question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Are there any speedy alternatives to the EM algorithm for learning models with latent variables (especially pLSA)? I'm okay with sacrificing precision in favor of speed.</p> | g44357 | [
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<p>I'm using euclidean distance for kNN. I have labeled data, I have took logarithm of some variables to make them look more like normaly distributed and scaled them all. And now I would like to multiply some variables by weights, then compute euclidean distance and train kNN. But how to find those weights ? My idea is... | g59511 | [
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<p>The <code>qqnorm()</code> R function produces a normal QQ-plot and <code>qqline()</code> adds a line which passes through the first and third quartiles. What is the origin of this line? Is it helpful to check normality? This is not the classical line (the diagonal $y=x$ possibly after linear scaling).</p>
<p>Here i... | g59512 | [
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<p>I am calculating PCA using a numpy/python approach. The principal components are in the form of GIS grids (rasters), created in a manner very similar to the GRASS GIS approach described here: <a href="http://grass.fbk.eu/gdp/html_grass62/r.covar.html" rel="nofollow">http://grass.fbk.eu/gdp/html_grass62/r.covar.html... | g44360 | [
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<p>I have performed a simple regression analysis between one dependent variable (DV) and one explanatory variable (IV).</p>
<p>If the p-value from the regression analysis for the IV is not significant, should I still use residual plots to verify that the regression model used was correct (and the statement of non-sign... | g59513 | [
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<p>I have inherited a dataset with two types of data from an employee opinion survey project spanning multiple organizations. </p>
<p>We have responses by individual employees on questions to do with their work situation (such as "I have the resources I need to do my job"). </p>
<p>Then we also have metrics data from... | g59514 | [
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<p>I'm looking for good panel data analysis references. I've Baltagi & "Panel Data Econometrics in R". But I want something which is short (max 100 pgs), lucid (know this criteria differs) & have examples to work through.</p>
<p>I'll be grateful if somebody can give me some references.</p> | g44361 | [
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<p>If $\text{RMSEA} = 0$, it means $\chi^2 < df$. </p>
<p>Does it disqualify RMSEA as a criterion to evaluate the model fit, or is it just the explanation why it is zero?</p> | g532 | [
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<p>I came across the word <em>subjective interestingness</em> measures in my book, where author says that:</p>
<blockquote>
<p>Subjective interestingness measures are based on user belief in the
data. These measures find patterns interesting if they are unexpected
(contradicting user's belief) or offer strategic... | g59515 | [
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<p>Multiple regression model<br>
$H_0$:$\beta_2=0$, $H_1$:$\beta_2 \neq 0$<br>
where $\beta_2$ is the vector of elements ($\beta_2, \beta_3, \dots, \beta_k$) and $\beta$ is slope of regression line.</p>
<p>Why it is equivalent to a test based on the statistic
$$\frac{R^2/(k-1)}{(1-R^2)/(T-k)}$$
where $R^2$ is the squa... | g59516 | [
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<p>I have points in a 2D graph (coordinates: X,Y property: Z). I would like to find for every point the closest, for example, 5 points and save their properties.</p>
<p>What would be the easiest approach?</p>
<p>Update:<br>
Using the following code:</p>
<pre><code>%Synthetic data
A = {[1,1]; 'A'};
B = {[2,2]; 'B'};
... | g59517 | [
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<p>I have a servlet-based application wherein I measure the time taken to complete each request to that servlet. I already compute simple statistics like the mean and maximum; I'd like to produce some more sophisticated analysis however, and to do so I believe I need to properly model these response times.</p>
<p>Sure... | g59518 | [
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<p>Is there an issue with the output of the Huynh-Feldt correction when running an ANOVA for both between and within factors (mixed design) in R? My issue is that when I run a 'within-subject (only)' ANOVA using either the 'Anova' or 'ezANOVA' functions, the output for the Huynh-Feldt correction is the exact same I get... | g41088 | [
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<p>I need to calculate the Probabilistic Sensitivity Analysis for a function.
