question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>According to various sources, the variance of ML estimators can be obtained from the Hessian matrix of the likelihood function. If $H$ is the Hessian of the negative log-likelihood function, then $H^{-1}$ is the variance-covariance matrix of the ML estimators.</p>
<p>Knowing that, we can do a simple test. We can ca... | g65739 | [
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<p>In the following discussion on Stack Overflow, <a href="http://stackoverflow.com/q/4145400/420055">How to create factors from factanal?</a> (see answer from @Joris), what is the interpretation of the $F=ML$ transformation, where $M$ is the original data matrix, and $L$ is the loadings matrix? Should it not be $L^{-1... | g44560 | [
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<p>I want to check if I really understood factor analysis (FA), especially assumptions that are made before (and possibly after) FA.</p>
<p>Some of the data should be initially correlated and there is a possible linear relation between them. After doing factor analysis, the data are normally distributed (bivariate di... | g65740 | [
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<p>I am using <a href="http://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.gaussian_kde.html" rel="nofollow"><code>scipy.stats.gaussian_kde</code></a> to estimate a pdf for some data. The problem is that the resulting pdf takes values larger than 1. As far as I understand, this should not happen. Am I mista... | g49345 | [
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<p>I couldn't see a question addressing this. I think I'm just off the mark somewhere with my thinking. Here is a simple model:</p>
<pre><code>mod <- lm(hp ~ factor(cyl), data=mtcars)
summary(mod)
Estimate Std. Error t value Pr(>|t|)
(Intercept) 82.64 11.43 7.228 5.86e-08 ***
factor(... | g24454 | [
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<p>My wife is a server at a restaurant and I've been tracking her tips over the last 9-10 months. The domain of her set is $[\$75,\$702]$ with a mean of \$236.7 and a standard deviation of \$106.64. Because of the small amount of data (206 total days of tips) in comparison to the number of possibilities she could mak... | g23184 | [
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<p>Let's suppose I have a set of measurements on a continuous variable which follows a power law distribution, and I’m interested in deriving the exponent of such a distribution. </p>
<p>So far I've used the binning method, so I was dividing the interval in n bins, plotting the number of observation for each bin in lo... | g43106 | [
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<p>Given a Bayesian network that looks like the following:</p>
<pre><code>A->B->C
</code></pre>
<p>How do we compute P(A|C)? My initial guess would be:</p>
<pre><code>P(A|C) = P(A|B) * P(B|C) + P(A|not B) * P(not B|C)
</code></pre> | g44566 | [
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<p>I am a beginner level programmer preparing for the interview in medical research company. Job sounds damn interesting and I would like to get there.
To show my skills and interest, I want to write a program related to the topic.</p>
<p>I think, statistical analysis is quite used in that field, isn't it?
What would ... | g32390 | [
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<p>If I have a reference data set comprising repeated measurements of 3 variables of a system in state $A$. Given new observations of these variables for a different system I would like to classify individual observations as being in state $A$ or not. </p>
<p>My initial inclination would be to compare the new value of... | g65741 | [
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<p><a href="http://stats.stackexchange.com/questions/11887/is-this-design-a-one-way-repeated-measures-anova-or-not">Here</a> I described my general situation. How to calculate 95%CI between means in R?</p> | g65742 | [
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<p>I have a question on the distribution of betas in a multiple linear regression scheme</p>
<p>The estimated parameter vector is $\hat{\beta}=(X^′X)^{−1}X^′y$ where $X = [1 \; \;x]$ is the $n \times 2$ data matrix.</p>
<p>Substitute $X \beta + \epsilon$ for y.</p>
<p>Calculate $\text{var}(\hat{\beta})=\text{var}[(\... | g65743 | [
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<p>I am comparatively new to the Johansen cointegration test(new to everything of this level).</p>
<p>I am trying to validate a model I have created based on simple statistics such as: Mean, Standard deviation etc. </p>
<p>When I run the test in Matlab I get the following results:</p>
<pre><code>Results Summary (Te... | g65744 | [
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<p>In my current project I need to build a <strong>model returning a vector of actions</strong> for each observation. I need a suggestion which statistical technique is used in general in such cases.</p>
<p>In a project, I have a dataset of about 100k observations, 7 vars (quantitative, qualitative). The variables des... | g23185 | [
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<p>I am comparing 8 means and want to set up a planned comparisons, rather than having my Bonferroni adjustment become overly-conservative in a post-hoc. For my groups I need to make a total of 16 comparisons, and some of these comparisons are orthogonal to each other, while others are not. I am curious if there is a... | g65745 | [
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<p>As the title: Do Bayes factors require mutliple comparion correction?</p>
