question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I am trying to evaluate my recommender system which uses Non-negative Matrix Factorization. Some things that I evaluate are</p>
<ul>
<li>How does the size of the feature matrix affect the recommendations</li>
<li>How does the amount of "rated movies" affect the recommendation</li>
<li>...</li>
</ul>
<p>Should I ev... | g67737 | [
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<p>I came across a result in a time series textbook the other day and have not been able to understand why it is true (the authors don't give a proof but just state it as true). I want to show that the eigenvalues of the matrix $\mathbf{G}$ given by</p>
<p>$$G=
\begin{pmatrix}
\phi_1&\phi_2 &\phi_3 &...&a... | g67738 | [
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<p>Let's say I have a sensor that measures pressure in a range from 10 - 60 mmHg.</p>
<p>This sensor has an error of +/- 0.8 mmHg.</p>
<p>Is there a way to quantify how large this error is with respect to the range of values the sensor can sense? I want to figure out what the relative size of this error is.</p>
<p>T... | g67739 | [
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<p>If possible, please explain things like I'm 5. I know very little about this subject, but would like to learn more.</p>
<p>I have a data frame (in R) containing <code>player_id</code>, <code>points</code>, <code>away</code>, <code>opponent_fact_1</code>, <code>opponent_fact_2</code>. <code>points</code> can be ne... | g67740 | [
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<p>I am using ordinal regression (parallel) on a total dataset of 15706 points, for 10 categories, and testing whether additional predictors significantly improve the model fit.
I started with 2 predictors, obtained a deviance of 16530 and plotted expected vs observed counts: <img src="http://i.stack.imgur.com/6R6Oh.p... | g67741 | [
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<p>When there are two change points in a piecewise constant hazard model then the density function becomes some triangle exponential distribution. In this situation I can't generate the survival time from the CDF using probability integral transformation. Can any one help me to generate the survival time from this mod... | g27406 | [
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<p>I would really appreciate it if people could give me advice on which statistical test that I should be using. I have a dataset which comprises of categorical data: presence or absence of different types of behaviour. Specifically, I am investigating, out of those who engage in a given behaviour, how many engage in d... | g67742 | [
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<p><strong>UPDATE Jan 10th 2014:</strong> <em>the mistake was found - a math typo in one of the sources used. Preparing correction...</em></p>
<p><strong>UPDATE Jan 25th 2014:</strong> <em>the mistake is now corrected. Please ignore the calculated values of the Expected Value in the image uploaded - they are wrong- I ... | g67743 | [
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<p>If $X \sim N(0,1)$ and $Y \sim \chi^2(n),$ then it's "known" that $Z = X/\sqrt{Y/n}$ is $t$ distributed.</p>
<p>Is there anywhere a proof for this? That in the end one can see the $t$ distribution?</p> | g67744 | [
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<p>I'm analysing a study of 4 raters and 34 subjects. I'm looking at the inter rater reliability.
For the ordinal results, I did a weighted kappa of Fleiss and for the other continuous results I calculated an ICC (2,1).</p>
<p>My question is if the data has to follow a normal distribution to be able to use the Kappa o... | g27407 | [
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<p>I'm comparing the performance of multiple algorithms on multiple data sets. Since those performance measurements are not guaranteed to be normally distributed, I chose the Friedman Test with the Nemenyi post-hoc test based on <a href="http://machinelearning.wustl.edu/mlpapers/paper_files/Demsar06.pdf" rel="nofollow"... | g67745 | [
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<p>I am trying to make some sense out of the results of a linear regression model. I have a dependent variable X, and, say, 3 independent variables Y1 Y2 Y3. I set up 5 models :</p>
<p>(m1) X ~ Y1</p>
<p>(m2) X ~ Y1 + Y2</p>
<p>(m3) X ~ Y1 + Y3</p>
<p>(m4) X ~ Y1 + Y2 + Y3</p>
<p>(m5) X ~ Y1 + Y2*Y3</p>
<p>In mod... | g681 | [
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<p>I'm playing the <a href="http://www.fifa.com/stickeralbum">FIFA Panini Online Sticker Album</a>, which is an Internet adaption of the classic Panini albums that are usually published for the soccer world cup, European championship, and possibly other tournaments.</p>
<p>The album has placeholders for 424 different ... | g67746 | [
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<p>Can you show me what I'm doing wrong here? This is the homework problem:</p>
<p>Consider a random sample $Y_1, \ldots , Y_n$ from the pdf $f_Y(y;\theta) = 2y\theta^2$ where $0\le y \le \frac{1}{\theta}$. Find the maximum likelihood estimator for $\theta$.</p>
<p>The likelihood function for this pdf is $\prod_{i=... | g67747 | [