I was given this:</p>
<p>beta distributions assigned to represent uncertainty<br>
And have this parameter with this data:</p>
<pre><code>variable = d_progress
probability of variable : 0.1
n = 100
r = cases = 3
</code></pre>
<p>Now, I need... | g59519 | [
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<p>I have spent much time looking for a special package that could run the Pesaran(2007) unit root test (which assumes cross-sectional dependence unlike most others) and I have found none. So, I decided to do it manually; however, I don't know where I'm going wrong, because my results are very different from Microsoft ... | g15084 | [
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<p>I get a little bit confused by the conclusions I can take or not with these small samples.</p>
<p>I have been measuring the degradation of a pollutant for 9 days. I measured the remaining concentration and only took triplicates each day, so that gives me a very small sample size. I want to check at which point ther... | g44364 | [
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<p>I recently learned about using bootstrapping techniques to calculate standard errors and confidence intervals for estimators. What I learned was that if the data is IID, you can treat the sample data as the population, and do sampling with replacement and this will allow you to get multiple simulations of a test sta... | g18752 | [
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<p>I should not be here, I am a designer by trade and all these numbers scare me. I am attempting to help someone display their information; they sent me an excel spreadsheet and asked me to make graphs out of certain information. </p>
<p>Unfortunately the spreadsheet contains ~13,000 rows and 32 columns, and I need t... | g59520 | [
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<p>We draw $N$ samples, each of size $n$, independently from a Normal $(\mu,\sigma^2)$ distribution.</p>
<p>From the $N$ samples we then choose the 2 samples which have the highest (absolute) Pearson correlation with each other.</p>
<p>What is the expected value of this correlation ?</p>
<p>Thanks
[P.S. This is not ... | g44365 | [
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<p>I have a data set with about 6,000 Fishers exact tests. If I want to do a multiple testing correction to control the FWER what are the advantages of one of these methods vs the other</p>
<p>calculating a q-value for each test <a href="http://www.jstor.org/stable/3448445" rel="nofollow">Cite</a></p>
<p>Using a Ben... | g9363 | [
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<p>Assume that there is a 5 $\times$ 6 matrix that records the ratings of six users on five movies. </p>
<p>I have computed the singular value decomposition (SVD) for such a matrix. </p>
<p>Suppose I add another movie so now it becomes 6 $\times$ 6 matrix. </p>
<p>However, I only have a rating of that movie for two ... | g59521 | [
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<p>what I am interested in learning is how to calculate the std error of the marginal effects of a X variable when it is part of an interaction, especially in robust regression.</p>
<p>There are tipically two cases that interest me: when there is an interaction between two continuous variables and when there is an in... | g59522 | [
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<p>Okay, so I'm having a conceptual issue with using the f-distribution to build a Working-Hotelling confidence band.</p>
<p>It makes sense to me that we use a tα/2 or a zα/2 value when building a standard confidence interval, as there are two tails to equally take into account. Now, doesn't the f-curve also have two ... | g59523 | [
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<p>I do not know which distance function between individuals to use in case of nominal attributes.
I was reading some textbook and they suggest Simple Matching function but some books suggest that I should change the nominal to binary attributes and use Jaccard Coefficient. However, what if the values of the nominal at... | g59524 | [
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<p>In Markov decision processes, what is the guarantee that value iteration chooses the same policy action from a given state for every iteration? I am referring to the slides given by AWM at <a href="http://www.autonlab.org/tutorials/mdp09.pdf" rel="nofollow">http://www.autonlab.org/tutorials/mdp09.pdf</a>. </p>
<p>T... | g59525 | [
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<p>A very new European “Rapid Reaction Force for Fire” has been created today and begins operation between three Countries “A”, “B” and “C”. It’s main resource is a super aircraft “Funderbird2” with a massive water cannon that even carries a small mini-submarine for fighting fires at sea. Unfortunately, it can only b... | g59526 | [
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<p>I'm trying to estimate the design effect of a series of relatively small sample size surveys ($n\sim 70$) with multiple responses. Design effects roughly correspond to how much larger actual sample variance than would be expected from naive random sampling. The simplest way to parametrize this is for Effective Sampl... | g44371 | [
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<p>I'm compiling a survey that will have several questions which would lend to the creation of an index of a main dependent variable (level of engagement in sucession planning). The questions will involve topics like: </p>
<ul>
<li>PROCESS: linking strategic planning to succession planning, identifying critical positi... | g44374 | [
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<h3>Context:</h3>
<p>I am trying to analyze an experiment on plant community response to two treatments. Here’s a simplified description of the experiment, there are a few extra complications in reality. </p>
