question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>In <a href="http://www-stat.stanford.edu/~tibs/ElemStatLearn/">ESL</a>, Section 9.7, there is a paragraph stating that the computation time of a split in the growing of a classification (or regression) tree <em>typically</em> scales like $p N \log N$ where $p$ is the number of predictors and $N$ is the number of sam... | g15247 | [
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<p>I am fitting a 3-level model in Bugs. The data are in long format. The data consists of 885 Treatments in 1:3 COURSEs of treatment in 108 Patients (MRNs).</p>
<pre><code>model{
for(DMRN in 1:NMRN) {
RMRN[DMRN] ~ dnorm(meanMRN[DMRN], TMRN)
meanMRN[DMRN] <- intercept
for(DCOURSE in SMRN[DMRN]:(SMRN[DMRN+1... | g37926 | [
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<p>I am trying to decide if zero inflated poisson is appropriate for my data vs. a Poisson hurdle model.</p>
<p>In background reading between the two I've run across a statement saying that a zero inflated model attempts to distinguish between true zeros and excess zeros. I'm having a problem understanding what is the... | g59621 | [
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<p>I have some score values that are output from a program. There are about 10 such values. The data set is a measure of the "quality" of a speech waveform received over a mobile phone and landline channel. The waveform is passed through an algorithm and a score is received of its quality relative to a "golden" wavefor... | g15252 | [
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<p>I have data from two different sets (each with fields named <em>Mobile</em> and <em>Landline</em>). There are about 5 elements from each field in each set. They go something like so: </p>
<p>Set A: </p>
<pre><code>Mobile: 45 61 78 65 71
Landline: 56 71 75 98 12
</code></pre>
<p>Set B: </p>
<pre><code>Mobile... | g43199 | [
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<p>I generate 3 or 4 lists (really tables? but read.csv gives me lists) all with a similar Time column on the far left. I have to format the time column since they all format it their own way (some including dates etc.), now I'm wondering if I should format it in # seconds instead of HH:MM:SS.mm. I thought I would ment... | g15253 | [
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<p>My data best fit is the 3 parameter inverse gamma distribution(thereby giving a, b, y variables with each event having a specific value for each variable) but I am not sure how to create a general equation for these equation...do I average each variable? or is there some other method?</p>
<p>I've seen one research... | g59622 | [
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<p>SUR means Seemingly unrelated regression, and SEM means simultaneous equation model.
What is the difference between them? </p> | g15257 | [
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<p>If parameter p ~ Beta(1,1), this would reflect we know nothing about parameter $p$. Generalizing to the multivariate case, how would the same be said about a vector $P$ of probability parameters $p_i$? </p> | g59623 | [
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<p>The setup for this question is as follows. Lets say we have count and denominator data for six different study sites, by month for 12 months. They're all using a uniform diagnostic standard at the time, so theoretically their counts are all roughly the same. The goal of this is to get an estimate of the typical mont... | g59624 | [
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<p>I am performing (rare events) logistic regression analyses in R and want to test several categorical variables consisting of more than two classes. I understood that I can do this by using factor(). However, I am not sure what to do in case some, but not all categories are significant. Can I (1) just leave out the o... | g59625 | [
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<p>I am interested in calculating the power for the beta effect size, for example</p>
<pre><code>Call:
lm(formula = log1p(y) ~ x)
Residuals:
Min 1Q Median 3Q Max
-0.5684 -0.1881 -0.0413 0.1494 1.2312
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 0.59725 ... | g59626 | [
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<p>I use "boot" package to compute an approximated <strong>2-sided</strong> bootstrapped p-value but the result is too far away from p-value of using t.test. I can't figure out what I did wrong in my R code. Can someone please give me a hint for this</p>
<pre><code>time = c(14,18,11,13,18,17,21,9,16,17,14,15,
... | g49844 | [
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<p>So I've been digging into the math of correlations and covariances and one of my articles mentioned finding the covariance by using the common component, specifically with regards to, say, $cov(A + B, C + B)$.</p>
<p>I know that
$$Cov(A + B, C + D) = cov(A, C) + cov(A, D) + cov(B, C) + cov(B, D)$$
but it seems lik... | g59627 | [
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<p>I have a couple of questions related to estimation of high-dimensional precision matrix (inverse of the covariance matrix) in the case where p is close to 100 and n < p. As a measure of estimation accuracy I am calculating a 'relative squarred error' defined in the following manner:
$$
RSE(\Sigma^{-1},\hat{\Sigm... | g14375 | [
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<p>Are there ways to <strong><em>estimate</em></strong> the finite sample bias with instrumental variables? I guess this would be conditional on assuming some structure to the problem and also would involve simulation, but, at least in applied econometrics papers, I have never seen people do it.</p>
<p><em>PS: If poss... | g3360 | [
