question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I was referred to this site from mathoverflow. After some brief searching, I haven't seen another thread on my particular question, but if it's already been answered elsewhere then I hope you'll forgive the spam.</p>
<p>Has anyone ever "ranked" the various commonly-used parametric and non-parametric hypothesis tes... | g41298 | [
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<p><img src="http://i.stack.imgur.com/ZoPHf.png" alt="enter image description here"></p>
<p>I'm interested in how one can calculate a quantile on a multivariate distribution. In the above picture, I have drawn the 5% and 95% quantiles on a given univariate normal distribution (left). For the right multivariate normal ... | g22757 | [
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<p>I am wondering how I could express the variance of log-odds into understandable terms.</p>
<p>For example the variance in the log-odds of crime being reported to the police between neighbourhoods is 0.07 (0.01), and the mean log-odds is -0.65 (0.03). Just transforming this variance to probability given me 0.51. So ... | g63956 | [
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<h1>The problem</h1>
<p>I am trying to fit a calibration curve from known x and y with jags. I would then like to predict new xes, based on the measurement of new ys. For this, I am following Hamada et al. (2003), J Quality Technology 35:194-205. Since I have subject effect, I wanted to incorporate that in my calibrat... | g37452 | [
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<p>I have 1 continuous dependent and 1 continuous predictor variable that I've logarithmically transformed to normalise their residuals for simple linear regression. Can someone give me some pointers on how to relate these transformed variables to their original context?</p>
<p>My situation:</p>
<p>I want to use line... | g63957 | [
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<p>I have a training data set for a binary classification problem. There exist two possible scenarios, one is that all of the training data set are labeled as positive; another one is that the training data set includes labeled positive ones and labeled negative ones.</p>
<p>Assume that I use this training data set to... | g21866 | [
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<p>I'm trying to use different distance metrics like Euclidean, Manhattan, cosine, chebyshev among other distance metrics in my k-means algorithm to calculate distances between the data points and the centers. In what situation would one distance metric be more useful over the other in a clustering scenario? [Comparing... | g49575 | [
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<p>I am new here, so I might have missed a similar question.
I am trying to do things good in my research and using proper statistical approaches, but in computer science, we had quite a weak training on statistical methods applied to our research.</p>
<p>So, what I am asking is probably trivial. Here is the problem:... | g21869 | [
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<p>For a multilabel dataset, i would like to find the number of clusters involved in it. The below example gives more details about the problem:</p>
<pre><code>Label_A: feature values
Label_B: feature values
Label_A, Label_C: feature values
Label_C: feature values ... etc
</code></pre>
<p>We have say $n$ datarecord.... | g21870 | [
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<p>Consider a single x axis representing points along a line in space. I've got a set of data (in this case the receptive fields of hippocampal place cells recorded as a rat runs along a linear track), which are themselves spatially extensive, ie. if displayed graphically against the axis they would look like a series ... | g13925 | [
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<p>I am working with the dataset of some heights and weights at different ages. My professor wants me to plot the residuals from regression of <code>soma.WT9</code> against the residuals from regression of <code>HT9.WT9</code> (don't mind the notation it's just two columns where soma is being regressed on <code>WT9</c... | g21871 | [
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<p>What's it called when I'm trying to remove the effect of a variable on another variable? Am I in the right ballpark using the terms "detrending" or "normalizing" or "controlling for Y on X"? What's the general process for doing this?</p>
<p>The problem I'm working with currently is as follows:</p>
<p>I work at a m... | g63958 | [
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<p>I have 6 random number generators. They are "black boxes", i.e. I do not know if they are the same or different. For example I do not know if they provide the same arithmetic averages and/or root mean square deviations. My goal is to check if they are the same or different. The problem is that I can generate a limit... | g38149 | [
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<p>I have a dataset of height and weight measurements for adult patients in hospital clinic and want to calculate a standardized measure of boy mass index (BMI). For a given pair of measurements, it is easy to calculate BMI:</p>
<p>$BMI = weight (kg) / \left( height (m) \right)^2$</p>
