question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have a question about Scientific Data Mining.</p>
<ol>
<li><p>Do you know successful case studies of applying Data Mining / Machine Learning techniques in hydrodynamics?</p></li>
<li><p>In general, does it make actually sense to try to apply DM/ML techniques to such deterministic systems as gas/fluid flows which ... | g18633 | [
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<p>First: I'm not well versed in statistics terminology so please forgive me - I'll try to be as verbose as possible with my problem.</p>
<p>This is a problem which I've previously solved very naively. I'm looking to apply more standard statistical theory to this problem in an attempt to get more accurate results. Any... | g18637 | [
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<p>I have an experiment that will produce observations of the time until an event occurs. Some basic properties are that</p>
<ol>
<li>We count the number of events that have occurred at some point $t_1,...,t_n$.</li>
<li>Event times are interval censored, between $(t-1,t]$,</li>
<li>Individuals will not leave the tri... | g61863 | [
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<p>I'm getting this error when conducting fisher.test() in R:</p>
<pre><code>freqTable =
1 2 3 4 5 6 7
1 14 0 2 0 0 0 0
2 0 0 0 9 0 0 0
3 0 6 0 0 0 0 0
4 0 0 0 0 6 0 0
5 0 0 0 0 0 10 0
6 0 0 10 0 0 0 0
7 2 4 9 1 0 0 30
> fisher.test(freqTable, workspac... | g61864 | [
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<p>We often hear of project management and design patterns in computer science, but less frequently in statistical analysis. However, it seems that a decisive step toward designing an effective and durable statistical project is to keep things organized. </p>
<p>I often advocate the use of R and a consistent organizat... | g61865 | [
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<p>I have been reading about Bayesian methods for performing survival analysis. One of the things that strikes me is that in the three or so books that I have read, there has been no mention of handing ties, e.g. Efron, Breslow, or exact.</p>
<p>Is this complication limited to frequentist statistical treatments?</p> | g18639 | [
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<p>When you are the one doing the work, being aware of what you are doing you develop a sense of when you have over-fit the model. For one thing, you can track the trend or deterioration in the Adjusted R Square of the model. You can also track a similar deterioration in the p values of the regression coefficients of... | g18641 | [
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<p>I am talking about the regression method that measures the impact of several layers of independent variables upon a dependent variable.</p> | g49763 | [
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<p>I am running into a problem where an independent variable, which should have no predictive power on the dependent variable based on domain knowledge, comes out with very small p-value because the sample size is very large(~100,000). If I only use < 5000 data points, then the p-value becomes large enough to suppor... | g49494 | [
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<p>I have 2D data (I have a zero mean normalized data). I know the covariance matrix, eigenvalues and eigenvectors of it. I want to decide whether to reduce the dimension to 1 or not (I use principal component analysis, PCA). How can I decide? Is there any methodology for it?</p>
<p>I am looking sth. like if you look... | g61866 | [
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<p>Are Lorenz curves and QQ-plots the same? If not, where are the differences? I read about both of them and they appear to be two terms for the same type of plot / statistical technique to compare distributions. I was not able to find any confirmatory source for this. Perhaps you know?</p> | g37890 | [
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<p>I'm doing a retrospective study looking at how the mortality of piglets differs with increasing age of pigs. </p>
<p>Since my data is for each sow over seven years and each sow may only have mortality in one or two years, I'm running into a lot of trouble with descriptive stats. My Friedman's test showed a signific... | g18644 | [
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<p>I have vectors of same length consisting of 1 and 0. I am trying to find out how similar they are. So far I am using hamming distance that I calculate sum of one vector then sum of second vector and the difference between this is the difference of the days. With 1 and 0 it works pretty well.</p>
<p>My problem is th... | g61867 | [
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<p>I have a research project about finding out user's interaction on Twitter. If I want to calculate the mutual information between two users A,B: I(A,B), to know the probability of A and B appearing in the same discussion. So how can I calculate this? What can be the p(A), p(B) and p(A,B) in this case?
