question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I am trying to calculate inter-rater reliability scores for 10 survey questions (on which there were 2 raters)--seven questions are binary (yes/no), and 3 are Likert-scale questions.</p>
<ol>
<li><p>Should inter-rater reliability be tested on EACH of the 10 questions, or is there an overall inter-relater reliabilit... | g66039 | [
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<p>I am a bit confused about parameter estimation using evolutionary methods and their ability to do such a job. Since I am not that pro in stat I am describing my problem with giving an example.</p>
<p>Given different response variable, say Y and in my example molecular weight there are different constant value/weigh... | g588 | [
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<p>Yes, I know there are many questions on comparing these two types of intervals, but none of them appear to answer this exact question.</p>
<p>Here is a blog post demonstrating one case where the two intervals are the same and one where they are different:</p>
<p><a href="https://jakevdp.github.io/blog/2014/06/12/f... | g66040 | [
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<p>This is my first time posting here, so please forgive me if I am not following some form of etiquette.</p>
<p>My question is in regard to the following evaluation design:</p>
<p>We are examining the impact of policy X. It was implemented at the same time for all units j. We have the ability to collect measurements... | g38108 | [
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<p>I have a GPS unit that outputs a noise measurement via covariance matrix $\Sigma$:</p>
<p>$\Sigma = \left[\begin{matrix}
\sigma_{xx} & \sigma_{xy} & \sigma_{xz} \\ \sigma_{yx} & \sigma_{yy} & \sigma_{yz} \\ \sigma_{xz} & \sigma_{yz} & \sigma_{zz}
\end{matrix}\right]
$</p>
<p>(there's also ... | g66041 | [
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<p>According to the wikipedia article on the lognormal distribution, the lognormal distribution is "the maximum entropy probability distribution for a random variate $X$ for which the mean and variance of $\log(X)$ is fixed".</p>
<p>Is there a not too complicated account of what this means and how this is derived?</p... | g66042 | [
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<p>I am doing modeling for say response y ~ a+b+c+e+f.. x+y+z ( say I got model for decision tree ) </p>
<p>if my dataset is big, say 1M records : </p>
<p>I have a-z independent variables , but having x,y,z are very predictable ( x,y,z are binary variable - 0,1) : say correlation of almost 1. , but very small say ... | g45081 | [
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<p>Can anyone give some advice on how to start proving this algebraically?</p>
<p>Define the residual from a regression (one independent variable) algebraically and show that:</p>
<ol>
<li>the mean of the residuals is zero</li>
<li>the correlation of the residuals and the independent variable is zero</li>
</ol> | g66043 | [
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<p>hopefully you can help me with the meaning of the following, I don't really understand the terminology:
"regression of a vector of ones on the matrix $W$",
where $W$ is something like $(W_t)' = (w_{1t},w_{2t},w_{3t}, w_{4t})$.</p>
<p>I don't understand, which regression I actually have to compute. If it is of h... | g46458 | [
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<p>"Under what condition (or conditions if you think it necessary) would one observe no change in the regression coefficient (e.g., b-hat Y on X1) for some variable when another variable is added to the regression equation?"</p>
<p>I think the answer is when the exogenous variables are perfectly uncorrelated - is that... | g66044 | [
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<p>Can anyone explain why having too many p-value less than 0.001 is alarming? Like what happens to my model right now:</p>
<p><img src="http://i.stack.imgur.com/rkeDb.jpg" alt="enter image description here"></p>
<p><img src="http://i.stack.imgur.com/Y1IYY.jpg" alt="enter image description here"></p>
<p>All independ... | g24903 | [
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<p>I want to estimate the dynamic conditional correlation GARCH in stata 12. I just ran the following line:</p>
<pre><code>mgarch dcc (x y =, noconstant) , arch(1) garch(1)
</code></pre>
<p>The x and the y variables are log first differences from two price series. </p>
<p>My questions are as follows:</p>
<ol>
<li>D... | g13042 | [
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<p>Say you have a game that asks you whether you think the next card will be higher.