<p>The problem I have is that so... | g849 | [
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<p>Suppose that there is a field where cabbages grow. We have weighed all the cabbages in spring and got Gaussian distribution of weights. The same we did in autumn and got another Gaussian distribution. The question is how to get distribution of growth rates (times over the summer) if cabbages are not numbered? Will i... | g63959 | [
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<p>I am using R to calculate lagged correlation. Instead of getting lag values -20 to 20, I am getting the following values:</p>
<pre><code> [,1]
[1,] -0.83333333
[2,] -0.75000000
[3,] -0.66666667
[4,] -0.58333333
[5,] -0.50000000
[6,] -0.41666667
[7,] -0.33333333
[8,] -0.25000000
[9,] -0.16666667
[10... | g8125 | [
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-0.0... |
<p>I'm doing survival analysis and using the survival package from R to do it. I have 7 variables, 5 of which are time-dependent (all except sexo and peso).</p>
<p>Here is my model:</p>
<pre><code>Call:
coxph(formula = Surv(tempo1, tempo2, status) ~ sexo + clima +
CODE_06 + TP_media7 + ndvi + peso + epoca, data ... | g21874 | [
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0.0361... |
<p>While reading some articles about High frequency statistics in financial markets, more precisely wile reading about microstructure noise, I was confronted by some signature plots simulated graphics. </p>
<p>It seems me to be a basic concept in statistics or, at least, just a well known term. However for a lack of c... | g63960 | [
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<p>I've been trying to fit a SEM model, using misconceptions and the correct conception as latent variables.</p>
<p>My instrument is a set of items that ask a binary yes or no question. (Is something in a particular category?) The correct conception would have all items that would be correct if yes was chosen loaded o... | g41317 | [
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<p>I've encountered interesting prediction of Eurovision Song Contest <a href="http://mewo2.com/nerdery/2013/05/12/eurovision-2013-first-predictions/" rel="nofollow">http://mewo2.com/nerdery/2013/05/12/eurovision-2013-first-predictions/</a> it based on some kind of Bayesian model I assume but I don't understand how it... | g41318 | [
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<p>Assume I want to use a (nonparametric) bootstrap test for a hypothesis with a sample size of $n_1$ and I already have $n_0$ actual samples on which to base my power estimates. Usually, we would also have $n_1 > n_0$.</p>
<p>Is it a valid procedure to estimate the power of my test by using nested bootstrapping? B... | g63961 | [
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<p>I am in doubt whether in my thesis I should report on the subject specific predictions of the probability to respond with an 'I don't know' answer, or the population average. Consider for example the following graphs (I have not gotten them smaller yet):</p>
<p><img src="http://i.stack.imgur.com/Df5cw.png" alt="ent... | g41321 | [
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<p>I am doing some forecasting in R using Rob Hyndman's <em>forecast</em> package. The paper belonging to the package can be found <a href="http://www.jstatsoft.org/v27/i03" rel="nofollow">here</a>.</p>
<p>In the paper, after explaining the automatic forecasting algorithms, the authors implement the algorithms on the ... | g41322 | [
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<p>I conducted a PCA on dichotomous variables (0's and 1's). The dataset consists of human subjects and a few thousand genetic variants, where the presence of a genetic variant is indicated with 0's and 1's. </p>
<p>My first PC correlates >.9 with the nr of 1's in a subject.</p>
<p>Is this expected?</p>
<p>Could thi... | g63962 | [
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<p>I would like to calculate the jensen-shannon divergence for he following 3 distributions. Is the calculation below correct? (I followed <a href="http://en.wikipedia.org/wiki/Jensen%E2%80%93Shannon_divergence" rel="nofollow">the JSD formula from wikipedia</a>):</p>
<pre><code>P1 a:1/2 b:1/2 c:0
P2 a:0 b:1/1... | g21876 | [
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-0.0028694651555269957,
-0.04229829087853432,
0.0026940335519611835,
0.04279487952589989,... |
<p>My problem is that I have a state space model that I estimate using the Berndt–Hall–Hall–Hausman (BHHH) algorithm. The state space model is relatively simple in that the hidden part follows a pure AR(1) process.</p>
<p>From tests on simulated data I know I need a time series of 500 observations to get good converge... | g63963 | [
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0.007890496402978897,
0.036483388394117355,
0.047602102160453796,
0.06... |
<p>Can somebody tell me or give a reference about the "Market Basket Problem" in data mining. What is this problem about? Any scientific reference with application will be greatly appreciated.</p> | g63964 | [
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0.0479104220867157,
0.01222... |
<p>What are the key differences between the following two models?</p>
<pre><code>lmefit = lmer(MathAch ~ SES + (1 |School) , MathScores)
lmfit = lm(MathAch ~ SES + factor(School) -1 , MathScores)