As my thought,... | g61868 | [
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<p>I am new to modelling percentage data, and I would be greatfull for some advice. I have proportion data (0,1] on a percentage of money sent by Player B to Player A. Participants received an amount of money, and could decide what percentage they will send back. I have two categorical predictors (1<sup>st</sup> with 3... | g61869 | [
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<p>What are the approaches for characterizing the failure rate from usage and maintenance data of a fleet of repairable units? The usage data contains risk indicators (typically vibration levels, or operation limit exceedances), operational time durations, operating conditions, and recording times. The maintenance da... | g61870 | [
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<p>I am designing a questionnaire by using five-point Likert scale. What is the advantage of five-point Likert scale over seven-point Likert scale? </p>
<p>Thank you.</p> | g34194 | [
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<p>Say I have 16 work days in a month, and I have 16 days of production data so that I have a mean and variance for this daily data (e.g. mean is 3750 and variance is 500).</p>
<p>I can construct a confidence interval for the daily data, but how do I inflate the interval width to construct a confidence interval of the... | g61871 | [
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<p>I am having some trouble running an Anova on categorical variables in R and matching SPSS output. What I need to do is run an anova on the dataset below (its a made up data set). But, I need to know if the mean of each category is significantly from the total mean of all races. </p>
<pre><code>Satisfaction Rac... | g61872 | [
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<p>In R, if I set.seed(), and then use the sample function to randomize a list, can I guarantee I won't generate the same permutation?</p>
<p>ie...</p>
<pre><code>set.seed(25)
limit <- 3
myindex <- seq(0,limit)
for (x in seq(1,factorial(limit))) {
permutations <- sample(myindex)
print(permutations)
}... | g38192 | [
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<p>I made a visualization of Amazon related products. Every link in visualization means two products are often bought together.</p>
<p>Now I'm applying various graph analysis techniques and am fascinated by the results. The biggest problem though is translating scientific terms to human language (please pardon me if i... | g61873 | [
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<p>I ran the same code in R and in R-studio, but got two different results. Does anybody know why this is occurring, and if there is a fix for this? If there is no remedy, which is the "correct" program to use? </p>
<p>Some information about the code I am running:</p>
<p>I am using smooth.spline() as the only built i... | g61874 | [
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<p>I have a theoretical economic model which is as follows,</p>
<p>$$ y = a + b_1x_1 + b_2x_2 + b_3x_3 + u $$</p>
<p>So theory says that there are $x_1$, $x_2$ and $x_3$ factors to estimate $y$.</p>
<p>Now I have the real data and I need to estimate $b_1$, $b_2$, $b_3$. The problem is that the real data set contains... | g49359 | [
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<p>I have data on sea temperatures at different depths. With these data I need to remove seasonal and non-seasonal oscillations by fitting a function that consists of two sinusoids with periods of 12 and 6 hours on temperatue data (for every depth). The function needs to be put in seasonal diagram. And this adjustment ... | g61875 | [
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<p>I have some ranges of values and frequencies of each range. Participants choosed an entire range when asked, and not a particular value. </p>
<p>Example:</p>
<p>Range [0,20] : frequency = 20 </p>
<p>Range (20,60], frequency = 10 </p>
<p>Range (60, 100], frequency = 15 </p>
<p>I'm trying to figure out how to ge... | g61876 | [
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<p>In R I use a lot the packages plyr, stringr, Hmisc and ggplot2. Each of these packages take the base code and make functions that are more intuitive and easier to work with. Each of these packages tend to focus on the data munging and exploration side of data analysis. Are there any packages that make working with l... | g61877 | [
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<p>I'm using the R package Penalized (0.9-42) on a Cox PH model. I'm using L2 (Ridge) on the grounds that I don't want to shrink my coefficients to 0.
I don't understand why when I ask for:</p>
<pre><code>fit <- penalized(Surv(ttocomplete2, event)~ x1 + x2 + as.factor(x3), lamda2=15.96))
print(coefficients(fit, "a... | g61878 | [
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<p>I am familiar with the log-rank test for comparing multiple Kaplan-Meier curves, but I am looking for a test that will compare across ordered groups (an ordinal variable). A significant result from the log rank test indicates that at least one of the groups has a survival curve different than the others. I want a te... | g18652 | [
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<p>Suppose, I have done:</p>
<ul>
<li>$n_1$ independent trials with an unknown success rate $p_1$ and observed $k_1$ successes.</li>
<li>$n_2$ independent trials with an unknown success rate $p_2$ and observed $k_2$ successes.</li>
</ul>
<p>If, now $p_1 = p_2 =: p$ but still unknown, the probability $p(k_2)$ to obser... | g61879 | [
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<p>First off let me say that I had one stats course in engineering school 38 years ago. So I'm flying blind here.</p>