In this game ace is 1. If the next card is equal to the first one then another random card is taken until the next card is either higher or lower. Suits are disregarded in this game. One deck is used and cards are recycled.</p>
<p>Wha... | g66045 | [
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<p>A classic example for students, when teaching Bayesian statistics, is to make inference on the mean parameter $\mu$ of a normal distribution, when it has a prior normal distribution.</p>
<p>I would like to find a real-life example of why such a construction would be not only elegant, but also useful.</p>
<p>Can an... | g66046 | [
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<p>The question is as in the title. The GMM estimator (in my Econometrics notes) is as follows:</p>
<p>$\hat \delta_{GMM}(W_n) = (S'_{xz} W_nS'_{xz})^{-1}(S'_{xz}W_ns_{xy})$</p> | g66047 | [
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<p>When using SAS callable IVEware for multiple imputation it will occasionally throw out a warning for too many iterations. Can someone give me an idea of how many warnings are acceptable (if any) for a particular variable?</p> | g66048 | [
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<p>I have a call center data (such as one below) that has call data collected every 15 minutes. For a day the periodicity is 96 and for a week the periodicity is (7 x 96 = 672). If I would like to forecast this data I can use models that handle multiple seasonality such as <code>DSHW, TBATS and BATS</code> in R <a hre... | g24910 | [
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<p>I am trying to follow someone else's notes. They have two matrices. </p>
<p>One is called <code>comfact</code> (company factors). This is a 580 x 5 matrix. The 580 rows represent 580 different companies. The 5 columns represent 5 betas for the 5 different factors that were used to model a companies growth rate. The... | g23591 | [
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<p>Suppose we have a Cox proportional hazards model with covariates including the patient's age, where the log hazard ratio for age is positive and significant, indicating increased risk for outcome in older patients.</p>
<p>Then, with the same data and covariates we run a relative survival model. The (raw) coefficien... | g66049 | [
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<p><strong>Intro</strong></p>
<p>I am running <code>cv.glmnet</code> from the <code>glmnet</code> package in <code>R</code>. I am running 10-fold cross validation 100 times on a dataset that has 25,000 observations and 150 variables. I am using the <code>parallel = TRUE</code> option, as that greatly speeds up results... | g66050 | [
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<p>It is said that kMeans clustering works as long as we don't have clusters of differing</p>
<ol>
<li>sizes,</li>
<li>densities,</li>
<li>and non-spherical shapes</li>
</ol>
<p>I understand how one might check the sizes and densities of data points, but I am unsure how one would check for non-spherical clusters, esp... | g66051 | [
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<p>I know this question has been asked in a slightly different form <a href="http://stats.stackexchange.com/questions/14500/how-can-a-regression-be-significant-yet-all-predictors-be-non-significant">here</a>. But my question differs and because of the forum rules I can't post on that thread. I have 2 independent variab... | g49368 | [
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... |
<p>Simple question: I have a dataset, in which all the multivariate x variables (x0, x1, x2, x3..) are continuous, and all the y variables are categorical (distributed (equally) between 1-20 categories). Can this type of data be processed via multiple linear regression?</p>
<p>example:</p>
<pre><code>data = [2.3, 4.5... | g23339 | [
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0.002679944271221757,
0.007333405781537294,
... |
<p>Suppose you want to estimate a linear model: ($n$ observations of the response, and $p+1$ predictors)
$$\mathbb{E}(y_i) = \beta_0 + \sum_{j=1}^p \beta_j x_{ij}$$</p>
<p>One way to do this is through the OLS solution, i.e. choose the coefficients so that the sum of square errors is minimum:</p>
<p>$$(\beta_0,\beta_... | g66052 | [
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0.... |
<p>I assume that my population is a sample of an unknown multivariate categorical distribution $\mathbf{X} = (X_1, X_2, \ldots, X_k)$. From this population, a sample $\mathbf{X^*}$ is available, I assume $\mathbf{X^*} \sim \mathbf{X}$. I am evaluating different methods to reconstruct $\mathbf{X}$ from such a sample.</p... | g66053 | [
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<p>I frequently do something like: load a bunch of data, and then scan some fraction of it randomly to verify that no errors occurred. The more data I verify, the greater my certainty that no errors occurred anywhere.</p>
<p>I'm curious about how I can express this formally. My thought process is: </p>
<p>Suppose the... | g66054 | [
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<p>Is it good practice to consistently use a correlation matrix when the direction of the relationship between dependent and independent variables is unknown (that is, when we’re uncertain about an inverse or direct relationship between variables)? Or, should established research be used as the basis for determining th... | g37963 | [
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<p>I have a question about which is the best way to specify an interaction in a regression model. Consider the following data:</p>
<pre><code>d <- structure(list(r = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("r1","r2"),
class = "factor"), s = s... | g37456 | [
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<p>(this is the opposite of "<a href="http://stats.stackexchange.com/questions/414/introduction-to-statistics-for-mathematicians">introduction to statistics for mathematicians</a>")</p>
<p>I'm a programmer who loves writing logic and even a <a href="https://github.com/seamusabshere/vector_embed" rel="nofollow">libsvm ... | g37840 | [