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<p>I have a categorical response variable. It is binary and represents the win or loss of a deal. Some of the independent variables used to predict the response are also categorical (like Geo, Region, and others...). These categorical variables have more than 3 categories. The rest of the variable are counts (like #fac... | g27409 | [
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<p>I am training a random forest for binary classification. Here is a plot of one of my features, which is an integer giving the number of months since an event. The y-axis gives the proportion of cases ($y_i=1$) for each value of the feature. Error bars indicate the $95\%$ binomial confidence interval.</p>
<p><img sr... | g67748 | [
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<p>Dividing sample data into several sets seems to be a common approach in statistics. This is especially evident in predictive modeling, where samples are traditionally divided into two sets, usually called <em>training set</em> and <em>test set</em> (<strong>two-way partition</strong>). Training sets are supposed to ... | g67749 | [
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<p>As many people know Net Promoter Score is a customer feedback measure calculated from the response to the question: "How likely would you be to recommend [us] to a friend or colleague". The response is a discrete value from 0 [very unlikely] to 10 [very likely].</p>
<p>The responses are then used to calculate NPS: ... | g67750 | [
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<p>Let $X \sim N(0, 1)$. Can you confirm that the Kendall's correlation coefficient between $X$ and $X^2$ is equal to $0$. The way I interpret this, is that Kendall's tau only measures monotonic dependence.</p> | g67751 | [
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<p>for my Master thesis I want to model co-movements between two commodity forward curve. First, I specify the model for a single forward curve</p>
<p>$F(t,T)= \bar{F}_0(t)e^{s(T_i)-y(t,T-t)(T-t)}$</p>
<p>where $F(t,T)$ is the forward curve at time $t$ for maturity $T$, $\bar{F}_0(t)$ is the forward curve level (is m... | g67752 | [
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<blockquote>
<p>Question: Suppose $X_1, \cdots, X_n$ are $iid$ normal random variables with unknown mean $\mu$ and known variance $\sigma^2$. Find the UMVUE for $\Phi(\mu)$, where $\Phi(\cdot)$ is the cdf of a standard normal random variable.</p>
</blockquote>
<p>I used to guess the desired UMVUE is or similar to $\... | g67753 | [
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<p>Hello I am using SPSS trees - CART functionality for classification. I have a number of classifying variables such as Business_Size, Location, Previous_Record etc. I want to know how do I set configuration so that a particular classification variable is used at only one level of the tree. E.g say at the first level ... | g23747 | [
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<p>I am trying to fit a finite mixture model to a dependent variable which is bounded (practically) between -0.594 and 1 (theoretically, the latent variable is bounded between -Inf - 1). The data are also bimodal, with a large number of values at '1'. The objective of the analysis is prediction of the dependent variabl... | g27413 | [
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<p>I have found somewhere a mention to the possibility of using dummies variables instead of the Chow test to test whether the coefficients in two linear regressions on different data sets are equal.</p>
<p>Could someone please direct me to a reference where I could study the details?</p> | g67754 | [
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<p>I have to do a logistic regression with independent categorical variables with more than two possible values. Which is the best way to deal with such variables using Stata or spss? I need to have Odds ratios in the output. Thanks.</p> | g67755 | [
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<p>I need to show that F test is equal to T test squared, when the T test is for 2 independent groups and assuming variances are equal.</p>
<p>I know that $F=\frac{MSB}{MSW}=\frac{SSB/k-1}{SSW/N-K}$
and I know that $T=\frac{X-Y}{S_p \sqrt{\frac{1}{n}+\frac{1}{m}}}$, </p>
<p>so $T^2=\frac{(X-Y)^2}{S_p^2 ({\frac{1}{n}+... | g45822 | [
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<p>I am a masters in Computer Science and am interested in pursuing a career in Machine Learning, possibly academic, in the long run.</p>
<p>I have been offered a position related to Financial Modelling at Goldman Sachs that mostly would provide experience in optimization and stochastic methods, which are also require... | g67756 | [
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<p>What is the significant difference between the Fligner Wolfe test and 2-sample Wilcoxon test?<br>
How can I compare the treatment groups with the control groups of different studies after pooling?</p> | g67757 | [
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<p>I am working on developing an insurance risk predictive model. These models are of "rare events" like airline no-show prediction, hardware fault detection, etc.