<p>I've got the results of what are essentially 18 separate diagnostic tests for a disease. Each test is binary -- yes/no, with no threshold that can be adjusted to "tune" the test. For each test I ... | g18656 | [
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<p>In a previous question I asked about the <a href="http://stats.stackexchange.com/questions/13011/when-was-the-autocorrelation-function-invented-and-what-was-the-motivation-for-i">history of auto-correlation</a></p>
<p>In this question I'm interested in the discovery process behind cross-correlation.</p>
<ul>
<li>W... | g18657 | [
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-0.025062493979930878,
-0.06090486794710159,
0.019468529149889946,
0.04962461441755295,
0.00352... |
<p>I have run several Chi-square tests and want a measure of effect size. I have some 1x2 tables, 1x4 tables, 4x9, and 3x4 tables of frequency data.</p>
<p>What measure of effect size can I use on these rectangular frequency tables, if each cell has a different expected frequency?</p>
<p>(I would like to use somethi... | g61880 | [
0.005177825223654509,
0.01019118633121252,
0.011902233585715294,
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0.041632916778326035,
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0.... |
<p>I'm just very curious about the discovery process behind the autocorrelation function. </p>
<ul>
<li>When was it invented? </li>
<li>Was it independently invented multiple times, for example?</li>
<li>What was the motivation for it?</li>
</ul> | g61881 | [
0.07161799818277359,
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<p>I am looking for an optimization routine that can optimize a non-linear objective function with integer constraints. <a href="http://spotfire.tibco.com/products/splus-nuopt.aspx" rel="nofollow">NuOPT</a> for S-Plus, <a href="http://en.wikipedia.org/wiki/CPLEX" rel="nofollow">CPLEX</a>, or <a href="http://www.mathwor... | g48598 | [
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<p>I want to learn data mining. Are there any free video lectures out there which explain the process of data mining in depth?</p> | g61882 | [
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<p>I'd like to fit a <strong>longitudinal model</strong> for where <em>multiple subjects experience binary outcomes over time</em>. To accomplish that, I'd like to use an additive random effect for each subject and an autoregressive error process to model the temporal stability in the "success probability." </p>
<p>To... | g61883 | [
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<p>I estimated the mean and variance of two latent variables through two groups of data. I can't use the data to do hypothesis testing, because I am interested in the latent variable. Is there a way to test the whether the two latent variables are significantly different?</p> | g61884 | [
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<p>There is such a problem: we have to process multi-label classification (assignmet of tags) of text articles, using some pre-labeled training set. But for many texts in the training set, should be assigned more tags, that it was done by their authors.</p>
<p>For example, there is a text about war medicine, and there... | g61885 | [
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<p>After reducing the dimensions of a matrix using PCA, I want to transform the "big" components (i.e. they cumulatively account for 90% of the variance) of each row into a single value. The value does not have to be unique, only relative so that they can be compared. </p>
<p>Is there a statistical technique that wi... | g61886 | [
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<p>If I want to find how strongly a dependent variable is related to another dependent variables in a study, do I make use of multiple regression?</p>
<p>The reason I am asking is because the book mentions that for instance to conduct a standard regression, I will need to input all the independent variables and the co... | g61887 | [
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<p>I'm new here and have some doubts.
I'm working with a large data set of water quality and want to test for differences between the hydrological stations and between stretches of the river. There is a large internal variability into class factors.
For this, I intend to do the following analyses:
Exploratory PCA: to s... | g18666 | [
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... |
<p>Background:<br>
I had to perform a data analysis for a client (some kind of lawyer) who was an absolute beginner in statistics. He asked me what the term "statistical significance" means and I really tried to explain it... but since I'm not good at explaining things I failed ;)</p> | g18667 | [
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<p>In simple linear regression, what is the covariance between the error term and the residual?</p>
<p>Model: $y_i = \beta_0 +\beta_1 x_i + \varepsilon_i$</p>
<p>What will be the $\rm {cov}(\varepsilon_i,\ e_i)$, where $e_i = y_i - \hat y_i$?</p> | g61888 | [
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<p>If I have a normal distribution with a given mean and variance and apply a logistic transform to it, what is the mean and variance of my transformed variable? </p>
<p>This seems like it has to be a well known problem, but I haven't been able to find a quick reference anywhere. </p> | g61889 | [
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<p>Trying to fit a linear mixed effects model with 2 categorical predictors (group & worker) where worker is a random effect and group a fixed effect. I'm trying to figure out 1) whether I should specify intercept=0 and 2) why these 2 model results seem to give different conclusions about the effect of group.</p>
... | g61890 | [
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<p>I have a long time series data (running several years). I have split the data into several series, each of 1 month duration.</p>