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<p>Assume a true population of size N consisting of red and blue balls, where p represents the frequency of red in the population and q represents the frequency of blue in the population.</p>
<p>Let's say that N=1000, p=0.7 and q=0.3.</p>
<p>If I take a sample from the population and observe the frequencies in the sa... | g59628 | [
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<p>I'm doing a mixed model analysis of a model with a categorical predictor (using glmer, binomial model). To my surprise, the variance I obtain for the intercept does not change when I change the reference level of this categorical predictor. This goes against my understanding that as the intercept is the log-odd for ... | g15266 | [
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<p>I once read the following statement:</p>
<p>Given the following equation</p>
<p>$ Y_t= c + a Y_{t-1} + \theta_t$</p>
<ol>
<li>If $c\neq 0$, then the t-ratio for testing $H_0 : a=1$ is asymptotically normal. </li>
<li>If $c=0$, then the t-ratio for testing will converge to another nonstandard asymptotic distributi... | g15267 | [
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<p>In addition to <code>proc varclus</code>, <code>randomForest</code>, and assessing multicollinearity among potential predictor variables, I am seeking other methods of variable selection in lieu of using stepwise methods for building more parsimonious binary logistic regression models from a wide array of potential ... | g15433 | [
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<p>Suppose I've a model such as </p>
<p>$Y = \beta_0 + \beta_1 X_1 + \beta_2 X_2 + \cdots + \beta_k X_k + \epsilon$.</p>
<p>Now, there's high correlation between $X_1$ & $X_2$ (say over 60% but below 75%). Does that means this model has multicollinearity problem? Is there any relationship between highly correlate... | g49567 | [
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<p>I am trying to fit some binomially distributed data to a model. There is a reasonable systematic error associated with the measurements. This uncertainty comes from imperfect theoretical knowledge of one of the parameters assumed by the model. I can calculate this number by 3 or 4 different methods and model the unc... | g15270 | [
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<p>Suppose the set-up is that of typical logistic regression with individual-level covariates and binary outcomes, but instead of observing those outcomes, one only observes the proportion of 'successes' among known groups of the individuals. So the outcome is an aggregation of individual-level outcomes, but the indiv... | g59629 | [
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<p>I have objects from two class -- 11 objects in each class. Where each object has 3 features. with such small dataset, does it make any sense to train & use Naïve Bayes to classify new objects (test cases) ? </p> | g15434 | [
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<p>I have what appears to be a relatively simple question, but am struggling to understand how to go about answering it.</p>
<p>The general question is as follows:</p>
<p>What is the expected value of $S_{I}$, where:</p>
<p>$S_{I} = S$ if $S <3000 $</p>
<p>$S_{I} = 3000$ if $S >3000$</p>
<p>where $S$ is a co... | g15278 | [
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<p>I would like to pose this question in two parts. Both deal with a generalized linear model, but the first deals with model selection and the other deals with regularization.</p>
<p><b>Background:</b> I utilize GLMs (linear, logistic, gamma regression) models for both prediction and for description. When I refer to ... | g37926 | [
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<p>I am using the R package <em>penalized</em> to obtain shrunken estimates of coefficients for a dataset where I have lots of predictors and little knowledge of which ones are important. After I've picked tuning parameters L1 and L2 and I'm satisfied with my coefficients, is there a statistically sound way to summariz... | g59630 | [
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<p>I'm working on a little project involving the faces of twitter users via their profile pictures.</p>
<p>A problem I've encountered is that after I filter out all but the images that are clear portrait photos, a small but significant percentage of twitter users use a picture of Justin Bieber as their profile picture... | g59631 | [
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<p>I am totally confused: On the one hand you can read all kinds of explanations why you have to divide by n-1 to get an unbiased estimator for the (unknown) population variance (degrees of freedom, not defined for sample size 1 etc.) - see e.g. <a href="http://en.wikipedia.org/wiki/Bessel%27s_correction" rel="nofollow... | g59632 | [
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<p>Given a panel of countries over time, a fixed effects estimator makes sense to control for country-specific effects. My intuition tells me that if the dependent variable is correlated with lags of the independent variables, then bias will be introduced into the estimator. However, I'm having difficulty rigorously un... | g59633 | [
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<p>I have made a heatmap based upon a regular data matrix in R, the package I use is <code>pheatmap</code>. Regular clustering of my samples is performed by the <code>distfun</code> function within the package. </p>
<p>Now I want to attach a precomputed distance matrix (generated by Unifrac) to my previously generated... | g59634 | [
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0.06795938313007355,
-... |
<p>I am running a logistic regression with customer event data with multiple predictors.