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<p>I would like to set up an experiment in MATLAB, to predict the class of a set of text instances in a two-class problem (e.g., the text talks/does not talk about <code>basketball</code>). </p>
<p>By doing this, I would like to draw <strong>learning curves</strong> by varying the number of samples <code>M</code> and ... | g66055 | [
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0.044400326907634735,
0.046808503568172455,
0.... |
<p>Using the ‘mediation’ package by Tingley and colleagues in R, I’m trying to conduct a bootstrapped mediation analysis for an interaction between a 2-level categorical IV (‘condstorm’) and another 3-level categorical IV (‘condmean’). The mediator (‘trustmed2’) is dichotomous, and the dependent variable (‘AttInd’) is... | g66056 | [
-0.006770848296582699,
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0.0037959881592541933,
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0.011241139844059944,
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0.06646628677845001,
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0.049430206418037415,
0.021807214245200157,
... |
<p>We are investigating Bayesian statistical testing, and come across an odd (to me atleast) phenomenon. </p>
<p>Consider the following case: we are interested in measuring which population, A or B, has a higher conversion rate. For a sanity check, we set $p_A = p_B$, that is, the probability of conversion is equal in... | g66057 | [
0.00800339411944151,
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<p>I have a generalised linear mixed model with 34 explanatory variables (over 130,000 observations for each). 10 of these variables are different unprotected habitat types, and another 10 are the same habitat types but protected for conservation. (The factor for the random effect E.V. is region).</p>
<p>I want to com... | g66058 | [
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... |
<p>Does including a regressor with minimal variance behave analogously to including an additional fixed effect in the regression? If yes, what could be the implications for that? </p>
<p>I am using a panel dataset of 29 cross-sectional units in 47 years.</p> | g125 | [
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<p>Dear StackExchange community, </p>
<p>I have an unbalanced data set / data set with missing values, consisting of 20 submersible acoustic receivers that have been range tested on 8 days (Both receiver ID and Day are treated as random effects in my model). My aim is to test the effects of multiple environmental vari... | g66059 | [
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<p>I work with a regression with ARMA errors and I want to use LASSO to shrink the coefficients and select my variables. This topic is discussed in the article <a href="http://www.sciencedirect.com/science/article/pii/S0378375812000948" rel="nofollow">Wu et al. (2012)</a>.
So, the problem I have to minimize is:</p>
<p... | g66060 | [
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<p>I have been reading medical journals and they repeatedly show baseline characteristics of samples from a randomised controlled trial, which they have then tested to ensure no differences between the two groups under study. For example in the operation group you have 39 males and 3 females. And in the non-op group yo... | g66061 | [
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<p>I have searched for many days trying to find the answer to this question, and am still not 100% sure I am happy with my conclusion. I am interested in looking at the effects of environmental variables on detectability of marine mammals. I have Animal Counts as my response variable, and have Cloud cover, sea state, g... | g23631 | [
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<p>Consider a regular 52 card deck of playing cars. Suppose 2 cards are drawn at random from the deck with-out replacement. What is the probability that the second card is an ace, given that the first card is a king? </p> | g66062 | [
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<p>First off, I'll state that I'm aware many questions get asked about the c-index. I've searched this site and others, and I haven't found an answer for my situation. I can successfully use <code>validate()</code> in the <code>rms</code> package to calculate the Dxy and c-index for my boot-strapped internal validati... | g24923 | [
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<p>My data set includes 400 records. Each record comprises values for the binary outcome variable $y$ and 12 categorical predictor variables $x_1, ..., x_{12}$, most of which are binary too. The records originate from 10 different studies, of which one is much larger than the remaining ones (it contributes nearly three... | g66063 | [
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<p>I am performing survival analysis on credit data. I created a simple model with using interest rate:<br>
<code>cox <- coxph(Surv(periods,charged_off) ~ int_rate, data=notes)</code>
I assumed that <code>int_rate</code> was a time-independent variable, but the following test rejects H<sub>A</sub>:</p>
<pre><code>... | g24925 | [
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0.006926446687430143,
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0... |
<p>I am having trouble in implementing neural network to predict N points ahead. My only feature is previous time. I used elman recurrent neural network and also newff.</p>
<p>In my scenario I need to predict 90 points ahead. First how I separated my input and target data manually:
For Example:</p>
<pre><code>data_i... | g24926 | [
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0.014375374652445316,
0.03747910261154175,
0.005029168911278248,
0.01107... |
<p>I have done a live cell imaging time course over 24 hours, and have a result for each hour. I have 3 experimental groups and 1 control group. What I want to know is if any of the experimental groups are significantly different from the control group, and if so, at what time does this first occur? I have 3 experiment... | g66064 | [
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... |
<p>I'm working on fitting an exponential model </p>
<p>$\mathrm{Flux} = A+Bt+F\left(\exp(t_0-t/T_r) + \exp(t-t_0/T_f)\right)^{-1}+...$</p>
<p>to astronomical data (a light curve).