As I prepared my data set, I tried to apply classification, but I couldn't obtain useful classifiers because of the high proportion of negative cases.</p>
... | g67758 | [
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<p>I have used a 2x3 mixed between-within subjects ANOVA to assess the impact of three feedback conditions (Grade, Comment and No Feedback) on participants’ scores on the Specific-Self Efficacy Scale on two occasions, pre- and post- task. </p>
<p>I did not get a significant main effect but I did get a significant int... | g67759 | [
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<p>How do I determine the Cholesky ordering for a set of endogenous variables to obtain the variance decompositions in eViews?</p>
<p>Is there anyway we can cross check if our order is right apart from intuition.</p> | g67760 | [
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<p>If this is a duplicate question, please point to the right way, but the similar questions I've found here haven't been sufficiently similar. Suppose I estimate the model $$Y=\alpha + \beta X + u$$</p>
<p>and find that $\beta>0$. However, it turns out that $X=X_1+X_2$, and I suspect $\partial Y/\partial X_1 \ne \... | g67761 | [
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<p>Is there any timeline or historical overview of the most important breakthroughs in machine learning and data mining?</p> | g67762 | [
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<p>If I have determined a curvilinear relationship between my dichotomous y and continuous x, what should I do before running a logit regression?
Should I log transform my x variable, etc?</p> | g27422 | [
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<p>Does the multiple hypothesis testing problem apply to the calculation of an F statistic for joint significance? It seems to me that the more variables you are including in your test for joint significance, the more you are accepting that any one of your tests will produce a false positive, right?</p>
<p>If so:</p>
... | g67763 | [
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<p>I was having this conversation with someone, and I feel like I have an explanation, but would greatly appreciate if someone could verify whether what I'm thinking is just completely wrong.</p>
<p>He made the argument that if you know that a variable [a] is correlated with a linear combination of variables [C], then... | g67764 | [
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<p>Say that I have a real-valued discrete distribution $p(x)$ and $N$ samples, $x_1, \ldots, x_N$, and I want to test whether the samples came from the distribution without making any further assumptions whatsoever. Note that there are very few samples; in the application that motivated me to make this post, we have $N... | g27427 | [
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<p>Sorry if this question is oft repeated.</p>
<p>Let's say I'm doing regression and I want to know whether I should use Linear Regression or Random Forests. I do 10-fold cross validation on each model to obtain scores of R^2 and Mean Squared Error. </p>
<p>How do I then compare these lists of numbers to see which is... | g67765 | [
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<p>I am fitting a linear model in R using <code>glmnet</code>. The original (non-regularized) model was fitted using <code>lm</code> and did not have a constant term (i.e. it was in the form <code>lm(y~0+x1+x2,data)</code>).</p>
<p><code>glmnet</code> takes a matrix of predictors and a vector of responses. I've been r... | g48101 | [
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<p>After running a study based on interactive genetic algorithms, I have a univariate data file containing multiple participants each doing multiple generations (blocks) of multiple trials.</p>
<p>Is there an established approach used to analyse this?</p>
<p>I've looked at using a grand mean on each of the component ... | g67766 | [
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<p>Please provide R code which allows one to conduct a between-subjects ANOVA with -3, -1, 1, 3 contrasts. I understand there is a debate regarding the appropriate Sum of Squares (SS) type for such an analysis. However, as the default type of SS used in SAS and SPSS (Type III) is considered the standard in my area. ... | g27432 | [
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<p>I am writing up results from regression analysis where I used AICc model averaging to arrive at my final parameter estimates. I am wondering how best to refer to these parameters and their 95% confidence intervals. It seems like "significantly different" is taboo in the AIC world, but writing out "the parameter wa... | g27435 | [
