question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have a model for multiple moderated regression with <code>payment</code> (continuous) as the DV, one continuous predictor (neuroticism), and two binary categorical between-subject-factors: stress vs. no stress and self-payment vs. other-payment. </p>
<p>Essentially, I want to know if the increase in the differenc... | g59458 | [
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<p>Say I have a data set composed of $N$ objects. Each object has a given number of measured values attached to it (three in this case):</p>
<p>$x_1[a_1, b_1, c_1], x_2[a_2, b_2, c_2], ..., x_N[a_N, b_N, c_N]$</p>
<p>meaning I have <em>measured</em> the properties $[a_i, b_i, c_i]$ for <strong>each</strong> $x$ objec... | g14996 | [
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<p>Suppose we have a random number generator, and we do not know anything about the generator, including the distribution of its outputs. We are allowed to use the generator some number of times to get draws and observe the sample. </p>
<p>Then, from the sample(s), we want to find a number M such that we can say somet... | g49557 | [
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<p>I am a physicist who is a few years out of doing his last course in statistics, so I am hoping to get some advice when comparing some data I recently generated. I asked this question on the Mathematics Stack Exchange website, but received no answers, so I thought I would try here as well.</p>
<p>The context is as f... | g49558 | [
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<p>Mahalanobis distance, when used for classification purposes, typically assumes a multivariate normal distribution, and the distances from the centroid should then follow a $\chi^2$ distribution (with $d$ degrees of freedom equal to the number of dimensions/features). We can calculate the probability that a new data ... | g15000 | [
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<p>Would you please explain me the difference between <em>Probability distribution and Sampling distribution</em> easily ?</p>
<p>Is that the difference : in probability distribution we have probability for every individual whereas in sampling distribution we get probability for statistic ?</p>
<p>Does sampling distr... | g49539 | [
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<p>I'd like to evaluate a multilabel classification algorithms and I was thinking of using both Accuracy and F1-Measure with:</p>
<pre><code>Accuracy = #Intersection(suggestions,correct_labels) / #Union(suggestions,correct_labels)
F1 Measure = 2 * (P * R) / (P + R)
</code></pre>
<p>The above is for a single example a... | g59459 | [
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<p>Boosting takes a bunch of weak learners and creates a strong learner. But why is it so difficult to create a strong learner right from the beginning without using boosting techniques? And therefore remove the need for boosting.</p> | g59460 | [
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<p>Is there a book that explains why there aren't better standard techniques than Tukey and ANOVA, for example?</p>
<p>For comparison consider for example I read about the null hypothesis one-sample $t$ test and didn't even bother considering that there could be better tests. But that is probably just a biased belief ... | g59461 | [
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<p>For sake of a simple example assume that there are two linear regression models</p>
<ul>
<li>Model 1 has three predictors, <code>x1a</code>, <code>x2b</code>, and <code>x2c</code></li>
<li>Model 2 has three predictors from model 1 and two additional predictors <code>x2a</code> and <code>x2b</code></li>
</ul>
<p>Th... | g15003 | [
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<p>I'm working on determining the Frechet mean of several curves. I am using this equation:</p>
<p>$$ \sum_{n=1} (P_a - P_b)^2 $$</p>
<p>but I'm not entirely sure how I would do this across multiple curves. Also, the answer should be, unless I am completely mistaken, should be a curve but I am getting a single number... | g15004 | [
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<p>I have a sample with millions of points. Every point $x$ has two values associated, let's say $A_{x}$ and $B_{x}$. I calculated the mean values of A and B in the sample:</p>
<p>$\overline{m}_{A} = 0.19 \quad \text{and} \quad \overline{m}_{B} = 0.21$</p>
<p>The distributions of the values are different and not norm... | g59462 | [
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<p>I have a system where arrival rate is assumed to be Poisson but there is a condition on accepting this arrival which is
if $Z$ (uniform dist. random variable) $\le$ some value $X$
and $X$ can vary between the values $[0.5, 0.25, 0.125]$.
Actually X takes value of 0.5 first and if Z>X for two times --> X became 0.25... | g59463 | [
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<p>I'm interested in determining whether two or more groups of data share the same mean, and it seems like the ANOVA framework is a good way to approach this. However, ANOVA assumes residuals are normally distributed, while each of my data is a number between 0 and 100 (a percentage). Because normal distributions have ... | g59464 | [
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<p>I kinda have some trouble trying to start with this question.</p>
<p><img src="http://i.imgur.com/JKeSBhN.png" alt="a busy cat"></p>
<p>I know how to derive a Neyman-Pearson Test and its critical region. My main concern is deriving the Likelihood function of the sample given its null hypothesis and its alternativ... | g59465 | [
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<p>I have two function. First function have a positive value for AIC and the second function have a negative value fir AIC. How to make comparisons? algebraic or absolute values?? Thanks :)</p> | g59466 | [
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<p>Should the weights of a neural network without hidden layer and a logistic activation function be the same as the parameters of a logistic regression? Mine are not the same?</p>
<pre><code>nnallnohidden=nnet(
PartialPrepayzo~FIXPER+MEDSAL2+DREL+LEEFTIJD+HH2CRED+LTV_curr+
rate1Y+rate5Y+CIremFIRP+URB+WELSTAN2... | g59467 | [
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<p>For my master's thesis I am examining a mediated relationship. I need to write out the equation model, but do not know exactly how to do this. In my case I have four independent variables, one mediated variable and one dependent variable. How do I add the mediated variable to the equation? Until now I got this:</p>
... | g59468 | [
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<p>I'm trying to understand how to compute the optimal cut-point for a ROC curve (the value at which the sensitivity and specificity are maximized).
