question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I received this elementary question by email:</p>
<blockquote>
<p>In a regression equation am I correct
in thinking that if the beta value is
positive the dependent variable has
increased in response to greater use
of the independent variable, and if
negative the dependent variable has
decreased in re... | g68469 | [
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<p>I'm wondering how to proceed to perform Canonical Correspondence Analysis and Multiple Correspondence Analysis in <em>R</em> on the following three-way contingency table</p>
<pre><code>Eco_region3 Eco_region4 Species Freq
A A1 S1 10
A A1 S2 12
A ... | g68470 | [
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<p>I hope this is a stats question :) There's a game (RftG) with cards, each of which has various attributes (generally bonuses of some kind) and a price. I'm wondering if there's some kind of technique for determining the average value of each attribute, and therefore calculating the expected cost of each card as a wh... | g68471 | [
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<p><em>I'm not a statician/mathematician, so please be gentle with me</em></p>
<p>This is a cross-post <a href="http://stackoverflow.com/questions/6021170/formula-to-discard-items-by-votes-lower-bound-of-wilson-score-confidence-interva">from Stack Overflow</a>. I'm working with a site that lets the users create 'secti... | g68472 | [
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<p>Consider the one parameter exponential family on a <strong>finite</strong> sample space $S$: $$p(x;\theta)=\frac{e^{\theta x}}{\sum_{x\in S} e^{\theta x}}, \theta\in \mathbb{R}.$$</p>
<p>My objective is to find an MLE for $\theta$ having observed a sample $x_1,\dots,x_n$ from $p(\cdot,\theta)$. In the continuous ca... | g68473 | [
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<p>Say I want to classify my data into two categories. I am pretty sure that my data has been generated by two mixtures of Gaussians -- on has a bimodal and one a trimodal form.</p>
<p>I then train the generating models $p(x|c_1)$ and $p(x|c_2)$ and combine them via Bayes' theorem into a classifier of the form $p(c_i|... | g28512 | [
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<p>I have $n$ ARIMA(1,1,1) models. </p>
<p>$Y(t)= \mu + Y(t-1) + \phi(Y(t-1)-Y(t-2))-\theta\epsilon(t-1)$</p>
<p>They are all trained on different blocks of data for the same univariate time series. Now I get a list of candidate parameters fits composed of $\phi_{1..n}$ and $\theta_{1..n}$. I know I can forecast for ... | g68474 | [
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<p>I'm trying to work on an anomaly detection problem, so I am currently exploring my options on which algorithm is best to use for me.</p>
<p>I've been looking at the one-class SVM in the scikit-learn library for Python. It has a parameter <code>nu</code> that you pass it, which roughly determines what percentage of ... | g5524 | [
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<p>I am reviewing PCA concepts. I came across this nice tutorial - <a href="http://cran.r-project.org/web/packages/HSAUR/vignettes/Ch_principal_components_analysis.pdf">http://cran.r-project.org/web/packages/HSAUR/vignettes/Ch_principal_components_analysis.pdf</a> on how to do PCA in R language. I don't understand the ... | g38448 | [
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<p>I am attempting to create a model which looks at the effect that age, supplementary food use, and nest initiation date (converted to Julian days) is having on female reproductive success (success =1 and failure=0). Unfortunately I have a very small sample size of only 17 individuals. I believe that my data does incl... | g574 | [
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<p>I've collected data from my website.
The website is about cars. The data are about user reviews and the cars.
what we see in the graphs is the probability of some car type (Ford Focus 2008) to have <em>X</em> reviews.</p>
<p>The interesting thing is that when I limit the types of cars to a certain % of the cars pop... | g11604 | [
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<p>I am trying to discover whether a correlation exists between improvements in exam scores (0-100%) and improvements in Quality of Life (rated using a 5-point Likert scale).
I have a set of pre and post results.