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<p>I'm trying to fit a <code>tobit</code> model for a response outcome where both sides were censored and the distribution is heavily skewed, even for the none-censored observations. Here is an example:</p>
<pre><code>set.seed(123)
x<-10:100
a<-rnorm(length(x), sd=5)
b<-(x+a)^(-1/1.5)
y<-c(rep(min(b), 20),... | g67767 | [
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0.016311265528202057,
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<p>In PCA , consider a 4 x 3 data matrix ( 4 examples each with 3 features ). After getting the 3 eigenvectors (a/b/c) and projecting data on the first 2 vectors, the equation looks like this :</p>
<p>[ first 2 eigen vectors transposed ] x [ data set transposed ] = [ data projected ]</p>
<p>so the first example in th... | g67768 | [
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<p>this will probably look like a trivial question but I am having trouble explaining the difference between the output plots of two models I built.</p>
<p>My data are disease counts on algae. I would like to test the relationship between disease counts and percentage cover (continuous covariable) including the effect... | g67769 | [
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<p>I'm working on protein multi-classification problem. I'm using libsvm and the edit distance kernel. This kernel depends from a parameter (gamma). I'm able to get the best parameters (gamma and C) through grid search. If i use a kernel that depends from 3 or more parameters, the grid search is computationally heavy, ... | g27440 | [
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<p>Let's say I collect data from an experiment where for each measurement device, 5 trials are conducted at different temperatures. Each device is calibrated separately, and the 5 trial temperatures are constant across devices. In other words, I have values at Temperature 1, 2, 3, 4, and 5 from each device.</p>
<p><st... | g27442 | [
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0... |
<p>This is really puzzling... </p>
<p>I have this data which has a lot autocorrelations...</p>
<p>The data is about 60000 data points of 15min data.</p>
<p>I tried fitting it to ARIMA(6, 0, 6) and even GARCH(1, 1) with mean model ARMA(6, 6), still there are lots of autocorrelations in the residuals.
<img src="http:/... | g27443 | [
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<p>Let me first give you a hypothetical example to make things more clear: </p>
<p>Let's say your task is to classify art as either professional or amateur work, based on image data. You extracted 100 features from each artwork using image processing. The artworks fall into different genres (like sketch, abstract pain... | g67770 | [
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<p>Suppose I have a die and I throw it a large number of times (a billion times) and have proven that it lands on each side an equal number of times so it is proven to be fair.</p>
<p>Next suppose I started a second round of throwing of the same die and it lands on 1 through 5 say a 10,000 times each and the count for... | g27444 | [
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<p>I have the time series of the prices of two securities, A and B, over the same period of time and sampled at the same frequency. I would like to test whether there is any statistically significant difference over time between the two prices (my null hypothesis would be that the difference is null). Specifically, I a... | g27450 | [
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<p>I am trying to find the correlation between a dichotomous and a continuous variable.</p>
<p>From my ground work on this I found that I have to use independent t-test and the precondition for it is that the distribution of the variable has to be normal.</p>
<p>I performed Kolmogorov-Smirnov test for testing the nor... | g67771 | [
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0... |
<p>Let's say I have a structure like this : </p>
<p><img src="http://i.stack.imgur.com/UID7o.png" alt="enter image description here"></p>
<p>This is a spatial region with measurement of plant population in each site. Black and red represent two regions with different intensities.The question is that I want to ask abo... | g67772 | [
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<p>It seems that most authorities agree that dark or otherwise prominent gridlines in plots are "chartjunk" by any reasonable definition and distract the viewer from the message in the main body of the chart. So I won't bother to give references on that point.</p>
<p>Equally, we can all agree that there will be times... | g48126 | [
