experiment. <code>10,000</code> coins are tossed <code>1000</code> times, with the number of times <code>N</code> heads appearing recorded in a table. Call the number of times <code>N</code> heads appear during a run of the experiment <code>Q</code>. The average value of <cod... | 35,578 |
<p>I'd like to review published papers or book chapters (so I could formally refer to them) that graphically illustrate the parametric relationships between univariate distribution families. The papers by Lawrence M. Leemis are well-known, see e.g. here for <a href="http://www.mat.ufrgs.br/~viali/exatas/material/textos... | 73,282 |
<p>When one bootstraps a parameter to get the standard error we get a distribution of the parameter. Why don't we use the mean of that distribution as a result or estimate for the parameter we are trying to get? Shouldn't the distribution approximate the real one? Therefore we would get a good estimate of the "real" va... | 73,283 |
<p><a href="http://stats.stackexchange.com/questions/71302/power-of-a-mann-whitney-test-compared-to-a-t-test">In a previous question</a>, I asked about comparing the power of a t test to a Mann Whitney test under different situations. One of the answers pointed out that the worst that the Mann-Whitney can ever perform ... | 73,284 |
<p>I am trying to determine how to use machine learning models such as for eg., random Forest with (non-financial) time-series data.</p>
<p>Using an example, suppose we wanted to find based on monthly scores on subjects for each student how well he/she will do in a month-end exam that occurs every month.</p>
<pre><co... | 73,285 |
<p>I have a classifier that gives its decisions as probability estimations: for each datum it returns a set of probabilities $p_j$ for each known class $j$: $p_j(\vec{x})=P(c_{real}=j|\vec{x})$.</p>
<p>I have a training dataset, on which I trained the classifier, and I have a test dataset to test it. In both datasets ... | 35,580 |
<p>I am interested to know why residual plots are plotted with residuals against predicted variable of y and not against y?</p> | 35,581 |
<p>I am using Silhouette width to compute the best value for k in k-means. As I am performing document clustering, I am calculating the values of <code>a</code> and <code>b</code> as follows in Python:</p>
<pre><code>a = distance(data[index], centroids[clusters[index]], metric=metric, p=p)
b = min([distance(data[index... | 49,369 |
<p><em>Disclaimer: I'll happily admit to not really knowing what I'm doing when it comes to General Mixed Models but hopefully this thread can bring me a little bit closer to some kind of understanding. If, however, this is an "OMG, you're such a n00b" question which should be closed and never spoken of again, I'll tot... | 73,286 |
<p>I'm pretty lost at how to approach this, and particularly with regards to the terminology; so please feel free to point to resources, fix my question name, etc. Thanks.</p>
<p>I used R back in college, I've got Orange installed. I've heard of MiniTab. I've got Excel installed. I've got access to SQL Server 2008 w/ ... | 35,583 |
<p>I recently read an <a href="http://www.psychologytoday.com/blog/golden-slumbers/201210/increase-longevity-seven-hours-sleep" rel="nofollow">article</a> about how you can increase longevity by sleeping less. This article, like many others I've read, references a statistical study and implies that causation was found ... | 73,287 |
<p>With this data:</p>
<pre><code>y <- c(1.105808, 1.000000, 5.304166, 33.665875, 139.865451, 109.033703, 176.639245, 1.000000, 28.521134, 44.281121 ,150.478570, 18.465554, 85.096431, 81.907537, 124.631226, 1.000000 , 11.237294 , 20.480519 , 68.642176 , 30.047630, 54.051613 , 134.068889... | 46,994 |
<p>I am trying to use a Negative Binomial regression model for some count data in which the dependent count variable takes on the values 0, 1, 2, 3 or 4. I am using SAS and keep running into the warning: "The relative Hessian convergence criterion of X is greater than the limit of 0.0001. The convergence is questionab... | 1,004 |
<p>I have a set of t-rflp fragment-length profiles from an investigation into microbial degradation of hydrocarbons as part of my undergrad dissertation. I want to study the effect of various variables on the microbial community of uncontaminated soils - specifically if the presence of surfactants and soil from oil-con... | 46,997 |
<p>Does anyone know how / if can you treat an independent variable as BOTH a between AND within subjects variable (ideally in SPSS ANOVA-repeated measures). That is, we have a repeated measures study where the independent variable is DEVICE (6 levels). The catch is, each respondent will only be exposed to 3 devices a... | 35,585 |
<p>I am a research assistant for a lab (volunteer). I and a small group have been tasked with the data analysis for a set of data pulled from a large study. Unfortunately the data were gathered with an online app of some sort, and it was not programmed to output the data in the most usable form. </p>
<p>The pictures ... | 1,735 |
<p>I am looking into gamma-bridge sampling, as described in for example [1]. </p>
<p>What are the benefits of sampling in this method? Is it purely a computational aspect? </p>
