question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have a situation where I have a bunch of noisy observations with known (and normal) sampling error and a non-trivial co-variance structure between the observations. In an uncorrelated setting, I'd generate weights by taking the inverse variance of the observations and calculate the standard error of the mean by ta... | g9789 | [
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<p>I'm having trouble deriving the KL divergence formula assuming two multivariate normal distributions. I've done the univariate case fairly easily. However, it's been quite a while since I took math stats, so I'm having some trouble extending it to the multivariate case. I'm sure I'm just missing something simple.</p... | g67271 | [
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<p>There are several posts on this site talking about the need of normality when interpreting the meaning of the p.value of a linear regression. But not much I think is said about how to deal with non-normal data set. On <a href="http://stats.stackexchange.com/questions/29636/robust-regression-setting-the-limit-between... | g67272 | [
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<p>I would like to perform multiple regression with two variables that have the same unit but have very different gradient lengths. (one has a range from 1-20, the other has a range from 1-40) How do I cope with variables of different lengths in regression? Is centering of the data enough to avoid that the variable wit... | g7073 | [
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<p>I am looking at probability of an event ($E$) for a number of customers. Each customer qualifies for the analysis through a qualifying Action ($A$), and has a finite Duration ($D$) to complete Event. There are a number of interim actions that should have an effect on reaching the Event. Unlike the time-to-event m... | g17381 | [
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<p>Want to see if there is a statistically significant difference between the % of students who did a gap year across 8 different degrees.</p>
<p>$$
\begin{array}{l|r}
\text{Degree} & \text{Gap } [\%] \\\hline\\\hline
\text{Architecture}& 8.82 \\\hline
\text{Biology}& 22.41 \\\h... | g67273 | [
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<p>I've got a dataset on agricultural trials. My response variable is a response ratio: log(treatment/control). I'm interested in what mediates the difference, so I'm running RE meta-regressions (unweighted, because is seems pretty clear that effect size is uncorrelated with variance of estimates). </p>
<p>Each stu... | g67274 | [
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<p>What does it means if no CI was given for binary logistic regression analysis in SPSS output?</p>
<p><img src="http://i.stack.imgur.com/rAGyE.jpg" alt="enter image description here"></p> | g47328 | [
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<p>I've been trying to familiarize myself with some of the statistics behind conducting A/B testing on a website and trying to pick a relevant sample size. I've come across several articles that talk about power analysis (<a href="http://37signals.com/svn/posts/3004-ab-testing-tech-note-determining-sample-size" rel="no... | g67275 | [
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<p>Let $(\Omega,\mathcal F)$ and $(\Omega^\prime,\mathcal F^\prime)$ be two measurable spaces and $X:\Omega \to \Omega^\prime $, show that $X^{-1}(\mathcal F^\prime)$ is a $\sigma$-algebra.</p>
<p>I know that I must show three things, so I think first I write the definition of $X^{-1}(\mathcal F^\prime)$ and then I c... | g67276 | [
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<p>I'm somehow stuck about the way I should verify regression models.</p>
<p>For instance, an extremely over-simplified version of the Solow Growth Model might look like this:</p>
<p>$$ growthrate = \beta_0 + \beta_1 savingsrate + u $$</p>
<p>So how can I make sure now that there is not only correlation, but causati... | g67277 | [
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<p>I am dealing with linear data with outliers, some of which are at more the 5 standard deviations away from the estimated regression line. I'm looking for a linear regression technique that reduces the influence of these points. </p>
<p>So far what I did is to estimate the regression line with all the data, then dis... | g67278 | [
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<p>I am in desperate need for help. I am trying to calculate the likehood ratio test in R, but I don't have allot of experience using R.</p>
<p>For example, to calculate the following</p>
<p>Suppose $X_1, X_2,\ldots, X_n$ is a random sample from a normal population with mean $\mu$ and variance $16$. Find the test wit... | g26747 | [
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<p>If I have the following var-cov matrix:</p>
<p>$\Sigma_{A,B,C} = \left(\begin{array}{ccc}
1 & 2 & 3 \\
2 & 4 & 6 \\
3 & 6 & 9 \\
\end{array}\right)$</p>
<p>(1) How can I find a constant a, so $avv'$ becomes a projection matrix of rank 1?