Am I right in thinking I should use a Spearman's Correlation? Do I need to make the interval data into ordi... | g68475 | [
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<p>I have a question relating to Poisson which I would like to get some advice on. I am doing this on a self-help exercise, but unfortunately it doesn't provide answers for me to verify.</p>
<p>Basically in the question, it provides me with the premise that a server in a datacenter will under-go an unplanned system re... | g23824 | [
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<p>I'm currently trying to work with scikit-learn classification tree. </p>
<p>I followed the example on iris dataset : <a href="http://scikit-learn.org/stable/modules/tree.html" rel="nofollow">http://scikit-learn.org/stable/modules/tree.html</a> and everything is working fine. </p>
<p>I do not understand the final g... | g68476 | [
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<p>I'm trying to model a weekly process of adoption (adoption events could only occur on Fridays) using the <code>coxph</code> function, but a large quantity of observations are missing for the first 6 years, leaving me with psuedo annual data at irregular intervals.</p>
<p>The problem is, R's method for handling inte... | g38463 | [
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<p>At the moment I'm using linear regression of 4 series with:</p>
<pre><code>mod <- lm(x ~ y + z + v + 0) # I need zero intercept
</code></pre>
<p>I'm using the linear regression to calculate the coefficients of <code>y</code>, <code>z</code> and <code>v</code> to predict the <code>x</code> value.</p>
<p>Is ther... | g68477 | [
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<p>I've been implementing the GLMNET version of elastic net for linear regression with another software than R. I compared my results with the R function glmnet in lasso mode on <a href="http://www.stanford.edu/~hastie/Papers/LARS/diabetes.data">diabetes data</a>.</p>
<p>The variable selection is ok when varying the v... | g38464 | [
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<p>I have 100 datasets. All of them have varying number of features. There are around 20,000 samples in each of them. Every $i$-th sample in the 100 datasets has the same label ($0/1$). The data is highly imbalanced, so there are much fewer positive labels than 0 labels.</p>
<p>I want to give a score/weight to each da... | g20428 | [
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<p>This question is in some sense the intersection of <a href="http://stats.stackexchange.com/questions/8485/a-good-gibbs-sampling-tutorials-and-references">this question</a> and <a href="http://stats.stackexchange.com/questions/414/introduction-to-statistics-for-mathematicians">this question</a>. I have read up on the... | g38465 | [
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<p>I am getting a bit confused about feature selection and machine learning
and I was wondering if you could help me out. I have a microarray dataset that is
classified into two groups and has 1000s of features. My aim is to get a small number of genes (my features) (10-20) in a signature that I will in theory be abl... | g49371 | [
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<p>So, working in web analytics, it's common to use a chi-square test for A/B tests to test statistical significance. I often use a calculator like this: <a href="http://www.usereffect.com/split-test-calculator" rel="nofollow">http://www.usereffect.com/split-test-calculator</a> , so if each variation gets 1000 impressi... | g28523 | [
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<p>Consider the random variable $y_M$ which equals the sum of $M$ independently uniformly distributed random variables; i.e., $y_M = x_1 + x_2 +\ldots + x_M$, with the assumption that each of the $x_i$ are independently and uniformly distributed. The variance of the sum equals the sum of the variances of each of the $x... | g68478 | [
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<p>Can the group recommend a good introduction text/resource to applied resampling techniques? Specifically, I am interested in alternatives to classical parametric tests (e.g. t tests, ANOVA, ANCOVA) for comparing groups when assumptions such as normality are clearly violated. </p>
<p>An example problem type I would ... | g68479 | [
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<p>Working on probabilistic outputs of kernel methods I found the formulation of the SVM as a Penalized Method using the Binomial Deviance (described for example in "<a href="http://www-stat.stanford.edu/~tibs/ElemStatLearn/" rel="nofollow">The Elements of Statistical Learning Theory</a>, 2nd edition" by Hastie et al.,... | g28525 | [
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<p>I have a load of point data in 3D, and I wish to cluster them like so:</p>
<ul>
<li>Each cluster contains points all of which are at most distance $d$ from another point in the cluster. </li>
<li>All points in two distinct clusters are at least distance $d$ from each other.</li>
</ul>
<p>The distances used are Euc... | g68480 | [
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<p>How to keep statistical lessons that we catch growing? Is there any model to learn statistics in a way to get the best use of them in engineering applications? I don't mean recommendations on basic statistics via books etc. Practical ideas are inquired in the level of intermediate-high statistics.</p> | g68481 | [