<p>Treatments were applied to small patches of ground arranged in blocks with a mix of naturally occurring ... | g44375 | [
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<p>I have a few questions regarding quantile regression and how to interpret the results. I have several independent variables and I want to figure out which combination of variables have the highest predictive value. I have preformed quantile regression, in Eviews, on all possible combinations of the 10 independent va... | g15094 | [
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<p>I've been using the Johansen Procedure to check and correct for cointegration in my model, by estimating a VECM instead of VAR. But now I want to estimate a new model, in which I expect the same cointegrated relationships, however, some of my variables are now stationary (because they are one of the former variables... | g15095 | [
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0.0... |
<p>Edit:
I've conducted an item analysis on four variables - two quizzes and two psychological attributes, namely emotional intelligence and happiness. Its a within-subject design with students as participants. They all have Cronbach's alpha above .70 or have been revised to meet that criteria. I have a scenario where ... | g15096 | [
0.0163885485380888,
-0.057933561503887177,
-0.00288712908513844,
-0.03214268758893013,
0.009125815704464912,
0.01609315164387226,
0.019535209983587265,
0.022770442068576813,
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0.05482308566570282,
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-0.0... |
<p>Consider I have the following probabilities:</p>
<p>$$P(A|B) = 0.86 $$</p>
<p>$$ P(A|B^C) = 0.35 $$</p>
<p>$$ P(B) = 0.80 $$</p>
<p>$$ P(A) = 0.758$$</p>
<p>Is there necessary information given to calculate $P(B^C|A^C)$? If so please guide me how. Thanks in advance.</p> | g15097 | [
0.08545543253421783,
0.018290413543581963,
0.013926563784480095,
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0.01749587617814541,
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0.03686653450131416,
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-0.0... |
<p>So I'm working with logistic regression models in R. Though I'm still new to statistics I feel like I got a bit of an understanding for regression models by now, but there's still something that bothers me:</p>
<p>Looking at the linked picture, you see the summary R prints for an example model I created. The model ... | g41955 | [
0.01847868598997593,
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0.0025600476656109095,
0.044662512838840485,
0.03365666791796684,
0... |
<p>I have a few questions with regards to a solution to the problem below:</p>
<p><img src="http://i.stack.imgur.com/aTeir.png" alt="Question and Answer:"></p>
<ol>
<li><p>How is it possible to have $max_{1\leq{i}\leq{n}}x_i-1<\theta<min_{1\leq{i}\leq{n}}x_i$?
How can a value of $\theta$ be both greater than a ... | g59527 | [
-0.030260346829891205,
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0.03591747209429741,
0.02903522551059723,
0.... |
<p>Am trying to set a few binary/dummy variables against each other, i.e. <code>propensity_to_dance</code> and <code>gender</code>.</p>
<p>I assume that it' ok to be using a binary logistic regression in SPSS (or otherwise) to investigate the interaction on these two variables; I've previously been using that kind of ... | g59528 | [
0.013319194316864014,
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-0.07929899543523788,
0.011272164061665535,
0.043370168656110764,
0.03155585378408432,
0.... |
<p>I'm currently using a matrix factorization method to generate recommendations (for info on this, check: <a href="http://www2.research.att.com/~volinsky/papers/ieeecomputer.pdf" rel="nofollow">Matrix Factorization Techniques for Recommender Systems</a>). At the moment, my rating estimate is given by the global mean, ... | g15102 | [
0.019377445802092552,
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0.0012481367448344827,
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0.019322598353028297,
0.025797907263040543,
0.0201013945043087,
-... |
<p>I'd like to wrap my head around this topic but learning from white-papers and tutorials is hard because there are many gaps which are usually filled in textbooks. </p>
<p>If it is important I have relatively strong mathematical background as I did my Ph.D. in applied mathematics (CFD to be more precise).</p> | g15103 | [
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-0.03888032212853432,
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-0.003015300026163459,
0.09794358909130096,
-0.001... |
<p>I have a sample with very small sample size ($n<10$) and I would like to estimate the population mean. However, some of the samples are replicates (for instance, sampled at the same location).
According to a previous discussion:</p>
<p><a href="http://stats.stackexchange.com/questions/49480/sampling-with-or-with... | g41996 | [
0.017202410846948624,
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0.01599530503153801,
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0... |
<p>I have a couple of questions regarding the maximum likelihood solution in a classification problem (with only two classes $C_{1}$ and $C_{2}$) Basically, I have the following likelihood function:</p>
<p>$$p({\bf{t}}|\pi, \mu_{1},\mu_{2},\Sigma)=\Pi_{n=1}^{N}[\pi N(x_{n}|\mu_{1},\Sigma)]^{t_{n}}[(1-\pi)N(x_{n}|\mu_{... | g44388 | [
0.0203938540071249,
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0.022442065179347992,
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0.034927401691675186,
0.04344674572348595,
0.01969... |
<p>I am currently doing my statistics thesis on modelling football data which requires quite a great knowledge of Bayesian Theory especially MCMC methods.