I'm using the dataset <code>aSAH</code> from the package <code>pROC</code>.</p>
<p>The <code>outcome</code> variable could be explained by two independent variables: <cod... | g59469 | [
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<p>Under-educated non-statistician seeks short-term relationship for very one-sided benefit.</p>
<p>System in question involves rocks and physical properties. Modelling bits of the earth typically means few real measurements compared to volume of model. Many estimates are required, and I have NO IDEA how to handle the... | g59470 | [
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<p>I'm writing a CFA paper, and I have run into some trouble interpreting the AIC and BIC. This is my first paper using continuous variables, thus the first time I will be reporting these fit statistics and I'm still learning the SEM method overall so bear with me, please.</p>
<p>The paper in question looks at an exis... | g49597 | [
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<p>Do I understand this correctly:</p>
<p>You fit a model with unknown parameters to a dataset. You choose the parameters so the likelihood of the dataset under the model is maximal. Let this be $L_{max, model1}$. You do the same with a more advanced model. Again you pick the coefficients of the model so that the like... | g59471 | [
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<p>It's multivariate linear regression meaning multiple dependent variables (Y). Data A has both X (explanatory variables) and Y, but data B has only Y. </p>
<p>I wonder if there is any way to incorporate data A and B into the regression model.</p>
<p>If I remember correctly, Statistical Analysis with Missing Data by... | g59472 | [
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<p>I'm using the function <code>adk.test</code> (<a href="http://en.wikipedia.org/wiki/Anderson%E2%80%93Darling_test" rel="nofollow">AD test</a>, <a href="http://cran.r-project.org/web/packages/adk/adk.pdf" rel="nofollow">adk package</a>) to estimate if a data sample follows a distribution family.</p>
<p>My question i... | g59473 | [
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... |
<p>I have a few datasets of "interactions" between pairs of elements like so:</p>
<pre><code>element1 element2 1
element2 element3 1
element4 element5 1
...
element505535 element4 2
</code></pre>
<p>where the value in the 3rd column is the "strength" of interaction. Almost all of these strengths are "1." A strength o... | g37657 | [
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<p>Let $A=o_{a.s.}(1)$; $A:k\times k$ matrix and $Vu=O_p(1)$; $V:k\times k$; $u: k\times 1$.<br>
Specifically, $Vu$ converges in distribution to $\mathcal N(0,I_k)$.</p>
<p>Can we show that $VAu=o_p(1)$ or $\|VAu\|=o_p(1)$?</p>
<hr>
<p>If $V=O(1)$ and $V^{-1}=O(1)$ then we can show that $VAV^{-1}Vu=o_p(1)$. However,... | g59474 | [
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<p>In R, I use the decompose method on my time series object and it gives me seasonal + trend + random component. For seasonal component, it gives me absolute value which is good but I would also like to know the monthly seasonality index as well (like Jan .084, Feb 0.90, Mar 1.12, etc., for example). Is there a quick ... | g59475 | [
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<p>I am trying to implement random walk metropolis in Python for generate from a pdf $f$, which is defined in the domain:</p>
<p>$$(0, \infty) \times [3, 4] \times (0, \infty)$$</p>
<p>I am using Metropolis Random Walk with a trivariated normal. Can someone just take a look and see if my algorithm is correct?</p>
<p... | g59476 | [
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<p>I'm looking for a <strong>set of weak classifiers</strong> that work with <strong>Adaboost</strong> to test on <strong>popular datasets</strong>.</p>
<p>Most of the examples on the web use some kind of random weak learners which work on their own randomly generated dataset.</p>
<p>Could you point me to any usable ... | g59477 | [
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<p>I want to find the sample size for logistic regression where I have a covariate with 15 levels and the covariates interacts with time, which means that the effect of the covariates is different for different periods of times. Can anyone help me find the sample size and effect size? I wish I could do this using simul... | g15023 | [
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0.021841540932655334,
... |
<p>I need to analyze some data obtained from "in vivo" software testing. Unfortunately I’m a SW engineer, not a statistician. </p>
<p>The dataset contains observations for a number of messages sent between 2 nodes (actually, sent and returned). </p>
<p>There are two independent possible outcomes: 1. “message was flag... | g44294 | [
-0.019225966185331345,
0.010231698863208294,
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0.06112125143408775,
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0.032682646065950394,
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0.0227130725979805,
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0.03906848654150963,
0.... |