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<p>Suppose we have some data (say around 10,000 cases) that sample a variable of interest; e.g., the concentration of metal in soil. By generating a random series of indices we choose some of those samples and then compute some statistics, for instance the mean. We do this many times and finally get the mean of mean v... | g2 | [
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<p>Given N data points <em>x</em> and N targets <em>t</em>, considering a new point <em>x</em> and the corresponding new target <em>t</em> </p>
<p>What would be:</p>
<ul>
<li>The conditional density </li>
<li>The conditional mean</li>
<li>variance </li>
</ul>
<p>of the Nadaraya-Watson model<br>
<img src="http://i.... | g68482 | [
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<p>I am new to R and some help would be of great use to me.</p>
<p>Basically, I need to perform a GLM analysis with negative binomial errors and with fixed factors, no covariates and no random effects. My factors are of type: year (1-4), site (1-3), sex (1-2), age (1-3), with a sample size of around 5000.</p>
<p>Curr... | g38470 | [
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<p>I am running a logistic model on insurance data. I have a field agent gender which matters for a channel A (say) and doesn't matter for B. I want to put null values in case of B. The only thing I risk is exclusion by SAS (as SAS excludes every missing case by default). I heard that pairwise exclusion can solve my pr... | g68483 | [
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... |
<p>If I am trying to generate hypotheses, what are the drawbacks of setting my p-value cutoff after looking at the various p-values I get for my set of results?</p>
<p>For instance, if I initially did a large number of experiments looking at the effects of several thousand chemicals individually on cell growth and I f... | g39660 | [
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<p>I have my statistician supervisor wanting me to plot a series of graphs using splines. On the x axis I have volume of milk, on the y axis days. </p>
<p>Now, he says I need to "correct for age and birth date" before I plot the predicted cubic value in splines. My question age and birth date are fixed effects, but ho... | g68484 | [
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<p>My ACF- and PACF plots are illustrated below: </p>
<p><img src="http://i.stack.imgur.com/A7Mxa.png" alt="Normal view"></p>
<p><img src="http://i.stack.imgur.com/v0CHT.png" alt="Zoomed"></p>
<p>The first one is in original scale and the second picture is zoomed. What process would you classify this? AR, MA or ARMA... | g68485 | [
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<p>Is it true that under the Gauss Markov assumptions the ordinary least squares method gives efficient and unbiased estimators?</p>
<p>So:</p>
<p>$$E(u_t)=0 $$ for all $t$</p>
<p>$$E(u_tu_s)=\sigma^2 $$ for $t=s$</p>
<p>$$E(u_tu_s)=0 $$ for $t\neq s$ </p>
<p>where $u$ are the residuals.</p> | g68486 | [
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<p>I include MDS analysis in a customer survey and have about 10 brands I want to include in the perceptual map at the end. Meaning the customers would have to rate 45 comparisons and give a similarity rating of 1 to 7 to each of the 45 comparisons.</p>
<p>Now my question. Is it a problem when NOT all customer rate th... | g28529 | [
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<p>I am trying to run the Perron's test in R, which allows testing for the broken trend stationarity.</p>
<p>I was trying to find the package and code which is running this test, but without success. While doing the search engine, I was usually finding solutions and codes for Phillips-Perron test, which is not what I ... | g68487 | [
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<p>To prove the efficacy of a test (to be more precise, a moderated t-test from two groups of samples), I need to compare the p-values obtained from my test against a null distribution of 1000 random p-values generated by permutation (rationale: show that Type I errors are accounted for properly).</p>
<p>My goal is to... | g47862 | [
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<p>Kevin Murphy's <a href="http://rads.stackoverflow.com/amzn/click/0262018020" rel="nofollow">book</a> discusses a classical Hierarchical Bayesian problem (originally discussed in <code>Johnson and Albert, 1999, p24</code>):</p>
<blockquote>
<p>Suppose that we are trying to estimate the cancer rate in $N$ cities. I... | g68488 | [
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<p>I am performing a parametric bootstrap to test whether I need a specific fixed effect in my model or not. I have mainly done this for exercise and I am interested if my procedure so far is correct.</p>
<p>First, I fit the two models to be compared. One of them includes the effect to be tested for and the other one ... | g68489 | [
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<p>I have a data monthly as well as daily data of no of patients and I want to employ time series model .How can I estimate missing counts.Any one would please guide me</p> | g68490 | [