However I have some minor problems regarding the Metropolis algorithm:</p>
<ul>
<li><p>Any distribution can be attributed to the proposal density function?</p></li... | g59529 | [
0.004694785922765732,
0.00164597958792001,
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0.06296097487211227,
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0.11337903887033463,
0.0... |
<p>Suppose $ \textbf{Y} = (Y_1, \dots, Y_n)'$ are independent and </p>
<p>$$\eqalign{
Y_i = 0 & \text{with probability} \ p_i+(1-p_i)e^{-\lambda_i}\\
Y_i = k & \text{with probability} \ (1-p_i)e^{-\lambda_i} \lambda_{i}^{k}/k!
}$$ </p>
<p>and </p>
<p>$$\eqalign{
\log(\mathbf{\lambda}) &= \textbf{B} \beta... | g13127 | [
-0.02114468440413475,
0.006052971817553043,
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0.0002794009924400598,
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0.026356274262070656,
0.03065481036901474,
0.0245... |
<p>Is there some standard procedure (such that one might cite it as a reference) for selecting the subset of data points from a larger pool with the strongest correlation (along just two dimensions)?</p>
<p>For instance, say you have 100 data points. You want a subset of 40 points with the strongest correlation possib... | g59530 | [
0.03906300291419029,
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0.04185553640127182,
0.02129380963742733,
0.07604143023490906,
-0.0022... |
<p>Is there a good expository account of Sheppard's correction, written in a way that any ordinary mathematician can readily follow? </p>
<p><a href="http://mathworld.wolfram.com/SheppardsCorrection.html" rel="nofollow">http://mathworld.wolfram.com/SheppardsCorrection.html</a></p>
<p>(I've thought of writing a Wikipe... | g42019 | [
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0.00377817009575665,
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0.04750474914908409,
0.01... |
<p>What are the standard statistical tests to see if data follows exponential or normal distributions?</p> | g59531 | [
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-0.0181... |
<p>According to <a href="http://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation" rel="nofollow">the Wikipedia article</a>, the following estimator of the standard deviation
$$s=\sqrt{\frac{1}{n-1}\sum_{k=1}^n(x_i-\bar{x})^2}$$</p>
<p>for a normal variable, verifies $E[s]=C_4(n) \sigma$, where</p>
<p>$... | g42022 | [
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0.009238691069185734,
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0.0164903923869133,
-0.02876579947769642,
0.01871... |
<p>I'm using the LIBSVM in Java for classification with 200 documents in inputs. I build/train the SVM using the same input training data.</p>
<p>My response time for preprocessing of documents (tokenization, filtering and ngrams and then writing results out to files) and loading file into memory is 8 second.</p>
<p... | g3904 | [
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0.00830292608588934,
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0.06031864508986473,
0.01... |
<p>I am attempting to write a program in Javascript to estimate where a radio-tracked animal is. Basically, it should take 3+ bearings as inputs, along with the locations they were taken, and output a good estimate of where the animal is. From what I've read, it seems like Lenth's 1981 method of Maximum Likelihood Esti... | g59532 | [
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0.023334508761763573,
0.10366053879261017,
-0... |
<p>Okay I will explain this as best as I can. </p>
<p>I have an additive risk score for each of my observations (i.e. I'm putting 100 individual effects into a single variable). The means of this risk score variable are significantly different between sets of observations from two different populations. </p>
<p>I now... | g59533 | [
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0.05821617692708969,
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0.0... |
<p>My professor has this slide up here:</p>
<p><img src="http://i.stack.imgur.com/ok8iy.png" alt="enter image description here"></p>
<p>Here, $y$ is an observed signal. $H$ is a deterministic transformation, which is assumed known. $f$ is the original signal (which we dont know), and $w$ is random gaussian noise. We ... | g59534 | [
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0.03597484901547432,
0.07918097823858261,
0.01... |
<p>I am wondering whether there exist a closed-form expression for the expected assortativity coefficient (<a href="http://arxiv.org/pdf/cond-mat/0205405.pdf" rel="nofollow">http://arxiv.org/pdf/cond-mat/0205405.pdf</a>) of an Erdos Ranyi random graph model $G(n,m)$, where $n$ is the number of nodes and $m$ is the dens... | g59535 | [
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0.002325375797227025,
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0.042919740080833435,
... |
<p>I am considering writing an article that discusses the Bayesian MMSE and MAP of the posterior predictive distribution. I was wondering if there are acronyms that have been used so that instead of always saying: "The MMSE of the posterior predictive distribution..." I might just say: "The MMSPE..." or "The MMSEP" or ... | g15113 | [
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0.013666165061295033,
0.053609203547239304,
-0.0134394196793437,
0.11595672369003296,
0.0221... |
<p>Suppose we have a data set <strong>test</strong>:</p>
<pre><code>1
8
12
14
.
