question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I'm a SQL/C++ developer who recently has been asked to generate a report from our database to predict some future performance based on historical data; the problem is that I don't have much experience of this sort of data modelling.</p>
<p>I initially thought I could take an average of each month's results and use ... | g24373 | [
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<p>It is <a href="http://stats.stackexchange.com/questions/17320/mixing-and-dividing-point-processes/17346#17346">well known</a> that the superposition of $N$ Poisson processes is itself a Poisson process with an intensity given by
$\sum_{n=1}^{N} \lambda _{n}$.</p>
<p>Conversely a superposition including any non-Poi... | g65680 | [
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<p>From this link <a href="http://www.inf.ed.ac.uk/teaching/courses/inf2b/learnnotes/inf2b-learn-note07-2up.pdf" rel="nofollow">Text Classification using Naive Bayes</a>, there are two models described for classification, Naive and Bernoulli. My question is if i want to make this classifiers for multiclass (multivariate... | g24376 | [
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<p>As the issue of p value is still inconclusive and many papers point out that the confidence intervals are more informative in selecting factors in fixed effects, I would like to ask about interpretation of linear mixed model in R. Is it possible to select the important factors from the t value comparing to the range... | g65681 | [
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<p>I'm working on project in Matlab which aim is to demonstrate how Luby Transform codes work. I need to generate generation matrix and I need to get some values from Robust Soliton Distribution, can someone explain me how to generate numbers according to this distribution, I need to generate one value for each column ... | g65682 | [
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<p>I have a two-mode network which looks into relationship between forum threads. Two forum threads are connected if the same user has replied to both. The nodes are sized based on number of people who have only replied to the given forum thread, and no other ones (it would be the users who are unique to the given thre... | g65683 | [
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<p>This is a homework question where I have not been able to reach any conclusion . I have an exam tomorrow . Please help me out .</p>
<blockquote>
<p>We have a set of data from patients who have visited a hospital . A set of features ( eg temperature , height ) have been also extracted for each patient . Our goal i... | g65684 | [
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<p>I am trying to comprehend the proof of the Least Angle Regression algorithm and I am stuck at certain points. I would appreciate any help that I can get. </p>
<p>Let me set the stage:
I am following the paper in the following <a href="http://www.stanford.edu/~hastie/Papers/LARS/LeastAngle_2002.pdf" rel="nofollow">l... | g65685 | [
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<p>Let us have $N$ random variables generated by uniform distribution. That is, $$u_i \sim \mathcal{U}(0,1),\quad i=1,\ldots,N$$.</p>
<p>What is the probability of $u_N$ being the largest? I.e., how can I compute $$p\Big(u_N\geq \max(u_1,u_2,\ldots,u_{N-1})\Big)$$</p> | g24380 | [
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<p>Can you please check my work in the problem below?</p>
<hr>
<p>Consider a location model:</p>
<p>$$X_i =\theta +e_i, \quad i=1,\ldots,n $$</p>
<p>where $e_1, e_2, \ldots e_n $ are iid with pdf $f(z)$. Define $\mathbf{\mu}=\theta \mathbf{1}$ where $\mathbf{1}$ is a vector with all its components equal to $1$. Let... | g65686 | [
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<p>I'm working on practice exercises with R. From the data, I now have to determine the difference in predicted male compared to female spending while keeping all other predictors constant.</p>
<p>I replaced the sex <code>0,1</code> with <code>male, female</code>:</p>
<pre><code>> spending$sex=factor(spending$sex)... | g65687 | [
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<p>I have data that is of the form $y = \frac{\beta_1}{1 + \exp(\beta_2 + \beta_3 * x)}$. For the estimation of $\beta_1$ to $\beta_3$ I use the formulas of this paper: <a href="http://www.google.at/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CB8QFjAA&url=http://cran.r-project.... | g65688 | [
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<p>I have a question on a survey that asks students how useful a feature of the software was that they used for learning. I then have three questions that assess in what way the feature was useful. The measures use a 7-point Likert scale from Very Strongly Disagree to Very Strongly Agree:</p>
<pre><code>The [[feature]... | g65689 | [
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<p>My question is how to make an interaction effect become significant in two-way ANOVA.</p>
<p>If my main effect A has an F value of F(1,80)=25.5 for example, and my main effect B has an F value of F(3,80)=15, but my interaction effect has a value of F(3,80)= 2.06 which is not significant, how do I change the score i... | g65690 | [