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<p>Conceptually we learn that the sample variance formula, we have to divide by n-1 such that it gives the correct estimation for the true variance.</p>
<p>However if we have this example,</p>
<p>let a sample $X_i = 1$ with probability $p$, and $0$ with probability $1-p$.</p>
<p>so if we define a statistic $\hat{p} ... | g27451 | [
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0.02309386618435383,
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<p>I am using logistic regression to predict electricity spike prices (price that exceeds a certain threshold).</p>
<p>I directly use the following variables as my independent variables together:</p>
<p>(a) demand/load - a continuous IV<br>
(b) is a binary IV<br>
(c) days of the week<br>
(d) months of the year.</p>
... | g67773 | [
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<p>I have variables A, B, C, D, and E. I am interested in building a classifier for A. </p>
<p>I learned a Bayes net structure from the data using greedy search and BIC as a score. Call this network 1. Using cross validation, I got the mean prediction error for node A in network 1.</p>
<p>I then, thought to create a ... | g67774 | [
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<p>Following the Stata Manual - Item–response theory (IRT) models'
example 28g — One-parameter logistic IRT (Rasch) model:</p>
<p>use <a href="http://www.stata-press.com/data/r13/gsem_cfa" rel="nofollow">http://www.stata-press.com/data/r13/gsem_cfa</a> , clear
gsem (MathAb -> (q1-q8)@b), logit var(MathAb@1)</p>
<p>it... | g67775 | [
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0.048293761909008026,
... |
<p>I have ran a negative binomial regression. I'm guessing the use of a negative binomial regression is not ideal given my design, but I'm hoping I can 'get away with it', as it seems to be working fairly well. </p>
<p>Here's my design:</p>
<ul>
<li><p>Count the the total number of geese in a flock</p></li>
<li><p>Co... | g17490 | [
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0.006268313154578209... |
<p>So this might be not the smartest question. But I defined this function:</p>
<pre><code>trans.arcsine <- function(x){
asin(sign(x) * sqrt(abs(x)))
}
</code></pre>
<p>which I got from <a href="http://math.stackexchang... | g67776 | [
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<p>I am doing a least squares polynomial interpolation for 10,000 data sets that look mostly like one period of a sine curve, but whose values are not evenly spaced in the time domain, and can sometimes be quite noisy. A lot of them do just fine with a 3rd order fit (a + bx + cx^2 + dx^3) but some oscillate wildly (Run... | g27452 | [
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<p>Suppose you are simulating a population of 1000 individuals, each of which have a probability p of being infected with some condition. How do you determine how many individuals are infected in a individual round.</p>
<p>To get a number for each round you could do:</p>
<p>total = 0;
for i = 1 to 1000 { if random nu... | g67777 | [
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0... |
<p>I have a standard event history data set, which I used to fit a Cox proportional hazards model in Stata and R. The time variable is measured in days. There are no time-varying covariates on the RHS of the equation. </p>
<p>I have recovered the usual output (coefficients, hazard ratios, SEs, etc.) as well as the pre... | g27453 | [
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<p>I am using a moving average filter to smooth data for outlier removal. By changing the number of average points, I am getting different result. </p>
<p>My data are multi-dimensional feature vectors. </p>
<p>I applied the moving average to the entire matrix and then on individual variables. </p>
<p>They give diffe... | g67778 | [
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<p>After stumbling upon the concept in a statistics textbook, I tried to wrap my head about it, and finally came to a conclusion which seems to fit all the explanations which I have seen so far: A credible interval is what non-statisticians think a confidence interval is. </p>
<hr>
<p><em>Digression for those like me... | g67779 | [
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<p>This is probably a very basic question so apologies in advance, but we are stuck. </p>
<p>We currently change prices by varying amounts (both positively and negatively)every 3 months,and would like to calculate the price elasticity of demand. </p>
<p>Questions:</p>
<p>1) Should we eliminate a period of time immed... | g67780 | [
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<p>I have a grey-box model of the form</p>
<p>Y= a + b X1 + c X2.</p>
<p>Where a, b and c are the coefficients based on regression. </p>