</code></pre>
<p>To me, they seem to be the same, except that lmefit takes less parameters (because it used Normal dist... | g63965 | [
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0.... |
<p>I'm surprised I haven't run into this question yet, but I was wondering if there is a sound way of testing the difference in predicted means between two points on the <em>same</em> slope.</p>
<p>For example:
Let's say my predictor is the age of a car, and my predicted variable, its price. Let's assume that the down... | g63966 | [
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<p>I switched from <code>SAS</code> to <code>R</code>. I was using <a href="http://www.ats.ucla.edu/stat/sas/library/SASExpDes_os.htm" rel="nofollow">"SAS Code for Some Advanced Experimental Designs"</a> as a reference whenever I had data from experimental design studies. With advanced experimental designs I always hav... | g21883 | [
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0.05831079185009003,
... |
<p>I plan to do a simulation study where I compare the performance of several robust correlation techniques with different distributions (skewed, with outliers, etc.). With <em>robust</em>, I mean the ideal case of being robust against a) skewed distributions, b) outliers, and c) heavy tails.</p>
<p>Along with the Pea... | g21885 | [
0.04111330211162567,
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0.0344206728041172,
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0.07563921064138412,
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0.04471873864531517,
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<p>I was fiddling with PCA and LDA methods and I am stuck at a point, I have a feeling that it is so simple that I can't see it.</p>
<p>Within-class ($S_W$) and between-class ($S_B$) scatter matrices are defined as:</p>
<p>$$
S_W = \sum_{i=1}^C\sum_{t=1}^N(x_t^i - \mu_i)(x_t^i - \mu_i)^T
$$</p>
<p>$$
S_B = \sum_{... | g21886 | [
-0.041767418384552,
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0.001105613773688674,
0.05286266282200813,
0.009729618206620216,
0.03... |
<p>I have a question about interaction terms in logistic regression: I find an interaction effect between two binary variables. One of the four categories (0*0) consists however of only 15 respondents (5% of the sample). Is this a problem? </p> | g63967 | [
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0... |
<p>I am Ashenafi</p>
<p>I would like to ask, Is it possible to know the maximum order of GARCH(p, q); value of p and q (For example, using R software)automatically?
Example: In ArchTest, I got some where the result like the following</p>
<pre><code> Chi-squared = 4.3044, df = 1, p-value = ... | g63968 | [
-0.0026317485608160496,
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0.004071206320077181,
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0.018655002117156982,
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0.033179871737957,
0.06302258372306824,
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<p>We ran advertising to a certain group of demographic profiles in one single television region. The advertising ran for 4 weeks. We measured the conversion rate for the period of the advertising and for the prior 4 weeks. We were then able to measure the difference in conversion rates.</p>
<p>I would like to know... | g21896 | [
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0.009841418825089931,
0.048607464879751205,
0.07292352616786957,
0.04709213227033615,
0.026... |
<p>I have a data set with N ~ 5000 and about 1/2 missing on at least one important variable. Comparing the people with missing data to those with complete data it is fairly clear that the data are not missing at random (nonignorable nonresponse). The missing data pattern is not monotone missing and at least some data ... | g21898 | [
0.03918188437819481,
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0.008652711287140846,
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0.0648568868637085,
0.06... |
<p>I'm evaluating a few supervised feature selection algorithms, with a focus on redundancy.</p>
<p>As a base correlation statistic, I'm using Mutual Information - so discrete variables are also a focus for simplicity.</p>
<p>Does anyone know any good methods of redundant feature generation for discrete data? Either ... | g63969 | [
0.00019151192100252956,
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<p>I am doing statistics for the first time in my life and I am not quite sure what to include and how to interpret the results. I am doing a logistic regression in R. Here is what I have so far:</p>
<ol>
<li><p><code>GLM</code> with family = binomial (dependent ~ indep1 + indep2 + ...+ indep7 +0)
If I dont include t... | g63970 | [
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<p>I'll preface this by stating I'm very new to computer vision. I took a Stanford Machine Learning course on Coursera, and that is the extent of my experience. I'm working on a free-time project to learn more about the subject. I fully acknowledge the steep learning curve.</p>
<p>What I'm trying to do is to create a ... | g63971 | [
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<p>I have a dataset that describes the daily history of occurrences of a certain phenomenon P among a certain population. (These are subdivided into certain classes or forms that the phenomenon can take: for every day, we have numbers of occurrences of P_1, P_2, ..., P_N.) The phenomenon is rather rare: more than 90% o... | g63972 | [