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<p>18 boys and 2 girls are made to stand in a line in a random order.Let $X$ be the number of boys standing in between the girls .Find $P[X=5]$ and $E[X]$. I proceed in this way:
Note that $$P[X=0]=\frac{19.18!.2!}{20!}=\frac{19-0}{20\choose2}$$
$$P[X=1]=\frac{18.18!.2!}{20!}=\frac{19-1}{20\choose2}$$$$P[X=2]=\frac{17.... | g24383 | [
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<p>I am analyzing some data and want to look at one particular point and see how "extreme" it is.</p>
<p>Do I exclude this outlier from the data, calculate the dataset's standard deviation and average, then compare my outlier to THAT, or do I calculate the standard deviation and average WITH the outlier included and T... | g65691 | [
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<p>I have written some code which uses AdaBoost to generate a set of weak classifiers. I'm finding, however, that when I use the resulting strong classifier to classify examples, it seems that almost every weak classifier classifies an example the same way. Either they all think it's negative, or they all think it's po... | g65692 | [
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<p>I have a relatively complicated model-fitting procedure, the output of which is a set of coefficients $\beta$ (one for each feature in the training set) and a set of hyperparameters $\lambda$ (which control the amount of regularization).</p>
<p>I would like to compute p-values for each feature. At the moment, my pr... | g65693 | [
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<p>Eg. such as those on this page <a href="http://store.steampowered.com/hwsurvey" rel="nofollow">http://store.steampowered.com/hwsurvey</a></p>
<p>Is there any ready-made software that can do this? Alternatively, any recommendations for other software that does something similar? I know this is not really a statistic... | g65694 | [
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<p>Most of my reference on matching has been Rosenbaum's book "Observational Studies". From what I understand, the usual process of matching involves administering a treatment that is represented by a binary value of either 0 or 1, depending on whether the patient got the treatment or not. In the case that I am looking... | g24386 | [
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<p>I am analyzing growth over time for 5 different cultivated forms (cultivars) of maize. Graphing the data reveals a clear linear pattern for all the cultivars in the time interval I am interested in. Multiple linear regression with categorical (5 cultivars) and continuous (7 time points) explanatory variables appears... | g65695 | [
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<p>Imagine we regress <code>y</code> on <code>x1</code>...<code>x4</code>. Now, we want to find out if <code>x5</code> is a stronger predictor than <code>x6</code> (given the other variables). Note that all variables are scaled.</p>
<p>Would it be okay to use the residuals to see which one would be a stronger predicto... | g65696 | [
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<p>I would like to produce a regression analysis model. I have ordinal categorical data. I can use SPSS. I do not know what analysis to perform or what assumptions to check. </p>
<p>What are the statistical tests that can be performed? How can I test the accuracy of the model? </p> | g65697 | [
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<p>In a famous plot, Charles Minard visualised the losses of the French Army in the Russian campaign of Napoleon:</p>
<p><img src="http://i.stack.imgur.com/A7z2Q.png" alt="enter image description here"></p>
<p>(another nice example is <a href="http://synapticnulship.com/blog/wp-content/uploads/2010/09/movie_narrative... | g24387 | [
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<p>I am interested in examining the association between cardiorespiratory fitness and PCA derived dietary pattern scores in 264 adolescents. My cardiorespiratory fitness predictor is vo2max, and my outcomes are a "Treat Foods" pattern and a "Fruit and Vegetable" pattern. Both vo2max and my pattern scores are continuous... | g24389 | [
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<p>Initially, I had only heard of MLE and use it for almost everything, e.g. point estimate and model selection (with some penalty).</p>
<p>Then, MSE appeared, which seems to play the same role as MLE does. I learned that both MSE and MLE are results from loss functions (entropy vs quadratic). Choose which one to use ... | g24390 | [
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<p>If X is taken from a uniform discrete distribution, how can I find the MSE of the MLE of N? (I got disturbing and contradictory answers).</p>
<p>I am having some trouble with calculating the mean squared error of the MLE and it seems that I am getting two answers depending on which definition I am using. </p>
<p>I... | g65698 | [
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<p>Well, I have these values: $\mathrm{Mean}=5.77$; $95\%\mathrm{CL}=5.30-6.11$</p>
<p>How can I simulate a normal distribution using these parameters? I do not have standard deviations.</p>
<p>How can I obtain random values (for example, 1000 of them) that fit to these parameters? (like using the <code>rnorm</code> ... | g49731 | [