<p>The regression variables X1 and X2 are determined based on experimental/simulation data. I can experimentally run for a large number of cases and train the model (but it is time... | g67781 | [
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<p>I have the following problem: I have already set up a model and MCMC sampler for a mixed model without weights, i.e., every observation contributes the same amount of information. Now I would like to implement weights, thus I change the likelihood to</p>
<p>$f(y|\theta) = |2\pi R\sigma_e^2|^{-1/2} \times \text{exp}... | g27458 | [
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<p>I am reading a book on time series and I came across the following: "In addition to being a parsimonous approximation to a high-order AR(p) model, ARMA models...". Why is an ARMA model a (parsimonous) approximation to an AR model?</p>
<p>Also, somewhat later on I read that the coefficients of an MA model can be est... | g12619 | [
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<p>I want to see if the <code>proportion of 'I don't know'</code> responses correlates with the progression through the survey. Generally we expect this proportion to increase through the survey due to a fatigue effect. However, the following chart suggests this effect is not present in my data: </p>
<p><img src="http... | g23658 | [
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<p>I would like to try the following algorithm in order to win in the roulette:</p>
<ol>
<li><p>Be an observer until there are 3 same parity numbers in a row ($0$ has no defined parity in this context)</p></li>
<li><p>Once there were achieved 3 numbers with the same parity in a row: init $factor$ to be $1$</p></li>
<l... | g27460 | [
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<p>I am observing strange patterns in residuals for my data:
<img src="http://i.stack.imgur.com/p8jqs.png" alt="enter image description here"></p>
<p>[EDIT] Here are the partial regression plots for the two variables:</p>
<p><img src="http://i.imgur.com/Lh36l.png" alt="http://i.imgur.com/Lh36l.png"></p>
<p><img src=... | g49912 | [
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<p>I'm trying to create a prediction model using regression. This is the diagnostic plot for the model that I get from using lm() in R:
<img src="http://i.stack.imgur.com/JRNM0.png" alt="diagnostic plots from R"></p>
<p>What I read from the Q-Q plot is that the residuals have a heavy-tailed distribution, and the Resi... | g67782 | [
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<p>Is there any freeware or commercial alternative to SAS EnterpriseGuide?</p>
<p>I'm looking mostly for it's ability to save complex structured queries so the statistical libraries are of secondary importance.</p> | g27465 | [
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<p>I am doing a self-study on Exponential Distribution and noted an exponential on my text giving that:</p>
<p>CDF of Exponential Distribution
$$
F(x) = 1 - e^{-λx} ,
$$
PDF of Exponential Distribution
$$
f(x) = λe^{-(λx)} .
$$
However, I was wondering on what conditions do I use what?</p>
<p>From what I understand, ... | g49784 | [
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<p>I am trying to plot the decision boundary of a perceptron algorithm and am really confused about a few things. My input instances are in the form [(x1,x2),target_Value], basically a 2-d input instance and a 2 class target_value [1 or 0].</p>
<p>My weight vector hence is in the form: [w1,w2]
Now I have to incorporat... | g67783 | [
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<p>Short version: When solving for the pdf of a function of a continuous random variable(say, $Y=X^2$), why can't you just plug in inverse of that($\pm\sqrt{x}$) into the pdf of the RV? Why do you have to start from the cdf of the $Y$, substitute $Y$ with $X^2$, and differentiate that to get the pdf? </p>
<p>The poin... | g49729 | [
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<p>I'm looking for a method to determine if the number of survey response received from a regional office are substantial enough to compare to each other year over year. For example, one year we might get 29 survey responses in a month from one site but only 5 responses for the same month the next year. Can I say tho... | g67784 | [
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<p>I have read that the posterior probabilities of Naive Bayes classifiers are unreliable. Is this true? and if so, in what sense, and why?</p>
<p>Specifically, I am interested to know if the probabilities can be used as some measure of confidence of the predictions. For example, can I say that higher posteriors are m... | g67785 | [