$A$, $B$, $F$, $t_0$, $T_r$, and $T_f$ are all free parameters in the model. </p>
<p>I am trying to determine if a two-peak, three-peak,... | g24927 | [
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0.026315974071621895,
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... |
<p>I am researching how people watch video lectures together. I have two conditions as follows:</p>
<p>(1) 3 groups of 4 learners watch one video lecture on a shared display, but there is only one control (to pause for jump in video)</p>
<p>(2) 3 groups of 4 learners watch one video lecture separately on individual d... | g35394 | [
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0.1... |
<p>Suppose I am using two Markov Chain Models, one with order $k=1$ and a second one with order $k=2$. I am "reducing" the higher order model to a $k=1$ model in order to have easier calculation possibilities.</p>
<p>I train each model on the same data and also calculate the log likelihoods on the same data. Now I wan... | g46732 | [
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<p>There are 1100 data points split into about 35 discrete groups and distributed towards the left. After running a logistic regression which failed, then running it again by only predicting based on subsets of the data which worked, it seemed likely that there is a nonlinear relationship.</p>
<p>I am trying to deter... | g66065 | [
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0.00... |
<p>I have a model:</p>
<p>$$
\mathbf{y} = \mu\mathbf{1}_n + \mathbf{X}\boldsymbol{\beta} + \boldsymbol{\epsilon}
$$</p>
<p>where $\boldsymbol{\epsilon} \sim N(\mathbf{0},\sigma^2\mathbf{I}_n)$.</p>
<p>I have a joint prior:
$$
\pi(\boldsymbol{\beta}, \sigma^2, \mu) = \pi(\mu) \pi(\sigma^2) \prod\limits_{j=1}^{p}\frac... | g46734 | [
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<p>To find a Hotelling $T^2$ score it is necessary to calculate the covariance matrix and then invert it.</p>
<p>Now, when the test is a two-sample $T^2$ test, the covariance matrix is a pooled matrix. When there is a high degree of correlation / collinearity in the variables the covariance could be close to a singula... | g24930 | [
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0.004040703643113375,
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<p>I'm working in R, using glm.nb (of the MASS package) to model count data with a negative binomial regression model. I'd like to compare the relative importance of each of my predictor variables regarding their impact on the response variable (note: the predictors each have quite different scales - sometimes by orde... | g24931 | [
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0... |
<p>I am currently using the <code>glmnet</code> package in R along with its' cross validation function <code>cv.glmnet</code>. As a reminder, <code>cv.glmnet</code> is an additional function that can be used to automatically run cross-validation on the regularization parameter, <code>lambda</code>. </p>
<p><code>cv.gl... | g66066 | [
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0.07050321251153946,
0.0018095612758770585,
... |
<p>What are best and / or standard practices for MCMC early stopping?</p>
<p>I have an algorithm which I want to compare with existing non-MCMC algorithms for accuracy and speed. When assessing the speed it's a bit tricky, since the speed is a function of the number of iterations I use in the Markov chain, and curren... | g66067 | [
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0.021509233862161636,
0.04362732172012329,
0.009837125428020954,
0.03691812977194786,
0.0469... |
<p>Could someone recommend a link or help me out here: where can I find the formula for the regression without an intercept, and how is it deriveed differently than the formula with the intercept? (matrix form)</p> | g66068 | [
0.0349922776222229,
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/45807/what-are-the-chances-my-wife-has-lupus">What are the chances my wife has lupus?</a> </p>
</blockquote>
<p>A day or two ago a man posted a question on math.stackexchenge about whether his wife likely ... | g49374 | [
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... |
<p>I have read/heard many times that the sample size of at least 30 units is considered as "large sample" (normality assumptions of means usually approximately holds due to the CLT, ...). Therefore, in my experiments, I usually generate samples of 30 units. Can you please give me some reference which should be cited w... | g66069 | [
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... |
<ul>
<li>If you look at <a href="http://www.wolframalpha.com/input/?i=world+population">Wolfram Alpha</a></li>
</ul>
<p><img src="http://i.stack.imgur.com/x0ILQ.png" alt="alt text"></p>
<ul>