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<p>Given a sample of n units out of a population of N, population median can be estimated by the sample median.</p>
<p>How can we get the variance of this estimator?</p> | g24391 | [
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<blockquote>
<p>A single observation of a random variable having a geometric distribution is used to test the null hypothesis $\theta=\theta_0$ against the alternative hypothesis $\theta=\theta_1 > \theta_0$.</p>
<p>If the null hypothesis is rejected if and only if the observed value of the random variable is... | g65699 | [
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<p>After making some variable transformations, I chose this model because I works well with the assumptions and gives the largest R-Squared and the smallest Overall MS in cross-validation between a set of linear models.</p>
<pre><code>> gn<- lm(NA.~ I(PC^0.25) + I(((PI)^2)),data=DSET)
> summary(gn)
Call:
lm(... | g24393 | [
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<p>I'm trying to calculate the optimal portfolio regarding Foster-Hart riskiness measure satisfying following equation:</p>
<p>1) E(log10(1+v/R))=0</p>
<p>where:
R is the value of riskiness
v is the vector of daily returns of the portfolio.</p>
<p>v is composed as a sum of products of individual investment return... | g65700 | [
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... |
<p>As for the title, the idea is to use mutual information, here and after MI, to estimate "correlation" (defined as "how much I know about A when I know B") between a continuous variable and a categorical variable. I will tell you my thoughts on the matter in a moment, but before I advice you to read <a href="http://s... | g65701 | [
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<p>I have 5 variables for each countries of the world and I need to analyze their effect and interactions on an independent variable.
Random Forest would be adequate for my scope as it deals with non-linear relationships and predicts variables importance. However, I'm wondering if spatial dependence may be an issue. I'... | g65702 | [
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<p>When I run a standard Difference in differences specification with a log-transformed dependent variable, like:</p>
<p>$log(Outcome_{it}) = \beta_1 + \beta_2*Treat_i +\beta_3*Post_t +\beta_4(Treat*Post)_{it} +\epsilon_{it}$</p>
<p>How do I interpret the coefficient $\beta4$ ?</p>
<p>Normally in log-level models I ... | g65703 | [
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<p>I am a fresh graduate student. I want to do research in machine learning and data mining. There is no professor in our department doing this! </p>
<p>I want to try to do this by myself, at least for a while. But I don't where should I start. What books or review papers should I read at the beginning? </p> | g4843 | [
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<p>Say we're working on a random effects model of some count data over time, and we want to control for some trends. Normally, you'd do something like:</p>
<p><code>lmer(counts ~ dependent_variable + (1+t+I(t^2)|ID), family="poisson")</code> to include a quadratic shape for t. Is it possible to use some more sophistic... | g65704 | [
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<p>I have a question regarding the statistical method necessary to determine a correlation between a set of individual correlations. Below is an example of a situational question I currently face.</p>
<p>To clarify as requested. I have gathered data on over 400 hotel properties. I then determined if there is a correla... | g17006 | [
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<p>I am looking into continuous time markov chains which I think are capable of answering questions like "what is the probability that after time $t$ (where $t$ is in discrete time steps in this case) a transition from current state $i$ will occur", or more precisely "what is the probability that a transition from curr... | g65705 | [
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<p>I estimated the so called translog production function:</p>
<p>$$
y_{it} = \beta_0 + \beta_1 k_{it} + \beta_2 l_{it} + \beta_3 k_{it}^2 + \beta_4 l_{it} \times k_{it} + \beta_5 l_{it}^2 + \epsilon_{it},
$$
where $y$ is the natural logarithm of gross output; $l$ is the log of labour; and $k$ is the log of capital. ... | g32026 | [
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<p>I am having trouble to understand the min {X,Y} where X and Y are independent random variables.</p>
<p>From the online source, it says that min{X,Y} < x if and only if X>x, Y>y.</p>
<p>First of all, what exactly do you mean by the term "minimum " of the two random variables? Does it refer to the domains that ... | g65706 | [
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<p>I have series with 62 observations. How do I create a series with just the first 26 observations so that I can run an estimation on it?</p>
<p>Sorry, really really beginner with gretl. I tried the square bracket but it just gives a single element. (I know general purpose programming languages very well.)</p> | g347 | [
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<p>Can someone please explain the difference behind <strong>WHY</strong> the cross correlation function <code>ccf()</code> chooses to keep the same denominator for all lags and chooses to ignore the reduction in observations? Here's an example of the two methods not matching:</p>