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<p>The data generating process is given by the following differential equation:<br>
$y(t) = a + b u(t - \theta) + c \frac {dy} {dt}$<br>
Now imagine having as data a long time series for both $y$ and $u$.</p>
<p>If $\theta$ is known, this is an easy linear regression. But is there a "correct" procedure when the delay ... | g27473 | [
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<p>Given the 7 different samples with mean and variance for each group. What can I use to tell if these samples from the same population with 0.05 and 0.01 significance level?</p>
<pre><code>Sample Mean Variance
A 50 5
B 47 4
C 52 5
D 51 6
E 49 5
F ... | g67786 | [
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0.019278310239315033,
0.0028822722379118204,... |
<p>To do a meta analysis, I try to calculate effect sizes. In <a href="http://www.sciencedirect.com/science/article/pii/S0272696302001080" rel="nofollow">an article by Shah and Ward</a>, the authors do a regression analysis after combining various factors by a CPA to four factors. The factor loadings are provided in th... | g67787 | [
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<p>I have spent two days grappling with this question, and the range of ambiguous answers online has driven me to ask. I am working with R.</p>
<p>I have a dataset where my dependent variable is an ordered categorical variable with 5 levels ("dislike very much" to "like very much"). I intend to use the <code>ordinal</... | g67788 | [
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<p>I have a 2x2 factorial unbalanced between-subject design, <strong><em>n</em> = 355</strong>. My DV is a subjective probability estimate (i.e., a number between 0 and 100). </p>
<p><strong>My ANOVA model:</strong> </p>
<pre><code>aov1 <- aov(prob ~ utility * imagination, data = e3nndata)
</code></pre>
<p>To <st... | g27475 | [
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<p>I've read "<a href="http://stats.stackexchange.com/questions/19507/ab-testing-other-factors-besides-conversion-rate">AB Testing other factors besides conversion rate</a>", but I don't know if it's relevant with my question, even if it seems similar.</p>
<p>Here is my problem. Let's assume I am creating a new tools ... | g67789 | [
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<p>I am a beginner in R. I am using the plm package and I want to know the easiest way to get cluster robust standard errors for the fixed effects estimator. My data (called Mydata) is on poverty, GDP, investment, and education in 130 countries over 33 years, and my index in plm is country and time. My model is somethi... | g609 | [
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<p>I am a civil engineering student and my research area is traffic engineering. I have encountered different types of statistical distributions e.g. Poisson, binomial, Gumbel, Gaussian, Pearson type III, etc in traffic engineering literature. I understand some of the distributions and what kind of data they fit. But t... | g49785 | [
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<p>Python is plenty of ML libraries (like the great scikit-learn). Is there any good for java/scala, containing many algos (regression, classification, clustering, cross-validation, feature processing), stable & maintained and able to deal with massive dataset?</p>
<p>I've just found Mahout, Breeze/Nak, and Weka, ... | g67790 | [
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<p>Has anyone seen any telco billing dataset available for analysis?</p>
<p>I looked at Kaggle or <a href="http://www.d4d.orange.com/en/presentation/data" rel="nofollow">http://www.d4d.orange.com/en/presentation/data</a> but couldn't find anything.</p> | g67791 | [
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... |
<p>I am trying to write my own ML library. For speed reasons I started out writing things in C using BLAS, but then I learned that NumPy and Theano also use BLAS. I am wondering if there are huge speed differences between implementations of ML algorithms in C/Python/Matlab/Octave. </p>
<p>Does anybody have some experi... | g48164 | [
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<p>I am using a logistic regression model with continuous independent variables and two log transformed size variables (total assets and total deposits).</p>
<p>My question is how to interpret the results and measure the economic impact?
The normal steps in interpretation I take is as follows: I firstly run stata test... | g37973 | [
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<p>I have a cohort of patients with different length of follow-up. So far I´m disregarding the time aspect and just need to model a binary outcome-disease/no disease. I usually do logistic regression in these studies, but another collegue of mine asked if Poisson regression would be just as appropriate. I´m not that in... | g27485 | [