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<p>From a given dataset X, I learn a 7-component gaussian mixture model using matlab's gmdistribution.fit:</p>
<pre><code>model = gmdistribution.fit(X,7,'Start', gmm_init,'Options',options, 'Regularize', 1e-05)
</code></pre>
<p>However, if I want to create a contour-plot using matlab's ezcontour, the result is that a... | g68491 | [
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<p>So I've been encountering this weird issue with LiblineaR where I get different results from just running LiblineaR with cross set to the size of my dataset and actually looping through the dataset, choosing each entry for testing and training on the rest, even though it seems like these should be exactly the same. ... | g68492 | [
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<p>I would like to estimate a multi level model in Stata or R (using lmer) where the first level coefficients are the same for all observations, but the coefficients within observation are correlated. </p>
<p>An example would look something like this:</p>
<p>$$Y_i = \beta_1 x_{1i} + \beta_2 x_{2i} + \beta_3 x_{3i} + ... | g68493 | [
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<p>How do you estimate degrees of freedoms for derived measurements?</p>
<p>I want to assess the significance of the distance of an independent data point to a regression line. I can easily calculate the (vertical) distance between the data point and the regression line, and I get the uncertainty of the distance from ... | g68494 | [
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<p>Does anybody know if there're common known disadvantages of a negbin regression? In my opinion it seems to fit every problem pretty good (measured with the estimated dispersionparameter). So why not always use it?</p> | g68495 | [
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<p>I have a set of true positive (TP) values which are used to train a model. </p>
<p>I am using 5-fold cross validation to train my model (i.e. split my true positives into 5, use 4/5ths for training and 1/5th for testing)</p>
<p>I repeat this using different 1/5ths as the test set.
For each run, I have a large set ... | g68496 | [
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<p>We are looking at how a change in the environment (confinement level) alters which of two behaviors our model organism chooses. We perform several trials at each confinement level. Each of these trials elicits one of the two possible behaviors. From this we get a fraction of trials which exhibited each behavior unde... | g28537 | [
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<p>I have random variables $X_0,X_1,\dots,X_n$. $X_0$ has a normal distribution with mean $\mu>0$ and variance $1$. The $X_1,\dots,X_n$ rvs are normally distributed with mean $0$ and variance $1$. Everything is mutually independent.</p>
<p>Let $E$ denote the event that $X_0$ is the largest of these, i.e., $X_0 ... | g68497 | [
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<p>I am working on zero-inflated count data models using the <code>pscl</code> package. I am just wondering why there is no development of models for one-inflated count data models! Also why there is no development of bimodal, say zero-and-2-inflated, count data models! Once I generated one-inflated Poisson data and fo... | g68498 | [
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<p>I want to generate series of 0s and 1s that exhibit some clustering. By this I mean that 1s and 0s should occur together. So I envisage series of 0s and 1s that will exhibit similar clustering of these elements, and not just random series of 0s and 1s.</p>
<p>In essence, for a single time series, I would go about t... | g38489 | [
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<p>Can somebody explain me how to perform cross validation while training Support vector machine via some example?</p> | g68499 | [
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<p>I have been quite happily using mixed effects models for a while now with longitudinal data. I wish I could fit AR relationships in lmer (I think I'm right that I can't do this?) but I don't think it's desperately important so I don't worry too much.</p>
<p>I've just come across generalized estimating equations (GE... | g49609 | [
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<p>I have a dependent variable ($y$ axis in the pictured graph) trending over time ($x$ axis). I also have a categorical variable, which was constant until one point in time, then changed to another value, with which value it has remained constant since; that point in time is indicated in the picture by a break in the ... | g28544 | [
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<p>I have two (vehicle velocity) signals that should consist of similar "latent" drivers, but have different autocorrelation structures. The driver-signals are quite nasty statistically, so I'm not attempting to model them.</p>
<p>I can get quite nice results by prewhitening the signals using AR(1)-residuals, but thes... | g68500 | [
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<p>I am working on a problem where we elicit medical residents perceptions regarding the importance of specific core medical competencies (professionalism, collaboration, medical expertise, etc.) on a 5 point Likert scale. For example, "In your current residency role how important is professionalism in your day-to-day ... | g68501 | [