<p>For more context, I am calculating very many likelihood ratio tests and I am thinking about how to handle multiple comparison correction. I thought Bayes factors might present a solution - if I am presenting the results in the Bayes factor... | g65746 | [
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<p>I'm reading Faraway's book (<a href="http://cran.r-project.org/doc/contrib/Faraway-PRA.pdf" rel="nofollow">http://cran.r-project.org/doc/contrib/Faraway-PRA.pdf</a>) to try to understand R's lm diagnostic plots. On page 72 of the book is this: </p>
<p><img src="http://i.stack.imgur.com/KEcHl.png" alt="http://i.stac... | g24465 | [
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<p>I've ben sent a forecast of sales from a consultancy. It uses Excel's LINEST function, taking 4 factors that seem to have affected sales in the past, and used them to make a prediction.</p>
<p>How do I go about adding error bars to this prediction? I believe LINEST provides a standard error, but using that would ... | g49410 | [
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<p>I don't really understand the difference between exponential and geometric distribution.</p> | g65747 | [
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<p>I have a dataset of counts (responses to a marketing campaign), collected at the zipcode level. I am trying to use a poisson regression to determine underlying response rate of each zipcode.</p>
<p>How do I account for the fact that some zipcodes have very large populations, while other have very small populations... | g65748 | [
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<p>I have following type of data:</p>
<pre><code>myd0 <- data.frame (matrix(sample(c(1,0), 200, replace = TRUE), ncol = 10))
myd <- myd0
myd$yvar <- rnorm (20, 5,2)
myd$yr <- rep(1:2, each = 10)
myd$gen <- rep(letters[1:10], 2)
X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 yvar yr gen
1 0 1 1 1 1 0 ... | g44575 | [
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<p>I have a dataset from a bank with demographic data and one variable telling if the customer is a good customer or not (binary variable). I would like to do prediction on if the customer is good or not based on this demographic data.</p>
<p>I managed to do it with a logistic regression, but would like now to compare... | g65749 | [
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<p>If in standard OLS regressions two assumptions are violated (normal distribution of errors, homoscedasticity), is bootstrapping standard errors and confidence intervals an appropriate alternative to arrive at meaningful results with respect to the significance of regressor coefficients?</p>
<p>Do significance tests... | g41748 | [
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<p>I have results from a likert scale 1 - strongly disagree-5 - strongly agree. I also had a N/A and a Not Sure category. How do I calculate the average response?</p>
<p>I am thinking to not include the n/a's and not sure's in my calculation because we only want to be evaluated by people who know about my company. </p... | g24472 | [
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<p>I'm new to statistics. </p>
<ol>
<li><p>What type of model should be used to predict a basketball team's winning percentage? I am currently using a multiple linear model, but the residual vs. predicted plot shows my data points clustered in a circle. I standardized my explanatory variables since they were either pe... | g24474 | [
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<p>Does anyone know of any good and accessible papers on the random walk modelling of financial data from a statistics perspective? Most of the papers I've found have been written by economists or suchlike, and while still mathematical, they don't quite have the theoretical depth I would like.</p> | g65750 | [
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<p>I am comparing means of ion intensities at many different chromatographic retention times for two non-paired groups (control and treated). So for example I have 6 control samples and 8 treated samples. At retention time 50, the control samples will have a mean ion intensity of 1000 and the treated samples have an io... | g65751 | [
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<p>I am using random forests to try and determine variable importance as part of feature selection for a model I'm working on, and while I can get ranked variable importance by mean decrease in Gini from removal, I'm not sure what a good cutoff would be for including a variable in a model or not. For example, if the de... | g65752 | [
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<p>I am trying to do habitat modelling using dismo package on R. I performed <code>glm()</code> as follows:</p>
<pre><code>gm2=glm(pa~.,family=gaussian(link="identity"),data=train1)
</code></pre>
<p>The glm work fine and gives very good result; but, when I tried to do model prediction as –</p>
<pre><code>pred=predic... | g4865 | [
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<p>I want to find a time series model for monthly precipitation data. </p>
<p>I checked SARIMA and Holt-winters seasonal multiplicative models. </p>
<p>I can't find an appropriate model. These models underestimate high precipitation. </p>
<p>I have 528 monthly precipitation observations. I used the initial 420 obser... | g23191 | [
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<p>I am wondering what the exact relationship between partial $R^2$ and coefficients in a linear model is and whether I should use only one or both to illustrate the importance and influence of factors.</p>
<p>As far as I know, with <code>summary</code> I get estimates of the coefficients, and with <code>anova</code> ... | g65753 | [
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0.028420407325029373,