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0... |
<p>First I'm sorry I couldn't figure out the most accurate title for this question (suggestions welcome).</p>
<p>Here's the case: I want to implement spinners like the ones on this page: <a href="http://www.nytimes.com/newsgraphics/2014/senate-model/" rel="nofollow">http://www.nytimes.com/newsgraphics/2014/senate-mode... | g63973 | [
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<p>This is a continuation of my <a href="http://stats.stackexchange.com/questions/50675/calculating-the-optimal-decision-boundary">previous question</a>.</p>
<hr>
<p>I have two classes, $C_1$ and $C_2$.</p>
<p>$C_1$ is a bivariate Gaussian with mean $\mu = (0,0)$ and covariance $\Sigma = I$</p>
<p>$C_2$ is a bivari... | g63974 | [
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0.01669105887413025,
0.0668599084019661,
0.0004007304087281227,
-0.... |
<p>With SPSS (v18), in the output of a logistic regression after the "Variables in the Equation" section, there is a Correlation Matrix which represents the correlation of the coefficients. </p>
<p>What do high correlations imply? Should I try to avoid high values by removing variables? My AUC drops severely when I do... | g63975 | [
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<p>Here is the scenario:</p>
<p>I am iteratively seeking a goal state by selecting from one of a set of sets of options. The set of sets defines the possible routes to the goal state, and each inner set defines the probability I will succeed, and what the failure penalties and probabilities are. A failure costs me a... | g63976 | [
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0.01379869133234024,
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0.03590409830212593,
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<p>I want to generate univariate time series in R using copulas.</p>
<p>Let $X_1, X_2, \ldots X_N,\ldots$ denote random variables such that joint distribution of $X_t$ and $X_{t-1}$ is $C(F(X_t), F(X_{t-1}))$, where $F$ denotes a marginal distribution function, and $C$ a copula.</p>
<p>I am a beginner in R, and at pr... | g45879 | [
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0.044285379350185394,
... |
<p>I have an 5297X26 imbalanced dataset, the class1 has 588 samples and class2 has 4709 samples. I used the following code to perform random forest:</p>
<pre><code>rfp<-randomForest(label~.,data=data,importance=TRUE,proximity=TRUE,replace=TRUE,sampsize=c(588,588))
</code></pre>
<p>Thus I could solve the imbala... | g21907 | [
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0.007639383431524038,
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0... |
<p>I would like to compare a series of actual values to predicted values in order validate the model used to generate the predictions. The model is a simple straight line and was derived from a regression analysis. The R squared value for the straight line is not brilliant at 0.62. What is the best method to use to det... | g63977 | [
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0.0038339311722666025,
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<p>I have an ordered response variable (stated preference from strong dislike to strong like) that is virtually uniformly distributed. I am using package ordinal in R to estimate the probability of an observation matrix X to fit into a specific ordered category Y. <a href="http://www.google.co.uk/url?sa=t&rct=j&... | g63978 | [
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0.02660539373755455,
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0.07573103159666061,
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0.02677598036825657,
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<p>I recently constructed a questionnaire to carry out a market survey on soap brands used. One of the questions which was asked was to rate few statements which influence the respondent to buy a certain brand. For each of the statements(Eg: price, advertisements etc) I gave four options strongly agree, agree, disagree... | g63979 | [
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0.008707973174750805,
... |
<p>I received this question by email from a Neuroscience PhD student.</p>
<blockquote>
<p>I would greatly appreciate if you
could please let me know whether
Factor Analysis could load positively
and inversely correlated variables
onto the same latent factor, whereas
Cluster Analysis can only cluster into
... | g63980 | [
0.00584595138207078,
0.01587802916765213,
0.02249828726053238,
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0.004359973594546318,
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0.0076281349174678326,
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<p>I know that "deviations in the data are devil", and when the distribution is highly skewed, it is better to consider median as average rather than mean, but how to decide these hard-limits.</p>
<p>For example:</p>
<ul>
<li><p>CASE 1:</p>
<ul>
<li>Assume X = 10,20,30,40,50,60,70</li>
<li>In this case, I think that... | g63981 | [
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0.034305404871702194,
0.003675048938021064,