(2) How can I use this result to find the direction ... | g67279 | [
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<p>In short, is there anything to be learned from performing a <a href="http://en.wikipedia.org/wiki/Phi_coefficient" rel="nofollow">Phi measurement of association</a> (MOA) on a Chi-Square test where it failed to reject the null hypothesis?</p>
<p>$$\phi = \sqrt{\chi^2/N}$$</p>
<p>where $\chi^2$ is the value returne... | g67280 | [
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<p>I recently read paper by <a href="http://www.cs.princeton.edu/~blei/papers/WangBlei2009d.pdf" rel="nofollow">Chong Wang and David M. Blei "Variational Inference for the Nested Chinese Restaurant Process"</a>. And I couldn't understand the next part (from p.5):</p>
<blockquote>
<p>The variational update functions ... | g67281 | [
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<p>I have a financial time series that has a linear down trend, but sometimes a jump happens (see image below).</p>
<p>What statistical methods can I use to detect these jumps as early as possible?</p>
<p><img src="http://i.stack.imgur.com/QgU9E.png" alt="linear trend with jumps"></p> | g26754 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/4220/probability-distribution-value-exceeding-1-is-ok">Probability distribution value exceeding 1 is OK?</a> </p>
</blockquote>
<p>I thought the area under the curve of a density function represents the pr... | g49345 | [
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<p>I am trying to see if there are differences between two groups (background genetic mutants) and some values associated to them. Every group has 4 different gene types with two replicates each and its respective value. </p>
<pre><code>> data
bg type value
a 3motif 0.7371446
a ... | g26761 | [
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<p>I am trying to calculate the error variance for the following question but I don't have clue where to start. Could anyone please help?</p>
<p><img src="http://i.stack.imgur.com/yaxsG.jpg" alt="enter image description here"></p>
<p><img src="http://i.stack.imgur.com/gC1ha.jpg" alt="enter image description here"></p... | g17387 | [
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<p>I am trying to implement a mixture model of probits to infer the best decision boundary for every latent subpopulation.</p>
<p>When doing Gibbs sampling, we eventually have to compute $P(y^* | w_c)$ where $y^*$ is the auxilary variable in the augmented version and $w_c$ are the weights or the $\beta$ coefficients i... | g17388 | [
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<p>I have noticed that the sign at the front of the log-likelihood ratio formula changes depending on what source I have been looking at.</p>
<p>Below are the two formula I have seen, exactly as they were written (in case the notation is offering something I am missing):</p>
<p>$LLR = -2 ( LL_{\rm Simple} - LL_{\rm G... | g67282 | [
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<p>Why don't epidemiologists ask people when they had sex? Why do they estimate time of conception from the birth date? This seems to introduce unnecessary error. Wouldn't it be better to record the time you had sex in some sort of database (assuming it was the time it resulted in pregnancy)?</p>
<p>Note that fertiliz... | g33592 | [
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<p>My question is about updating the parameters of a regression with ARIMA errors model
as new (monthly) data becomes available each month.
Similar question were asked here before:</p>
<ul>
<li><a href="http://stats.stackexchange.com/questions/34139/updating-arima-models-at-frequent-intervals">Updating ARIMA models ... | g67283 | [
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<p>I am performing backward selection for the Cox Proportional Hazards model with several variables (it is required that I do backward selection). One of these variables (let's call it "A") does not meet the proportionality assumption in the full model. So I would like to consider the possibility of stratifying on vari... | g67284 | [
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<p>I have a simple but difficult question. Does feature selection before SVM help? I have a data set that has ~1100 features but a lot of these are redundant data / uncorrelated data. Can someone give me a reason why it should / should not help? Thanks a lot. </p> | g26766 | [
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<p>In cluster analysis how do we calculate purity? What's the equation?</p>
<p>I'm not looking for a code to do it for me.</p>
<p><img src="http://i.stack.imgur.com/5YcWc.png" alt="enter image description here"></p>
<p>Let $\omega_k$ be cluster k, and $c_j$ be class j. </p>
<p>So is purity practically accuracy? it ... | g26767 | [
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<p>I'm stuck on a homework problem and I'm hoping you all might be able to help me out. I'd be very appreciative!</p>
<p>We were given this data set: <a href="https://www.webassign.net/mintrostat/data/11_24/data214.dat" rel="nofollow">Data</a>. I ran a regression in Minitab with GPA as the response and IQ and Self-Con... | g67285 | [
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<p>I wish to make a visualization of the separating hyperplane in the SVM algorithm along with my training features. As my feature vectors have 8 dimensions, we cannot directly visualize this. The only potential solution I can think of is to get a projection down to 2 dimensional space. </p>
<ol>