<p>I wonder whether it is possible to perform within R a clustering of mixed data variables. In other words I have a data set containing both numerical and categorical variables within and I'm finding the best way to cluster them. In SPSS I would use two - step cluster. I wonder whether in R can I find a similar techni... | g470 | [
0.023454001173377037,
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0.01573202572762966,
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0.018287265673279762,
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0.04134747385978699,
0.01378531102091074,
0.04945530369877815,
0.01... |
<p>I started my PhD study in Econometrics last month. Currently I am studying some compulsory course works (Probability theory and Statistical Inference), and also reviewing the literature in my field. I would also like to study some more mathematics, which I believe will make me more prepared for my formal research. C... | g15024 | [
0.0703192725777626,
0.032601166516542435,
0.014598711393773556,
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0.012467694468796253,
0.020529823377728462,
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0.08081137388944626,
-0.0... |
<p>I am defining the basic matrix:</p>
<pre><code>1 2 3 4
5 6 7 8
</code></pre>
<p>As follows:</p>
<pre><code>PROC IML;
RESET NOPRINT;
matrix = {1 2 3 4, 5 6 7 8};
EXIT:
</code></pre>
<p>I'm looking to resample each row (for using the bootstrap) with replaceme... | g41514 | [
0.002492851810529828,
-0.034359872341156006,
0.001983179245144129,
-0.03842300921678543,
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0.014751486480236053,
-0.02187076024711132,
0.03299251198768616,
0.0444028414785862,
0.03651... |
<p>What is the probability distribution function of the variable $y$ given by
$$y=\frac{x_1}{x_1-x_2},\quad \: x_i\ge 0,$$</p>
<p>given that $x_1$ and $x_2$ are independent and identically distributed and
$$x_i = c+z_i,\quad i=1,2 $$
where $c$ is a real nonnegative constant and $z_i\sim\chi^2_\nu$.</p> | g419 | [
0.03341255336999893,
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0.03832360357046127,
0.011427264660596848,
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0.013977084308862686,
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0.03793105483055115,
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... |
<p>I am doing a research in linguistics and I am not to sure what test to choose in the following problem.</p>
<p>There is a group of 26 students. They are asked a question and two possible variants are suggested. 12 of them choose the first answer, and 14 of them choose the second variant. </p>
<p>What test should I... | g15027 | [
-0.0007506709662266076,
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0.009039732627570629,
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0.005048852413892746,
0.06191062554717064,
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... |
<p>I want to fit a standardized generalized hyperbolid distribution to my data using the optim command.</p>
<p>Regarding my post <a href="http://stats.stackexchange.com/questions/58547/r-command-to-fit-a-standardized-generalized-hyperbolic-distribution-to-data">here</a>, I think I have to try it manually, by using the... | g38692 | [
0.01264139823615551,
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0.039576057344675064,
... |
<p>What is the most efficient way to find a set of 5 rigid, coplanar, non-collinear points within a 3D point cloud of, for example, 100 points?</p>
<p>(1) The configuration is specified by 2D coordinates (or in 3D with z=0). The points in the configuration and the ones in the point cloud we are intending to search ar... | g59478 | [
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0.024895919486880302,
0.0037395316176116467,
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0.0304326880723238,
-0.0229... |
<p>Please, I have a doubt in my study for doctoral thesis…</p>
<p>Title: “Development of a thermal cycling protocol for dental materials”.
Objective: to create a protocol for thermal aging, from measurements that were found in people mouth.
Doubt: What analyses could I use for this variation temperature data?
Experim... | g59479 | [
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0.0007658525719307363,
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0.017587995156645775,
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0.045692093670368195,
0.021020950749516487,
0.012793147005140781,
0.04363512620329857,
... |
<p>I have the following frequency table:</p>
<pre><code>35 0 4 3 7 6 5 4
39 1 9 6 7 7 6 8
36 0 7 10 11 11 10 16
41 0 9 8 8 7 6 7
41 0 8 9 10 9 12 11
55 2 12 9 11 12 11 13
55 1 10 10 11 10 12 11
47 1 14 8 12 15 12 12
45 1 10 11 10... | g12750 | [
-0.0362691655755043,
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0.015650419518351555,
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0.0005141071160323918,
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-0.01025450136512518,
0.005205127876251936,
0.028478235006332397,
0.03687623143196106,
0.0... |
<p>I'd like to do rank prediction (something very similar with regression) based on historical data, is there any package I can use in R ?