<pre><code>x = c(1,2,3,4,5,6,7,8,9,10... | g65707 | [
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<p>I am not well versed in statistics. I wanted to know why we use the determinant of the covariance matrix instead of having the covariance matrix itself when writing down the multivariate normal distribution. Why do we do this and what is the intuition behind it?</p>
<p>I have noticed that for a basic Maximum Lkikel... | g65708 | [
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<p>I have a question about terminology.</p>
<p>Suppose I have data categorized by three factors A, B, and C, with cell means $\bar{y}_{ijk}$ and cell frequencies $n_{ijk}$, where $i$, $j$, and $k$ index A, B, and C respectively. And suppose I want to summarize the results for factor A by computing some sort of weight... | g65709 | [
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... |
<p>This is not really a coding question but more of a statistical question.</p>
<p>I'm doing a proportions test on multiple proportions for many subjects.</p>
<p>For example, subject 1 will have multiple proportions (multiple "successes per total trials"), and subject 2 will have multiple proportions. And for each su... | g32035 | [
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<p>After training a support using the e1071 package of R, how can I calculate an information criterion such as AIC or BIC?</p> | g65710 | [
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<p>I am not a statistics expert so please bear with me. It is about making predictions about how long something should take based on measurements of how long things took in the past. (Things like fixing software bugs)</p>
<p>Up until now I have been using a normal standard deviation to be able to state things like "th... | g24404 | [
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<p>I have a bunch of experiments in which I am calculating precision and recall. I want to present a mean precision and recall for these experiments. Should these values be weighted by anything?</p> | g24405 | [
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<p>This question is in some way similar to <a href="http://stats.stackexchange.com/questions/3589/correlation-between-two-variables-of-unequal-size">this one</a>, but about another nuance.
I have two time series (update: stationary - with both mean and variance equal over time) with missing values in one of them, such ... | g65711 | [
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0... |
<p>I would like to do something in R that SAS can do using SAS's proc mixed (there is some way to do in STATA es well), namely fitting the so called Bivariate model from Reitsma et al (2005). This model is a special mixed model where the variance depends on the study (see below). Googling and talking to some people fam... | g24408 | [
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0.... |
<p>If i have the relative proportion for two sample.
For example : </p>
<p>group 1:</p>
<ul>
<li>Male: 50%</li>
<li>Female: 25% </li>
<li>children: 25% </li>
</ul>
<p>group 2:</p>
<ul>
<li>Male: 50%</li>
<li>Female: 20% </li>
<li>children: 30% </li>
</ul>
<p>How can I measure the % of similarity between the tw... | g65712 | [
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<p>If I have data on a time series with the following structure</p>
<pre><code> Day Value, p
1 1.2
2 2.1
3 4.0
4 3.2
</code></pre>
<p>How do I calculate the first order serial covariance of the value $p$ on day $t$ with the value from the previous day, i.e. $\text{Cov}(p_t,p_{t-1})$? (I am... | g65713 | [
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<p>I have a population of say 100,000 records that can be either Positive or Negative (true probability of Positive is very small, but unknown - may even be zero). </p>
<p>I want to take a sample and estimate how many Positive cases are in the population, to be able to say something along the lines of "I'm 95% confide... | g24412 | [
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<p>I would like to re-implement (or even better find an analogue in GNU GSL which I can easily use) R's "pt" function, since it's not native to my application's language.</p>
<p>My use case is to convert a t value, to a p value, along the lines of:</p>
<pre><code>if ( t >= 0 ) {
2 * pt(t, df, lower, tail=FALSE)
... | g65714 | [
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0.0... |
<p>What are some applications of Chinese restaurant processes?</p>
<p>I'm trying to learn a bit about non-parametric Bayesian methods, starting with Dirichlet processes and CRPs, but all the tutorials I've found are about theory, without describing any applications in depth.</p>
<p>Names of papers would be great. I'm... | g628 | [
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<p>I have been implementing some classification algorithms (Naive Bayes, SVM etc) recently on the iris data sets to get head start into the data science field. I enjoy working on machine learning problems and exploring more. </p>
<p>I am currently stuck with this problem of predicting variables based on just the time ... | g65715 | [
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<p>I have 20 subjects split between two conditions.