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<p>Hi I am trying to check the existence of change points in the mean and in the variance using R. My data is not normally distributed, so I want to use the cusum test. Also I want the significance level to be 0.05.</p>
<p>I am trying to use the package "changepoints", but for change points in the mean I couldn't find... | g37447 | [
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<p>After finishing a data collection season, there's a huge dataset containing n>>1 variables (columns) and a few different observations divided by group (rows; let's say cases and controls). The task is to find variables with "LARGE" differences between cases and controls, but before starting any test, there's a speci... | g68502 | [
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<p>I am using a scale which consists of discrete values: 0 (normal), 1 (mild), 2 (moderate), 3 (severe) and these values are for 4 components. I have measured 200 patients on this scale. Each patient has four discrete numbers. I am going to find the correlations between this scale and some continuous variables; these ... | g49806 | [
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<p>I have a set of numbers $S$, and for each $s_i\in S$, $0\lt s_i \lt 1$. I would like to transform them so that they sum up to $1$.</p>
<p>An obvious way to do it is to calculate $t_i=\frac{s_i}{\sum_i{s_i}}$, so that $\sum_i{t_i}=1$. I wonder if there is any other way to achieve the same effect, and what are the di... | g38501 | [
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<p>I am trying to do a very simple regression analysis using a truncated normal distribution with WinBUGS. </p>
<p>Let's suppose the following model $Y|\beta_0,\beta_1,\sigma \sim Normal(\beta_0+\beta_1X,\sigma)$ where $Y$ is the grade of 13 students (from 0 to 10) and $X$ is the gender of each student (1 for Males an... | g49848 | [
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<p>Suppose I have a sample with two covariates whose levels are associated with some response; e.g., the mean height of a plant at 6 months is modeled by two factors: cultivar of plant (say, $A$ versus $B$) and size of pot (e.g., "small" versus "large"). Furthermore, suppose that the truth is that cultivar $A$ in gen... | g68503 | [
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0.046244606375694275,
... |
<p>I'm working with land surface models. These models basically take a bunch of meteorological forcing data (downward radiation, wind, rain, humidity, etc), and run it through some biogeochemical/physical equations, and spit out a bunch of output data ($CO_2$ update/release, net radiation, evaporation, runoff, etc.). T... | g68504 | [
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<p>I have fitted my stress-strain data with $y=ax^3+bx^2+cx+d$ and also added tangent lines as shown in figure below. I am interested to see the deviation of the fit from the linearity. I am not aware of any theory that can be used to find the tangent point (the point of deviation of the fit from the linearity). Hence,... | g68505 | [
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<p>We are using Tingely et al's mediation R package for mediation analysis. Our study is a 2x2 design, say A (0 and 1) and B (0 and 1), with dichotomous mediator M and continuous dependent measure Y. Our model is
Y = a + b1* A + b2* B + b3* A*B + cX = u
where a, b's,and c are coefficient, u error term.</p>
<p>We found... | g68506 | [
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<p>I asked the same question on math.stackexchange and had some responses, but I would also like to hear some input specifically from statisticians and data analysts and I feel that you guys may have something to offer.</p>
<p>The question is about finding reasonable ways of dividing a prize among $n$ people in the fo... | g28553 | [
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<p>From my understanding for a random variable $X \sim Binom (n,p)$, $E(X)=n \times p$, correct?</p>
<p>I was looking at an example problem:</p>
<p>Every pair of the $n$ people is friends with probability $p$. What is $E(X)$? $X$= number of friendships.</p>
<p>$X\sim Binom (\binom{n}{2}, p)$ and $E(X)=\binom{n}{2}p$... | g68507 | [
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<p>I have a large data set containing children's scores on arithmetic tasks with a lot of missing values possibly due to the age of the children? My hypothesis is that the missingness is not completely at random but at random. I need to do a CFA and want to know whether I need to condition on age or not? I know SPSS 17... | g68508 | [
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<p>I'm analyzing pairwise correlations of time series between two different types of microarrays done for several samples as biological replicates. </p>
<p>So, I have M1 number of variables on type 1 array, M2 number of variable on type 2 array, N samples and T time points. For each sample, I calculate M1 x M2 correla... | g68509 | [
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<p>I have some Directed Acyclic Graph trees representing biological features.