-0.056599684059619904,
0.027459101751446724,
0.0708402693271637,
0.... |
<p>I've started with a “perfect” image 'without noise'.</p>
<p>Then I added some noise to it. I've used gaussian white noise for this purpose.</p>
<pre><code>In = In+0.5*randn(size(Io))
</code></pre>
<p>The combined image (my “noisy image”) has a signal to noise ratio with some meaning because I can compare it to th... | g49732 | [
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<p>I am trying to understand a GWAS paper which reports the effect of a SNP on outcome as a % variation, e.g., 15% variation in xxx levels.</p>
<p>The only information reported are the beta, standard error and p-values. I tried to read the paper but there is no mention of how this is calculated.</p>
<p>The paper in q... | g65754 | [
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<p>I'm new in the forum. I remember having read somewhere in the web a connection between $\ell_2$ regularization and PCA: while using $\ell_2$-regularized regression with hyperparameter $\lambda$, if $\lambda \to 0$, then the regression is equivalent to removing the variable with smallest eigenvalue.</p>
<ul>
<li>... | g65755 | [
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<p>I have an integral I need to evaluate that contains a random variable? How would I go about doing something like that. For instance lets say I have a random variable $C$ with PDF $f_C(x)=1/N \; 0\le x\le N$ (Uniform distribution) and I have an integral
$$
\int\limits_a^bC\mathrm{d}x
$$</p>
<p>Can I evaluate an in... | g65756 | [
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... |
<p>I'm looking to do some heavy-duty manipulation of some really large and often very sparse matrices and I'm looking for the right tool for the job. These matrices will be much, much larger than the RAM of any single machine and will therefore likely be spread to several different machines. </p>
<p>I will want to per... | g65757 | [
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0.0006... |
<p>I have a sample where subjects dedicate a variable <strong>number of hours</strong> to an activity. During these hours, an event might happen. I have a contingency table such as</p>
<pre><code> Event happened No event happened
Male 2000 30000000
Female 3400 ... | g65758 | [
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... |
<p>I am having trouble finding an answer for the following issue.</p>
<p>I am making a card game (Pitch) where your bidding is based off of the probabilities of getting 4 points. I have already figured out the probability for a given hand / game of the individual points but I am at a loss on how to correct figure out... | g24484 | [
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0.003346548415720463,
0.016938911750912666,
... |
<p>It is well-known that an AR(p) process
$$
x_t=\sum_{i=1}^p \varrho_i x_{t-i} + \epsilon_t \,,
$$
is causal and stationary if and only if the roots of the polynomial
$$
\mathcal{P}(u) = 1 - \sum_{i=1}^p \varrho_i u^i
$$
are all outside the unit circle in the complex plane. (Here is a <a href="http://stats.stacke... | g65759 | [
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0.05531328544020653,
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<p>Using caret, I want to train a SVM classifier and estimate its performance using repeated cross validation. My dataset has a very large number of predictors (300K) and I want to reduce this number using a super simple univariate approach (like t-test p-value below a threshold - or two-class anova is fine too). If ... | g65760 | [
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<p>Is it make sense that time series method to be compared with non-time series method ? and if it is possible could somebody tell me which non-times series method can I apply to make comparison between time series method and others for make a decision.</p> | g65761 | [
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<p>I am testing the reliability of my formative measurement model and I am using Variance Inflation Factor (VIF) and Condition Index (CI) (<a href="http://stats.stackexchange.com/questions/16602/whether-and-how-to-perform-vif-and-condition-index-on-formative-measurement-model">see this earlier question asking whether t... | g44601 | [
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<p>So I have setup testing code on a website, our conversion data is blocked per day and fed into R.</p>
<p>This is the R code that I am using to calculate the "confidence"</p>
<pre><code>t.test(a, b, paired=TRUE)
</code></pre>
<p>And this is the R code that I am using to calculate "sample size"</p>
<pre><code>n.tt... | g23193 | [
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<ul>
<li>What are good online or offline resources that give an overview of the history of statistics and the main breakthrough in statistics until now?</li>
</ul>
<p>I have read the page on <a href="http://en.wikipedia.org/wiki/History_of_statistics">History of Statistics on Wikipedia</a>.</p> | g24490 | [
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<p>All our text book examples are based on macro economic problems, but there must be many applications of time series models on other data, such as for example windspeed, average heartbeat, gas turbine efficiency, factory output, etc.</p>
<p>Do you know on the web textbook examples about these non economic applicatio... | g65762 | [
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... |
<h3>Context:</h3>
<p>In <a href="http://stats.stackexchange.com/questions/16689/why-is-gender-typically-coded-zero-one-rather-than-one-two/">this previous question</a> @adhesh asked about the benefits of coding a binary variable zero-one rather than one-two.