Each participant rated two items in terms of two attributes, A and B. </p>
<p>How do I calculate the correlation between A and B. How do I calculate the correlation (I'm performing analysis in R) between A and B given that there are two ratings per subject?</p>
<p>I... | g65716 | [
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<p>I'm not a huge stats buff and am wondering what the best approach to my problem is. </p>
<p>Say I have a list of PPC<sup>*</sup> keywords and if a desired action was taken. Let's say I put this data into two word count list: keywords with purchase and all keywords.</p>
<p>For example: </p>
<p>Keywords with purch... | g65717 | [
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<p>Consider a variable $Y$ (e.g., temperature). Suppose that we were able to estimate this variable each year for the past $N$ years using some type of model. This means we have access to annual estimated values for Y (denoted as $Y_1, \ldots, Y_N$) and associated standard errors $S_1,\ldots,S_N$. The goal is to pro... | g24417 | [
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... |
<p>As motivated by the recent change of the default model selection statistic in
the R's forecast package from AIC to AICc, I am curious whether the latter is
indeed applicable wherever the former is. I have a series of questions with this
respect and here is the first one. </p>
<p>I know that to replace AIC with A... | g65718 | [
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0.02069472149014473,
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0.0997004359960556,
0.006692... |
<p>I'm classifying text using the one-vs-all approach. There are three classes. I've trained 3 different binary SVM classifiers using 10-fold cross-validation. The accuracy of the binary classifiers is fairly high (above 0.8 for all three classes). Where I'm stuck is utilizing the result of the 3 classifiers to out... | g42813 | [
0.02159043215215206,
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0.011138253845274448,
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0.04543811082839966,
0.051142312586307526,
0.02101157046854496,
0.005474496632814407,
0.0314... |
<p>I'm trying to find bursty(trending) terms in a text stream. There are two frame in a stream; expected frame and observed frame. </p>
<p>For each frame, I tokenize documents(tweets/blog posts etc.) up into terms(words), so I have two term-frequency lists:</p>
<p>For Expected Frame:</p>
<ul>
<li>term a, 2500</li>
<... | g42814 | [
0.03587169572710991,
0.027928348630666733,
0.0028036825824528933,
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0.028218045830726624,
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0.04054362326860428,
0.03780080005526543,
0.0472055... |
<p>I understand how generative model of topic modeling works; for each topic there is a distribution of words, and for each document there is a distribution of topics. </p>
<p>Question is how words are determined for each individual topic ? Does this change algorithm to algorithm ?</p>
<p><strong>Edit:</strong></p>
... | g24418 | [
0.02061198465526104,
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<p>My company has a software system, which, amongst other things runs payroll for its client companies. In the near future, the number of companies running payroll will jump from 100 to 3000. I'm trying to investigate whether the system will be able to cope with the new load.</p>
<p>I can do a bit of basic analysis on... | g65719 | [
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0.0... |
<p>Please help.</p>
<p>I have 3 IVS and 1 DV in my model. The 3 IVs are rated by 150 Middle Managers while 50 Directors rate the DV. I need to conduct multiple regression. However for cases (rows in SPSS), where Middle Managers rate the 3 IVs, I have missing values for Directors' rating of the DV. How should I conduct... | g65720 | [
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... |
<p>I am trying to estimate a mean of a population in a sample = ${\{x_1,..,x_n\}}$. I currently use 2 estimators: </p>
<ol>
<li><p>Sample mean = $\frac{\sum {x_i}}{n} $</p></li>
<li><p>Horvitz–Thompson estimator (HT) = $\frac{\sum {p_i*x_i}}{\sum {p_i}} $</p></li>
</ol>
<p>Where
$p_i$ is the probability that the ... | g65721 | [
0.015306982211768627,
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0.004713576287031174,
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-0.0015034718671813607,
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-0.029730238020420074,
0.03827685117721557... |
<p>I am trying to plot a two-component mixture distribution $F_X(x):.7N(0,1)+.3N(3,1)$ with density</p>
<p>$$f_X(x) = {0.7 \over {\sqrt{2\pi}}} e^{−x^2/2} + {0.3 \over {\sqrt{2\pi}}}e^{−(x−3)^2/2} $$.</p>
<p>I have done the histogram for it but having trouble with plotting the true density,so far this is my code</p>
... | g65722 | [
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0.010565800592303276,
0.04762868583202362,
... |
<p>I read in Wilcox, 2003 p. 247 that the standard error of the difference between two sample means is (assuming the normality and homoskedasticity assumptions):</p>
<p>$\sqrt{\frac{\sigma_1^2}{n_1} + \frac{\sigma_2^2}{n_2}}$</p>
<p>Rather than simply adding the two sample standard errors as in:</p>
<p>$\frac{\sigma... | g4850 | [
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0.02546236477792263,... |
<p>I am using Python's scikit-learn to train and test a logistic regression.</p>
<p>scikit-learn returns the regression's coefficients of the independent variables, but it does not provide the coefficients' standard errors. I need these standard errors to compute a Wald statistic for each coefficient and, in turn, com... | g24421 | [
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<p>I have found one breakpoint in my linear regression but the slope of two lines have the same decreasing slope, I was wondering if the change of the slope is necessary in recognition of breakpoints.</p> | g24424 | [
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<p>Which is more important when selecting a model? The R2 or the accuracy of the model?