<p>Are there any problems with the way the function <code>rgamma()</code> in <code>R</code> samples? From what I can tell, it is an acceptanc... | 35,587 |
<p>I'm writing my diploma thesis about the interaction between warehouse management and data mining (specifically, association rules).</p>
<p>I started the topic data mining by considering Boolean association rules, created by the a-priori algorithm (for example, market basket analysis). Then I found out about quantit... | 35,588 |
<p>This is not a homework question, just sort of a mental block. Why do statistical analyses require clearly defined variables as response/dependent variable? Why can't my response variable be something [vague] like "Likely High Value Customer" or a yes/no question?</p> | 35,589 |
<p>I have three features that I use to solve a classification problem. Originally, these features produced boolean values, so I could evaluate their redundancy by looking at how much the sets of positive and negative classifications overlap. Now I have extended the features to produce real values (scores) instead, and ... | 47,001 |
<p>I am managing many people entering data into a database. I have a log of user, date, time, table, and action that each person makes:</p>
<pre><code>records <- data.frame(user = c('bob', 'bob', 'jane', 'jane', 'bob', 'bob', 'bob', 'jane', 'jane', 'bob'),
date = c("2010-06-24", "2010-06-28", ... | 47,002 |
<p>I’m reviewing an article, and can’t give details but here is the situation, and it’s got me puzzled</p>
<p>Patients were divided into 4 categories (call them A B C and D), which were exhaustive and exclusive. Adjusted hazard ratios were computed for these four groups for all patients and for two subgroups of patie... | 35,590 |
<p>readHTMLTable seems pretty robust, but when I try to use it on this page, I get an error. </p>
<p>Any ideas what it means or how I could get around it? The page's biggest table is nested inside another table... is that a problem? </p>
<pre><code>> tables<-readHTMLTable(myURL, header=NA,a.data.frame=TRUE)
E... | 47,004 |
<p>I would like to get the coefficients for the LASSO problem </p>
<p>$$||Y-X\beta||+\lambda ||\beta||_1.$$</p>
<p>The problem is that glmnet and lars functions give different answers. For the glmnet function I ask for the coefficients of $\lambda/||Y||$ instead of just $\lambda$, but I still get different answers.</... | 73,288 |
<p>Can we do a meta-analysis of data of 3 regions. A particular disease was treated with the same treatment but implemented thoroughly in 2 regions and not so thoroughly in 1 region. How to proceed with analysis? What is the best way to analyse these data. The data are of a disease (cases and deaths) as follows:</p>
... | 47,005 |
<p>I have been burdened with the task of coming up with a forecast plan for my company. I have no experience and am VERY new to the whole forecasting scene. As of right now, my company has no plans of investing in any forecasting software so my only tool is Excel. I've tried to do some research online myself and it ... | 73,289 |
<p>In the task of language identification, I would do the following:</p>
<ol>
<li>Take a sample of my data</li>
<li>Prepare the ground truth </li>
<li>Train my classifier on this sample data</li>
<li>Test classifier accuracy on the other part of my data that I did not sample (and possibly cross-validate) </li>
</ol>
... | 46,914 |
<p>Suppose I have a data set that represents circular data measured in degrees:</p>
<pre><code>x <- c(rnorm(1000, 0, 10), rnorm(700, 110, 3), rnorm(1100, 230, 5)) %% 360
</code></pre>
<p>The R package <code>circular</code> provides a very nice way to represent that data, and a basic tool for detecting change point... | 73,290 |
<p>If I have a population and want to draw samples from there, what are the steps to determine the number of samples to draw from the population? In other words, if I have population N and want to draw k samples from them so that the samples are representative of the entire population, how can I determine k?</p>
<p>I ... | 73,291 |
<p>I did correlation tests between a number of variables consisting of both interval and categorical scales ($n = 1274$, one sample). I used $\chi ^2$ test for categorical vs ordinal and Spearman's $\rho$ for interval vs ordinal data. </p>
<p>The correlation between climate zone (zone $1, 2, 3, 4$) and daily exposure ... | 35,593 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/13850/not-significant-f-but-a-significant-coefficient-in-multiple-linear-regression">Not-significant F but a significant coefficient in multiple linear regression</a> </p>
</blockquote>
<p>In my research, ... | 49,368 |
<p>Two tools completely agree on categorizing 85k sentences (my entire population). Now, I want to take a sample of sentences and give that to two humans. This is to check whether the tools agreed genuinely or both of them together miscategorized the 85k sentences. Now, I need to know how many sentences should I pick a... | 73,292 |
<p>I currently am trying to cluster "types" of changes on bitemporal multispectral satellite images.</p>
<p>I applied a thing called a mad transform to both images, 5000 x 5000 pixels x 5 bands.