I realised when I wrote <a href="http://stats.stackexchange... | g24492 | [
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0.02732398919761181,
0.015266317874193192,
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0.03482013940811157,
0.0122... |
<p>I see a <a href="http://stats.stackexchange.com/questions/66128/choosing-the-number-of-clusters-in-hierarchical-agglomerative-clustering">couple</a> <a href="http://stats.stackexchange.com/questions/34647/specifying-the-number-of-clusters-in-nearest-neighbor-clustering">of</a> <a href="http://stats.stackexchange.com... | g65763 | [
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0.06859156489372253,
0.05066911... |
<p>I am frequently reading some terminology But not understanding their difference .</p>
<p>Those are :</p>
<h3>$\bullet$Difference between <code>Population Projection and Population Forecast</code></h3>
<h3>$\bullet$Difference between <code>Population Projection and Prediction</code></h3>
<h3>$\bullet$Difference b... | g23195 | [
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0.03543885424733162,
-... |
<p>I need to apply the delta method principle using a Taylor expansion that retains higher order terms (i.e. to second or third order) in order to improve the accuracy of variance estimation. The literature on the higher order delta method seems to focus on the special case where the first order term is zero leaving o... | g24495 | [
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... |
<p>When making ordinal logistic models and you have two or more parameters how can you tell which one has a greater effect on the response variable? </p> | g44608 | [
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0.0759655013680458,
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<p>I've read PCA and few more dimension reduction algorithms and all of them talk about using eigen values and matrix operations. How are they so significant in discovering geometrical significance of data? More relevant what properties make them so relevant to Dimension Reduction</p> | g65764 | [
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<p>I have a data set with 5 different kinds of nutrient statuses and I want to see whether they are associated with categorical / ordinal grades at school. I have multiple covariates which I will included in the analyses. Due to missing values I have used the multiple imputation strategy (5 times). </p>
<p>So now I ha... | g65765 | [
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0.0008649551309645176,
0.0044108168222010136,
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0.05728685483336449,
... |
<p>I am trying to find conditional probability of the form <code>P(X<x|Y=y)</code> for two jointly distributed random variables based on the copula estimate from training data. I use R package <code>copula</code> but can not figure out the best way to do it. </p>
<p>What I do now - estimate empirical copula paramet... | g65766 | [
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0.04098270833492279,
-0.0187... |
<p>This is one integration problem I encountered during the calculation of Bayes factor between two models given data $D$</p>
<p>One of the model, $M_0$ assumes the data accords to multinomial distribution, with the parameter $(\theta_1, \theta_2, \dots, \theta_k)$ and $\sum_{i=1}^k\theta_i= 1$.</p>
<p>Also we assume... | g65767 | [
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0.03343744948506355,
0.0026834020391106606,... |
<p>First of all, very sorry for re-posting this question. I asked the same question before, and I wanted to clarify an answer to my question, but the comment looks messy. </p>
<p>I am trying to read about graphical models from this short course <a href="http://ai.stanford.edu/~paskin/gm-short-course/lec2.pdf" rel="nof... | g24500 | [
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0.042232535779476166,
0.08729860931634903,
0.01... |
<p>Assume we have 3 annotators, each one of which has assessed the quality of 3 products in a scale from 1 to 7. </p>
<pre><code>ANN PRODUCT SCORE
an1 pr1 5
an1 pr2 2
an1 pr3 3
an2 pr1 7
an2 pr2 1
an2 pr3 2
an3 pr1 3
an3 pr2 3
an3 pr3 4
</code></pre>
<p>We also ... | g65768 | [
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0.012282608076930046,
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0.08827204257249832,
0.0... |