In my database, I can retrieve all the links between every child and its ancestors: I have all the edges and the nodes.</p>
<p>Unfortunately, I have not only the direct links between every child and its parent, but I have also the indirect l... | g68510 | [
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<p>I would like to correctly specify that my data is temporally pseudo replicated in a mixed effects model in <code>R</code> using <code>lme()</code> of the <code>nlme</code> package. I have done this following the example in Crawley's <code>R</code> text book, but I need some confirmation that the fixed and random eff... | g28557 | [
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<p>In <a href="http://stats.stackexchange.com/questions/59815/how-find-a-distribution-for-a-set-of-data/59817#comment114660_59817">this comment</a>, Nick Cox wrote:</p>
<blockquote>
<p>Binning into classes is an ancient method. While histograms can be useful, modern statistical software makes it easy as well as advi... | g28558 | [
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<p>I am trying to understand (by reverse engineer) the method a program is using to calculate an average value over a population. The program displays a (very very large) image consisting of tiles. Each tile has some overlap with it's neighbors, expressed in pixels.</p>
<p>In total there are 8625 tiles, hence 8625 ove... | g68511 | [
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<p>I need a little help to move in the right direction. It's a long time since I studied any stats and the jargon seems to have changed.</p>
<p>Imagine that I have a set of car-related data such as</p>
<ul>
<li>Journey time from town A to town B</li>
<li>Distance from town A to town B</li>
<li>Engine size</li>
<li>D... | g28561 | [
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<p>I have six scatterplots (such as the one below) that show an insignificant interaction of the factor (X2) (e.g. gender, age, education etc.) with the predictor (X1) on Y. (X1 is significant.)</p>
<p><img src="http://i.stack.imgur.com/cq0GH.jpg" alt="enter image description here"></p>
<p>The simplest interpretation... | g38514 | [
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<p>How to add noise to an object, regardless of the amount of dimensions?</p>
<p>I would expect to try to use some sort of <code>apply</code> to add noise of the type:</p>
<p><code>runif(1, -0.00001, 0.0001)</code> for each cell.</p>
<p>What I tried before was to have a matrix of r * c, and then creating a matrix wi... | g68512 | [
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<p>I'm trying to test for the effect of soil moisture on transpiration rates. I have plot-level data for 18 plots in 6 different stands of trees (3 plots x 6 stands). I want to treat "stand" as a random effect. There are reasons (genetic similarities within a stand, differences in elevation, species composition, etc.)... | g68513 | [
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<p>I'm looking for research papers on estimating demographic information (age, wealth, location, gender etc.) out of internet activities (preferably social network activity or browser history). </p>
<p>Where would be a good place to look for?</p> | g20680 | [
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<pre><code>library(MASS)
bc <- boxcox(Volume ~ log(Height) + log(Girth), data = trees)
</code></pre>
<p>To find the $\lambda$ value with the highest log-likelihood, this command could be used:</p>
<pre><code>bc$x[which.max(bc$y)]
</code></pre>
<p>Is <code>x=log(Height)</code> in this example?</p> | g68514 | [
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<p>Here are my experimental factors: </p>
<ul>
<li>within-factor (two levels): time1, time2.</li>
<li>between factor (four levels): 4 groups.</li>
</ul>
<p>I want to test <em>specific post-hoc contrasts</em> comparing:</p>
<ol>
<li>group1: time1 vs. time2</li>
<li>group2: time1 vs. time2</li>
<li>group3: time1 vs. t... | g37861 | [
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<p>I am currently working on a project using a sales system and trying to come up with a way to use the current pipeline of potential sales to predict the amount of product that will be sold in the future. I’m looking for advice on how to approach this problem and hopefully some resources to teach me what approach to u... | g68515 | [
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<p>Suppose you have a discrete random variable, $Y$, with a large number (say, $300$) of discrete (which happen to be nominal) possible outcomes. The mass function, $p(y)=P(Y=y)$, is unknown but a sample is taken from $Y$ from 20 populations $i=1,2,...,20$. Let $Y_{ik}$ be the $k$'th sample from the $i$'th population a... | g299 | [
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<p>I am on a self-experiment quest to solve some health related problems I have, and I want to create a self-survey that I take every day. What's the best way to codify the survey so I can later analyze the data? I am not a statistics guru, as you can tell, so I'm probably asking a pretty basic question here. For th... | g28567 | [