Here's my problems:</p>
<p>I have a historical data of sports games, and all the rank of each team and some statistic of these teams, I'd like to use these data to predict these t... | g12751 | [
0.029320163652300835,
-0.04799530282616615,
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0.007838228717446327,
0.00993424840271473,
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0.05213373899459839,
0.06173177435994148,
0.027075817808508873,
-0.0... |
<p>Colleague draw my attention to the following <a href="http://mpra.ub.uni-muenchen.de/32706/" rel="nofollow">discussion paper</a>. In my opinion this discussion paper is clearly intended as a critique of the routinely published articles in the field. The discussion paper relates the growth of gross domestic product w... | g59480 | [
0.04316175729036331,
0.1072770208120346,
0.012750817462801933,
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0.0016068669501692057,
-0.005250069312751293,
0.029580865055322647,
0.0... |
<p>I'm going through my copy of Analysis of Financial Time Series, 2nd Edition, and I'm at the ARMA portion. One of the techniques for model selection is computation of the extended auto-correlation function, which indicates that, in a table of EACF's with MA coefficients listed across the top and AR coefficients liste... | g59481 | [
-0.0022230949252843857,
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0.017449425533413887,
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0.09199655801057816,
0.002119675511494279,
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0.027862878516316414,
-0.023744771257042885,
0.04473703354597092,
0.0741867870092392,
-0.0... |
<p>So I'm looking to compare different combinations of features and classifiers. But I'm getting a lot of combinations that achieve 100% cross validation accuracy. I'm trying to figure out how I would compare the usefulness of each combination.</p>
<p>For example I can both train an SVM using Features 1, 10, 15 to get... | g13645 | [
0.0013444223441183567,
0.005233610048890114,
0.02512899972498417,
0.03681306168437004,
0.07611572742462158,
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0.028717510402202606,
0.04744650423526764,
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-0.02296490967273712,
-0.009300551377236843,
0.026174843311309814,
0.05759471654891968,
0.02187... |
<p>I am writing my PhD thesis and I've realized that I rely excessively in box plots in order to compare distributions. Which other alternatives do you like for achieving this task?</p>
<p>I'd also like to ask if you know any other resource as the R gallery in which I can inspire myself with different ideas on data vi... | g44378 | [
0.019224386662244797,
0.03526666387915611,
-0.01523269060999155,
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0.0013941089855507016,
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-0.07869181036949158,
0.06591109186410904,
-0.029362723231315613,
0.1159970685839653,
0.0173... |
<p>I read online that it is only necessary to use adjusted-$R^2$ when you are working with a sample rather than the entire population.</p>
<p>The data I'm working with is information on a series of live educational seminars. Each datapoint represents a single seminar that was held in the past, and contains various inf... | g15033 | [
-0.00826784037053585,
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0.055861398577690125,
0.03716355934739113,
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0.010190093889832497,
0.016283320263028145,
-0.016356050968170166,... |
<p>In preparation for my end of semester R exam, I've been working on the following CSV file which was modelled on R, which I'm currently having problems figuring out. </p>
<p><img src="http://i.stack.imgur.com/cdRNC.png" alt="enter image description here">
<img src="http://i.stack.imgur.com/B6D61.png" alt="enter imag... | g59482 | [
0.01011408306658268,
-0.001277027651667595,
-0.0019557219929993153,
-0.045631181448698044,
-0.03445006161928177,
-0.03521149978041649,
0.03479447215795517,
0.036843761801719666,
-0.04246219992637634,
-0.009466293267905712,
0.025060102343559265,
0.00015732349129393697,
0.027557963505387306,
... |
<p>I'm trying to test the performance of posterior inference on a set of documents with hierarchical Dirichlet process for topic modeling.
How can i convert my data (document) to standard data format ?</p>
<p>such as this command :</p>
<pre><code>[M] [term_1]:[count] [term_2]:[count] ... [term_N]:[count]
</code>... | g59483 | [
0.05125957354903221,
-0.033926092088222504,
-0.00603879289701581,
-0.11394090950489044,
0.0031080630142241716,
-0.02194357104599476,
-0.02429833449423313,
0.028159810230135918,
-0.051492881029844284,
-0.05125394091010094,
-0.0023427323903888464,
0.027718277648091316,
0.014641119167208672,
... |
<p>Say I've got a predictive classification model based on a random forest (using the randomForest package in R). I'd like to set it up so that end-users can specify an item to generate a prediction for, and it'll output a classification likelihood. So far, no problem.</p>
<p>But it would be useful/cool to be able to ... | g41076 | [
-0.02388373576104641,
-0.025734905153512955,
0.016691632568836212,
-0.02952883578836918,
-0.024309204891324043,
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0.042904332280159,
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-0.04333090782165527,
0.015129227191209793,
0.02365475706756115,
0.038977280259132385,
-0.0... |
<p>1.AdaBoost updates the weight of the sample By the current weak classifier in training each stage. Why doesn't it use the all of the previous weak classifiers to update the weight. <strong>(I had tested it that it converged slowly if I used the previous weak classifiers to update the weight )</strong> </p>