<p>I want to evaluate the calibration of the random forest using val.prob (rms package, R). I have no problems using it and getting an output, but I feel the results may not be accurate because I don't believe that the class membership probabilities outputted by the random forest (predict.randomForest, also in R) are p... | g65769 | [
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0.05375096574425697,
0.006643272005021572,
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0.047... |
<p>In this <a href="http://en.wikipedia.org/wiki/Cross-validation_%28statistics%29" rel="nofollow">Wikipedia</a> page in subsection for K-fold cross validation it says "In k-fold cross-validation, the original sample is randomly partitioned into k equal size subsamples. Of the k subsamples, a single subsample is retain... | g24504 | [
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0.01677810773253441,
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0.004517320077866316,
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<p>Consider the <code>pairs()</code> function. Given a matrix $X$ with $p$ columns it will produce a $p$-by-$p$ matrix of plots with in each cell a bivariate plot of $X_k$ (the $k$ th column of $X$) against $X_l$ $1\leq l\neq k\leq p$.</p>
<p>I'm looking for a regression equivalent of this: given a vector $y$ and $X$ ... | g65770 | [
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0... |
<p>Starting out with arima models in R, I do not understand why fitted.values (of an AR(2) process for example) are not part of the output like they are in regressions. Did I miss them when running <code>str(result)</code> or did I get something completely wrong? </p> | g44613 | [
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<p>Would you please give an intuitive illustration of Newton's Method, when we deal with nonlinear regression?<br>
Basically I understand that if we can use Taylor's theorem to expand the RSS function of parameter beta, we can change it into quadratic form, and minimize RSS w.r.t parameter. Please give me a multivaria... | g65771 | [
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... |
<p>I'm searching for a library or tool that allows me to classify emails of a mailing list into what mails are very likely questions and what mails are very likely answers.</p>
<p>Can anybody recommend such a tool?</p>
<p>Anything else than counting the fraction of question marks against periods?</p> | g65772 | [
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<p>I am using Sweave and <strong>xtable</strong> to generate a report. </p>
<p>I would like to add some coloring on a table. But I have not managed to find any way to generate colored tables with xtable. </p>
<p>Is there any other option?</p> | g44615 | [
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<p>I would like to find the correlation between two variables. It was suggested to me that two variables should be independent; otherwise it is not meaningful statistically to calculate a correlation. For example, variable is x and another is $y$ which won't be calculated from $x$, e.g., $y=ab/c+x$. $a$, $b$, and $c$ a... | g65773 | [
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<p>I am trying to calculate ePCP and Brier scores in R for a mixed-effect binary logistic regression. It cannot seem to find any packages that work for mixed models. I have tried the packages OOmisc and ModelGood, and spent much time searching the web with no success.</p>
<p>I am using the lme4 package to fit the regr... | g65774 | [
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<p>I have a survival cancer clinical trials dataset from which I have generated Cox models using forward likelihood ratio testing within R. These models are based on 'traditional' cancer variables (eg. age, histology, metastasis etc). </p>
<p>I would like to extend the model using high dimensional data (where we have ... | g98 | [
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<p>Suppose I have a feature matrix $F = [f_1^T,f_2^T,...,f_m^T]$ whereby $f_j^T \in \mathbb R^{n_t \times 1}$ is the $j$th column vector of $F$ ($n_t$ is the number of different events/trials and $m$ is the total number of features per trial). All trials are labelled with classlabel $\omega = \{1,2\}$.</p>
<p>Therefor... | g65775 | [
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<p>I'm trying to determine the effect of three types of learning on a group of subjects.</p>
<p>I have their pretest scores and posttest scores.