Here are 2 different models using the same data with different transformations for the Xs, the Ys are a percentage and the same in both. </p>
<p>This is a classification problem in which correct classification has a higher growth ... | g65723 | [
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-0.01... |
<p>I'm reading some economics papers about the relationship between inequality and growth and some of them have sentences like these:</p>
<blockquote>
<p>an <em>increase of 0.07 (one standard deviation</em> in the sample) in the income share of the top 20 percent lowers the average annual growth rate just below half... | g65724 | [
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0.02630751... |
<p>I need to test how responsive are firms' investment to the level of the country's GDP. I have 90 firms, all in the same country; 10 annual observations for the GDP; and 10 annual observations for each firm's investment level. Do I have to test the relation for each firm separately; if yes is it possible to run a ... | g65725 | [
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<p>I am trying to do a multinomial logistic regression on some data that I generated. I am using R and the package mlogit. My data looks like the following:</p>
<pre><code>Class X1 X2 X3
V +0.0655197 +0.6418541 +1.8110291
V-0.6713268 -0.0262458 -0.3602958
V +0.2357610 -0.3602958 -0.6943458
M +0.3900129 +0.5583416 -1.... | g65726 | [
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0.006059509236365557,
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0.041766196489334106,
0.10887621343135834,
0.000... |
<p>I was going through some lectures related to MCMC. However, I don't find a good example of how it is used. Can anyone give me a concrete example. All I can see that is they run a Markov chain and say that its stationary distribution is the desired distribution.</p>
<p>I want a good example where the desired distrib... | g65727 | [
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0... |
<p>I am working on a monthly river flow time series and somebody has asked me to check my model by simulating innovations (or something like that). Can somebody help me about how can we simulate and how can check my model with that? I appreciate if you suggest a article or document in this regard.</p>
<p>Also, if my q... | g65728 | [
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0.... |
<p>I would like to fit multiple distributions that share one of their parameters. As a simple example, let's say I have two different datasets which I know follow a Gaussian distribution. let's say I know $\mu_1$ and $\mu_2$, and now I want to estimate $\sigma_1$ and $\sigma_2$. However, I know that $\sigma_1=\sigma_2$... | g65729 | [
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0.012187715619802475,
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0.0... |
<blockquote>
<p>$\textbf{Background:}$ When $\mathbb EX$ is hard to calculate, it is a common trick to use the following formula: $$\mathbb EX=\mathbb E[\mathbb E(X|Y)].$$ And similarly, $\mathbb VX$ can be calculated using the following formula: $$\mathbb VX=\mathbb E[\mathbb V(X|Y)]+\mathbb V[\mathbb E(X|Y)].$$ </p... | g65730 | [
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0.07566779106855392,
0.0003471336967777461,
... |
<p>Given a covariance matrix, it's simple to draw a venn diagram representing the independent and shared variance of two variables. How might one go about the same (at least, computing all pertinent areas; actual visualization not necessary) for the 3-variable case? Is this even possible?</p> | g65731 | [
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0.... |
<p>I want to do a logistic regression in SPSS. However, since I analyse unemployment spells the subjects are sometimes repeated (violating the independence assumption of the regression). One way of removing the within subject variation is by applying a Genlin model with the repeated subject subcommand (in essence a GEE... | g4857 | [
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<p>I'm a biology PhD student dealing with ordinal data (scoring of a medical effect: 0–3 points) for the first time and I'm looking for information regarding differences in treating ordinal numbers in</p>
<ul>
<li>calculating Mean, Median, SD, SEM etc.</li>
<li>performing significance tests between two ordinal dataset... | g24432 | [
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<p>General theories would be great. My specific problem is I'm trying to find a specific portfolio of all the stocks in the market. The possibilities are huge because I need the stock combination(itself massive) and weights for each stock(even larger than the quadrillion combination). To make matters more complicated,... | g24433 | [
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0.007657479960471392,
0.039102401584386826,
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0.06339672207832336,
0.0262... |
<p>Consider approximating the following integral:
$$
\mathcal{Z} = \int h(x) \pi(x) dx
$$
Where $\pi$ is known only up to a normalizing constant, that is, $\pi(x) = \hat{\pi}(x)/\mathcal{Z}_\pi$. We can simulate $\{x^{(i)}\}_{i=1}^m$ from an appropriate proposal distribution $q$ and use the ratio importance sampling e... | g24435 | [
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0.058147866278886795,
0.05695730075240135,
0.010105637833476067,
-0.017886437475681305,... |
<p>Is there any function for $M$-estimation in multivariate linear regression model in <code>R</code>. I can estimate the $\beta$'s in my model by using the <code>rlm()</code> by rewriting the $y$-variables into one column but, I would like to use one function to get the $\beta$'s. </p> | g24436 | [
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0.011608911678195,
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0.054226577281951904,
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0.0599... |
<p>I have a sample of 100 items, each associated to a random variable for which I can compute expected value and variance: $X_1, X_2, ..., X_{100}$. From these, we can define the mean $\overline{X}=\frac{1}{100}\sum{X_i}$. I'd like to test the hypothesis $H_0:\mu=0$, (where $\mu$ is the true population mean from which ... | g65732 | [
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0.03668922930955887,
0.02642367035150528,
-0.0... |
<p>In OLS, the conditional mean $E(Y \mid X)$ is modeled as a function of some regressors $X$, i.e.