<p>I then perform some custom calculations on each of the 'shortened' time series and collate some robust summary stats (mode, MAD etc on my calculated data). </p>
<p>I then want to see ... | g18670 | [
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<p>I have two datasets $X$ and $Y$ that have paired data, however one of the sets is larger than the other. I am interested in the standard error of the difference $Z = X - Y$.</p>
<p>I guess I could use the <a href="http://stats.stackexchange.com/questions/7754/how-to-calculate-the-difference-of-two-standard-deviatio... | g18671 | [
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<p>As stated in many textbooks, the Standard error of the slope in linear regression with one variable is</p>
<p>$\sqrt{\frac{s^2}{SSX}}$</p>
<p>or some rewrite, ${s^2}$ being the error variance and ${SSX}$ being the sum of the ${x}$-squares. </p>
<p>Can anybody help with an explicit proof? </p> | g49626 | [
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<p>When an extra shape parameter is added in the distribution than a statement in favour of this parameter is written "extra parameter can control both tail weights and adding entropy to the centre of the density function". I am quite clear about tail weight but cannot understand adding entropy to the centre and how to... | g61891 | [
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<p>I'm estimating a Random Effects model with an AR(1) disturbance for the errors (xtregar in Stata). The reported results show that the constant (in Stata terminology) is positive and significant.</p>
<p>The question is, in general terms, how do you interpret this constant term?</p> | g61892 | [
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<p>I am a newbie to this forum. I searched different white papers and codes on google but couldn't find a solution, that's when I registered on this forum.. Please share in case you guys have a idea as to how to go about this problem.. </p>
<p>I have a data set which consists of 30 prop. traders, and their historical ... | g61893 | [
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<p>I have a large set of variables measured on different scales/units, and want to standardize them to the same scale, with a mean of 0 and standard deviation of 1, so that I can run a PCA on them. I have heard that the <code>NORM.S.DIST</code> function in Excel is appropriate - can anyone verify this?</p> | g61894 | [
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... |
<p>From <a href="http://stats.stackexchange.com/a/2519/1005">a reply by John</a></p>
<blockquote>
<p>What is true is that trivially small effects can be found with very large sample sizes. That does not suggest that you shouldn't have such large sample sizes. What it means is that the way you interpret your finding ... | g49627 | [
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<p>In the spirit of this question <a href="http://stats.stackexchange.com/questions/21075/understanding-proof-of-a-lemma-used-in-hoeffding-inequality">Understanding proof of a lemma used in Hoeffding inequality </a>, I am trying to understand the steps that lead to Hoeffding's inequality.</p>
<p>What holds the most my... | g61895 | [
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... |
<p><strong>I'm currently studying a Statistics course and I'm trying to solve a simple probability exercise:</strong></p>
<p>A production facility employs:</p>
<ul>
<li>20 workers on the day shift</li>
<li>15 workers on the swing shift</li>
<li>10 workers on the grave- yard shift</li>
</ul>
<p>A quality control cons... | g61896 | [
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<p>I have some very high dimensional data, and performing Locally Linear Embedding (LLE) is very time consuming. I also have to perform several LLEs, with varying parameters, to compute the optimal number of neighbors via Spearman's Rho (a la Karbauskaite et al, <i>see</i> citation).</p>
<p>However, the data are highl... | g18678 | [
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<p>Suppose you are trying to predict height ($y$) based on age ($x$). A straight linear regression won’t work well, since humans stop growing at a certain age. This suggests instead trying to model height as something like:</p>
<p>$y = w\cdot \mathrm{squash}(x, a, b) + w_0$</p>
<p>where </p>
<p>$\mathrm{squash}(x,a,... | g18679 | [
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<p>When people implement permutation tests to compare a single sample against a mean (e.g., as you might do with a permutation t-test), how is the mean handled? I have seen implementations that take a mean and a sample for a permutation test, but it is unclear what they're actually doing under the hood. Is there even... | g3870 | [
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<p>I'm implementing the HMM algorithms described in Rabiner's tutorial. But there is several issues to considered when we apply HMM for real problems. One of this problems is how to consider new observations that hasn't emission probabilities. Anyone knows a way of considering a distribuition for new observations? I be... | g61897 | [
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<p>I am trying to write a tool which involves implementing logistic regression. With the batch gradient descent method, the convergence is guaranteed as it is a convex problem. However, I find that with the stochastic gradient decent method typically converges to some random points (i.e., not very close to the minimum... | g18683 | [
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<p>If I have 3 variables, $X$, $Y$ and $Z$, what statistical approach might I use to ask the question "is in population X correlated with $Y$ but is uncorrelated with $Z$"?</p>