The current goal is to determine which intervention reduce the percentage of questions wrong before the learning correctly answered after:
That is to say, (Post - Pre) / (100... | g65776 | [
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<p>I want to do a poisson multilevel analysis of item nonresponse over 27 countries. The model holds 3 levels: respondent, interviewer, and country.</p>
<p>I am using data from the European social survey, and these data have two weights: </p>
<p><code>Design weight:</code> Several of the sample designs used by countr... | g65777 | [
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<p>I want to estimate the quantile of some data. The data are so huge that they can not be accommodated in the memory. And data are not static, new data keep coming. Does anyone know any algorithm to monitor the quantiles of the data observed so far with very limited memory and computation? I find <a href="http://cites... | g32631 | [
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<p>I have to reduce the number of variables to conduct a cluster analysis. My variables are strongly correlated, so I thought to do a Factor Analysis. However, if I use the resulting scores of factor analysis, my clusters are not quite correct (compared to previous classifications in literature). </p>
<p><strong>Quest... | g37512 | [
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<p>I've been trying to remember my High School teachings and are falling short.</p>
<p>I'm working on a project where I need to give a % of correctness for an integer (How close a given number is to the actual number within a 300% difference). For example if the number we want is 50, any number from -100 to 150 will ... | g49708 | [
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<p>I'm quite new to machine learning, pattern recognition, statistics, etc. but I'm trying to wrap around how a machine learning system would interpret data that is something like this:</p>
<p>row0-> feature1:A, feature2: $, feature3: _, feature4:101.8</p>
<p>row1-> feature1:B, feature2: $, feature3: _, feature4:100.... | g65778 | [
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<p>I am working on yield of fisheries in three different pools. The yield output was measured in terms of their length gain and weight gain. The other variables considered are length of stay, outer temperature, pool temperature, PH level of water, etc. </p>
<p>In this case I want to develop a model of yield in terms o... | g24517 | [
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<p>This is a quite generic question: assume I want to build a model to predict the next observation based on the previous $N$ observations ($N$ can be a parameter to optimize experimentally). So we basically have a sliding window of input features to predict the next observation.</p>
<p>I can use a Hidden Markov Model... | g10929 | [
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<p>This is related to a <a href="http://stats.stackexchange.com/questions/62646/pooled-time-series-regression-in-r">question</a> I asked a couple weeks ago, but I've got a new question related to the same data. You can find the data and its accompanying explanation in the link provided.</p>
<p>I felt that a regression... | g65779 | [
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<p>My binary logistic regression gives P values significant at 0.05 level for some of the modeled independent variables. However, bootstrapping the same regression model gives P values significant at 0.01 or 0.001 levels for the same predictors which were mostly significant only at 0.05 level, or even for some of them ... | g65780 | [
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<p>for two real random $n$-vector $y$ and $x$
and a random $n$-vector $e$ with distribution
$F$ independent of $x$ we know (1) that the
estimator</p>
<p>$$\text{med}\left( \frac{y_i}{x_i}\right)$$</p>
<p>is minimax estimator for $\alpha$ in the model:</p>
<p>$$y_i=\alpha x_i+e_i$$</p>
<p>My question is the follo... | g10930 | [
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<p>Below are three ways to fit a MANOVA model in R and to extract ANOVA tables from the fitted model. The design is balanced. All methods give different results. </p>
<p>The data are 5 groups of 4 individuals with three repeated measures shown in figure below</p>
<p><img src="http://i.stack.imgur.com/OmqmA.png" alt="... | g24523 | [
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0.029598921537399292,
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0.02... |
<p>(I post this originally at <a href="http://stackoverflow.com/questions/15477282/what-exactly-the-roc-curve-can-tell-us-or-can-be-inferred">http://stackoverflow.com/questions/15477282/what-exactly-the-roc-curve-can-tell-us-or-can-be-inferred</a>, but people directed me to here. Sorry about posting this twice.)</p>
<... | g65781 | [
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<p>I think my question is similar to this one:
<a href="http://stats.stackexchange.com/questions/82242/how-do-you-plot-an-interaction-between-a-factor-and-a-continous-covariate">How do you plot an interaction between a factor and a continous covariate?</a></p>
<p>My IV and DV are both scales, and my interaction term h... | g65782 | [
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0.010337576270103455,
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... |
<p>I have a question regarding the definiton of estimators. In the german wikipedia it says that the distribution is determined by g($X_1,...,X_n$) where by g is the estimator function and $X_1,..X_n$ are the observed random variables, and g is evaluated for all possible samples. </p>
<p>Now my question is if the dist... | g65783 | [
0.02865706756711006,
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0.057... |
<p>It seems to me that to choose the right statistical tools, I have to firstly identify if my dataset is discrete or continuous.</p>
<p>Could you mind to teach me how can I test whether the data is discrete or continuous with R?</p> | g65784 | [
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<p>This is my first question, please should I write something wrong correct me. </p>
<p>I have a question when comparing two GLMs after applying stepwise selection. What I've always heard is that stepwise selection is not robust enough for the selected variables. Therefore, I use ANOVA to compare the most parsimonious... | g65785 | [
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<p>The parameters of a t distribution can be estimated via</p>
<p>1) ML or</p>
<p>2) method of moments</p>
<p>If we use the method of moments we have:</p>
<p>$\mu=E(R)$</p>
<p>$\sigma^2=V(R)=\frac{\beta \nu}{\nu -2}$</p>
<p>$\kappa = \frac{6}{\nu-4}$</p>
<p>we can rewrite the last two equations:</p>
<p>$\beta =... | g65786 | [
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<p>Let's say I have a <em>randomly</em> generated sequence consisting of letters A, C, T and G that's 1000 letters long. The probability of each letter occurring is 25%. What is the probability that the sequence 'AAAAA' will occur N times within the 1000-letter sequence?</p>
<p>The problem I have solving this is that ... | g65787 | [
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<p>I use semi-parametric models with linear and non-linear terms in SAS. I want to plot the predictions and confidence limits of the linear terms in the model. However, the output out statement and plots only show predictions and CL's for the non-linear terms (smoothers) in the model. How can I get the predictions and ... | g65788 | [
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<p>Is there a way to utilize Canonical Correlation Analysis when your data are time series and repeated measures (i.e. your experimental units are not independent)? How might one approach the analysis of two sets of variables when the question is what relationships, if any, are there between one set of variables and t... | g65789 | [
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<p>I've been trying to replicate the results in this online calculator:</p>
<p><a href="http://www.raosoft.com/samplesize.html" rel="nofollow">http://www.raosoft.com/samplesize.html</a></p>
<p>However, it seems that I am missing something. Exactly how do I solve the margin of error when all the other variables (sampl... | g24528 | [
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<p>I'm trying to find the MAP estimate for a model by gradient descent. My prior is multivariate Gaussian with a known covariance matrix.</p>
<p>On a conceptual level, I think I know how to do this, but I was hoping for some help with the details. In particular, if there is an easier way to approach the problem, the... | g65790 | [
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0... |
<p>I have been told $x$ is drawn from a symmetric triangle distribution.
If the lower bound is 3 and the median is 9, how do I calculate the upper bound?</p>
<p>I'm not sure which value to use (I have to substitute the value I find into a formula). I was thinking if perhaps I had the upper bound, lower bound and medi... | g24530 | [
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<p>I have individual panel-level data and am using conditional binomial fe logit regressions to estimate the effect of minimum wage on Employment. </p>
<p>1) When I try to include year dummies most of them are excluded due to multicollinearity. I have tried evertying - dropping variables, changing the values of the ye... | g65791 | [
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0.02674325555562973,
0.007387016899883747,
-0.0068321810103952885,
-0.010087135247886181,
0.002069407608360052,
0.0032603966537863016,
0.012974933721125126,
-0.008285769261419773,
-0.052729569375514984,
0.0018884429009631276,
-0.030998609960079193,
0.05722341313958168,
... |
<p>I have a random number generator of U(0,1), I apply the ks test on x, which has 10000 random numbers in [0,1]:</p>