0.03461334481835365,
... |
<p>In a technique that uses CUSUM for change-point detection in this <a href="http://www.cs.utexas.edu/~mahimkar/MERCURY_sigcomm10.pdf" rel="nofollow">paper</a>, the first step is given below:</p>
<blockquote>
<p>Let $x_1, x_2,..., x_n$ be the $n$
samples in an event-series. The
samples are ranked in increasing ... | g63982 | [
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0.03722298890352249,
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0.070556640625,
0.008193861693143845,
-0.030609... |
<p>My problem is to figure out an algorithm for summarising wind statistics over an area. The statistics are (24x) hourly but I want to end up with 2-3 'blocks' that summarise the conditions for the whole day.</p>
<p>My data is in the form of separate magnitude and direction NumPy arrays but I could convert them to u,... | g63983 | [
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0.0025326632894575596,
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0... |
<p>It has come to my attention that companies will rank resumes based on buzz words and only look at those that have high scores assuming enough people submit for the position.</p>
<p>I don't like this system but still want a job, so instead of inserting these meaningless terms into my actual resume I've compiled a li... | g21914 | [
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0.010697834193706512,
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0.0481436587870121,
-0.04286528378725052,
-0.03037588857114315,
0.02407122775912285,
0.005... |
<p>I'm working on 2D time series data where two attributes are depth and temperature. When I plotted depth-vs-temp curve and saw its variation over time, the fluctuation occurs at few places only.</p>
<p>I'm not saying temperature is dependent on depth. But given these data, what should I look into to establish relati... | g63984 | [
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-0.052510105073451996,
0.0019063608488067985,
0.033235564827919006,
0.10765925794839859,
-... |
<p>If $X$ and $Y$ are independent random variables, then the variance
of the product $XY$ is given by</p>
<p>$
\mathbb{V}\left(XY\right)=\left\{ \mathbb{E}\left(X\right)\right\} ^{2}\mathbb{V}\left(Y\right)+\left\{ \mathbb{E}\left(Y\right)\right\} ^{2}\mathbb{V}\left(X\right)+\mathbb{V}\left(X\right)\mathbb{V}\left(Y... | g21917 | [
0.006324819289147854,
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0.011593615636229515,
0.0016071123536676168,
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0.01966216415166855,
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0.06001880019903183,
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-0.00... |
<p>I came across an error of numerical overflow when running a maximum likelihood estimation on a log-linear specification. </p>
<p>What does numerical overflow mean?</p> | g41368 | [
0.06171155348420143,
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<p>My question is directed to techniques to deal with <em>incomplete</em> data during the classifier/model training/fitting.</p>
<p>For instance, in a dataset w/ a few hundred rows, each row having let's say five dimensions and a class label as the last item, most data points will look like this:</p>
<p>[0.74, 0.39, ... | g63985 | [
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0.0028213579207658768,
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0.009460941888391972,
0.05310678482055664,
0.014400690793991089,
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-0.008369427174329758,
0.015118797309696674,
-0.04218015819787979,
0.07294096052646637,
0.014... |
<p>I am trying to test the null $E[X] = 0$, against the local alternative $E[X] > 0$, for a random variable $X$, subject to mild to medium skew and kurtosis of the random variable. Following suggestions by Wilcox in 'Introduction to Robust Estimation and Hypothesis Testing', I have looked at tests based on the trimm... | g21918 | [
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0.037150781601667404,
-0.0007870005792938173,
0.06935147941112518,
-0.013977154158055782,
0.006394093856215477,
... |
<p>(migrating from math overflow, where no answers were posted)</p>
<p>suppose I have $K$ different methods for forecasting a binary random variable, which I test on independent sets of data, resulting in $K$ contingency tables of values $n_{ijk}$ for $i,j=1,2$ and $k=1,2,...,K$. How can I compare these methods based ... | g21920 | [
0.01965753175318241,
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-0.015839429572224617,
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0.02484029345214367,
0.06414396315813065,
0.038123853504657745,
0.020611196756362915,
0.0... |
<p>There's a lot of work done in statistics,
while state-of-art in lossless data compression is apparently this:
<a href="http://mattmahoney.net/dc/dce.html#Section_4" rel="nofollow">http://mattmahoney.net/dc/dce.html#Section_4</a></p>
<p>Please suggest good methods/models applicable for data compression.
To be specif... | g21921 | [
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<p>I am trying to run a power analysis using simulated data to compare the power of a glm versus a binomial proportion test to detect differences in proportions. For example, suppose you have some proportion that decreases by some amount over X number of time steps.