<li>Or this Wikipedia page <a href="http://en.wikipedia.org/wiki/List_of_countries_by_median_age">List of countries by median a... | g66070 | [
0.013796370476484299,
0.02767602913081646,
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0.04799270257353783,
0.0015239139320328832,
0.055988192558288574,
0... |
<p>I know that priors need not be proper and that the likelihood function does not integrate to 1 either. But does the posterior need to be a proper distribution? What are the implications if it is/is not?</p> | g66071 | [
0.046813495457172394,
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0.0011623699683696032,
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<p>Logistic regression models the log odds. That is for rv $Y$ which is binary </p>
<p>logit$(Y=1)=X\beta$. </p>
<p>Then with this model, you can estimate the class probabilities and hence prediction or classification is immediate. Ordinal regression does a similar thing with cumulative logits with which the class pr... | g66072 | [
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-0.06275670230388641,
0.021214881911873817,
0.04710693657398224,
0.06036871671676636,
-... |
<p>Why is the negbin distribution required when the analyzed count data is bounded? I don't really understand the following:</p>
<blockquote>
<p>"The Poisson distribution can form the
basis for some analyses of count data
and in this case Poisson regression
may be used. This is a special case of
the class of... | g66073 | [
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<p>Consider two datasets, a study dataset with $n$ points and a control dataset with $n_c$ points, with $n$
<p>I would like to evaluate the hypothesis that the study dataset has a different Y (in average or distribution) than that of the control dataset, after controlling for all independent variables $X_1$, $X_2$, $X... | g66074 | [
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0.015361852943897247,
0.013848758302628994,
-0.01151026040315628,
-0.018254345282912254,
0.018481222912669182,
0.025403011590242386,
0.031988464295864105,
... |
<p>I'm going to school to be an actuary and I am just now starting to learn the basics of different statistical software packages. I have used both STATA and R, and I'm not sure which I like better. If there are any actuaries out there reading this what do you prefer? I currently use STATA for my econometrics class, an... | g66075 | [
0.0662546306848526,
-0.047862034291028976,
0.02828141115605831,
0.02512010931968689,
-0.00039466898306272924,
0.0021634206641465425,
0.049589235335588455,
-0.026457641273736954,
-0.0024609190877527,
-0.023743193596601486,
0.07606486231088638,
0.03367423638701439,
0.018249845132231712,
-0.0... |
<p>I am trying to develop a <a href="http://en.wikiversity.org/wiki/Composite_scores" rel="nofollow">regression-weighted composite score</a>. I have 4 variables a, b, c, d that are not necessarily linearly related that I would like to transform to A, B, C, D such that I can combine linearly by regression weights. So I ... | g66076 | [
0.04654916375875473,
-0.014054933562874794,
-0.037234507501125336,
-0.08343225717544556,
0.014979815110564232,
-0.02072637341916561,
0.03578448295593262,
0.016146624460816383,
-0.028530219569802284,
-0.052365388721227646,
-0.0312366783618927,
-0.020181650295853615,
0.02937179058790207,
-0.... |
<p>The patients with depression had a significant improvement in their severtity of disease after 8 weeks antidepressant treatment and I found the serum BDNF levels of the patients with depression after 8 weeks antidepressant treatment were lower compared to those in baseline. </p>
<p>This study is a uncontrolled obs... | g24938 | [
-0.0028498503379523754,
-0.010150144807994366,
0.0064935507252812386,
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0.019425638020038605,
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0.03281587362289429,
0.01795484870672226,
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-0.04149346053600311,
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0.06128346920013428,
0.018151139840483665,
0... |
<p>Suppose you are trying to estimate the joint density $p(x,y)$ based on observed $(X,Y)$. However, you know that the marginal density $p(x)$ is uniform. How can you use this information to improve your density estimate?</p> | g37972 | [
0.038767021149396896,
-0.03995689004659653,
-0.006144517567008734,
-0.0642356127500534,
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0.01738041453063488,
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0.015199813060462475,
0.044917646795511246,
0.009492817334830761,
0.0489957258105278,
0.01... |
<p>I have a set of date covering petrol prices.</p>
<p>My example has two columns where each row represents a sequential date.</p>
<pre><code> unleaded diesel
1 1.39 1.35
2 1.3901 1.3502
3 1.3902 1.3501
.....