<p>2.It... | g59484 | [
0.012081149034202099,
-0.019418762996792793,
0.004456822760403156,
-0.02593160606920719,
0.021552402526140213,
-0.009732660837471485,
0.010550227016210556,
0.050591710954904556,
-0.038325559347867966,
-0.045936521142721176,
-0.04220804199576378,
0.02288179285824299,
0.04976679012179375,
0.... |
<p>I've searched everywhere for this answer, and come up empty handed. </p>
<p>I'm building a forecasts model for interface traffic reported in 5 minute intervals over a 1 year period. </p>
<p>To account for multiple seasonality, I came to the conclusion that the TBATS function in R would be most useful (with seasons... | g59485 | [
-0.0018735443009063601,
0.017842575907707214,
-0.024506447836756706,
-0.016490740701556206,
-0.013279970735311508,
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0.09580684453248978,
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-0.025085799396038055,
-0.0067926812916994095,
0.004252697341144085,
0.0816723108291626,
... |
<p>I'm using ridge regression for calculating optimal weights of a set of scores. These scores are correlated so the usage of ridge regression is used for penalizing large values of weights. So the purpose of ridge regression is to find beta that minimize the following:</p>
<p>$$
\sum_i{(y_i - x^T_i\beta_i)^2} + \lam... | g59486 | [
0.017510876059532166,
-0.02542443573474884,
0.005453136283904314,
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0.024808645248413086,
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0.005024073179811239,
0.05790654569864273,
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-0.0058623310178518295,
0.0019346850458532572,
-0.012920081615447998,
0.041262608021497726,
... |
<p>I have created training set and test set from my data. Then I performed auto.arima() and ets() in R on the training set to predict one-step ahead forecasts. These were then compared with the test set values to measure error, namely RMSE, MAPE & MAE.</p>
<p>This is the output of both ets and auto.arima</p>
<pre... | g15038 | [
-0.040287554264068604,
-0.0527559369802475,
0.022096697241067886,
-0.003383393632248044,
-0.03654855489730835,
0.0008275834261439741,
0.05518406629562378,
0.004997280426323414,
-0.010392207652330399,
-0.010397836565971375,
0.05766830965876579,
0.06405919790267944,
0.06487435102462769,
-0.0... |
<p>I have the following 2x2 table</p>
<pre><code> NO YES
9690 5 LOW
26354 39 HIGH
</code></pre>
<p>I want to</p>
<ol>
<li>plot the proportions and their exact confidence intervals in two bar</li>
<li>plots test if the proportion YES in LOW differs significan... | g49378 | [
0.030517347157001495,
-0.01868433505296707,
-0.003947701305150986,
-0.0016542315715923905,
0.0077226487919688225,
0.04986279830336571,
0.04878617450594902,
0.03860260173678398,
-0.04542787745594978,
-0.028277631849050522,
-0.019462769851088524,
0.0050620767287909985,
0.015249534510076046,
... |
<p>Is anyone aware of a re-parameterization of any asymmetric s-shaped function (like, but not necessarily the 5 parameter logistic curve), where one of the parameters is the first inflection point of the first derivative (i.e. the maximum of the second derivative).</p>
<p>I mean <strong>point 1</strong> in the upper ... | g37947 | [
0.0049319639801979065,
-0.05556892231106758,
-0.01814926043152809,
0.0375707633793354,
0.059070736169815063,
-0.06251212954521179,
0.00006716135249007493,
0.0185907743871212,
-0.06644278019666672,
0.047415442764759064,
-0.0304779764264822,
0.0276517104357481,
0.07476527243852615,
0.0443904... |
<p>Let's say I have the following logistic regression models:</p>
<pre><code> df=data.frame(income=c(5,5,3,3,6,5),
won=c(0,0,1,1,1,0),
age=c(18,18,23,50,19,39),
home=c(0,0,1,0,0,1))
> md1 = glm(factor(won) ~ income + age + home,
+ data=df, family=bin... | g59487 | [
-0.04154772683978081,
-0.03106566332280636,
-0.002175184665247798,
-0.02491188235580921,
0.008244461379945278,
-0.02601444348692894,
0.0708046704530716,
0.006479418370872736,
-0.06198849156498909,
-0.014131864532828331,
-0.06746122241020203,
0.011949626728892326,
0.07582258433103561,
-0.03... |
<p>i have the following tree</p>
<pre><code>Outlook(
[Sunny] => (Yes, Yes, No, No, No),
[Overcast] => (Yes, Yes, Yes, Yes),
[Rainy] => (Yes, Yes, Yes, No, No)
)
</code></pre>
<p>i want to know how to calculate the information value of each set</p>
<pre><code>info([2,3])
info([4,0])
info([3,2])
</co... | g49559 | [
-0.026263417676091194,
0.0016960898647084832,
-0.031527936458587646,
-0.04007704183459282,
-0.002304501598700881,
-0.045629922300577164,
0.0029500469099730253,
-0.03821580857038498,
-0.08183874189853668,
0.017593447118997574,
-0.07778562605381012,
0.08430686593055725,
0.03313643857836723,
... |
<p>From my model selection based on information criteria such as SBIC returns me a ARMA(0,0) model. Should I choose it or reject it? and Why?</p>
<p>Need some guidance on this.</p> | g59488 | [
0.04803945869207382,
-0.004455972462892532,
0.01655958592891693,
0.021907659247517586,
0.026130985468626022,
0.009022429585456848,
-0.003747976152226329,
0.014651131816208363,
0.013374408707022667,
0.013303291983902454,
0.049224089831113815,
0.013942995108664036,
0.048846982419490814,
0.02... |
<p>I'm studying by myself, and the text says « If $\epsilon_\alpha$ is the upper $\alpha$-quantile of the distribution of $\frac{\hat{\theta}-\theta}{\hat{\sigma}}$, then $P(\hat{\theta}-\epsilon_\beta\hat{\sigma}\leq \theta \leq \hat{\theta}-\epsilon_{1-\alpha}\hat{\sigma} )\geq 1-\beta-\alpha$ .»