<p>Obviously, I can assess if $X$ is correlated with $Y$ and separately if $X$ is correlated with $Z$ and have two p-values:</p>
<pre><code>p... | g18686 | [
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<p>Let us say that we have an event - variable (1/ 0) that denotes the occurence of an event on a daily basis e.g. a strike. Let us now say that we have a continuous variable (sales) that that we want to forecast. The interval on which the variable is measured is monthly. We want to incorporate the event variable in a ... | g45534 | [
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0.023460566997528076,
0.023328082635998726,
0.026636343449354172,
... |
<p>I am applying Neural network and SVM to predict buy-hold - sell signals. I have trained nn and SVM in R. I used nnet function to train NN and svm to train SVM. I provided 20,000 data points to train and 2000 data points to test. training data set contain list of 10-15 technical indciators and buy-sell-hold signals. ... | g18688 | [
-0.029138050973415375,
0.010682351887226105,
0.014547077007591724,
0.048609841614961624,
0.025123639032244682,
-0.046740978956222534,
0.035742007195949554,
0.056277573108673096,
-0.02122308686375618,
0.0034591436851769686,
0.01345756184309721,
0.04180490970611572,
-0.013124262914061546,
-0... |
<p><strong>How does the formula for the <code>lmer</code> function work?</strong></p>
<p>Some examples:</p>
<pre><code>library('lmer')
lmer(Yield~(1|Batch),Dyestuff)
lmer(Yield~(Batch)*(1|rep(c(1,2,3),10)),Dyestuff)
lmer(Reaction ~ Days + (1|Subject) + (0+Days|Subject), sleepstudy)
</code></pre>
<p>On the left of <c... | g49628 | [
-0.053060710430145264,
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-0.04569053277373314,
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0.05130886659026146,
0.03717977926135063,
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-0.08422056585550308,
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0.042113520205020905,
0.041677314788103104,
0.... |
<p>I just got a rejection from an economics journal. Among the reasons cited for rejection were:</p>
<blockquote>
<p>the benefits of using the semi-parametric method are not clearly
brought out compared to alternative simpler techniques with clean
identification of causal relationships</p>
</blockquote>
<p>It ... | g61898 | [
0.043666303157806396,
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0.006758938543498516,
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0.11857157945632935,
0.0039167688228189945,
0.00007379292219411582,
0.0348324216902256,
-0.011083775199949741,
0.02790353260934353,
0.021717077121138573,
0.... |
<p>I am trying to get a grasp on how to use machine learning to predict financial timeseries 1 or more steps into the future.</p>
<p>I have a financial timeseries with some descriptive data and I would like to form a model and then use the model to predict n-steps ahead.</p>
<p>What I have been doing so far is:</p>
... | g61899 | [
-0.0011270385002717376,
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0.009972392581403255,
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0.022340597584843636,
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0.032008279114961624,
0.022717077285051346,
0.07077019661664963,
... |
<p>Good evening everyone,</p>
<p>I'm faced with another question which I can't seem to be able to find a solution online. Thought I get some directions and advice here.</p>
<p>I have the following distribution, which represents the case of the number of events that happen in a single day.</p>
<ul>
<li>When (x=0), P(... | g61900 | [
0.027554718777537346,
0.0028167027048766613,
-0.00899052619934082,
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-0.018092967569828033,
0.0026435693725943565,
0.005588934291154146,
0.03398505225777626,
0.030428946018218994,
-0.06727264821529388,
-0.006284665782004595,
-0.01807684451341629,
0.03333612531423569,
-... |
<p>I have a uniform distribution that generates from the $\mathbb{Z}_q$ (so I have integers from the interval [$-q/2$, $q/2$). Then I subtract one from the other and take the result modulo $q$ (so again I have an integer from the interval above). </p>
<p>How to prove (or disprove) that the resulting distribution remai... | g61901 | [
0.024482522159814835,
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0.01310011651366949,
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0.030478816479444504,
-0.029533231630921364,
-0.0740794762969017,
0.019446294754743576,
0.013358363881707191,
-0.... |
<p>In statistical hypothesis testing we decide on and <em>set</em> the acceptable probability of error or <strong>significance level</strong> α (alpha) to a value that fits our theory. Traditionally alpha is .1, .05, or .01.</p>
<p>When we <em>calculate</em> the power function g of the parameter we test for, we reciev... | g61902 | [
0.044282011687755585,
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0.049930669367313385,
0.00750098517164588,
0.0129171721637249,
0.018529681488871574,
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-0.005796756129711866,
0.003699940163642168,
0.0036362288519740105,
0.06539948284626007,
0.02... |
<p>Is there a software or a R package that does a simulation of spatial distribution of alleles? I'm interested in how a distribution of alleles of functional loci is shaped by a pattern of environmental variables, such as temperatures and water quality.</p>
<p>I have data on geographical patterns of environmental var... | g61903 | [
0.01689130626618862,
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0.015867283567786217,
-0.024598196148872375,
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0.014002648182213306,
0.003804245498031378,
0.017184201627969742,
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0.038939833641052246,
0.009998632594943047,
0.058730948716402054,
-0.... |