<li><p>Will this solu... | g67286 | [
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<p>How can I construct parametric bootstrap confidence intervals in R without using the <code>boot</code> package?</p> | g67287 | [
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<p>I wrote a meta classifier which instead of aggregating various models on the whole data (like bagging, boosting, random forest), it splits the input space into some disjoint regions and builds a base model for each region.</p>
<p>The reasons why one would want to try this approach would be:</p>
<ul>
<li>remove all... | g9940 | [
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0.03312... |
<p>I conducted an ANOVA and one of the F-values for a main effect is .000 on SPSS, and the other is .003 on SPSS.</p>
<p>As I am rounding to two decimal places, how do I report these? Does F = 0.00, or is F < 0.01, or do I make an exception and report a third decimal place for the .003?</p> | g67288 | [
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<p>To Burr and other experts on this topic: I tested, well rather ad-hocly the R-package <code>multitaper</code>, and I succeeded getting graphical outputs. I got graphs for (a) spectrum, (b) spectrum with confidence interval and a graph for the F-test.<br>
I have a couple of questions related to the package and the ou... | g26770 | [
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<p>We conducted an experiment on hens with seven treatments (medicines) replicated three times. Every treatment was implemented on a flock of fifteen young hens and three of these treated hens were slaughtered after 7, 14, 21, 28, and 35 days and measurements were observed. I wonder whether</p>
<ul>
<li>these data sho... | g26772 | [
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<p>A person who is confined to a nursing home and is very talented at statistics/mathematics desires to earn an online bachelor's degree in statistics (or related discipline) from a good university. Do you have any suggestions for this person? Thank you!</p> | g67289 | [
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<p>In a cross-validation setting (LASSO penalized logistic regression), I'm calculating AUC. However, I'm interested in the variability of these estimates over the folds (this will give me <em>an</em> indication of the stability of my model selection over the folds). </p>
<p>As such, I want to find the empirical AUC i... | g26774 | [
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<p>I want to calculate the quantiles of a t distribution and a normal distribution fitted to my data (can be found here: <a href="http://uploadeasy.net/upload/nk0f.rar" rel="nofollow">http://uploadeasy.net/upload/nk0f.rar</a>). </p>
<p>The t distribution is leptokurtic, therefore there will be an area, where the quant... | g10014 | [
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<p>Would it please be possible to help me with a statistics query. I have asked for the partial eta squared on the output of a one-way within subjects ANOVA from SPSS and it has given me the value .137. According to Cohen (1992) the classifications for effect sizes should be; r=.10 small, r=.30 medium and r=.50 large (... | g26779 | [
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<p>I use kmeans for clustering a set of data. However, I have to specify the number of clusters. The problem is that sometimes I need 2 and other times I need 3 clusters.</p>
<ul>
<li>Is there a clustering algorithm that could incorporate that feature in it?</li>
</ul> | g26780 | [
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<p>Lets take as an example a repeated measures design with 10 subjects that are all reading the same letter strings and pressing a button as soon as they determine whether the string is valid English word, producing reaction times (RT). I wish to determine whether word length has a significant effect on the produced RT... | g26781 | [
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<p>I have a dataset in which the event rate is very low ( 40,000 out of $12\cdot10^5$).
I am applying logistic regression on this. I have had a discussion with someone where it came out that logistic regression would not give good confusion matrix on such low event rate data. But because of the business problem and the... | g67290 | [
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<p>I am using markov chain process for prediction. I created a transition matrix using training dataset .Now I want to experiment in test dataset and want to compute the accuracy of transition matrix for test dataset. How can I measure error rate of the prediction. </p> | g26782 | [
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<p>What is the difference in meaning between the notation $P(z;d,w)$ and $P(z|d,w)$ which are commonly used in many books and papers?</p> | g49858 | [
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<p>I'm wondering if someone might be able to help me locate an appropriate model for the following two time-series (the cyan and blue one, the reds are rolling means).</p>
<p><img src="http://i.stack.imgur.com/LN9RP.png" alt="[The time-series in question](http://i.imgur.com/pmXerft.png)"></p>
<p>I'm looking more for ... | g26784 | [
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<p>This follows on from the previous question on <a href="http://stats.stackexchange.com/questions/10030/difference-between-k-s-manual-test-and-k-s-test-with-r">differences between K-S manual test and K-S test with R</a>.</p>
<p>My frequency sample was </p>
<pre><code>a=c(0,1,1,4,9).