.
19
</code></pre>
<p>The <code> . </code> denotes missing values. When would it be better to use the average of the non-missing values to impute the missing values rather than assuming that the data comes from a normal distribution?</p> | g13234 | [
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<p>I'd like to get your opinions on how to interpret items that had to be eliminated in factor analysis (FA).</p>
<p>I've been researching consumer shopping motivations and ran a survey with 40 items, which included statements from previous research in the field (there is no developed go-to scale).
I expected items w... | g59536 | [
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<p>I am using <strong>linear-mixed effect models</strong> to analyse my data (the interaction between <code>on</code> and <code>arc</code>; both <code>arc</code> and <code>on</code> are continuous variables). I also used the <code>effects</code> library to plot the interaction of <code>on*arc</code>. However, I could n... | g15118 | [
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0.... |
<p>Let's assume we get <strong>1 point for predicting the result</strong> (win/lose/draw) and <strong>3 points for predicting correct score for both teams</strong> (e.g. 3:2). </p>
<p>We've got two separate accounts where we can bet, my question is: </p>
<p>(1) <strong>does betting twice each match</strong> (once per... | g15119 | [
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<p>I'm rather new to statistics, so please bear with me.</p>
<p>I would like to be able to say "to within 95% confidence, this data is exponentially-distributed." In this case, I know how the data <em>should</em> be distributed and I want to be able to say it <em>is</em> to some confidence.</p>
<p>In other words:</p>... | g15120 | [
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<p>When trying to code this in R, I'm getting very confused about what to do. Apologies if my terminology is incorrect but I would be grateful for any advice.</p>
<p><strong>The Problem:</strong></p>
<p>I have been given two normal distributions for the mean and standard deviation of rat weights. So:</p>
<ol>
<li>Th... | g59537 | [
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... |
<p>I have a large number of factors that categorize my numerical observations in different ways and no preconception which if any of these factors may be significantly explanatory, but I have a p-value threshold that I'm obliged to observe. I want to perform an analysis of variance for each factor and then select those... | g15121 | [
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<p>I am validating a logistic regression model. This is the first time i am validating a model. I am using split sampling method. I have split data randomly into two parts - 70% development and 30% validation data sets (70:30). Then i run logistic regression on development data set using SAS and rank their probabilitie... | g15122 | [
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0.02663329988718033,
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0.05794353783130646,
-0.027... |
<p>Has anyone attempted prediction using support vector regression? I'm using LIBSVM, but I'm not sure how to use SVR in either univariate and multivariate time series.</p>
<p>Say we have stock prices for $N$ days. For training inputs, $y$ are the stock prices for $N$ days, but what will we use for $x$? </p>
<ol>
<li... | g59538 | [
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0.0412428118288517,
0... |
<p>Any arbitrary distribution of a multivariate binary variable can be represented as a log-linear model. That is, for $X = (X_1,\dots,X_d)$ a $d$ dimensional binary rv, the distribution can be written as $\log(\text{p}(x)) = \sum\limits_{A\subseteq V} \beta_A (\prod\limits_{i \in A} x_i)$ where $V={1,\dots,d}$. E.g. f... | g59539 | [
-0.00807548314332962,
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... |
<p>In my current analysis, I have not found statistical significance to some of my conditions. So I was wondering how to predict or calculate the effect size with more subjects and items. I have 20 subjects and each have taken 120 items. My dependent variable is Reaction Time (RT) and my independent variables are Relat... | g159 | [
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<p>I have been lately testing the best training period length to perform a forecast.
I have tested it for various days of training period length, among them 60 days and 30 days.