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<p>I can't understand what is the difference between the algorithms EM (Expectation Maximization) and Gradient Ascent (or descent).</p>
<p>Is there any condition under which they are equivalent?</p>
<p>Thank you.</p> | g68516 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/45660/what-is-the-probability-of-tossing-k-heads-in-n-trials-of-a-fair-coin">What is the probability of tossing k heads in n trials of a fair coin?</a> </p>
</blockquote>
<p>What is the probability of toss... | g49389 | [
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<p>I am modelling data with a generalized mixed model with binomial error distribution and I am concerned about overdispersion. I know that dispersion parameter can be measured as deviance/df, but for mixed models (= with random effect), the number of degrees of freedom cannot be extracted (I am using the function lmer... | g68517 | [
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<p>The way I understand classifiers like kNN, ANN, SVM, Decision Trees... is that after being trained they will associate a new test object to one class out of a set of predefined classes. <br><br>My question is whether there are classifiers, or extensions to the once mentioned above where objects are not only classifi... | g68518 | [
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<p>I'm trying to figure out if there is a good model that can connect word counts to classifying whether or not a person might go to an event. Here's the description: I have users, and events. 100 features in events are word counts; I don't know what each word is, but I know that feature 1 is the most used word stem of... | g28568 | [
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0.0346568040549755... |
<h1>Background</h1>
<p>Background: in <a href="http://www.gwern.net/Conscientiousness%20and%20online%20education" rel="nofollow">an essay of mine</a>, I point out that if a selection process (like higher education) requires successful applicants to be above the mean on 2 different variables, there will necessarily be ... | g47714 | [
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0.003081281902268529,
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0.03697584196925163,
-0... |
<p>I am trying to solve this problem:
Assume that each child is male with probability $p$ independently of all other children.</p>
<p>We observed 19711 male births out of a total of 38562 births in American families with two children each.
Use the likelihood ratio test statistic to test the hypothesis $H_0: p=1/2$ aga... | g68519 | [
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... |
<p>I have a group of 6 animals.
I took the baseline reading (Time 0), put them under Treatment A, then take readings again at Times 2, 4, 6, and 12 hours.
I rest them for 2 weeks.
Then I took a baseline (time 0), put them under Treatment B, then take readings again at Times 2, 4, 6, 12 hours.
I believe this is a repea... | g68520 | [
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<p>I would like to develop a test to identify which variables in my data set have a variation higher than the "average variability".</p>
<p>I'm struggling with that since days, and I also tried in vain to look for help in other forums.</p>
<p>I have data from biological experiments, that look like this:</p>
<pre><co... | g28571 | [
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<p>Is there some theorem that allows us to work out:</p>
<p>$Cov\big( f(x+y), f(x)\big)$</p>
<p>We now the $Var\big(f(x)\big)$ and $Var\big(f(x+y)\big)$ and also the $Var(x)$, $Var(y)$ and the $Covar(x,y)$</p>
<p>Our specific case is the following:</p>
<p>What is the $Covar\big(\Phi(\beta_0+\beta_1),\Phi(\beta_0 )\... | g68521 | [
-0.035816509276628494,
0.02026689238846302,
-0.007153731305152178,
0.0006010354845784605,
0.0762418881058693,
-0.013023010455071926,
0.02000979706645012,
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-0.011275473050773144,
-0.04873141646385193,
0.06905204057693481,
-0.017111264169216156,
0... |
<p>I'm interested in the derivation of the Simpson diversity index. I found the normal interpretation of this index, but I'm not able to see what's the "mathematical background" of the formula. I read the original paper of Simpson, but I'm more interested in an easier explanation (my skills in probability theory are mo... | g28572 | [
0.020329216495156288,
0.046160660684108734,
-0.022510951384902,
-0.015709176659584045,
-0.03011900931596756,
0.02191949263215065,
0.09054604172706604,
0.00511901592835784,
0.025935200974345207,
0.03872489929199219,
-0.02322135493159294,
0.07043769955635071,
0.02267393469810486,
0.017304953... |
<p><img src="http://www.biomedcentral.com/content/figures/1471-2199-9-66-1-l.jpg" alt="a busy cat">
Dear community,</p>
<p>I used a figure obtained from internet to illustrate what I would like to solve. Imagine this exponential regression curve.