</code></pre>
<p>Then the observ... | g47365 | [
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<p>I'm querying a large (100 million row + ) SQL Server database and doing some preliminary work on the correlation between visits to the emergency room and total healthcare costs. I ran a query and the data is returned to me in something like looks like:</p>
<pre><code>personID num_er_visits_half_decile tota... | g67291 | [
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<p>I'm running a two-part model on a health insurance claims dataset where I predict the probability of nonzero health care costs using a logistic regression (1st part), then predict the magnitude of the log health care costs using an OLS regression (2nd part).</p>
<p>Question: When calculating the expected health car... | g67292 | [
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<p>There are at least three R packages providing some functions to perform a Bayesian selection variable in linear Gaussian regression model: LearnBayes, mombf and BMA.</p>
<p>I would be glad to know some opinions about which one is the best.</p> | g26786 | [
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<p>My data has three continuous predictors and one binary response. I built a logistic regression model but AUC is only 0.52..it's almost like the model did nothing.. Then I calculated the correlation between the response and predictor. The correlation are all very low, around 0.01, all less than 0.05. That is to say, ... | g67293 | [
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<p>When comparing two runs <em>(means)</em> of different benchmark tests I use an unpaired two-sample t-test assuming equal variance.</p>
<p>The problem I've run into is this often results in the same benchmark test result being statistically significantly different from re-runs of the same benchmark test on the same ... | g47370 | [
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<p>How does an ensemble classifier merge the predictions of its constituent classifiers? I'm having difficulty finding a clear description. In some code examples I've found, the ensemble just averages the predictions, but I don't see how this could possible make a "better" overall accuracy.</p>
<p>Consider the followi... | g47371 | [
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<p>I would like to implement a BUGS/WINBUGS or JAGS model that specifies the likelihood node by marginalizing over two parameters.
Is this feasible in BUGS/WINBUGS or JAGS?</p>
<p>This is the posterior
\begin{align}
&P\left( g_{x} , g_{y} | \mathbf{a}\right) \propto P\left( \mathbf{a} | g_{x} , g_{y}\right) P\left... | g67294 | [
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<p>I'm new to R, and despite trying to read as much as I can about how lmer works in R, I still don't feel like I know how to correctly specify more complex models using the lmer syntax. </p>
<p>For example, at the moment I want to use lmer for a two-level multilevel model, where the first level is features of a spec... | g67295 | [
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<p>One way to think about finding the eigenvectors of a matrix $A$ is that they are the critical points of the functional $\vec x^\top A \vec x$ subject to $\|\vec x\|_2=1$. To regularize this problem, it is easy enough to ask that we minimize $\vec x^\top A \vec x+\varepsilon\|\vec x\|_2^2$, since this corresponds to... | g67296 | [
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<p>So my basic query is just because you've binned and counted the data into a histogram are the error bars on the bins necessarily the Poisson $\sqrt{N}$?</p>
<p>Longer explanation: I have an image of pixel values which represent brightness values. I am binning them into a histogram to get the PDF of the brightness d... | g67297 | [
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<p>I am interested in determining if, for a certain type of trait, there is just as much variation between twins as there are between non-related individuals. However, I am having difficulties in figuring out how I can combine equivalence testing (as covered <a href="http://stats.stackexchange.com/questions/3038/how-to... | g67298 | [
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<p>I assume this is stats 101 level of question.</p>
<p>If you have PC that is set to "randomly" pick a number between 1 and 100 each time a button is pushed, the chances of getting a 50 is 1 in 100, right?</p>
<p>So if you have two PCs doing the exact same thing, and you can press a button on either, but you can onl... | g67299 | [
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<p>Independent Variable: I have a survey of 50 states indicating the amount of control the state board of education has in 31 areas answered on a three point scale (1 = total control; 2 = partial control; 3 = no control). I have a solid theoretical underpinning for all 31, or to be more precise, the literature review f... | g67300 | [
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<p>I am computing the RMS of a sample to estimate the standar error $\sigma$ of the underlying distribution (for simplicity let say a normal distribution $N[\mu$, $\sigma$]).</p>
<p>$ \text{RMS} = \sum_{i=1}^N (x_i - \bar x)^2 / (N-1)$</p>