However, one variable is extremely important, alone predicting 60% of the customers for the event. When this main predictor is included in the model, other predictors add very little to prediction over and above this main predictor... | g15283 | [
0.0507027842104435,
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<p>HI there: I have a one likert item I would like to analyze. I know that most scales require multiple likert items, but this is just an exploratory exercise of an existing survey. It's out of my control.</p>
<p>When I treat the likert categories (strongly support - support - oppose -strongly oppose) as a numeric va... | g27721 | [
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<p>I am a complete beginner at using R but have recently been running some code that a colleague gave me to connect R to a Microsoft Access database and pull out specific records. However a few days ago it stopped running. The error appears when trying to connect to the database (using the RODBC package) and import the... | g59635 | [
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<p>I'm working on the dataset with lots of NA values with sklearn and pandas.DataFrame. I implemented different imputation strategies for different columns of the dataFrame based column names. For example NAs predictor 'var1' I impute with 0's and for 'var2' with mean.</p>
<p>When I try to cross validate my model usin... | g20592 | [
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<p>I have a set of objects, each of which can be assigned to another object within the set in a many-to-one, directional assignment, like a vote. Objects cannot be assigned to themselves reflexively, but they can be in an unassigned state ("not voting"). So for example, the set <code>{A, ..., Z}</code> plus relation co... | g59636 | [
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<p>When computing the difference between means I can resolve a new mean, variance, standard error of the mean, and margin of error, but is there a way to compute a new/composite sample size value?</p>
<p>I ask because I use the difference between means as a way to calibrate the mean and later when comparing other cali... | g15292 | [
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<p>In a field experiment involving crops, what is the difference in considering block as random or otherwise as fixed factor?
As far as I understood, random means that conclusion can be extended to other levels not included in the study; fixed factor on the contrary restricts the analysis only to a specific experiment.... | g59637 | [
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<p>I have a problem. I am creating a wide barplot (50x grouped 4 columns) and printing it to ps. However the figure does not fit to printed ps - the x axis goes out of a page. It would fit if only I could remove a large left margin on yaxis. But I have no idea how to move picture left and reduce the margin. I have spen... | g37552 | [
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<p>I am trying to understand question 9-1 on p.334 in Cameron & Trivedi (<a href="http://www.centroportici.unina.it/centro/Cameron&Trivedi.pdf" rel="nofollow">link</a>) where I have to calculate the bias of a kernel density estimate at $x=1$ and $n=100$, where we assume that the underlying density is standard n... | g408 | [
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<p>After using <code>ezANOVA</code> as my primary way of specifying mixed ANOVAs, I've hit a stumbling block when it come to adding a covariate to the model. I am using an ANCOVA in order to determine if there is a developmental trajectory in my data; namely, I need to be able to see the F-statistic and p-values for in... | g59638 | [
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<p>A group of raters (about 20) will be watching a series of videos and will be classifying them into 4 categories. I will be running a Fleiss' kappa to measure the agreement. How does one compute for the sample size to arrive at 0.8 power, 0.05 alpha? Also, will that sample size be the number of videos to be evaluated... | g59639 | [
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<p>I'm struggling with analysing my survey results in SPSS and really hoping you can help.
I surveyed occupational therapists around aspects of their practice, on a national level and the seniority of my sample were made up of the following:</p>
<p>Band 5's- 8
Band 6's- 25
Band 7's-35
Band 8's- 6</p>
<p>This dist... | g59640 | [
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<p>If $X = \begin{pmatrix} X_{1} \\ X_{2} \end{pmatrix}$ (with $X_{1},X_{2} \in \mathbb{R}^{n}$) follows a gaussian distribution $\mathcal{N}(\mu,\Sigma)$. What is the distribution of $\Vert X_{1} \Vert^{2}$ (where $\Vert \cdot \Vert$ denotes the euclidean norm on $\mathbb{R}^{n}$). </p>
<p>If $\Pi=\left( \begin{array... | g15296 | [
-0.0053797936998307705,
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<p>I collect some data out of a survey. And now I want to analyse the answers. The question consists of needed features in a Tool.