<pre><code>> ks.test(x,"punif")
</code></pre>
<p>and obtain this result:</p>
<pre><code>One-sample Kolmogorov-Smirnov test
data: x
D = 0.0059, p-value = 0.8775
alternative hypothesis: two-sided
... | g49733 | [
-0.00894140638411045,
-0.01680944859981537,
-0.004798220936208963,
-0.02191982790827751,
-0.048448920249938965,
-0.020118698477745056,
0.004066248890012503,
0.05652477219700813,
-0.01575184240937233,
-0.039083730429410934,
0.018961500376462936,
0.029596896842122078,
0.039106979966163635,
0... |
<p>I need to develop an algorithm that will compare two signals and generate some metric(s) to describe changes between them. Signal processing and analysis isn’t my strong point so I would appreciate any help!</p>
<p>Here is an example of what the signals look like:</p>
<p><img src="http://i.stack.imgur.com/znm4r.jp... | g24531 | [
0.02545236609876156,
-0.06791891902685165,
-0.029838673770427704,
-0.07191959023475647,
0.010012958198785782,
-0.049914706498384476,
0.018740341067314148,
-0.013615303672850132,
-0.05661672726273537,
0.017013268545269966,
-0.030585166066884995,
0.02134452573955059,
0.07740601897239685,
-0.... |
<p>I am reviewing a study in which standard deviations (SDs) of an X variable, calculated for each individual in the study (measures on each individual were replicated 4 times), are used as predictors of a Y variable. They do not observe a significant correlation between Y and the SDs of X and they conclude by saying t... | g65792 | [
-0.016179705038666725,
-0.00284023629501462,
0.010332903824746609,
-0.0007746752235107124,
-0.07587818056344986,
0.012931167148053646,
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0.0014796039322391152,
-0.05662476271390915,
0.029341815039515495,
0.0008211407694034278,
0.020866727456450462,
... |
<p>In the typical environment for multiple linear regression, we have that $Y = \mathbf{X}\beta + \epsilon$ where $\epsilon$ is iid $\mathcal{N}(0, \sigma^2I) $ where $\sigma^2$ is unknown. In this case, regression sum of squares (SSR) has $\text{df}= p - 1$ ($\text{df}$ = degrees of freedom) where $p$ is the number of... | g65793 | [
-0.010506774298846722,
0.010344931855797768,
-0.02149135246872902,
-0.007197380531579256,
0.028888611122965813,
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0.06608562171459198,
0.01930510811507702,
-0.0005812200834043324,
0.013231219723820686,
-0.08392312377691269,
0.03839315101504326,
0.0676952674984932,
-0.00... |
<p>I am modelling a zero-truncated process with a count model, and am trying to determine whether the data are overdispersed. The Poisson distribution has a variance equal to its mean,
$$\newcommand{\Var}{\operatorname{Var}} \Var(y) = E(y) = \lambda $$
The negative binomial model relaxes this assumption by estimating a... | g44387 | [
0.011077556759119034,
-0.04678114503622055,
-0.012301160022616386,
-0.03622181713581085,
0.06791902333498001,
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0.03736881911754608,
-0.020825296640396118,
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0.02002660371363163,
-0.01789569854736328,
-0.02994418889284134,
-0.06541162729263306,
0.03... |
<p>I am struggling with a linear regression model of the shape $y = a + b_1\text{month} + b_2\text{year}$. I have 12 months for each year and 10 years. My dependent variable is a log transformed ratio. I have understood that much that when setting such a model up in R, R automatically picks a level for each variable to... | g37852 | [
0.008674896322190762,
-0.13099375367164612,
-0.024392144754529,
-0.05371658876538277,
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0.1127663254737854,
0.045225005596876144,
-0.03292529657483101,
-0.0012845569290220737,
-0.029110219329595566,
0.05817271023988724,
0.046386461704969406,
-0.047... |
<p>How to calculate sample size needed for GWAS for a given MAF, power, $p$-value and frequency of the disease ?</p> | g65794 | [
-0.029052946716547012,
0.03578565642237663,
0.004221610724925995,
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0.0348609983921051,
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-0.030955558642745018,
0.0071315155364573,
0.01794520765542984,
0.04051874577999115,
0.004... |
<p>I am reading <a href="http://www.stanford.edu/~hastie/local.ftp/Springer/OLD//ESLII_print4.pdf" rel="nofollow">Elements of Statistical Learning</a> and on page 12 (section 2.3) a linear model is notated as:</p>
<p>$$\widehat{Y} = X^{T} \widehat{\beta}$$</p>
<p>...where $X^{T}$ is the transpose of a column vector o... | g65795 | [
0.004373125731945038,
-0.0006438601994886994,
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-0.016409603878855705,
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0.07260259985923767,
0.04876448214054108,
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-0.027022017166018486,
-0.005869007669389248,
0.01801459677517414,
0.03577493503689766,
0... |
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