.4,.39,.38,.37 . . . . .01 and simulate data over tho... | g21922 | [
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<p>I`d like to extract the parameters of a two-component mixture distribution of noncentral student t distributions which first has to be fitted to a one-dimensional sample.</p>
<p>My question is closely related to this thread, but as pointed out I want to use Student t components for the mixture:
<a href="http://stat... | g63986 | [
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<p>Common factor analysis entails the eigendecomposition and subsequent interpretation of $\mathbf{C}$ which is often described the correlation matrix with the diagonal elements replaced with approximate "communalities"; $\mathbf{C} = \left(\mathbf{R} - \text{diag}(\mathbf{R}^{+})^{+}\right)$, where $\mathbf{A}^{+}$ i... | g63987 | [
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<p>I want to write a simple GAM model in SAS Enterpise Miner and then compare it with Neural Networks I made before using built-in methods. How can I do that? Of course I want to take advantage of the already partitioned set into learn, validate and test subsets.</p>
<p>Let's assume I want to use the following code ( ... | g63988 | [
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-... |
<p>In my probability class the terms "sums of random variables" is constantly used. However, I'm stuck on what exactly that means?</p>
<p>Are we talking about the sum of a bunch of realizations from a random variable? If so, doesn't that add up to a single number? How does a sum of random variable realizations lead us... | g63989 | [
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<p>I work with an escape response. Basically, I want to find differences between animals that should run and animals that stay still when a stimulus is applied to them. I've been trying several approaches related to velocity and normalization (due to non-normal data) but lately I've been thinking there could be an easi... | g21924 | [
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<p>I'm studying factors affecting the accuracy of taxpayers' perceptions of their own marginal income tax rates. The dependent variable (DV) is the misperception in percentage points. It ranges from 0 (i.e. accurate perception) to 35 (i.e. 35 percentage points mis-estimated). The frequency distribution is positively sk... | g21925 | [
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<p>I have some concerns related to the use of <code>nntool</code> in MATLAB toolbox. Following links like <a href="http://stackoverflow.com/q/11807184/395857">this</a>, I have found that <code>nntool</code> by default normalizes the inputs to the range <code>[-1 1]</code>. So I am a bit concerned, I created a neural ne... | g63990 | [
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<p>I'm working on a cross-sectional regression model. Is it correct to test the presence of specification error in the model using Durbin-Watson test (or the non-parametric Runs test) with residuals <strong>ordered according fitted-values</strong>?</p> | g63991 | [
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<p>In my lab, we are currently looking at how two handedness groups (mixed handed and consistent handed) differ in terms of lGI (<a href="https://surfer.nmr.mgh.harvard.edu/fswiki/LGI" rel="nofollow">local Gyrification Index</a>, a cortical folding measure) across 74 different brain regions. We are thinking of differen... | g63992 | [
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<p>I have complete data set that fits nicely into excel. One factor is rows (R). The other factor is columns (C). Another factor is related to the analysis of those (F3)...</p>
<p>So my experimental design was to subset by row(R), column(C) and the other factor (F3 - has 2 levels).</p>
<p>So all of my combinations... | g21926 | [
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<p>The modularity of a graph is defined on its <a href="http://en.wikipedia.org/wiki/Modularity_%28networks%29" rel="nofollow">Wikipedia page</a>. In a <a href="http://stats.stackexchange.com/questions/2948/how-to-do-community-detection-in-a-weighted-social-network-graph">different post</a>, somebody explained that mod... | g63993 | [
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<p>I have a dataset of two genetically different cell types, "A" and "B", and each of them can have four different morphologies, let's say "spiky cell", "elongated cell", "round cell", "triangular cell". This yields a 2x4 contingency table:</p>
<pre><code> Spiky Long Round Triangular
Type "A": ... | g63994 | [
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<p>I am using lmer in R to run LMM. My DV is continuous and my IVs are categorical. Many statistician said if the three-level parameter is significant, I cannot interpret the two-level parameter. Does it also include when the parameters are not contradict to each other too?</p>
<p>For example, in the two-level, Group2... | g21928 | [
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<p>I have a question regarding sticking-breaking model of Dirichlet process, which is defined as follows:</p>
<p><img src="http://i.stack.imgur.com/8llR3.png" alt="enter image description here"></p>
<p>There are further statements that</p>
<p><img src="http://i.stack.imgur.com/9jKL5.png" alt="enter image description... | g21929 | [
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<p>I did model test of in anova. once mod1 vs mod2 , other mod2 vs mod1. Does it matter? CAn I compare two models of different df and different parameters? </p>
<pre><code>anova(reg5,reg4, test="Chisq")
Analysis of Variance Table
Model 1: Gas ~ CODload
Model 2: Gas ~ Flow * CODin
Res.Df RSS Df Sum of Sq Pr(>C... | g16598 | [
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<p>I'm new here, and fairly new to statistics, so I apologize if this is an easy question, but I'm stumped. I'm doing a research project simply for fun (yes, I'm weird like that). I was never able to find a professor at my graduate school interested in sponsoring the study so IRB refused to sign off on it so I was left... | g63995 | [
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<p>Can you help me understand, or refer me to a source about, what is the sampling distribution of the sum of scores? I know how to get the sampling distribution of the mean to construct a t-test, etc. More specifically how does the variability of the sampling distribution of sums of scores relates to the variability o... | g21935 | [
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<p>I have some confusion related to how the density is estimated from the histogram. I have attached the screenshot of the paper as well. Any insights</p>
<p><img src="http://i.stack.imgur.com/AsOHR.png" alt="enter image description here"></p>
<p>I didn't get why you divide it into cubes and why is N=(1/h)^d and the ... | g37544 | [
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<p>I am largely inexperienced in the area of logistic regression. I was wondering if there were a good way to transform a continuous covariate in a logistic regression into a discrete one by subdividing the support of this continuous covariate in a smart way. </p>
<p>Any reference is welcome if the question is too gen... | g63996 | [
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<p>I have two groups a G1 and control. For both groups we measured their cell counts every 10 minutes: 0 to 650 min. </p>
<p>We are trying to find: </p>
<ol>
<li>Difference (in cell counts) between G1 and controls - significant</li>
<li>Effect of time (on the cell count) the same for both G1 and controls</li>
</ol... | g63997 | [
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<p>I have a hyperspectral image where the pixels are 21 channels.