These features can be rated from 1 to 5.</p>
<p>Table of the features an their rating:</p>
<pre><code>F.1 F.2 F.3 F.4 F.5 F.6
5 4 5 5 5 4
4 4 5 5 3 5
5 3 4 4 2... | g59641 | [
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0.043395835906267166,
0.05636967346072197,
... |
<p>I am doing multiple comparisons with several thousand independent alternatives. None are statistically significant when Bonferroni corrected; however, many more are significant when uncorrected than expected by chance, so I compute this probability to show that most of my low p-valued tests are true. </p>
<p>Can an... | g59642 | [
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0.00330263189971447,
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... |
<p>I am trying to make sense of the spearman test I am getting as a result of using <a href="http://stat.ethz.ch/R-manual/R-patched/library/stats/html/cor.test.html" rel="nofollow">cor.test on R package</a>. <a href="http://geography.uoregon.edu/geogr/topics/interpstats.htm" rel="nofollow">This page</a> seemed to me to... | g3369 | [
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0.016... |
<p>I have two data sets, one data set contains value in the range of 10,000- 1,000,000 and other data set contains the value between 1,000-10,000. I want to compare the variability means,which data has more variability.</p>
<p>Do I need to first standardized / normalized the data and then compare the variance, but sta... | g59643 | [
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<p>I am carrying out an analysis using a 4$\times$2 crosstab. I found an overall significant difference but I would like to find if there are significant differences among the 4 groups.
Is there a way to carry out these multiple comparisons?</p> | g59644 | [
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0.037985075265169144,
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<p>I have around 5 million observations of weights of patients over the course of a year. Some patients have one measurement during that year and others have 30-40 (or more). I've noticed a great deal of variability. For example, on one day a patient will have a recorded weight of 120 lbs and the next a recorded wei... | g59645 | [
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<p>Consider the following cell biology experiment. We are comparing $T$ different treatments of cultured cells. Each treatment $t$ is replicated in several <em>(microtiter) wells</em>, indexed by the variable $w \in \{1, 2, \cdots, W\}$. To measure the response to the treatment in well $w$, a total of $F_w$ non-over... | g59646 | [
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0.001777384546585381,
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<p>I have monthly precipitation for one site over a 35 year period. I would like to test if the total precipitation for a specific year is equal to the mean total precipitation for the rest of the period of record. In addition, I would also like to split the data into wet season [Nov-April] vs dry season [May-Oct]. </... | g59647 | [
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0.03854283690452576,
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0.045026879757642746,
... |
<p>This has come up in a few questions now, and I've been wondering about something. Has the field as a whole moved toward "reproducibility" focusing on the availability of the original data, and the code in question?</p>
<p>I was always taught that the core of reproducibility was not necessarily, as I've referred to ... | g15306 | [
0.02715885266661644,
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0.00017627517809160054,
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... |
<p>I'm running Linear Discriminant Analysis on a dataset and then performing clustering on it. I'm reducing it to dimensions 2,6,10. On comparing metrics like Accuracy and Normalized Mutual Information, the values at dimension 6 reduce by almost half. While at dimension 10 it is close to dimension 2. I'm not able to co... | g44644 | [
0.04583001136779785,
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0.02984437346458435,
0.04690573737025261,
0.08215709775686264,
0.030190... |
<p>I have got an important question concerning principal axis factor analysis:
Is it possible to extract the factors according to the MAP-criteria, or is this criteria only valid when using principal component analysis?</p> | g59648 | [
0.005065671168267727,
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0.029848922044038773,
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... |
<p>There have been studies done that report that heterosexual individuals are somewhat more likely to be right-handed than homosexual individuals. Does it necessarily follow that left-handed individuals are more likely to be homosexual than right-handed individuals? I feel like this is a mathematical concept I can't ... | g15307 | [
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0.012208045460283756,
0.01632000133395195,
0.010753119364380836,
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<p>The table below displays the number of accidents recorded at a particular intersection
during each of the four seasons last year:</p>
<pre><code> Season Spring Summer Fall Winter
no. of accidents 13 24 18 25
</code></pre>
<p>We would like to conduct a chi-square goodness-of-fit test to d... | g59649 | [
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0.00013992135063745081,
0.048377711325883865,
... |
<p>I have R-scripts for reading large amounts of csv data from different files and then perform machine learning tasks such as svm for classification.
<br>
Are there any libraries for making use of multiple cores on the server for R.