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0.013487487100064754,
... |
<p>Given a regression model of the form:</p>
<p>$$y_{i} = \beta_{0} + \beta_{1}x_{i}$$</p>
<p>The least squares estimators for $\beta_{1}$ and $\beta_{0}$ are given by:</p>
<p>$$\hat{\beta}_{1} = \frac{\sum x_{i}y_{i} - n\bar{x}\bar{y}}{\sum x_{i}^{2} - n \bar{x}^{2}}$$</p>
<p>and</p>
<p>$$\hat{\beta}_{0} = \bar{y... | g67792 | [
-0.020089901983737946,
-0.048000771552324295,
-0.02278677560389042,
-0.0005465532885864377,
0.0784820020198822,
-0.05419072508811951,
0.02993178926408291,
0.006357691250741482,
0.002670485293492675,
-0.022810282185673714,
-0.06607699394226074,
0.07249568402767181,
0.010618692263960838,
0.0... |
<p>What is the difference between operations research and statistical analysis?</p> | g67793 | [
0.04723844677209854,
0.0421232134103775,
-0.0059806788340210915,
0.03378094732761383,
-0.0196300707757473,
-0.021752143278717995,
0.01441444642841816,
0.0027257846668362617,
-0.025375282391905785,
-0.02264958806335926,
0.02646123804152012,
-0.05850719287991524,
0.0250918697565794,
-0.03032... |
<p>During every machine learning tutorial you'll find, there is the common "You will need to know x amount of stats before starting this tutorial". As such, using your knowledge of stats, you will learn about machine learning.</p>
<p>My question is whether this can be reversed. Can a computer science student learn s... | g27490 | [
0.025033149868249893,
0.04225560277700424,
0.023767521604895592,
-0.0059511493891477585,
0.005001420620828867,
0.00599959772080183,
-0.03383263573050499,
0.030728129670023918,
-0.04483349993824959,
-0.006697928067296743,
-0.006950811017304659,
0.07204616069793701,
0.0931391641497612,
-0.01... |
<p>Imagine I find a good fit of an <code>Arma 4,4</code> model on the levels, and on the first difference I find <code>Arma 3,4</code>.</p>
<p>Are both models related somehow?</p> | g67794 | [
0.033863529562950134,
-0.027235036715865135,
-0.014316940680146217,
0.014175422489643097,
0.06354032456874847,
0.029772760346531868,
0.0250028558075428,
-0.006610208656638861,
-0.021009642630815506,
0.0020923614501953125,
-0.07094959914684296,
-0.01993519626557827,
0.01902725175023079,
0.0... |
<p>I have the following table</p>
<pre><code>t Demand Level Trend Forecast
.
.
.
8 121,63 119,04 12.52 118,4
9 131.56
</code></pre>
<p>I want to calculate the Demand, Level and Trend for t=9 with the following formulas</p>
<p>$$ L_{t} = \alpha D_{t} + (1-\alpha... | g67795 | [
-0.037827588617801666,
0.03326769918203354,
-0.013486403040587902,
-0.03253748267889023,
0.0076552387326955795,
-0.07701738178730011,
0.020336396992206573,
0.0050553916953504086,
-0.071974016726017,
-0.03484523296356201,
-0.050657156854867935,
0.03690130636096001,
0.048835836350917816,
-0.... |
<p>Having a bit of difficulty identifying the appropriate ARIMA model by looking at ACF/PACFs. </p>
<p>I know that AR(1) models, the ACF has a geometric progression from its highest value at lag 1 and the PACF has a spike at lag 1 and then then cuts off afterwards. </p>
<p>Could someone possibly explain how I identif... | g67796 | [
0.041634947061538696,
-0.035258982330560684,
-0.02088521048426628,
-0.003356334287673235,
0.096641406416893,
-0.015356306917965412,
0.09287632256746292,
-0.020238425582647324,
-0.007714875042438507,
-0.00962015613913536,
0.0071091605350375175,
0.045240167528390884,
0.10872504860162735,
-0.... |
<p>I've heard that a lot of quantities that occur in nature are normally distributed. This is typically justified using the central limit theorem, which says that when you average a large number of iid random variables, you get a normal distribution. So, for instance, a trait that is determined by the additive effect o... | g67797 | [
0.06012391671538353,
0.029204100370407104,
-0.018145723268389702,
-0.06489480286836624,
0.0032465767581015825,
0.07255098223686218,
0.03526311367750168,
0.004733724053949118,
-0.002749590203166008,
-0.015442388132214546,
-0.025022096931934357,
-0.016510067507624626,
0.023512033745646477,
-... |
<p>I have conducted a repeated measures ANOVA using a Linear mixed-effects model fit with REML in R. When I report the results I include the ANOVA table output by <code>anova(model_object)</code></p>
<pre><code>anova(O2.rmtest)
numDF denDF F-value p-value
(Intercept) 1 131 168.08616 <.0001... | g67798 | [
0.03742580860853195,
-0.049831099808216095,
0.019987376406788826,
-0.016997836530208588,
-0.003227247390896082,
0.04505328834056854,
0.022937815636396408,
0.027349160984158516,
-0.019916051998734474,
-0.011178217828273773,
-0.035974957048892975,
-0.04203522205352783,
0.03304646536707878,
0... |
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