My methodology is quite rigorous. I have the nrmse growth for the 6 hours of forecast for each training period length. The nrmse growth is tel... | g59540 | [
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<p>A stochastic process is composed of a sequence of random variables ordered by time,<br>
and a time series is just a realization of such a process.<br>
The book that I'm reading says:
"if we assume stationarity, then we can get expectation and variance from time series data". </p>
<p>I don't understand this. Doesn... | g13336 | [
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<p>Let's assume I don't know of the existence of clocks, so I want to build a model to predict the current time of day based on a large amount of other things I can measure, for example pressure, temperature, noise, light, and so on. Some of these variables may be directly correlated with time, some may show some sort ... | g59541 | [
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<p>I would appreciate your help with this problem. I am trying to replicate <a href="http://www.bankofengland.co.uk/publications/Documents/externalmpcpapers/extmpcpaper0031.pdf" rel="nofollow">this study</a> which is about finding the optimal level of bank capital. All this is done using Stata. The only difference i... | g59542 | [
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<p>I have an implementation of an MCMC algorithm (Metropolis-Hastings and Adaptive Metropolis-Hastings) that I want to modify to suit my needs (it's pyMC, if anyone is interested on the details). </p>
<p>My problem is that the parameter space for my model is very high (10-20 parameters), so the burn-in period is cruci... | g44426 | [
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<p>I have 60 apps. For each app, I look at 10 review of that app, and count how many of the reviews say the app is unreliable. Let $X_i$ denote the number of such reviews, for the $i$th app. I want to check whether the reviews seem to be pretty consistent for each app. For instance, if one review says the app is un... | g59543 | [
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<p>I have reactions times in a no-normal distribution, so I am using logarithms.
Which can be the best way to estimate a regression?
Later, I would like to plot the results according to the age of my subjects.</p> | g59544 | [
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... |
<p>I normally use MATLAB, or JMP but right now am working with R.</p>
<p>I have ~150 dimensional data with a few hundred thousand rows. Some of the columns are non-informative, they only have one value. This makes some of the descendants of "pairs" to fail. </p>
<p>I wish that I could say "pairs(mydata)" but that ... | g59545 | [
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... |
<p>One criterion to access a confidence interval is that the smaller its area, the better.</p>
<p>For hypothesis testing, I was wondering if it is also that the smaller the area of the acceptance region, the better?</p>
<p>When we pursue maximum power while restricting type I error to be no more than the significance... | g59546 | [
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<p>I want to test existence of correlation between two time series but I suspect that there would exist only one way correlation. By one way, I mean that changes in Series A should bring about a change in Series B, but the converse may not be true.
Do any tests cater to this situation?</p> | g59547 | [
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<p>I have this dataset of flows:</p>
<pre><code>Source entity | Dest entity | Traffic | Cost | Source location | Dest location | Direction | more independent variables (mostly nominal)
</code></pre>
<p>There is also a unit price ($/unit traffic) of each entity which comes from a discrete set <code>{p1,p2,p3}</code> a... | g59548 | [
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<p>If I have many covariates $X_1, X_2, ... ,X_{15}$ in a linear regression model, how do I determine which two-way interactions to include? Obviously there would be too many potential models to do a best subset regression. Should I fit all the two-way interactions and do a stepwise selection?</p> | g59549 | [
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<p>I have initially run a 2x2x2 Anova and found some significant interaction between the independent variables. I then ran a ANCOVA where I added a covariate. I am confused with how to interpret the output from the ANCOVA as the significant interactions that I found with the ANOVA are now insignificant in the ANCOVA.</... | g38163 | [
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<p>I am trying to isolate the important predictors for my response variable "Y". I know that "TL" (which is an individual level predictor) affects "Y", and now I want to determine if adding the site level predictors "PC1" and "PC4" (both continuous variables) improve the fit of the model.</p>
<p>The data looks like th... | g42324 | [
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<p>I have a research design with a mediation effect between 3 variables over a period of 5 years (panel data). And I would appreciate it if you can provide advice for analysis. </p>
<p><strong>the independent variable</strong> = CEO