<br>
or
<br>
What is most suitable way to achieve that?</p> | g44649 | [
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<p>I am building a web application for used book trading and I am adding a feature to propose other book that would be interesting when they view an offer.</p>
<p>Currently the data that I store are the following (they are updated each time someone visit an offer) :</p>
<p>ISBN (book of the offer)<br>
SessId (a uniqu... | g59650 | [
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0.04866333305835724,
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0.... |
<p>I could use some guidance about presenting some data. </p>
<p>This first plot is a case-control comparison for the cytokine IL-10. I've manually set the y axis to include 99% of the data.</p>
<p><img src="http://i.stack.imgur.com/mm8Tk.jpg" alt="IL-10 With Manual Y axis"></p>
<p>The reason I set this manually is ... | g59651 | [
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0.041833337396383286,
0.007973628118634224,
0.020992374047636986,
... |
<p>I am not a statistician but my research work involves statistics (analyzing data, reading literature, etc.). I was again reminded from a comment on one of my questions posted <a href="http://stats.stackexchange.com/questions/80789/alternative-to-multiple-fishers-exact-tests">here</a> that there are some common words... | g59652 | [
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0.... |
<p>I am trying to use the dismo package to build up a BRT model with presence-only data. I have randomly sampled 10 000 background data. My questions is:
do I need to run 10 (or 5) replications of the brt model on the dataset like a conventional cv procedure? For example, for each replication, 60% of the presence data ... | g59653 | [
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0.04514751955866814,
0.02... |
<p>I want to analyze fish aquaculture data comparing growth rates by state and controlling for tank effects as a mixed effect. I will use the equation</p>
<p>$$
w = aL^b
$$</p>
<p>but I want <code>b</code> to be a function of state of origin. I can do this using the <code>nlme</code> function in the <code>nlme</code>... | g59654 | [
0.0053361100144684315,
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0.009607543237507343,
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0.061529699712991714,
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-0.010661431588232517,
0.014559327624738216,
0.03677673265337944,
0.12173277139663696,
0.0... |
<p>For some measurements, the results of an analysis are appropriately presented on the transformed scale. In most of the cases, however, it's desirable to present the results on the original scale of measurement (otherwise your work is more or less worthless). </p>
<p>For example, in case of log-transformed data, a p... | g59655 | [
-0.009026017040014267,
0.00848352164030075,
-0.011884811334311962,
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0.03731901943683624,
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0.005892117507755756,
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-0.03021690621972084,
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0.009314339607954025,
0.0406523235142231,
-0.0... |
<p>After reading a dataset:</p>
<pre><code>dataset <- read.csv("forR.csv")
</code></pre>
<ul>
<li>How can I get R to give me the number of cases it contains?</li>
<li>Also, will the returned value include of exclude cases omitted with <code>na.omit(dataset)</code>?</li>
</ul> | g44660 | [
0.03841114416718483,
0.004841385409235954,
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0.0009335681679658592,
0.035905349999666214,
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-0.05599568039178848,
-0.00393634382635355,
0.0031937211751937866,
0.08691596239805222,
... |
<p>I am trying to analyse some data using a mixed effect model. The data I collected represent the weight of some young animals of different genotype over time.</p>
<p>I am using the approach proposed here:
<a href="http://blog.gribblelab.org/2009/03/09/repeated-measures-anova-using-r/" rel="nofollow">http://blog.grib... | g43735 | [
0.0008109947666525841,
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0.039780937135219574,
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0.0024417294189333916,
0.006310171447694302,
... |
<p>Well, I'm an engineer by day. Although most of my work revolves around modeling, we generally do pretty basic stuff. An "Advanced" model would be a monte carlo simulation validated using R2 tests. </p>
<p>Currently, in my field, there is a lot of research using Logistic and bayesian analysis. </p>
<p>My question i... | g59656 | [
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0.0926254466176033,
-... |
<p>I am in doubt about which type of test I could performed on my data. </p>
<p>I have a data frame of the following type:</p>
<p>contig, pos, A1, A2, Ctrl_A1, Ctrl_A2, Treat_A1, Treat_A2</p>
<p>comp1293557_c0_seq1, 284, T, C, 38, 20, 43, 17,</p>
<p>comp1478014_c0_seq1, 252, A, G... | g59657 | [
0.024487221613526344,
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0.013191885314881802,
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0.04724220931529999,
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0.04004347696900368,
0.07954913377761841,
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0.02102159522473812,
0.03822261840105057,
0.006170217413455248,
0.019425811246037483,
0.02146... |
<p>Let
$Z_1,Z_2 $ i.i.d. standard normal </p>
<p>$$
X(t) =
\begin{cases}
0, & \text{if } t<Z_1, t<Z_2\\
1, & \text{if } Z_1\le t <Z_2 \text{ or } Z_2\le t <Z_1 \\
2, & \text{if } t\ge Z_1, t\ge Z_2
\end{cases}
$$</p>
<h2>Asked</h2>
<p>$E[X(t)X(t')]$</p>
<h2>Approach</h2>
<p>$E[X(t)X(t')] =... | g15322 | [
-0.023329339921474457,
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0.044184278696775436,
0.01000925898551941,
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0.05228745937347412,