So each pixel $\in \mathbb{R}^{21}$. I want to perform clustering on the pixels with similarity defined by two different measures, one how close the pixels are, and the other how similar the pixel values are.</p>
<p>Thus if $X_1$ and $X_2$ are the loca... | g63998 | [
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<p>I have a bioinformatic data set includes a very large negative examples (let's say 30000 examples) and just a few positive examples (let's say 150 positive examples). Since I need to feed an enough amount of positive examples (let's say 135 examples) to learn a model. I just have a few positive examples left for tes... | g26957 | [
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<p>I'm a little bit confused with precision recall. I read some papers about recommender systems, where in one paper they have a graphical representation and in other papers they don't (they just have the values for precision/recall). What is the advantage of a graphical representation?</p>
<p>Am I right, that for a g... | g37697 | [
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<p>Let's say I have <strong>N</strong> items to be ranked based on e.g. 5(it could be few or less) different performance measurements.
And ranking must reflect combined effect of all perfornance parameters.</p>
<p>Which stastical model should I use ?</p>
<p>I know this is too little information. But, I don't know wha... | g63999 | [
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<p>I try to sample a set of parameters $(x_i)$ from a posterior
$p((x_i)|(o_j))$ using a metropolis-hastings algorithm.
The fact is that a simple independent random walk on each of the $x_i$ as
proposal leads to poor convergence results. To alleviate this, I would like to reparametrise the $(x_i)$ as:</p>
<p>$(x^c_i)... | g46173 | [
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<p>In particular, I'm not seeing how a commutative group is defined on a graph, nor addition and multiplication.</p>
<p>So why is it a <a href="http://en.wikipedia.org/wiki/Field_%28mathematics%29#Definition_and_illustration" rel="nofollow">field</a>?</p> | g21941 | [
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<p>One way to find accuracy of the logistic regression model using 'glm' is to find AUC plot. How to check the same for regression model found with continuous response variable (family = 'gaussian')?</p>
<p>What methods are used to check how well does my regression model fit the data?</p> | g41615 | [
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<p>I wonder if it's possible to estimate a child's age given the child's measured height. </p>
<p>I have found this height chart:
<a href="http://resource.nhi.no/resource/4281-21-hoyde-gutter-5-19-who.pdf" rel="nofollow">http://resource.nhi.no/resource/4281-21-hoyde-gutter-5-19-who.pdf</a></p>
<p>Is it possible to u... | g64000 | [
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<p>I am aware that this question is vague, but after reading multiple standard books of the community, I am still wondering about the following applied problem.</p>
<p>Lets say I have a dichotomy problem and for training I have $M$ observations, each consisting of $k$ features (attributes).</p>
<p>I would be interest... | g38057 | [
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-0.042072366923093796,
-0.010253381915390491,
-0.06940053403377533,
0.042972367256879807,
0.045171529054641724,
-0.045270394533872604,
-0.010381164029240608,
-0.004650584422051907,
-0.0027812651824206114,
0.11471989005804062,
... |
<p>I'm using TraMineR to determine a certain clustering based on Optimal Matching distances:</p>
<pre><code># Define a sequence object
sequences.seq <- seqdef(sequences, left="DEL", right="DEL", gaps="DEL", missing="")
# Compute OM costs
costs <- seqsubm(sequences.seq, method="TRATE")
# Create OM object
sequen... | g41398 | [
0.009829813614487648,
-0.003204907989129424,
-0.01357506774365902,
-0.03692992031574249,
-0.03211115300655365,
-0.02963941916823387,
-0.011451907455921173,
-0.002670848276466131,
-0.038132015615701675,
-0.029512057080864906,
-0.032332535833120346,
0.029861776158213615,
0.09910488873720169,
... |
<p>I'm working on a problem and after an 1.5, I've not had much of a progress. I appreciate if you can guide me on how to solve it.</p>
<p>Consider
$$X = {X_{ij}: i = 1, \dots, I, j = 1, \dots J} \sim Multinomial (n,p)$$
Also consider $X_{.} = \{X_{i.} = \sum_j X_{ij}: i = 1, \dots, I\}$. How can I show that $X|X_{.}... | g64001 | [
-0.016189761459827423,
0.027535753324627876,
-0.009876581840217113,
0.010505804792046547,
-0.021670067682862282,
-0.05578123778104782,
-0.0084544001147151,
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0.013055769726634026,
0.026912473142147064,