which include the eduation(level of education: PHD, MSC, etc), workexperience info (w... | g59550 | [
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<p>Spectral leakage is obviously a function of several factors, including its underlying algorithm, precision of variables, etc.</p>
<p>Is there a body of work that explores the behavior and attempts to characterize the noise in spectral leakage? Both frequentist and Bayesian approaches?</p> | g42345 | [
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<p>I read a lot of forum to understand this, but I'm only more confused. I have a database with some comorbidities and I want to see if they could be divided in groups. I did a cluster analysis and a factor analysis and the results are similar. The difference is only in one comorbidity that is in another group. After I... | g59551 | [
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<p>I have a problem making time series predictions with SVM and Matlab. I tried to solve the problem by myself in several ways without success.</p>
<p>I downloaded, compiled and installed LibSVM scripts for Matlab. But I don't know how to format my data in input. I mean, I have a time series that is an array of values... | g59552 | [
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<p>First, I am no expert but I am analyzing some marketing data. I have information on two versions of the same site, and I have data on the number of times people filled out a form on each version of the site. I want to know if one of the site variation performs better at generating more filled out forms.</p>
<p>Samp... | g59553 | [
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<p>The textbook examples of metaregression I demonstrate how to combine coefficients when the dependent variable has the one distribution (for instance, exclusively binomial or exclusively continuous). </p>
<p>Is there a method of combining regression coefficients for a meta-regression when the dependent variables are... | g15138 | [
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<p>I am trying to implement the Kernel Ridge Regression algorithm but I am getting some quite strange results. I am afraid that I have made some silly mistakes, so I need your help to find out how to fix them. I quote my code bellow. All suggestions are welcome.</p>
<pre><code>function [MSE_train_mean,MSE_train_std,MS... | g59554 | [
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0.021354... |
<p>Let $X_1, X_2,\cdots,X_n$ be a random sample from the distribution with the p.d.f $$f(x)=\frac{1}{\beta -\alpha},\alpha<x<\beta $$ where $0<\alpha<\beta<\infty$. Obtain the minimum variance unbiased estimators of $\frac{\alpha+\beta}{2}$ and $\beta-\alpha$.</p>
<p>Here I try to use Rao Blackwell Meth... | g15140 | [
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0.... |
<p>are there any measures of similarity or distance between two symmetric covariance matrices (both having the same dimension)?</p>
<p>I am thinking here of analogues to KL divergence of two probability distributions or the Euclidean distance between vectors except applied to matrices. I imagine there would be quite a... | g59555 | [
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<p>I'm trying to fit a basic measurement error model (from Wansbeek and Meijer pg. 191), using a Bayesian latent variable model. The model appear to converge, but on the wrong answer. I've tried all kinds of variations, and can't get it to work. Why?</p>
<p>Here's the setup: We wish to regress y ~ chi. Unfortunatel... | g59556 | [
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... |
<p>I've got a dataset of demographic details of store customers and which store they (most frequently) visit. <strong>I would like to categorize the stores based on their customers.</strong> </p>
<p>To clarify: The issue here is to create clusters of shops, on the basis of the characteristics of the customers who ha... | g59557 | [
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<p>I have read that the k-means algorithm tries to minimize the within cluster sum of squares (or variance). With some brainstorming, a question popped up. Why is it that k-means or any other clustering algorithm that has <strong>within cluster variance</strong> as its objective to minimize, chose this as the objective... | g40294 | [
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0.043... |
<p>I have developed three a-priori candidate models that represent factors at three separate spatial scales. A factor in one model is correlated with a factor in another model. (there are debates in the literature about which factor is most influencing the independent variable, and I do not want to draw conclusions ab... | g59558 | [
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<p>I have been using linear Kalman Filters for several different applications. I wrote the implementation from scratch and it follows <a href="http://www.cs.unc.edu/~welch/media/pdf/kalman_intro.pdf" rel="nofollow">Welch & Bishop</a> verbatim in the simplest way.</p>
<p>I have also heard of implementations that em... | g44471 | [
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<p>One of the problems I've always had with mixed models is figuring out data visualizations - of the kind that could end up on a paper or poster - once one has the results.</p>