Each band is a "variable" as it is radiance information from a different spectrum of light.
This transform is basically equ... | 73,293 |
<p>How can assess the accuracy of the output of a deterministic mathematical model?</p>
<p>For example, a climate model can predict the mean annual temperature (MAT) for a specific location. I can use the model to predict thirty years of MAT in New York City, $T_\text{model}$. Now let's say I have the observed MAT in ... | 73,294 |
<p>My models look like:</p>
<pre><code>lme1 = lme(y~X+Y+V, random=~1|Subject, data=mydata, method ="ML")
lme2 = lme(y~X+Y+V2+V3, random=~1|Subject, data=mydata, method ="ML")
lme3 = lme(y~X+Y+V4, random=~1|Subject, data=mydata, method ="ML")
</code></pre>
<p>where X and Y are factors, but V, V2, V3,and V4 are continu... | 35,597 |
<p>What is the asymptotic time complexity of Lasso regression as either the number of rows or columns grows?</p> | 73,295 |
<p>The geometric mean is the appropriate measure of central tendency for log-normally distributed variables. However, the arithmetic mean still has some use in relation to log-normal variables - in inferring totals from survey data, for instance. It is my understanding that the arithmetic mean of the sample of a log-no... | 47,016 |
<p>I am trying to analyse the effects of clipping (33% and 66%) and season (1, 2 and 3) on species richness. I have a control (no clipping, in no season) that the values are nested in. </p>
<p>I am having difficulty building the code for this.<br>
This is what I have managed:</p>
<pre><code>lmm1 <- lmer(Species_... | 73,296 |
<p>In their 1999 book, Yates, Moore & McCabe specify that no more than 20% of expected counts should be less than 5 and all individual expected counts should be greater than 1. </p>
<p>Does this mean that, for any 2 by X contingency table that no more than 20% of the cells should be less than 5? </p>
<p>So, for a... | 73,297 |
<p>I have a dataset (x,y) where x is a n-dimensional vector and y is an m-dimensional vector. (m=3, n>2) My goal is to find the best polynomial in x fitting the (x,y) dataset.</p>
<p>The dimension of x is pretty big (right now it is 25), and I don't want to enter manually all the possibilities (ie x1*x3*x5, x1*x4*x6, ... | 195 |
<p>I did a study which produced 6 factors. One of the factors has only 1 variable at 0.75, with the next closest on 0.54. My class was told to only include >0.6 for interpretation and omit the rest. Is it possible to have a factor representing one variable?</p> | 73,298 |
<p><strong>Updated</strong></p>
<p>I have a data set with five continuous variables measuring an index in a population. For finding underlying classifications in the population based on the five observed variables,
I did a latent profiles analysis (LPA) for two and three categories model using all five variables.The t... | 73,299 |
<p>If, for example, I have <code>0011</code> as a set of known bits $x$, how do I determine the probability that a sequence of randomly generated bits is equal to $x$?</p>
<p>Thanks for the help! I'm sure this is a dumb question, but probability has always been my weakness (which my algorithms class is highlighting!).... | 26,476 |
<p>Is there an analytic form for the Hellinger distance between von Mises distributions?</p> | 195 |
<p>How do I carry out a repeated measures analysis using R?</p> | 73,300 |
<p>I'm just preparing for my exam, but I have no idea how to solve this problem:</p>
<ol>