<p>I am using a truncated version of the RMS to avoid outliers in the populati... | g67301 | [
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<p>I have an interesting data set for which I want to answer the question:</p>
<p><strong>Question</strong></p>
<p>How do I rank consumption of a key resource from my data set. I am not interested in predicting, rather measuring relative consumption of a resource. Ideally I would get a coefficient for each variable a... | g26797 | [
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<p>I have worked with scipy.signal.welch and spectrum.pptm to calculate power spectral density with Welch and Multitaper methods. However as far as I can see these functions are meant for one dimensional time series only. Are there any implementation for power spectral density estimation of time series with higher dime... | g67302 | [
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<p>I have a dataset with 3 variables (X,Y and Z) and I want to find the best estimates for the constants a,b,c & d. I have been looking into multiregression analysis, but that does not seem to work for this more complicated formula.</p>
<blockquote>
<p>Y = (a + b * Z) * X^(c + d * Z)</p>
</blockquote>
<p>Someon... | g67303 | [
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0.0466424934566021,
-0.002510670106858015,
0.02508... |
<p>Given a sequence of events
$$(a_1, a_2, \dots, a_n),$$
then the sequence of empirical probabilities of some event $\alpha$ is
$$\left(p_1 = \frac{\sum_{i = 1}^1 [a_i = \alpha]}{1}, p_2 = \frac{\sum_{i = 1}^2 [a_i = \alpha]}{2}, \dots, p_n = \frac{\sum_{i = 1}^n [a_i = \alpha]}{n}\right).$$
Assume that this sequence... | g67304 | [
0.019041726365685463,
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0.004306293558329344,
0.03524274006485939,
0.029727745801210403,
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-0.027414223179221153,
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0.0001613150379853323,
0.0410851426422596,
0.048... |
<p>I'm trying to see if there are any significant differences in 3 data sets that I have. The data is taken from around 1000 participants, each within different families who tried an experiment to see whether or not they tasted a particular flavour (salt, sour, sweet, bitter, umami) on the same part of their tongue (fr... | g67305 | [
0.03313646465539932,
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0.02398850955069065,
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0.01919063925743103,
0.0... |
<p>Consider the case where we have two Gaussian distributions and we are trying to find the area of overlap between them. This is also called the Overlapping Coefficient and I think it is also related to the Weitzman Measure. </p>
<p>I am wondering about a specific limiting case when one (but not the other) of the Gau... | g67306 | [
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0.005176043603569269,
0.0026648007333278656,
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0.013499042019248009,
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-0.027000656351447105,
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0.0031091612763702... |
<p>I'm looking for a visually compelling yet immediately understandable way to visualize a range of data (min, median, max)</p>
<p>Considerations: </p>
<ol>
<li>The approach should be understandable to a wide variety of people</li>
<li>Ideally, would allow for the comparison to another set of data</li>
<li>Ideally, ... | g26804 | [
-0.02326933853328228,
0.04163122922182083,
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0.052198320627212524,
0.011426176875829697,
0.0930224061012268,
... |
<p>I am puzzled as to why the <a href="http://cran.r-project.org/web/packages/caret/index.html" rel="nofollow">caret</a> package in R does not allow tuning on the number of trees (ntree) in a random forest (specifically in the <a href="http://cran.r-project.org/web/packages/randomForest/index.html" rel="nofollow">rando... | g67307 | [
-0.04937966167926788,
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0.026080427691340446,
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0.0009099711896851659,
0.021131765097379684,
0.03198140114545822,
0... |
<p>Let $X,Y$ be input and output (observed) continuous variables in $\mathbb{R}$. Let $\{y_1,...,y_n\}$ be the set of $n$ observations. Is there a name for the estimator $\hat x = \int_{x \in X} x \,p(y_1,y_2,...,y_n|x) \,dx $ (mean of likelihood)? I tried googling but I could not find its name.</p> | g67308 | [
-0.015316340140998363,
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... |
<p>After a bidirectional step wise, I have the following generalized linear model:</p>
<pre><code>Y = -8.18 + 1.18 v1 - 7.32 v2
</code></pre>
<p>In a simple linear model (with one explanatory variable), the coefficient of my variable corresponds to the slope of my line. If the coefficient is positive, the line goes u... | g67309 | [
-0.005891929380595684,
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0.02144511230289936,
0.011799785308539867,
... |
<p>What is quantile regression? How can I use quantile regression to analyse technical efficiency in rubber farmers? I also want to use the production frontier.</p>
<p>The response (y) variable is production.</p>