However, from wiki, ... | g15044 | [
0.002285702619701624,
-0.0322406105697155,
-0.018189232796430588,
-0.05990619584918022,
0.08669305592775345,
0.0028529204428195953,
0.041703641414642334,
-0.020436368882656097,
-0.015935232862830162,
-0.006974940188229084,
-0.016960928216576576,
0.032471664249897,
0.03637809678912163,
0.05... |
<p>I have the following survival <a href="http://dl.dropbox.com/u/45635510/simple_sample.csv" rel="nofollow">data</a> and have constructed a survival plot however cannot mark the right censored points (which makes me think my survival graph is also incorrect) - how can I manage this please?</p>
<p>Now answered! -
<im... | g59489 | [
-0.04778511822223663,
-0.06868533790111542,
-0.010043177753686905,
0.03541209548711777,
0.03672808036208153,
0.021305566653609276,
-0.03397783637046814,
0.016149016097187996,
-0.01746060512959957,
0.017595358192920685,
0.040336206555366516,
0.005729260854423046,
0.06632382422685623,
0.0197... |
<p>I have instances of data that are composed of 6 attributes. Each attribute takes values between 1-10. Any instance has a utility calculated by some utility function:</p>
<p>Example: {1,1,2,5,5,2} , utility = 0.89</p>
<p>In some readings for these attribute values, undefined values may appear in the instance, I mar... | g59490 | [
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0.006187645252794027,
0.01996702142059803,
0.0714702159166336,
0.00165... |
<p>Recently I am studying a probability problem related to the multivariate hypergeometric distribution. The problem is stated as:</p>
<blockquote>
<p>Given well-mixed $n$ balls of $m$ colors, and assume that $n_i$ is the number of balls with color $i$, where $i \in {1, ..., m}$. So we have $\sum_{i=1}^{m}n_i = n$</... | g59491 | [
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0.0197... |
<p>I have a data set of 40,000 individuals which I clustered using k-means. I used 30 variables, each ordinal from <code>1=minimum</code> to <code>5=maximum</code>. I reduced these 30 variables to 10 factors and ran K-means on these new variables. I kept a clustering of 12 clusters. </p>
<p>I now have 7000 new observa... | g15047 | [
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0.06758192926645279,
0.0478... |
<p>I dont get the difference between the <code>rfobject$importance</code> and <code>importance(rfobject)</code> in the MeanDecreaseAccuracy column.</p>
<p>Example:</p>
<pre><code>> data("iris")
> fit <- randomForest(Species~., data=iris, importance=TRUE)
> fit$importance
setosa versicol... | g15049 | [
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<p>Suppose I sample many times independently from each of two normal distributions. Given the means, standard deviations, and number of samples from each distribution, how can I calculate the probability that the highest sampled value came from the first distribution?</p>
<p>I can solve this question by simulating it ... | g59492 | [
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0.008991418406367302,
0.04121291637420654,
0.01... |
<p>If I have random variables $X_1,X_2,\ldots,X_n$ that are Poisson distributed with parameters $\lambda_1, \lambda_2,\ldots, \lambda_n$, what is the distribution of $Y=\left\lfloor\frac{\sum_{i=1}^n X_i}{n}\right\rfloor$ (i.e. the integer floor of the average)?</p>
<p>A sum of Poissons is also Poisson, but I am not c... | g15051 | [
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<p>I am given a set of almost 100 crosstabulations (most 2D, but some three dimensional) based on a single, yet unavailable dataset. My task is to perform basic statistical tests ($\chi^2$, Mann-Whitney, Kruskal-Wallis, etc.). I could calculate them by hand, by it would be over one order of magnitude faster to use my "... | g59493 | [
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<p>I want to run PCA on a set of variables and then regress the scores on my dependent variable.</p>
<p>I have the following questions:</p>
<ol>
<li>Should I scale and center my variables?</li>
<li>If yes, should I also standardize my dependent variable before running linear regression?</li>
<li>What if I don't stand... | g15053 | [
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<p>I'm trying to understand a passage in Koenker's Quantile regression book (p.33).
It says: (note that y,x, are vectors and w is the direction vector)
<img src="http://i.stack.imgur.com/KZVlI.png" alt="enter image description here"></p>
<p>With the first part of the outcome no problem: I apply the product rule for de... | g59494 | [
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<p>I am trying to fit a model to binomially distributed data, which I have done via the maximum likelihood method. Normally I'm working with normally distributed data (or data which I can convince myself and occasionally others is normally distributed) and I'm a little confused about how to find asymmetric errors on my... | g44741 | [
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<p>I wish to simulate survival data for the following probabilistic model which will be analyzed using a Cox model:</p>
<p>An exposure $X$ is modeled as binary having $X \sim_{iid} \mbox{Bernoulli}(p)$ where $p = \frac{1}{3}$. The hazard is a function of $X$ with:</p>
<p>\begin{eqnarray}
\log \left( \lambda(t|X=0) \r... | g59495 | [
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<p>My colleague and I disagree on the following data, and the calculation of the mean: </p>
<p>Given $n$ respondents, each respondent has three chances to score a hoop at basketball. A respondent has 'hooped' successfully if they score 1 or more hoops. </p>
<p>Given the following table of scores</p>
<pre><code>respo... | g59496 | [
0.004998322110623121,
0.024699097499251366,
0.007756268139928579,
0.005865178536623716,
0.004327121656388044,
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0.07612494379281998,
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0.... |
<p>I am investigating the relationship between temperature fields obtained from numerical weather models and electricity demand. I am applying a PCA-based approach, i.e. I study the linear relationship between main temperature patterns/modes and main demand patterns/modes. Given that I am working on summer yearly deman... | g49118 | [
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0.016975026577711105,
0.02941322512924671,