0.03831060230731964,
-0.03601597994565964,
0.05176752060651779,
0.015071948990225792,
0.045334190130233765,
0.0282270610332489,
0.00561... |
<p>Suppose, there is some classification/regression problem. It seems for me, that sometimes division of training sample by some feature (or maybe by some other reasonable method, say feature generation and then devision by it.) and then fitting two models is better then fitting one model. For example, you anylize life... | g21732 | [
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0.03762635216116905,
0.003861275501549244,
0.07002311944961548,
0.00896... |
<p>I should do Variance Ratio Test on two vectors in R.</p>
<p>I found the a builtin function: <strong>var.test</strong> but I don't know how to interpret its results (p-value).</p>
<p>What result do I have to wait if these two vectors have constant variance? I think I also could use it to understand if the ratio is ... | g15323 | [
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0.07479754090309143,
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<p>I have 5 emerging market foreign exchange total return series, for which I am forecasting single period future returns (1 year). I would like to construct a Markowitz mean variance optimized portfolio of the 5 series, using historical variances and covariances (1) and my own forecast expected returns. Does R have an... | g15324 | [
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0.0004095142357982695,
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0.022743063047528267,
... |
<p>I have some code that looks for clusters in x,y data. To check the number of clusters I use, I want to get the BIC. This is not possible (easily) using <code>kmeans()</code>, and so I've switched to the <a href="http://cran.r-project.org/web/packages/mclust/index.html" rel="nofollow">mclust package</a>. Specifically... | g59658 | [
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0.0019909185357391834,
0.01238249707967043,
0.04953290522098541,
0.07805550843477249,
0.03... |
<p>I've been using R to run GLMs with the logit link to compare clutch sizes (a binomial data set) and proportional data among several years. I now need to compare 2 groups of years (good years and poor years) between 2 sites for the same data.</p>
<p>I am not interested in any interactions between year-type (good or ... | g43821 | [
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-0.018960101529955864,
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0.004076470620930195,
0.06331790238618851,
-0.... |
<p>I am building a big data frame by merging the content of a few files together. These files share the same columns layout.</p>
<pre><code>c = read.delim('bigfile1.txt')
c1 = read.delim('bigfile2.txt')
c2 = read.delim('bigfile3.txt')
ctmp1 = merge(c, c1, all=TRUE)
ctmp2 = merge(ctmp1, c2, all=TRUE)
</code></pre>
<p... | g59659 | [
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0.007645783480256796,
0.047100551426410675,
-0.012808920815587044,
0.008980680257081985,
-0.0... |
<p>Lets say I have a dataset where I want to estimate the relative risk of outcome X based on a binary treatment level Y, using PROC GENMOD to fit a logistic regression model. I can use the BAYES statement to have SAS 9.2 produce nice, MCMC-based prior distributions for my data.</p>
<p>My question is, what if I then w... | g15326 | [
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0.04608893394470215,
0.07156947255134583,
0.04832378402352333,
0.003... |
<p>I have 2 dependent variables (DVs) each of whose score may be influenced by the set of 7 independent variables (IVs). DVs are continuous, while the set of IVs consists of a mix of continuous and binary coded variables. (In code below continuous variables are written in upper case letters and binary variables in lowe... | g44675 | [
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-0.009318013675510883,
-0.03965764865279198,
0.036231208592653275,
0.02074521966278553... |
<p>I have two samples $ X_1,\cdots,X_n $ and $ Y_1, \cdots, Y_n $, and would like to re-order them so that they have a pre-specified value of rank correlation such as Kendall's tau.</p>
<p>I do know that there are many ways to generate two samples that have a specific Pearson's correlation coefficient, but don't know ... | g613 | [
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0.006119066849350929,
0.03890417143702507,
0.02187245711684227,
... |
<p>I'm having trouble understanding why calculating the standard error of the mean:
$$
\widehat{SE} = \frac{\widehat{SD}}{\sqrt{n}}
$$
gives me a different SE estimate than the SE estimate of a coefficient from a Gaussian GLM (identity link function) in R. Can someone explain why the maximum-likelihood estimators of t... | g14690 | [
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0.012730156071484089,
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0.04905744642019272,
0.... |
<p>I have got two questions on an agricultural field trial that was conducted at two sites in two conscutive years.
Virtually everything was the same in all trials (crop variety, planting density...).
The data permits that all data can be analysed in a joined model. </p>
<p>As there are two questions I open two thre... | g59660 | [
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0.034285563975572586,
... |
<p>I am building a model and I think that geographic location is likely to be very good at predicting my target variable. I have the zip code of each of my users. I am not entirely sure about the best way to include zip code as a predictor feature in my model though. Although zip code is a number, it doesn't mean any... | g59661 | [
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0.0369998961687088,
0.010211821645498276,
0.06989682465791702,
-0... |
<p>I have got two questions on an agricultural field trial that was conducted at two sites in two conscutive years.
Virtually everything was the same in all trials (variety, spacing, planting density...).