-0.08204883337020874,
0.010840903967618942,
-0.015718288719654083,
... |
<p>I am trying to use SVM to make a prediction (True or False) on a dataset with many independent variables. I am wondering how I can identify the most useful variable in making the prediction. I understand that there is a function that allows me to calculate the "weights" of the variables in R package <code>e1071</c... | g64002 | [
0.005281592253595591,
-0.009092088788747787,
-0.01220279186964035,
0.017137838527560234,
0.008816991932690144,
-0.04981078580021858,
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0.08078299462795258,
-0.0724107027053833,
0.03508838638663292,
-0.02172652818262577,
-0.003210370661690831,
0.06036042422056198,
0.048... |
<p>I am currently conducting a longitudinal research on learner reading development in second language. Let me explain it briefly. I am using eye tracking procedures and trying to describe the development of reading skills of my participants. Saccade lenght (how fast they read), fixation durations (how long they look a... | g64003 | [
0.009546402841806412,
-0.003444996662437916,
-0.012876825407147408,
-0.03146519884467125,
0.0021240226924419403,
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0.05138153210282326,
0.01133750006556511,
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-0.031065721064805984,
0.04434839263558388,
0.01679917424917221,
0.025662962347269058,
0... |
<p>We are preparing an experiment that will run during the coming winter, where we assess certain energy performance indicators on a set of single-family houses in Europe.</p>
<p>We are interested in finding out which factors have the greatest impact on these indicators. These factors will include the age of the build... | g21953 | [
0.022096537053585052,
0.022889073938131332,
-0.010503661818802357,
-0.01902739889919758,
-0.006530523765832186,
-0.05639811232686043,
0.04604477807879448,
0.032322127372026443,
-0.058298058807849884,
-0.057469286024570465,
0.004544041585177183,
0.018585382029414177,
0.03480847179889679,
0.... |
<p>I am trying to implement Beta-t-EGARCH model in R, however, I fail to understand what is the unconditional variance of this model. I know for simple GARCH model, unconditional variance is</p>
<pre><code>ARCH0/ (1-ARCH1 - Beta1),
</code></pre>
<p>but what I have read for Beta-t-EGARCH model the unconditional varian... | g64004 | [
-0.040767572820186615,
-0.011089884676039219,
0.01455907803028822,
-0.0721421092748642,
0.056315723806619644,
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0.05300705507397652,
0.033859822899103165,
-0.025201978161931038,
0.005283101927489042,
-0.05792362242937088,
0.04822377860546112,
0.05453149229288101,
0.026... |
<p>I would like to solve a linear regression (in R) with weights $w$ and a constraint.</p>
<p>In other words, I would like to find $x$ that minimizes the sum of squares
$$\sum_i w_i(b_i-Ax_i)^2$$</p>
<p>On top of that I have an external vector $d$, which I would like to use in a constraint, such that $d \cdot x \le 5... | g64005 | [
0.014938163571059704,
-0.007278466131538153,
-0.01897813007235527,
-0.005110882222652435,
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0.03361689671874046,
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-0.03322548046708107,
-0.013581017963588238,
0.06135264411568642,
0.04624691978096962,
-0.0... |
<p>Can someone point me to an example of how to do <a href="http://en.wikipedia.org/wiki/Randomized_response" rel="nofollow">randomized response</a> with a <em>continuous</em> outcome $Y \in [ 0,\infty ]$, rather than a binary one? I am interested in the mean and variance of this outcome or the entire distribution if p... | g19304 | [
0.013347514905035496,
-0.01855803281068802,
-0.004863045644015074,
-0.035184863954782486,
-0.023804012686014175,
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0.048759300261735916,
0.011997409164905548,
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-0.051537759602069855,
0.016515694558620453,
-0.02914387732744217,
0.04061570018529892,
... |
<p>I have a multi-class classification problem. In order to reduce the feature space, I have mapped my weights ($w$) to a multinomial manifold (or k-simplex) and compute the new weights ($v$) as follows:</p>
<p>$$
v_i = \frac{w_i}{\sum\limits_{i=1}^n w_i}
$$</p>
<p>Clearly, in the new manifold space, my weights lie o... | g21956 | [
0.006151381880044937,
0.009822356514632702,
-0.050846245139837265,
-0.01250343956053257,
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0.023998374119400978,
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0.003485381370410323,
-0.056057557463645935,
0.03325289860367775,
-0.012585969641804695,
... |
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