How can I get the exact point of the curve where it is maximum the chan... | g68522 | [
0.019618261605501175,
-0.03283253684639931,
-0.013356160372495651,
-0.03477327898144722,
0.07403258234262466,
-0.06003416329622269,
0.036383334547281265,
0.012436234392225742,
-0.067447729408741,
0.03319017216563225,
0.0018124659545719624,
0.06577476859092712,
0.0830715075135231,
-0.012503... |
<p>I have several data sets on wildlife disease incidence. One of the issues with my dependent variable is that it represents only current infection status, therefore 0 (no disease) can represent either an animal who has never had the disease or has had it and recovered (it is an acute viral infection). </p>
<p>There ... | g949 | [
0.02040705643594265,
-0.06275317072868347,
0.007084052078425884,
-0.03541439399123192,
0.006325168069452047,
0.0024308410938829184,
0.022898878902196884,
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0.004403113387525082,
0.027349330484867096,
0.018111703917384148,
-0.022052088752388954,
-0... |
<p>I am starting a new product. I need 100 clients to be viable, out of a market of 12000 target companies.</p>
<p>I'm doing direct marketing in 2 steps: Call / Emailing.</p>
<p>After 50 calls, I collected 30 emails.
Out of 30 emails, I got 37.5% opens, 13.6% clicks, and 0% new customers.</p>
<p>But where should I s... | g28574 | [
-0.024874011054635048,
0.005631572566926479,
-0.016337795183062553,
0.015715425834059715,
0.019750278443098068,
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0.021291103214025497,
-0.019978374242782593,
-0.0466691330075264,
-0.007671289145946503,
-0.003499518847092986,
-0.008463977836072445,
... |
<p>I am trying to understand where the p-value of a F-test comparing two variances comes from. More specifically, the p-value given by R's <code>var.test</code> function does not match p-value assigned to a F-test by the <code>pf</code> function with the same F value and degrees of freedom.</p>
<p>For example, p-value... | g28575 | [
0.0520857572555542,
-0.037556242197752,
-0.008289266377687454,
0.0031862540636211634,
0.040562599897384644,
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0.055821456015110016,
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-0.06469099223613739,
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0.020689591765403748,
0.029580453410744667,
-0.... |
<p><em>Somewhat related to <a href="http://stats.stackexchange.com/questions/7155/rigorous-definition-of-an-outlier">this</a> post.</em></p>
<p>However my question is a little specific. I have some data from gene expression quantification from single cells using RNA sequencing. I haven't had a look at it but I suspect... | g28576 | [
0.04149299114942551,
0.011235199868679047,
0.0027139338199049234,
-0.06244881451129913,
0.014351577498018742,
-0.06640850752592087,
0.030854862183332443,
0.047327637672424316,
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0.015439405106008053,
0.016780301928520203,
-0.000548789743334055,
0.01438524667173624,
0.0... |
<p>I need to make regression on big amount of data, each row have around 1000 features.
Did will outcome will be same or better when i make 4 separate regressions of 250 features and after that i will make one regression that will have 4 features equal to underlying regression outputs?</p>
<p>I can't make one regressi... | g68523 | [
0.0035557483788579702,
-0.006564159411936998,
0.009637504816055298,
-0.026723314076662064,
0.0019119890639558434,
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0.09207295626401901,
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0.04399259015917778,
0.010524672456085682,
0.... |
<p>Does the importance of the normality assumption in MANOVA decrease as group sample size increases?</p> | g68524 | [
-0.04383721575140953,
0.04120125249028206,
0.010236936621367931,
0.01479159016162157,
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0.0104701928794384,
-0.014868734404444695,
-0.04168416187167168,
0.0709... |
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