<p>The explanatory (x) variables are tappable tree, fertilizer, chemical, total labour.</p> | g67310 | [
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0.04614944383502006... |
<p>I have skewed data requiring non-parametric tests. Following Kruskal Wallis tests, I want to carry out post-hoc analysis. I have chosen
<code>nparcomp</code> within R because of recommendations here: <a href="https://stat.ethz.ch/pipermail/r-help/2012-January/300100.html" rel="nofollow">https://stat.ethz.ch/pipermai... | g26806 | [
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... |
<p>Let X1 and X2 be two independent random variables. Let X1 and Y=X1+X2 have Poisson distributions with means μ1 and μ>μ1, respectively. Find the distribution of X2.</p>
<p>I don't know how to start solving with this kind of problem. I would appreciate if someone could help me. Thanks.</p> | g67311 | [
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0.016254492104053497,
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... |
<p>I've done a hierarchical clustering on a data-set composed
by 33 subjects and 2 continuous variables (called V1 and V2),
which produces 3 clusters.</p>
<p>Now I'm wodering if it make any sense to perform a statistical
significance test on this result.</p>
<p>If I calculate the average value of the variable V1 (one... | g67312 | [
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0.... |
<p>I am looking to find the ACF of a time series, but after it is differenced. </p>
<p>$y_t = a_1y_{t-1} + \epsilon_t , \mid a_1 \mid < 1$</p>
<p>I understand that to find the ACF this process needs to be stationary, but I am struggling to difference the equation due to the constant $a_1$</p>
<p>Any help would ... | g67313 | [
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0.008309577591717243,
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0.0581292062997818,
0.002038754289969802,
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<p>I have a count dataset that contains many zeros and a discrete variable that contains many zeros as well. I would like to see graphically which kind of correlation exists between these two variables.
When I try in R to plot these two variables (<code>plot(X, Y))</code>) I get something that I'm not able to interpret... | g67314 | [
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0.0015523030888289213,
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0.015509611926972866,
0.0... |
<p><em>I recently received the following question via email. I'll post an answer below, but I was interested to hear what others thought.</em></p>
<blockquote>
<p><strong>Would you call logistic regression a non-parametric test?</strong> My understanding is that
simply labelling a test non-parametric because its d... | g67315 | [
0.0371665321290493,
0.027481289580464363,
0.004069559276103973,
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-0.03956151008605957,
0.02564244531095028,
0.013401994481682777,
0.03354983776807785,
-0.0085... |
<p>Suppose I believe a sample is drawn from a population that is distributed according to some specified distributional family. I intend to estimate the parameters of the distribution using some appropriate method. However, somewhere along the way I may come to suspect that my original assumptions with respect to the ... | g39765 | [
0.023747816681861877,
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0.0018425401067361236,
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0.01123002264648676,
0.0011260834289714694,
0.03914712741971016,... |
<p>I am performing $N$ independent statistical tests with the same null hypothesis, and would like to combine the results into one p-value. After some googling it seems to me that there are two "accepted" methods: Fisher's method and Stouffer's method.</p>
<p>My question is about Stouffer's method. For each separate t... | g26807 | [
0.03288554400205612,
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0.0029815041925758123,
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0.021466568112373352,
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0.0022580355871468782,
0.011851681396365166,
-0.0069738575257360935,
0.008182881399989128,... |
<p>This is a problem with which I have been grappling with for days. From my research on self-organizing maps, I know that a common feature of self organizing maps is to reduce the dimensionality of data. For example, if you had a 3x3 SOM, and an input space consisting of 50 10-Dimensional vectors, the SOM would reduce... | g67316 | [
0.012424343265593052,
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0.012621071189641953,
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0.000014631040357926395,
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0.023745549842715263,
... |
<p>Given a known number of white and black balls in an urn, what is the number of trials <strong>without replacement</strong> required to achieve a given x probability of drawing <strong>at least</strong> one white ball. </p>
<p>Which function gives me this number of trials?</p>
<p>Thank you very much</p> | g10152 | [
-0.03449676185846329,
0.055071908980607986,
0.007060184143483639,
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0.05748451128602028,