The data permits that all data can be analyised in a joined model. </p>
<p>There is another question about the t... | g59662 | [
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0.0697333812713623,
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0.008982245810329914,
0.03645003214478493,
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<p>I'm trying to work out how you do this from first principles. The <a href="http://en.wikipedia.org/wiki/Linear_regression" rel="nofollow">Wikipedia page on linear regression</a> gives me enough to solve it with matrix operations through the origin but I can't find much literature on implementing an algorithm for an ... | g44682 | [
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0.0655691996216774,
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<p>Suppose you have two groups $A$ and $B$ and you want to find the odds ratio of some outcome. How do you denote this odds ratio? Is it just $OR(\text{A} \ \text{and} \ B)$? </p> | g705 | [
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0.007163076661527157,
0.003683499526232481,
0.00... |
<p>I'm comparing two groups A, B after cross tabulating them with cases and controls.</p>
<p>I get a table as such:</p>
<pre><code> Control Cases
A 8 0
B 14 0
</code></pre>
<p>Obviously, I can't do an odds ratio because of the 0's. Doing a Fisher's exact test gives me a p-value of 0.5152 but th... | g59663 | [
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0.03761637955904007,
0.02333112433552742,
0.009544255211949348,
0.014... |
<p>From a large sample of triples $(X, Y, U)$ I need to estimate a function $(x, y, u) \mapsto f(x, y, u)$, such that for each fixed $x, y$, the function $u \mapsto f(x, y, u)$ is a density function; namely, the marginal density function of $U$, given $X = x$ and $Y=y$.</p>
<p>Is there a standard way of doing this? My... | g59664 | [
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0.020471353083848953,
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0.024118557572364807,
0.08407837152481079,
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<p><strong>Should the distribution of composite scores be normal (bell curve)?</strong></p>
<p>The composite scores that I have developed is from a weighting of their separate components. </p>
<p>The component scores are in response to a normal survey (i.e. proper sampling proceedures were used). I have then weighted... | g59665 | [
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<p>I am doing a probit on a binary dependent variable. The binary dependent variable has observed outcomes of 227 successes and 1704 failures. If I run predict after the probit I get probabilities that make sense for each set of observations, but I want to be able to make sense of the beta coefficients that I get fro... | g15337 | [
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0.011278192512691021,
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0.03612184152007103,
0.04588383436203003,
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<p>I have a collection of highly non-normal behavioral variables measured for each animal in a given test. I would like to reduce to 2 or 3 scores to characterize the individual's test using PCA. I see in the literature where others have referenced Multivariate Statistics books to justify using non-normal data for th... | g59666 | [
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0.01080346666276455,
0.01325803343206644,
0.016042383387684822,
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... |
<p>I have a classification process which I test using leave-one-out.</p>
<p>Precisely, how do I compute the standard deviation of the result?</p>
<p>If I compute it normally, I get a very large deviation which makes sense because each test is either 100% or 0%.</p>
<p>What is the accepted convention in this case?</p... | g59667 | [
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0.052014950662851334,... |
<p>I'm trying to gain a better understanding of kmeans clustering and am still unclear about colinearity and scaling of data. To explore colinearity, I made a plot of all five variables that I am considering shown in the figure below, along with a correlation calculation.
<img src="http://i.stack.imgur.com/W5MZJ.jpg" a... | g44686 | [
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0.01280561089515686,
0.07907485216856003,
0... |
<p>I am trying to find a statistical or machine learning tool that replicates this analysis I am doing manually in excel.</p>
<p>Each row in my data set is a user.</p>
<pre><code>User | sites visits | pages viewed | items added to cart | Purchased (1 or 0)
</code></pre>
<p>I set up a pivot table so Purchased is in t... | g59668 | [
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0.03157658874988556,
0.01119545754045248,
0.06227996200323105,
0.0077... |
<p>In canonical correlation analysis where</p>
<p>max { a'COV(X,Y)b / sqrt[a'COV(X,X)a * b'COV(Y,Y)b] }</p>
<p>where U = a'X, and V = b'Y</p>
<p>the standard tools to solve the canonical correlation analysis (MATLAB, R, etc.) yield solutions (as many as min rank of both variables) where</p>