<p>Right now, I'm working on a Poisson mixed effects model with a formula that looks something like the following:</p>
<p><code> a <- glm... | g44472 | [
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<p>I would like to perform fuzzy clustering on a data set $\boldsymbol{X}$ that contains missing elements. The fuzzy clustering algorithm requires the computation of covariance matrix $\boldsymbol{C}$ of the distance matrix $d_i = \boldsymbol{x}_i - v_j$ where $\boldsymbol{x}_i$ is a row vector from $\boldsymbol{X}$ an... | g59559 | [
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-0.004053855314850807,
0.013903179205954075,
0.006018247455358505,
-0.010828632861375809,
-0.010514819994568825,
-0.026111511513590813,
0.0398821160197258,
-0.0359296090900898,
0.024073919281363487,
-0.015389327891170979,
0.007035849150270224,
0.02279619313776493,
0.00... |
<p>I have my jags output object. In order to understand how MCMC coda chains work, I tried to see if first iteration in each MCMC chain is equal to the initial values supplied. And it is different! The initial value is not there! Is it an error?</p>
<p>Note that I specified burnin = 0 for this purpose.</p>
<p>How I r... | g44474 | [
-0.0012444629101082683,
-0.08080322295427322,
-0.000020045201381435618,
-0.08985073119401932,
0.057833801954984665,
-0.06845501810312271,
0.019887764006853104,
-0.01919187419116497,
-0.0952429324388504,
-0.02510088123381138,
-0.05562019348144531,
0.06334775686264038,
0.017324933782219887,
... |
<p>In an assignment, I am provided with the following output from R:</p>
<pre><code>> summary(myfit)
Call:
lm(formula = Blood_pre ~ Heart_wt)
Residuals:
Min 1Q Median 3Q Max
-41.655 -29.796 -8.198 27.425 48.161
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) ... | g44476 | [
-0.0031766497995704412,
-0.0689808800816536,
-0.023861344903707504,
-0.01744488812983036,
-0.04733394831418991,
-0.041615188121795654,
-0.0009052628884091973,
0.007869255729019642,
-0.047524724155664444,
-0.022393258288502693,
-0.050744980573654175,
0.09315618872642517,
0.0072977798990905285... |
<p>I'm wondering if someone is familiar with the NLMEFITSA algorithm in matlab. This algorithm gives me as result the fixed effects parameters (beta) for a mixed effects model as well as their covariance matrix (psi), but it also gives me, in the "stats" struct, one covariance matrix called "covb" I know this one has t... | g59560 | [
0.04320288449525833,
-0.0803423598408699,
0.0016389023512601852,
-0.035933054983615875,
0.011493081226944923,
0.029202431440353394,
0.02962426096200943,
0.03979312255978584,
-0.06410524994134903,
-0.015977341681718826,
-0.006764305755496025,
-0.01854240521788597,
0.01889493130147457,
-0.01... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/1815/recommended-books-on-experiment-design">Recommended books on experiment design?</a> </p>
</blockquote>
<p>I will be working with three treatments of egg replacers in bakery applications and would like... | g49563 | [
0.016682729125022888,
0.061115384101867676,
0.007832713425159454,
-0.006465421058237553,
-0.024968059733510017,
-0.05282247066497803,
-0.004552952013909817,
0.03560972213745117,
-0.024338938295841217,
0.024202002212405205,
-0.002203228184953332,
-0.0209041815251112,
0.027449477463960648,
0... |
<p>I've been doing a bit of research into bootstrapping as I've been told one method of performing it, and this seems to differ from what I can find in other sources.</p>
<p>I have a sample, and want to estimate the mean or median. I generate 1000 resamples, without replacement, calculating the mean/median for each. B... | g37904 | [
-0.0319933257997036,
-0.020642992109060287,
0.0027148863300681114,
-0.021860074251890182,
-0.020961768925189972,
0.012609217315912247,
0.009836219251155853,
0.023538080975413322,
-0.06059947609901428,
-0.03354676440358162,
0.0023746860679239035,
-0.011867435649037361,
0.025404643267393112,
... |
<p>Suppose you want to find clusters based on a set of variables $Y$, and that you want to estimate the effects of some variables $X$ on membership in those clusters. Here is how I am doing it now.</p>
<p>Step 1: Perform model-based clustering on the variables $Y$ (using the <code>mclust</code> package for this).</p>
... | g59561 | [
0.03934920206665993,
-0.05014043673872948,
-0.018348943442106247,
0.0300605446100235,
-0.00016967968258541077,
-0.11381810903549194,
-0.04816773533821106,
0.035919662564992905,
-0.03599487617611885,
0.010162212885916233,
-0.007022805046290159,
0.011290740221738815,
0.06432916224002838,
0.0... |
<p>I have some survey data from employees in different companies and I would like to perform a regression with company-level variables (based on employee perception) as both the dependent and independent variables. I am wondering which strategy to use - straight OLS, hierarchical linear modeling, or mean aggregation ac... | g59562 | [
0.05551636591553688,
-0.015141697600483894,
-0.037268176674842834,
-0.007018298376351595,
-0.014435598626732826,
0.0072477106004953384,
-0.015286778099834919,
0.000829781754873693,
-0.0400380901992321,
-0.00287248776294291,
0.07372111827135086,
0.05574684217572212,
0.03917938098311424,
0.0... |
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