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0.018857916817069054,
0.04918234422802925,
0.0024699214845895767,
-0.0028995878528803587,
-0.08885055035352707,
-0.0007375943823717535,
0.04849371314048767,
-... |
<p>I want to perform a changepoint analysis with the help of the PELT method:
<a href="http://arxiv.org/abs/1101.1438" rel="nofollow">Killick & al</a>,
<a href="http://www.lancs.ac.uk/~killick/Pub/KillickEckley2011.pdf" rel="nofollow">Killick & Eckley</a>
I assume that the data are normally distributed before... | g26809 | [
0.04478778317570686,
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0.010665256530046463,
0.00261854799464345,
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0.07630527764558792,
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0.009892563335597515,
0.05644432082772255,
0.... |
<p>Let $x=(x_{1},\dots,x_{n})^{T}$ be $n$ dimensional random vector uniformly distributed over the $L1$ unit sphere. That is, all $x$ such that $\|x\|_{1} = 1$ have equal probability and all other $x$ have zero. </p>
<p>Let $\{c_{i}\}_{i=1}^{n}$ be $n$ vectors such that $\|c_{i}\|_{2}=1$.</p>
<p>How can one show tha... | g67317 | [
0.00046512673725374043,
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0.043547555804252625,
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0.04753246158361435,
0... |
<p>I am using the mlogit package in R to run a multinomial logistic regression on pooled discrete choice data collected using two different questionnaire formats. I want to test whether the format had a significant effect on choices. When I run the basic model I get a result. But when I run the same model with a dummy ... | g67318 | [
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0.016044745221734047,
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0.007767012342810631,
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0.0264567993581295,
0.0710127055644989,
... |
<p>There are many tests in statistics. I noted that some of them may be grouped together, since they are used for similar purposes. For example </p>
<ul>
<li>tests of independence </li>
<li>tests that compare distributions (Kolmogorov-Smirnov, Shapiro-Wilk, Chi-Square)</li>
<li>tests that compare location parameters (... | g67319 | [
0.018136736005544662,
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0.0027671619318425655,
0.0020314056891947985,
0.035176146775484085,
0.010513280518352985,
0.017450576648116112,
0.0254905354231596,
0.017168233171105385,
... |
<p>I have a simple <a href="http://en.wikipedia.org/wiki/Autoregressive_model#Definition" rel="nofollow">auto-regressive</a> function:</p>
<p>$x_{i+1} = c - cx_{i}$</p>
<p>It is <code>linear</code> and <code>first order</code>. There is <strong>no noise</strong> in the model although there is in the data. I am using ... | g26812 | [
0.04716133326292038,
-0.0399976521730423,
-0.02548585645854473,
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0.04803118109703064,
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0.04235599562525749,
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-0.04049253463745117,
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0.02153349295258522,
0.08476445823907852,
0.01883... |
<p>I have no idea about statistical testing yet I am doing a research project on a sample size of 40; it is a correlational study using Pearson's r (SPSS). My results indicate Pearson's correlations (2-tailed p) of </p>
<pre><code>-.264 (.100): self efficacy
-.113 (.489): social support
-.172 (.290): happiness
</cod... | g67320 | [
0.03972103074193001,
-0.009871321730315685,
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0.0015115599380806088,
0.013839596882462502,
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-0.056001216173172,
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0.04149741679430008,
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... |
<p>I've had four students coding the frequency of certain verbal and nonverbal behaviours. In hoping to generate some sort of intercoder reliability, I've had them all code the same 10 interviews. For each of these interviews, each of the four coders have coded the number of certain verbal and nonverbal behaviours. I'm... | g67321 | [
-0.01660926453769207,
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0.005043495912104845,
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0.03578517213463783,
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0.025005925446748734,
0.013640772551298141,
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-0.0185314379632473,
0.01248042844235897,
-0.020835701376199722,
-0.04582571983337402,
0.08... |
<p>What is the difference between doing linear regression with a Gaussian RBF basis
and doing linear regression with a Gaussian kernel?</p> | g67322 | [
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0.02201724797487259,
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0.019930025562644005,
0.005927493795752525,
-0.01560355443507433,
0.0066... |
<p>I have two categorical variables that I want to add: fruit portions = portions of fruit per day (a portion representing a handful): 1= never to 7=5 or more portions, and fruit juice frequency = how often drink fruit juice per week:1=never, 2=once a month, 3=1-2 times per week to 5=everyday.