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<p>I'm implementing various algorithms to estimated the best number of bins to use for histograms. Most of the ones I am implementing are described on the wikipedia page:</p>
<p><a href="https://en.wikipedia.org/w/index.php?title=Histogram&oldid=548769683#Number_of_bins_and_width">https://en.wikipedia.org/w/index.... | g59497 | [
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<p>I want to implement the EM algorithm manually and then compare it to the results of the <code>normalmixEM</code> of <code>mixtools</code> package. Of course, I would be happy, if they both lead to the same results.</p>
<p>The main reference is Geoffrey McLachlan Finite Mixture Models 2000.</p>
<p>I have a mixture ... | g15056 | [
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0.0024188158567994833,
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0.010312297381460667,
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0.08662179857492447,
-0.0... |
<p>I am a bit confused with this. </p>
<p>Independence - The response variables are independent. I only have a single response variable so OK? Or observations are independent of each other? E.g Auto Correlated </p>
<p>Normality - The response variable is normally distributed. My response variable (Y) fails a number o... | g49560 | [
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... |
<p>Suppose I have two data sets. The average of one data set is 5.5 secs and the standard deviation is 0.0435. The average of the other data set is 5.2 secs but the standard deviation is 0.5123. I know that something is wrong with the second data set because the standard deviation is too high.</p>
<p>My question is ho... | g44339 | [
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... |
<p>I use hierarchical clustering to cluster users which are similar to each other based on a Jaccard coefficient. </p>
<p>I have now coded a solution to extract similar users based on hierarchical clustering: To group users that are similar I compute the Jaccard coefficient between all the different users. I then che... | g13648 | [
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0.016898831352591515,
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<p>I have a data set based on 14 field sites, the dependent variable I am investigating is count data recorded at each site (on 3-5 visits). The independent variables (I have around 45) are fixed at each site (apart from wind speed and temperature). An example data set, illustrating this is below:</p>
<pre><code> ... | g59498 | [
0.027773896232247353,
-0.041231825947761536,
-0.01550010871142149,
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0.015638316050171852,
0.014559726230800152,
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-0.042266976088285446,
0.003971636760979891,
0.021982913836836815,
0.006657746154814959,
-... |
<p>I fitted a cox model as:</p>
<p><code>cfit <- coxph(Surv(tr$start, tr$end, tr$event1) ~ imp+sec + cluster(tr$compid))</code></p>
<p>Now i want to get the probability of event1 for the test dataset for each start and stop time interval, given it has other variables present.</p>
<p>How can i use the predict func... | g59499 | [
0.009887545369565487,
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0.012308980338275433,
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-0.0... |
<p>Suppose I have a process <strong>X1</strong>, for which I do not have a generator matrix, only a transition (probability) matrix <strong>P1</strong> for some time interval <strong>T</strong>, e.g. <strong>T</strong>=100. Suppose I have another process <strong>X2</strong>, such that <strong>X2</strong> is identical t... | g59500 | [
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0.0008090790361166,
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0.023544691503047943,
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0.02493363246321678,
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0.00... |
<p>What is the difference between data 'Normalization' and data 'Scaling'? Till now I thought both terms refers to same process but now I realize there is something more that I don't know/understand. Also if there is a difference between Normalization and Scaling, when should we use Normalization but not Scaling and vi... | g59501 | [
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<p>I was unable to figure out how to perform linear regression in R in for a repeated measure design. In a <a href="http://stackoverflow.com/questions/12182373/plot-of-a-linear-regression-with-interactions">previous question</a> (still unanswered) it was suggested to me to not use <code>lm</code> but rather to use mixe... | g59502 | [
0.03576786071062088,
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0.012765701860189438,
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<p>We have trained about 200 Linear Support Vector Machines (hand-coded in C#) belonging to our 200 categories and we use them in text categorization. Due to the shortness of the text in our training samples and other uncontrollable factors, very often every machine returns a negative number for (classifies as negative... | g59503 | [
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0.06612534821033478,
... |
<p>I am doing a modearated moderation using the process add on. There is no significant 3-way interaction for my 3 moderator (one is gender) but the conditional effects suggests that the signficant 2-way interaction is different for males and females. How do I interpret/report this?</p> | g59504 | [
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0.009975334629416466,
0.012619361281394958,
0... |
<p>Formality says that when computing the sample variance or sum of squares one computes a sample mean with the sample data given. </p>
<p>If for some reason I had access to a better estimate of the mean (from a bigger sample) then can I use that mean instead of the mean from the given sample?</p>
<p>I want to comput... | g59505 | [
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0.04695308580994606,
0.06333231180906296,
0.0... |
<p>I have 2 study areas</p>
<p>Study area 1: 12 meteorological stations-years available 1981-2000(same data and step)</p>
<p>Study area 2: 10 meteorological stations-years available 1985-2011(same data and step)</p>
<p>From the 1st study area I have to use the above mentioned data series.