<p>I have recently begun to analyse data from a survey where participants rated 64 images of models on a Likert scale and then selected whether they consider the model in-group or out-group. </p>
<p>I am trying to discern whether the fact that participants consider the model in-group or out-group has an impact on the ... | g61904 | [
-0.04094040021300316,
0.030680181458592415,
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0.02191796898841858,
0.0007798420847393572,
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0.008032027631998062,
0.05537862703204155,
0.030417729169130325,
0.04492950066924095,
0.0513... |
<p>I always have a hard time explaining statistical techniques to audience with no statistical background. If I wanted to explain what GLM is to such audience (without throwing out statistical jargon), what would be the best or most effective way?</p>
<p>I usually explain GLM with three parts -- (1) the random compone... | g48636 | [
0.029710838571190834,
0.025529060512781143,
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-0.05021362751722336,
0.0479724146425724,
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0.06024116277694702,
-0... |
<p>I have a couple things to add together- two different pools of material, and I need to know the total material. Because of various things related to the sampling, I would like to bootstrap the sampling data from each pool. So I generate a list of 100 masses for one pool, and 50 masses for the second pool. Plus, I... | g61905 | [
-0.01720978505909443,
0.008201519027352333,
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-0.04122690483927727,
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-0.01855376362800598,
0.061546217650175095,
-0.... |
<p>I have experimental data of response times that differ according to the factor <code>TrialType</code>: <code>Regular</code> or <code>Random</code>. I also have two groups, <code>A</code> and <code>B</code>, which I expect to behave the same (they were created for counterbalancing purposes). </p>
<p>I want to test t... | g61906 | [
0.011561752296984196,
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-0.07950883358716965,
0.060894422233104706,
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0.03160850703716278,
-0.01973288133740425,
0.004791604820638895,
-0.0118882916867733,
0.02851647324860096,
0.07516693323850632,
-0.03563179820775986,
0.018... |
<p>The traditional approach to variable selection is to find variables that contribute the most to predicting a new response. Recently I learned of an alternative to this. In modeling variables that determine the effect of a treatment--as for example in a clinical trial of a pharmaceutical--the variable is said to be... | g18695 | [
0.015881268307566643,
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0.019088273867964745,
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0.03276569023728371,
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0.018022894859313965,
0.05462414771318436,
0.0020881302189081907,
0.04874589294195175,
0.0... |
<p>As a beginner statistician, discussing the need to be accurate with the interpretation of statistical results with non-statistician is not an easy task. In particular, I am trying to convince some colleagues not to dive into the common mis-interpretation of confidence-interval (maybe I should not?).</p>
<p>For some... | g61907 | [
0.04527435451745987,
0.016938695684075356,
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0.05417022854089737,
0.033670686185359955,
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0.011497187428176403,
0.06148064136505127,
0.006397784221917391,
0.0017959283431991935,
-0.01... |
<p>How to incorporate costs (into logit model) of false positive, false negative, true positive, true negative responses, if they are different costs ? Is it possible to do that on the level of likelihood function ?</p>
<p>Edition :
I see know that likeligooe function could be quite easily modified to incorporate cost... | g48639 | [
-0.03570956736803055,
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0.0008316210005432367,
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0.024498092010617256,
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0.04254310950636864,
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0.011828050017356873,
0.04376228153705597,
... |
<p>I have a large collection of time series - measurements taken every 15 minutes (96 measurements in a day) over the span of 1 year at various different locations.</p>
<p>I've broken up each time series into 365 separate smaller time series, 1 for each day of the year. Looking at these time series, there are certain... | g61908 | [
0.03770570084452629,
0.01536563690751791,
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0.06213310733437538,
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0.011011403985321522,
0.018040576949715614,
0.04485976696014404,
-0.05737927183508873,
0.0992075502872467,
0.0112... |
<p>I need to calculate the coefficient of the Kolmogorov-Smirnov test for any given null hypothesis rejection level. </p>
<p>For example, have a look at the table <a href="http://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Smirnov_test#Two-sample_Kolmogorov.E2.80.93Smirnov_test" rel="nofollow">in this wikipedia entry</a>... | g61909 | [
0.0022022929042577744,
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-0.029629269614815712,
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-0.004256343934684992,
-0.04521087557077408,
0.008508197031915188,
0.05481484904885292,
0... |
<p>When people say that lasso regression can under certain assumptions recover "the support", i.e. non-zero regression weights, what does this mean?</p>
<p>This cannot mean <em>causal</em> recovery, because Pearl has taught us you cannot infer causality from correlation (and lasso is just glorified correlation). So ar... | g18701 | [