I want to add them into ... | g67323 | [
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0.011541057378053665,
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0.... |
<p>Is it possible to have a model that aims to classify and regress at the same time?</p>
<p>For example if I have five independent variables and I want to use these 5 variables to predict the gender of the observation. Subsequently I let the predicted gender be the 6th independent variable and predict for income of t... | g67324 | [
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0.00562307657673955,
0.029068723320961,
0.04866253212094307,
-0.0205... |
<p>I am conducting a mixed model, but do not well understand how df is calculated, can someone help me to clarify it? I have been searching very hard on the internet but could not find the right answer. Thanks!</p>
<p>The data in fact contains "Animal" as random effect, Breed and DFC (day from calving) and squared_DFC... | g26821 | [
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<p>I am trying to run an econometric panel data (fixed effects) model with about 4000 observations (so not a small dataset). My data consists of transactions (buy and sell). The transactions are linked to a rank (1 to 5) based on the B/M ratio for the company related to the transaction. However, I am having enormous am... | g67325 | [
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0.031172683462500572,
0.04788186401128769,
0.008220753632485867,
... |
<p>So I am having trouble understanding what this problem is asking. (I am not asking someone to solve it but simply help interpret what the problem wants me to do.)</p>
<p>The problem goes like this:</p>
<blockquote>
<p>"Let $A$, $B$, and $C$ be three events. Show that exactly two of these events will occur with ... | g3027 | [
0.051816176623106,
0.04606422409415245,
0.03954588249325752,
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0.06763993948698044,
0.006741703487932682,
0.02448558248579502,
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0.053753551095724106,
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-0.01555... |
<p>I have got some small data sets (about 8 to 11 data points for each set), following Normal distribution. I would like to find out the 95% confidence interval of the 0.005 and 0.995 percentile of each set.</p>
<p>Firstly, moment estimation method is employed to estimate the Normal distribution parameters, and their ... | g67326 | [
0.0409027524292469,
0.009901395998895168,
-0.01631610095500946,
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-0.025240018963813782,
0.02340025268495083,
0.04970872029662132,
-0.02046314999461174,
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0.018663089722394943,
0.04257389158010483,
0.020797358825802803,
0.018650243058800697,
-0.0253... |
<p>We have a variable "pos" in the regression which has three values : guard, forward, and center. My regression looks like y~a+factor(pos)
But one of the factor's value is insignificant (i.e. forward).
How can we remove it from the regression without eliminating others in R?</p> | g67327 | [
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0.04981866106390953,
0.07645171880722046,
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-0.005059496965259314,
0.023803221061825752,
0.03950062394142151,
-0.030059995129704475,
... |
<p>I am modeling a Gaussian distribution for a computational biology application, and I am working in the statistical package "R". In this regard, my problem is that I have to construct a covariance matrix with variables (non-numeric) and the covariance matrix is to be used in an maximizers of the likelihood function t... | g67328 | [
-0.02919090911746025,
-0.04110264033079147,
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0.0007030573324300349,
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0.04354443401098251,
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-0.003735251259058714,
-0.009998789057135582,
-0.023693373426795006,
-0.0002112274960381910... |
<p>I need to choose a non linear regression model for this kind of data</p>
<p>The experiment was a time course, for a drug, so I get phosphorylation response behaviour in time</p>
<p>In enzyme kinetics or a binding non linear regression model, you do not take into account time, instead you plot the substrate concent... | g26825 | [
0.0030843927524983883,
-0.017253650352358818,
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0.0019990489818155766,
0.008307747542858124,
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0.055322885513305664,
0.02572256699204445,
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0.040499139577150345,
0.014553595334291458,
-0.013918021693825722,
0.0035576440859586,
... |
<p>Let $Y=(Y_1,Y_2,\ldots,Y_n)^{T}$ and $Y_1,\ldots,Y_n$ are independent normal random variables with mean $0$ and variance $ \sigma^2$. Find the distribution of the following statistics and give your reasons</p>
<p>a) $T=\displaystyle \sum_{i=1}^{6}(Y_i-\overline{Y})^2$ </p>
<p>b) $U =\displaystyle\frac{\sqrt{5}\ti... | g39058 | [
0.019617779180407524,
0.044663891196250916,
-0.030082030221819878,
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-0.013914608396589756,
-0.036302633583545685,
0.05191655084490776,
-0.04912843555212021,
0... |
<p>Can we derive this from the summability methods (Zeta function regularization) that assigns finite values to divergent sums or products or any other?</p> | g67329 | [
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0.01817169040441513,
0.05194275081157684,
0.05... |
<p>I'm a software engineer who has been tasked with doing statistical analysis on data collected from a physical test system. The system collects data on a part by setting input conditions, reading in measured data, then changing the input conditions and doing another measurement. A typical data collection file ramps... | g67330 | [
0.02475125901401043,
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0.003679810557514429,
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0.03018946945667267,
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-0.04163135215640068,
0.026736410334706306,
0.008828243240714073,
0.02497921884059906,
-0.0166... |
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