I would like to know which ... | g15065 | [
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0.00988610927015543,
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0.03206810727715492,
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0.034922998398542404,
0.023380890488624573,
0.007905365899205208,
-0.0142... |
<p>Canonical correlation analysis (CCA) aims to maximize the usual Pearson product-moment correlation (i.e. linear correlation coefficient) of the linear combinations of the two data sets.</p>
<p>Now, consider the fact that this correlation coefficient only measures linear associations - this is the very reason why we... | g59506 | [
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... |
<p>I'm looking for ideas on how to discover cheating in sports that have judges awarding points. I can't name the sport since I participate in it at the moment. It's been known for a long time that this sport has rampant collusion behind the scenes. </p>
<p>In each competition there are competitors who are evaluated o... | g59507 | [
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<p>I have 3 vectors which are unequal in size (lengths: 21, 33 and 7). Each vector contains ratio of bug-to-duplicate bugs in 3 different time periods. I have to find whether there is a difference between the 3 groups.</p>
<p>I cannot use one-way ANOVA since the groups have unequal sample sizes and unequal variances. ... | g15066 | [
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<p>I normally cross-validate my tree-models (rpart) only on cp-value, e.g. by using caret or xpred or the internal rpart cross validation function. </p>
<p>However, there are other rpart parameters -- for example <a href="http://stat.ethz.ch/R-manual/R-devel/library/rpart/html/rpart.control.html" rel="nofollow">minimu... | g15067 | [
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0.015012294054031372,
0.008219709619879723,
-0.028827564790844917,
0.0066275037825107574,
... |
<p><a href="http://en.wikipedia.org/wiki/Spiking_neural_network">Pulsed or Spiking</a> neural networks incorporate more of the membrane dynamics of biological neurons, where pulses carry information to the next layer. The neurons do not necessarily have to "fire" all at the same time, as they would in a backprop, for ... | g37434 | [
0.007103277835994959,
0.057245414704084396,
0.028201721608638763,
0.05915375053882599,
0.04280148074030876,
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0.06955328583717346,
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-0.022830218076705933,
0.027314838021993637,
0.012163136154413223,
0.05258004739880562,
0.0307... |
<p>If I have a time series regression model with serially correlated errors:</p>
<p>$Y_t=\beta_0+\beta_1X_t+\epsilon_t$</p>
<p>$\epsilon_t=\rho\epsilon_{t-1}+v_t$</p>
<p>why is the estimate of the correlation ($\rho$) in the second equation NOT the autocorrelation of the residuals from the first equation?</p>
<p>Th... | g59508 | [
0.06109779328107834,
-0.0864534080028534,
0.0019349886570125818,
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0.03772146627306938,
0.019370416179299355,
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0.030507739633321762,
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-0.030639182776212692,
0.003416551975533366,
0.07029738277196884,
0.009665751829743385,
-0.02... |
<p>I ran a regression in which I have an interaction term of two factor variables.</p>
<p>The one of the variables has 2 levels: Condition_A & Condition_B (therefore the first one is the reference category) but the other one is called Group.Membership has 3 levels: Group_1, Group_2 & Group_3 (therefore the fir... | g49561 | [
0.02878028154373169,
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0.07927591353654861,
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0.019062766805291176,
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0.0... |
<p>Apparently Wooldridge, <a href="http://rads.stackoverflow.com/amzn/click/0324660545" rel="nofollow">Introductory Econometrics</a>, 2002ed is the only book showing that two-stage least squares (2SLS) is asymptotically efficient. I cannot get a copy of the proof. </p>
<p>Is it correct to just use the generalized meth... | g59509 | [
0.03730599954724312,
-0.03910493105649948,
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0.06535084545612335,
0.009834622964262962,
0.03601471334695816,
0.0692828819155693,
0.0169... |
<p>Prove that FGLS is asymptotically efficient. Does one have to use Cramer Rao to do this?</p> | g44350 | [
0.02686951495707035,
0.061030253767967224,
0.009415394626557827,
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0.03697953000664711,
0.010296083986759186,
0.029283421114087105,
0.0... |
<p>Given $f\left(x|\theta\right)=1/\theta, 0\leq x\leq \theta,L\left(\theta, a\right)=\left(a-\theta\right)^2,$ and $\pi\left(\theta\right)=\theta e^{-\theta},\theta\gt 0$</p>
<p>I've seen <a href="http://stats.stackexchange.com/questions/7631/problem-calculating-joint-and-marginal-distribution-of-two-uniform-distribu... | g59510 | [
0.055789195001125336,
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0.02095988765358925,
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0.031121600419282913,
-0.... |
<p>I am having difficulty interpreting the results of a colleague. I don't know much about ANOVA other than it is a regression from classifications to floating point numbers.</p>
<p>From reading Gotelli's Ecological Statistics book, I have figured out more or less that the F-ratio is a step in getting the P value. The... | g49562 | [
0.0477573461830616,
0.019247744232416153,
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-0.019055569544434547,
0.015184258110821247,
0.04510294646024704,
0.004... |
<p>What kind of plot are normally used in Generalized linear model and what are their interpretations?</p>
<p>Especially for Standardized deviance residual vs fitted value plot, what can we see from the plot?</p> | g15072 | [
-0.0008611715747974813,
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0.00926997885107994,
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... |
<p>I have a question about different ways of specifying a response variable in a model and what effect this could have on my results. </p>
<p>In my example, I wanted to model the number of times a bird visits a nest to feed its young during a set period of time. So the data would be a set of counts, let's call it <cod... | g15073 | [
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0.03927355632185936,
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-0.021084556356072426,
0.007183251436799765,
-0.014526154845952988,
0.09040062129497528,
... |
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