0.11206664144992828,
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0.011609268374741077,
0.02008337900042534,
-0.... |
<p>How can I investigate the sensitivity of a regression model to noise?</p>
<p>A basic idea is to add some (Gaussian) noise to the dependent and/or independent variables and (re)evaluate the RMSE. </p>
<p>However, the problem with this approach is, that one is mostly interested in modeling the true data, and not the... | g61910 | [
-0.01685679517686367,
-0.06682410091161728,
-0.017154082655906677,
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-0.00378538784570992,
-0.01881706528365612,
0.05261065810918808,
0.05380501598119736,
0.04... |
<p>I have the following kind of data (coded in R):</p>
<pre><code>v.a = c('cat', 'dog', 'dog', 'goat', 'cat', 'goat', 'dog', 'dog')
v.b = c(1, 2, 1, 2, 1, 2, 1, 2)
v.c = c('blue', 'red', 'blue', 'red', 'red', 'blue', 'yellow', 'yellow')
set.seed(12)
v.d = rnorm(8)
aov(v.a ~ v.b + v.c + v.d) # Error
</code></pre>
<p>I... | g61911 | [
-0.02186097577214241,
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0.0014707022346556187,
-0.0644514411687851,
0.019769810140132904,
-0.026965275406837463,
0.014329303056001663,
0.0016329064965248108,
-0.040409717708826065,
-0.0075233676470816135,
0.0012391029158607125,
0.05768155679106712,
0.05007462948560715,
... |
<p>I was wondering whether my reasoning is correct and whether I've written it down correctly:</p>
<p>Given the following equation $bread_i=\beta_{0} + \beta_{1}wage + u_{t}$, where $u_{t}$ is normally distributed with a mean of zero and a variancce of $\sigma^{2}$ and is independent of $wage$.</p>
<p>Furthermore we ... | g18702 | [
0.027941793203353882,
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0.05353756994009018,
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0.0730622187256813,
0.013971514068543911,
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0.003687426680698991,
-0.0936894565820694,
0.06849965453147888,
-0.013577324338257313,
0.01... |
<p>I use a neural network with a topology of 17-30-1 (sigmoid, atan error function, mse as cost function, 5-fold cv) for text classification. (It's closely related to a previous question <a href="http://stats.stackexchange.com/questions/22189/how-to-interpret-poor-performance-when-using-neural-network">of mine.</a>)</p... | g61912 | [
-0.003609397215768695,
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0.006567966192960739,
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0.05273819342255592,
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0.0855717808008194,
0.05372050404548645,
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-0.009142614901065826,
0.017775554209947586,
0.014945138245821,
0.037573982030153275,
0.01299... |
<p>I have completed analysis on the effects of two drug treatments over a period of time on the CD4 cell count of a number of patients. I have taken the square root of the initial CD4 count as a covariate and I have taken a summary measure of the 'slopes' for each patient. </p>
<p>My model is the following:</p>
<pre>... | g61913 | [
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0.07389576733112335,
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0.003348467405885458,
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0.042088232934474945,
0.036010853946208954,... |
<p>I'm trying to figure out the distribution over a number of trials until a stopping condition is met. In particular, imagine we are observing samples of a uniformly distributed random variable, $X \in \{a,a+1,...,b\}$. We continue to observe samples until the sum of these numbers passes some threshold $Z$ then we sto... | g61914 | [
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0.04229879379272461,
-0.015559433959424496,
0... |
<p>Given survival analysis relates to an analysis/prediction of time to an event, I was wondering if it was possible to be used to predict eathquakes. If so, how would one go about carrying out that analysis on say one particular region say Japan or California?</p>
<p>So I guess a question related to that say...for ex... | g61915 | [
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0.016358429566025734,
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0.011126828379929066,
0.014119184575974941,
-0.02496650628745556,
0.08300669491291046,
-0.... |
<p>$Y^n$ are the observations of our HMM, where $Y_i=a_i$ is a single observation, where $a_i \epsilon \{0,1\}$. For example, $Y^n = k^n$ where $k^n=\{0,1,1,0\}$</p>
<p>$X^n$ are the actual states of our HMM, of which we know some (any) $X_i$.</p>
<p>How can I both 1.intuitively and 2.carefully (using actual math) re... | g61916 | [
0.015536201186478138,
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0.00893219280987978,
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0.028418101370334625,
0.04157065227627754,
0.0804... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/11009/including-the-interaction-but-not-the-main-effects-in-a-model">Including the interaction but not the main effects in a model</a> </p>
</blockquote>
<p>I have an experimental design with pretest and p... | g49299 | [
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-0.006294209975749254,
0.010510067455470562,
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0.027526171877980232,
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0.015584763139486313,
-0.007844323292374611,
... |
<p>I estimated a nonlinear exponential $f(t)=\alpha-(\alpha-\beta)*\exp(-\gamma*t)$ random effects model in <code>R</code>. I estimated the same model form using the identical data set but with <code>nlme()</code> from the <code>nlme</code> library and <code>nlmer()</code> from the <code>lme4</code> library.</p>
<p>Th... | g61917 | [
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0.03519705682992935,