<li>Durable Press cotton fabrics are treated to improve their recovery from wrinkles after washing. Unfortunately, the treatment also reduces the strength of the fabric. A study compared the breaking strength of fabrics treated b... | 29,227 |
<p>I have almost the same question as:
<a href="http://stats.stackexchange.com/questions/5347/how-can-i-efficiently-model-the-sum-of-bernoulli-random-variables">How can I efficiently model the sum of Bernoulli random variables?</a>
But:</p>
<p>(1) The number of random variables for summation is ~ N=20 (case 1) or N=90... | 37,565 |
<p>Does any body know of a Java implementation of McNemar's Test?</p> | 73,301 |
<p>A common formulation of multilevel/hierarchical regression models is
$y = Xb + Zc + e$, where $X$ is an $n \times p$ matrix of $p$ individual level predictors, $Z$ is an $n \times q$ matrix of $q$ group level predictors, $y$ is an $n \times 1$ vector of observations at the individual level and $e$ is the error term... | 46,989 |
<p>All, </p>
<p>I am trying to create a regression model where the (continuous) outcome is multimodal: </p>
<p><img src="http://i.stack.imgur.com/FLsNy.jpg" alt="enter image description here"></p>
<p>The outcome is the retail price of a certain product, and prices tend to fall around distinct amounts (750, 1000, 125... | 73,302 |
<p>I am trying to do "variable selection" using Elastic Net method (Matlab Lasso function with alpha of 0.5). I have 75 predictors in total (some are correlated with each other, hence using Elastic Net instead of Lasso), and I would like to get a subset of them, which are good predictors for my outcome.</p>
<p>So my q... | 35,605 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/29364/probability-associated-with-no-of-fleet-calculation">Probability associated with no of fleet calculation</a> </p>
</blockquote>
<p>Assuming I have 7 cards (Ace - 7) shuffled, and I draw one card and ... | 49,918 |
<p>I am about to receive a dataset for multivariate regression where we are trying to find $X\in\Re^{m\times n}$ such that it best fits the loss function $$\|AX-B\|_F^2$$ where $A\in \Re^{l\times m},B\in\Re^{l\times n}$.</p>
<p>For some other purposes, what I was wondering was, what are the typical proportions for $A,... | 73,303 |
<p>I heard that $AR(1)$ can be written as $MA(\infty)$. </p>
<p>Can $AR(p), p \in \mathbb N, p \ge 2$ be written as $MA(q)$ for some $q$?</p>
<p>Thanks!</p> | 73,304 |
<p>Can anyone provide a clear list of differences between log-linear regression and logistic regression? I understand the former is a simple linear regression model but I am not clear on when each should be used.</p> | 73,305 |
<p>I've been reading about stratified sampling, 2-stage SRS sampling, and ratio estimation in finite populations and I have a question. When the ratio estimator is introduced, it seems that in order for it to perform well it is necessary that the population follows the following model (which I'll denote $\xi$):
$$y_{ij... | 35,609 |
<p>I want to do "Nutritional Causal Analysis". Basically my objective is to identify possible factors associated with acute malnutrition in children under five years of age in developing countries. What types of factors are related with malnutrition? What will be conceptual framework of casual path of malnutrition?</p> | 35,610 |
<p>We had an exercise in statistics class where we did a small ANOVA analysis. We were comparing how the two levels of a factor influenced the response under different conditions (combinations of other factors).