$$
E(Y \mid X) = X \beta.
$$</p>
<p>Is there a regression technique that allows to model the conditional trimmed mean of $Y$? </p>
<p>(Least absolute deviations will lead to the extreme case of maximal trimming.)</p>... | g4859 | [
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0.00... |
<p>If $a\times b\times c=t$ and I change $a$, $b$, and $c$, how do I calculate the effect of each change.</p>
<p>I believe the equation is: $(a+\Delta a)(b+\Delta b)(c+\Delta c)=(t+\Delta t)$, and then I solve for $\Delta a$, $\Delta b$, and $\Delta c$.</p>
<p>Is this correct? And how do I describe what I'm solving f... | g65733 | [
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0.04424... |
<p>For normal-distributed interval/ratio data, we can apply linear mixed effect model for analysing longitudinal data, where each subject is measured multiple times. How about dichotomy (binomial) data?</p>
<p>My experiment is as follows:</p>
<p>There are two conditions A and B, and M is an interaction technique that... | g24440 | [
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0... |
<p>I'm struggling to grasp the concept of bias in the context of linear regression analysis. </p>
<ul>
<li><p>What is the mathematical definition of bias?</p></li>
<li><p>What exactly is biased and why/how?</p></li>
<li><p>Illustrative example?</p></li>
</ul> | g44554 | [
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<p>I want to create an RF model, with about 100 weak variables and one very strong variable.</p>
<p>The strong variable is a probability score, I do not have visibility on how it was derived. It may be using many of the variables I already have, and also some I do not have.</p>
<p>If I create Random Forest, wouldn't ... | g65734 | [
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0.04483595862984657,
... |
<p>I apologize if this is too basic or whatnot, if it is just flag the question away.</p>
<p>I have the following computer code situation:</p>
<p>We need to insert 1000 <em>new</em> random numbers into a set. The set won't tolerate collisions, and each time we execute this job we need to add exactly 1000 random numbe... | g65735 | [
-0.02349204383790493,
0.046400461345911026,
-0.00899083074182272,
-0.05842292308807373,
-0.00514875166118145,
0.01125506404787302,
0.03790856525301933,
-0.0014626790070906281,
-0.0966402068734169,
-0.03423776105046272,
-0.009053296409547329,
0.039655573666095734,
-0.020892519503831863,
0.0... |
<p>I've searched a good bunch of literature but have failed to find an exact distinction between the two. My impression is that in the Machine Learning literature you'll find allusions to hierarchical Bayesian modeling, but in the Statistics literature you'll seldom find allusions to PGMs. Hopefully you guys will be ab... | g65736 | [
0.0579378567636013,
0.03285464644432068,
0.00850868783891201,
-0.009084338322281837,
-0.009675825946033001,
-0.017915181815624237,
0.020761463791131973,
0.044827256351709366,
-0.049407269805669785,
-0.07143201678991318,
-0.008324808441102505,
-0.00283672078512609,
0.04813678190112114,
0.02... |
<p>This might be a basic question, but I have no clue what this descriptive method could be named. Simplified, I have a cross-table with Occupations (e.g., doctor, lawyer, engineer) as rows, and Hobbies (e.g., sports, reading, gardening) as columns. Cell values are integer occurrences of the corresponding OH combinatio... | g24445 | [
0.04100688919425011,
0.03657156229019165,
-0.013164925388991833,
-0.0045302631333470345,
-0.016656585037708282,
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0.037664350122213364,
-0.03279760852456093,
0.001024178578518331,
0.008610351011157036,
-0.0010392223484814167,
0.009667870588600636,
0.12551937997341156,
-... |