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0.004072578623890877,
-0.004131664056330919,
0... |
<p>I am trying to perform an regression analysis where the response variable is ordinal and the 15 out of the 16 predicting variables are also ordinal. Besides treating all these ordinal predictors as factors, is there any other option? What is the best way to treat these ordinal predictors? Thank you.</p> | g18711 | [
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0.07030477374792099,
0.025954337790608406,
0.026971565559506416,
0.00... |
<p>I'm attempting to estimate the effect of 2 drugs (<code>drug1</code>, <code>drug2</code>) on the likelihood of a patient falling (<code>event</code>). The patients can fall more than once and can be put on or taken off of the the drugs at any point. </p>
<p>My question is how the data should be structured with re... | g942 | [
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0.044598594307899475,
0.00854623131453991,
0.04874516651034355,
... |
<p>I've a frame containing</p>
<blockquote>
<p>Participant----Condition----Duration<br>
Participant1,One,2000<br>
Participant1,One,2780<br>
Participant1,One,200<br>
Participant2,Two,2000<br>
Participant2,Two,2340<br>
Participant2,Two,2120<br>
Participant2,Two,2420<br>
Participant2,Two,2990<br>
Part... | g61918 | [
-0.02331358753144741,
-0.0038547588046640158,
-0.011938810348510742,
-0.1043061912059784,
-0.05375426262617111,
-0.049080196768045425,
0.02688157558441162,
-0.01787177287042141,
-0.03418971598148346,
-0.0017465464770793915,
0.027136344462633133,
-0.0011831691954284906,
0.01199702825397253,
... |
<p>I am not clear how to compare all the tests in Unit Root. Which one is the most powerful among:</p>
<ul>
<li>ADF</li>
<li>PP</li>
<li>KPSS</li>
<li>Elliott, Rothenberg & Stock Unit Root Test</li>
</ul> | g61919 | [
0.03266290947794914,
0.020283376798033714,
-0.007472545839846134,
0.0193730928003788,
0.055086977779865265,
-0.05917470529675484,
0.004451589658856392,
-0.001791299437172711,
0.04142371565103531,
0.01738850586116314,
0.057897549122571945,
0.04225654900074005,
-0.021943718194961548,
0.00822... |
<p>I have a logistic regression model (fit via glmnet in R with elastic net regularization), and I would like to maximize the difference between true positives and false positives. In order to do this, the following procedure came to mind:</p>
<ol>
<li>Fit standard logistic regression model</li>
<li>Using prediction ... | g61920 | [
-0.00046916952123865485,
-0.05705813318490982,
0.00611677672713995,
0.012229169718921185,
0.004986894782632589,
-0.040070515125989914,
0.028387384489178658,
0.06462789326906204,
-0.039620112627744675,
-0.00043638216448016465,
-0.0019700147677212954,
-0.015628231689333916,
0.0634753555059433,... |
<p>I have this question to answer for a class and am completely stumped. </p>
<p>"The GLM log link and a dummy variable for gender (1=male, 0=female) has gender estimate 0.308. The SE is 0.038 assuming a Poisson distribution and 0.127 assuming a negative binomial model. Why are the SE values so different?" </p>
<p>A... | g61921 | [
0.007624172605574131,
0.009138667955994606,
0.0001838774624047801,
-0.01987820863723755,
0.013003945350646973,
0.02935255877673626,
-0.013952314853668213,
-0.03340940177440643,
-0.06626279652118683,
-0.019253170117735863,
-0.03913229703903198,
0.020907457917928696,
0.011416211724281311,
-0... |
<p>Hi I need to prove that $X^T$e = 0 where e is the residual in multiple linear regression model in matrix algebra?</p>
<p>Need some guidance on how to do it... Is there any good pdf for the proofs for multiple linear regression model for matrix alegbra?</p> | g18716 | [
0.029194675385951996,
-0.04704158753156662,
0.008030286990106106,
0.012211853638291359,
-0.014178181998431683,
-0.023955175653100014,
0.0031388024799525738,
0.05964624509215355,
-0.027713915333151817,
0.05731373280286789,
0.005821372848004103,
0.039642252027988434,
0.037870511412620544,
-0... |
<p>I understand intuitively why this is a horrible idea - you assume your model is correct and then increase your number of observations which will likely result in a poor fit on future data.</p>
<p>I'm wondering if there is some mathematical/statistical property to describe this, or if there is any rare case where th... | g579 | [
0.02987467683851719,
0.07547713071107864,
-0.008556528016924858,
-0.012156091630458832,
0.04194518178701401,
-0.0031571811996400356,
-0.004132881760597229,
0.019937684759497643,
-0.027638597413897514,
-0.03559676557779312,
0.020327584818005562,
-0.017772601917386055,
0.07610831409692764,
0... |
<p>I have two frequency distributions; which each are frequency of an event. I would like to compare these distributions, and conclude that these events and conclude if these events are statistically 1 event or they are two distinct events. however, it seems the size of these distributions are playing an important role... | g61922 | [
0.022951092571020126,
0.01982366107404232,
0.007219862658530474,
-0.01385216973721981,
-0.009802702814340591,
-0.044375404715538025,
-0.0017050427850335836,
0.008792984299361706,
-0.03532577306032181,
-0.02966056391596794,
0.045009318739175797,
-0.03525916859507561,
0.03700493276119232,
0.... |
<p>Suppose $Y_1,\dots,Y_n\mid\mu,\sigma^2 \sim \text{ iid } N(\mu,\sigma^2)$ and suppose the priors $\mu \mid \sigma^2 \sim N(\mu_0, \sigma^2 / \kappa_0)$ and $1/\sigma^2 \sim \text{gamma}(\nu_0/2, \nu_0 \sigma_0^2 / 2)$ are placed on the unknown parameters. Then
\begin{align*}
p(\sigma^2 \mid y_1,\dots,y_n) &\prop... | g61923 | [
0.010462218895554543,
-0.042258501052856445,
0.001076912390999496,
-0.0693858414888382,
0.020589129999279976,
0.019755840301513672,
0.035147614777088165,
-0.02155282534658909,
-0.015116425231099129,
0.009620413184165955,
0.026903050020337105,
0.08060230314731598,
-0.009841552935540676,
0.0... |
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