My analysis ended up as a tree where a leaf corresponded to each condition and I could see were/how my fact... | 73,306 |
<p>Manyl et al defined an index called Standardized Selection Ratio (SSR). <a href="http://books.google.ch/books?hl=fr&lr=&id=hNy8aM8HmrwC&oi=fnd&pg=PR9&dq=Statistical+design+and+analysis+for+field+studies&ots=e3F4Z714o0&sig=ULzWk1pfmm2vkrbb6nK2YKEAYms#v=onepage&q=standardized%20selectio... | 73,307 |
<p>I am trying to fit a model in R that doesn't have censoring. In other words, I know that each event will eventually happen. There are several experimental groups with people in each group receiving surgery. However, each group receives the surgery on different dates. I only have data for who died. Hence, my data set... | 73,308 |
<p>I think I understand how the fundamentals of <a href="http://en.wikipedia.org/wiki/Bootstrapping_%28statistics%29" rel="nofollow">bootstrapping</a> work, but I'm not sure I understand how I can use bootstrapping for model selection or to avoid overfitting. </p>
<p>For model selection, for example, would you just ch... | 73,309 |
<p>I'm working on my thesis and I am trying to lower the amount of runs I need to do in an experiment so I thought I'd use the Taguchi method, however I don't understand how to use the <a href="https://controls.engin.umich.edu/wiki/images/5/52/Selector.jpg" rel="nofollow">selector table</a>. I've been over and over how... | 24,972 |
<p>I am currently reading about fractional integration in the context of error correction models. Does anyone know of a package in r that has a function for Sowells maximum likelihood estimator of d?</p> | 47,045 |
<p>I was wondering if there is an R package to perform incidence density sampling for a case-control design. That is, for matching in a case-control design; accounting for multiple matching covariates. </p> | 73,310 |
<p>Let's say I'm optimizing <a href="http://en.wikipedia.org/wiki/Mean_reciprocal_rank" rel="nofollow">MRR</a> with a GBM in R:</p>
<pre><code>library(gbm)
generate.data <- function(N) {
# create query groups, with an average size of 25 items each
num.queries <- floor(N/25)
query <- sample(1:num.querie... | 35,619 |
<p>I have a GLMM with Poisson distribution and random spatial block. My experimental design is 2x2 factorial, with 4 blocks, resulting in 16 total data points. Here is the specification of the model in R using the lme4 package.</p>
<pre><code>lmer(rich ~ morph*caged + (1|block), family=poisson, data=bexData)
</code></... | 26,610 |
<p>I want to verify using a bootstrap approach the hypothesis about a lack of the intervention effect within a group of six patients: pre-(X) post(Y) intervention measurement. My data</p>
<pre><code>ID X Y
1 9.856 8.992
2 19.512 4.573
3 1.936 1.572
4 14.575 1.529
5 8.476 12.000
6 1.862 1.417
</code>... | 73,311 |
<p>I have a three level multilevel model (therapists, patients, repeated measures) in which I have included 4-way interactions, for instance:</p>
<p>therapist self-efficacy * treatment condition * patient on track (yes/no) * time</p>
<p>This tests the hypothesis that therapist who are in condition A and are higher no... | 73,312 |
<p>I would be grateful if somebody could assist me with the questions below This is for my dissertation (I am relatively new to SPSS and indeed to statistics).</p>
<p>I have a small set of cases (N=41) of companies who took my questionnaire.
There are 2 5-point Likert scale sets of questions:
- one set is intended to ... | 35,622 |
<p>I am practicing basic EM problems for qualifying exams.</p>
<p>I am having trouble with truncated/censored data problems. There is something I don't understand about the complete-data likelihood.</p>
<p>Consider the basic formulation: </p>
<blockquote>
<p>Observed data X1...Xr and Z1 ... Zq have pmf/pdf f(~|p)... | 35,624 |
<p>I need to collect a two group sample for a comparison analysis (perhaps using logistic regression).</p>
<p>The population that I need to extract a sample from is all firms from country A with activities in country B. The firms are classified into two categories: having a subsidiary in country B (S), or not having a... | 73,313 |
<p>I'm trying to create AR-model on wheather data and I wondered is there a method or algorithm which can find the optimal order for an AR-model?</p>
<p>I'm using Matlab for my data-analysis, is there a function which can do this?</p>
<p>Thank you</p> | 73,314 |
<p>Suppose the probability of a "random" event is very small (call this probability $p$). In real life, true randomness seems impossible. So would the actual true probability of the event be greater than $p$?</p> | 73,315 |
<p>The ecdf (empirical cumulative distribution function in CDF) in R, instead of giving $P(X \le x)$ for a random variable $X$, it gives the proportion of observations in the data that are $\le X$. </p>
<p>I tried to look up modified ECDF but couldn't find any. Is there any standard function to do the mathematical EC... | 73,316 |
<p>Suppose that we have a categorical variable $X$ that can take three values: $0$, $1$, or $2$. We use $X=0$ as the reference level. The following dummy variables are created: $$X_1 = 1 \ \text{if} \ X=1 \ \text{or} \ X_1=0 \ \text{if} \ X \neq 1$$</p>
<p>$$X_2 = 1 \ \text{if} \ X=2 \ \text{or} \ X_2=0 \ \text{if} \ ... | 73,317 |
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