<p>can I do my statistics work based on the central limit theorem? I need to perform a t-test, ANOVA and multiple regression. my outcome variable is highly not normally distributed (Highly positively skewed) and my sample size N=115. I'd like to keep the non-parametric tests as a last option for me.</p> | g65737 | [
-0.02573646418750286,
0.01294724177569151,
-0.005523887928575277,
0.03314455971121788,
-0.0211836826056242,
0.008067856542766094,
-0.007064673118293285,
0.04132858291268349,
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-0.0026363995857536793,
-0.012276103720068932,
-0.043488871306180954,
-0.028204331174492836,
-... |
<p>wage=b0+b1exper+b2exper^2+other variables </p>
<p>How can I find the marginal effect of experience on wage? I thought it was just the derivative: b1+2b2, but, for example, if I try plugging in numbers that are different by one year (experience 10 years => experience 11 years), that doesn't seem to be right:</p>
<... | g24446 | [
-0.009946292266249657,
0.019135605543851852,
-0.0037565475795418024,
-0.02471756376326084,
0.03000926598906517,
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0.061943624168634415,
0.03049582988023758,
-0.06140729784965515,
-0.013890780508518219,
-0.011649766936898232,
0.04793782904744148,
-0.007744669448584318,
... |
<p>If you take a random and uniformly continuous number that is generated by the sum of $x1+x2$ (so $y=x1+x2$), the probability $P(0.9<y<=1.8)$ the calculated results are:</p>
<p>$y$~$u(0,1)
= 0.575$</p>
<p>$y$~$exp(2)
= 0.3371$</p>
<p>$x1~u(0,1)$
$x2~u(0,2)$</p>
<p>$P(y=0.25)=0.8$
$P(y=1.5)=0.2
= 0.2$</p>
... | g24447 | [
0.008051577024161816,
-0.0007987776771187782,
-0.00027075165417045355,
-0.04344397410750389,
0.009995833970606327,
0.03164288029074669,
0.00437275180593133,
-0.025493532419204712,
-0.03803642839193344,
0.0037912260740995407,
-0.012614229694008827,
0.02993430383503437,
-0.0018034531967714429,... |
<p>A linear model has t-distributed noise
$$
Y= bX + \epsilon
$$
where $\epsilon \sim t(0, \sigma^2, df)$, with mean 0, variance $\sigma^2$ and dof $df$.</p>
<p>Given an independent sample $(x_i, y_i), i=1, \dots, n$, suppose we already have estimates of $b, \sigma^2, df$.
How would you estimate a $1-\alpha$ predictio... | g741 | [
-0.006381366401910782,
-0.034072473645210266,
-0.036396753042936325,
0.008188730105757713,
0.019054146483540535,
-0.028235310688614845,
0.004146979656070471,
0.016298385336995125,
-0.023532135412096977,
-0.004321381915360689,
-0.03177383169531822,
0.053985096514225006,
0.01074755284935236,
... |
<p>Dear CrossValidated community,</p>
<p>Can anyone help me to prove the bias in a given parameter of a regression when there is omitted variable?</p>
<p>I know to do it using matrices and matrix algebra. For instance, consider the true equation:</p>
<pre><code>Y = BX + dZ + e
</code></pre>
<p>Where X is the matrix... | g24448 | [
0.0548645444214344,
-0.03354724124073982,
-0.019345898181200027,
-0.007965079508721828,
0.047007642686367035,
-0.02678059972822666,
0.08556865900754929,
0.031220046803355217,
-0.007407124619930983,
0.0889379233121872,
-0.007444340735673904,
0.10641665011644363,
-0.02009875699877739,
0.0253... |
<p>I am trying to analyze some data and wondering if I have the right approach.</p>
<p>Each subject viewed seven messages. The outcome variable is acceptance of the message. We want to see if acceptance of messages is related to emotional response and some other variables. Messages were viewed in random order.</p>
<p... | g65738 | [
-0.02070135809481144,
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-0.0026365576777607203,
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0.004195902496576309,
0.03228754550218582,
-0.031128743663430214,
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-0.07037650793790817,
-0.004244014620780945,
-0.03969964385032654,
0.005425265524536371,
0... |
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