<p>CORR(U1,U2) = CORR(V1... | g59669 | [
0.021235836669802666,
-0.019016919657588005,
0.025276996195316315,
-0.0459020771086216,
0.0066618421114981174,
-0.0018010612111538649,
0.01690995879471302,
-0.006659762002527714,
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0.02211463451385498,
0.01869271695613861,
-0.010606280528008938,
-0.018395038321614265,
0... |
<p>So, I have data set and I calculate the model parameters and errors using statsmodels:</p>
<pre><code>result = sm.OLS(y, X).fit()
result.summary()
</code></pre>
<p>Now, <code>result.mse_resid</code>, <code>result.mse_total</code> provide MSE of the residuals and total mean squared error.</p>
<p>Reading the statis... | g59670 | [
0.018163016065955162,
-0.05532875657081604,
-0.03988032415509224,
-0.02597077190876007,
-0.007903430610895157,
-0.002630458679050207,
0.06117383390665054,
0.06343832612037659,
-0.04727742820978165,
-0.03742417320609093,
-0.023231783881783485,
0.011398687027394772,
0.09623543173074722,
-0.0... |
<p>I am confuse with difference between empirical Bayes method and hierarchical Bayes method. </p>
<p>Take an example (ref : <a href="http://www.cs.cmu.edu/~xuerui/papers/ctr.pdf" rel="nofollow">http://www.cs.cmu.edu/~xuerui/papers/ctr.pdf</a>). </p>
<p>Suppose we have : </p>
<ul>
<li>$C$ is the number of clicks we ... | g59671 | [
0.04215662553906441,
0.00845826230943203,
-0.019659895449876785,
-0.011167222633957863,
0.0419098436832428,
0.02089308388531208,
0.05609213933348656,
0.01119739655405283,
-0.06835851818323135,
-0.020093604922294617,
-0.01020036917179823,
0.06886372715234756,
0.015557918697595596,
0.0228533... |
<p>Hey guys I found one or two papers which use ridge regression (for basketball data). I was always told to standardize my variables if I ran a ridge regression, but I was simply told to do this because ridge was scale variant (ridge regression wasn't really part of our course, so our lecturer skimmed through it).</p>... | g15341 | [
0.05899307131767273,
-0.03948693722486496,
-0.006069839932024479,
-0.08857577294111252,
0.0762486681342125,
-0.0004743929603137076,
-0.04801890254020691,
0.052994254976511,
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-0.005612504202872515,
-0.025006402283906937,
-0.004894495941698551,
-0.021460767835378647,
0.... |
<p>I tried to use the Kernel Density plot method from <a href="http://www.jstatsoft.org/v27/i05/paper/" rel="nofollow">Hayfield and Racine (2008)</a> <a href="http://cran.r-project.org/web/packages/np/vignettes/np.pdf" rel="nofollow"><code>np</code> package</a> for my own data, but somehow ended up with different type ... | g44691 | [
0.03772395849227905,
-0.0015514800325036049,
0.002218486974015832,
-0.033305272459983826,
-0.021770160645246506,
0.047793492674827576,
0.03415747359395027,
-0.06847729533910751,
-0.05926501750946045,
-0.05703310668468475,
0.03562670573592186,
0.006836642511188984,
0.027769342064857483,
-0.... |
<p>I have a database with many attributes. I would like to know which attributes has the minimum variation in the data. Is there some standard technique? It should be like clustering without split records in clusters. I would like to know what the records in particular cluster have in common. </p>
<p>I was going to co... | g59672 | [
-0.008937283419072628,
-0.02063046582043171,
0.001340928371064365,
-0.02012959122657776,
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0.03224535286426544,
0.02860167622566223,
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-0.023365071043372154,
-0.014540174044668674,
0.009363916702568531,
0.04417817294597626,
-0.... |
<p>I guess I understand the equation of the detailed balance condition, which states that for transition probability $q$ and stationary distribution $\pi$, a Markov Chain satisfies detailed balance if $$q(x|y)\pi(y)=q(y|x)\pi(x),$$</p>
<p>this makes more sense to me if I restate it as: </p>
<p>$$\frac{q(x|y)}{q(y|x)}... | g59673 | [
0.03721702843904495,
-0.013863661326467991,
-0.015773441642522812,
0.023822598159313202,
0.03982109948992729,
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0.04704289510846138,
0.015073999762535095,
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-0.01155457179993391,
-0.04223425313830376,
-0.0018960878951475024,
0.011613658629357815,
0.00... |
<p>I have a problem interpreting the notion of "weak exogeneity in a VAR process". Assuming we have the following structural form:</p>
<p>$y_t = b_{12}z_t + \gamma_{11}y_{t-1} + \gamma_{12}z_{t-1} + \epsilon_{yt}$</p>
<p>$z_t = b_{21}y_t + \gamma_{21}y_{t-1} + \gamma_{22}z_{t-1} + \epsilon_{zt}$</p>
<p>Does weak exo... | g59674 | [
0.027855029329657555,
0.03480463847517967,
-0.018046218901872635,
-0.02898048609495163,
0.09917184710502625,
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0.034057408571243286,
0.0071863820776343346,
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-0.0011634501861408353,
-0.0405140146613121,
0.05704686418175697,
-0.03216499462723732,
0.01... |
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