</code></pre>
<p>I generate eigen values:</p>
<blockquote>
<p>my.eigen
$values
[1] 7.... | g24940 | [
0.013130788691341877,
-0.04980771243572235,
-0.01906917430460453,
-0.06867477297782898,
0.012607043609023094,
-0.0434439517557621,
0.01361533347517252,
-0.017855271697044373,
-0.07720999419689178,
-0.00951768271625042,
0.027433818206191063,
0.006921681575477123,
0.05015508458018303,
0.0370... |
<p>I would like to compare before-and-after "scores" on five quality of life questions across two groups. What I would like to know are:</p>
<ol>
<li>Are the baseline scores across the two groups similar?</li>
<li>Is the change in scores significant (before and after) within each group?</li>
<li>Is the change in score... | g66077 | [
-0.0013427439844235778,
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0.0024876720272004604,
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-0.04470747709274292,
0.02556299790740013,
0.0015265301335602999,
-0.008871497586369514,
-0.032644059509038925... |
<p>I know for PCA, it's true that the first N eigenvectors have N greatest variance.</p>
<p>But I'm not sure whether that's also true for NMF(Non-negative Matrix Factorization). For example, this method(Standard Nonnegative Matrix Factorization (NMF) [Lee2001], [Lee1999].): <a href="http://nimfa.biolab.si/nimfa.method... | g66078 | [
0.031076302751898766,
0.015906106680631638,
0.026967762038111687,
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0.05108879506587982,
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0.021875770762562752,
0.006481511518359184,
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-0.03542438521981239,
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0.... |
<p>I have two time series showing very high dependency, in the order of 99.99% correlation, and I need to study their lead-lag relationship. So far I've been looking at the Pearson correlation with 7/8 decimals precision, but I wonder if there is a better approach. The problem is that most of the time the series value ... | g24942 | [
0.042430419474840164,
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-0.008579702116549015,
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0.008382203988730907,
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0.031917065382003784,
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0.00309545686468482,
-0.0049828458577394485,
0.03502720966935158,
0.03327358514070511,
0.019717998802661896,
-... |
<p>I use the generalized form of the Student's-t distribution:
\begin{align*}
f(l|\nu ,\mu ,\beta) = \frac{\Gamma (\frac{\nu+1}{2})}{\Gamma (\frac{\nu}{2}) \sqrt{\pi \nu} \beta} \left(1+\frac{1}{\nu}\left(\frac{l - \mu}{\beta}\right)^2 \right)^{\text{$-\frac{1+\nu}{2}$}}
\end{align*}</p>
<p>I want to have standardized... | g45153 | [
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0.026025915518403053,
0.05467400699853897,
-0... |
<p>I have data from an infection study that I did and I'm trying to figure out if the differences I have observed are significant or not. </p>
<p>I have infections with 4 different bacterial strains, with 10 mice infected per strain (40 mice total). Then a colleague blindly scores the inflammation induced by the bact... | g66079 | [
-0.025485018268227577,
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0.008310399018228054,
0.04329044744372368,
-0.00048262104974128306,
... |
<p>I'm using the Spearman correlation coefficient test for multiple non-parametric ranked categories in excel. I used the built in rank function in excel to calculate the rank of each individuals but i have many ties because there are 10 to 208 categories for 2k instances. In the variable with 10 categories excel ranks... | g24944 | [
0.008635828271508217,
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0.03904278948903084,
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0.03658471256494522,
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<p>The Encyclopedia of survey research indicates that super-population is similar to what may be termed as infinite population. However, in a meta-analysis of effect-sizes, we use outcomes of sample studies that seem to originate from the specific target populations i.e, we may treat the study outcomes from a single sp... | g66080 | [
-0.024319471791386604,
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0.05611570179462433,
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0.006790696177631617,
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0.027568833902478218,
-0.0... |
<p>I developed a measure of "sentiment" and I have time based data and used the measure to derive a daily sentiment time series. I am looking for some way to establish reliability or maybe stability. For example, when there are dramatic changes in the "sentiment" is this "real". Two ideas for doing this numerically sta... | g24945 | [
-0.01300542987883091,
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0.0006163079524412751,
0.017544077709317207,
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0.04334896057844162,
... |
<p>I am doing a case-control study with 80 disease cases matched 1:3 to non-diseased controls and examining whether they had a binary exposure prior to developing the disease. I am using multivariable conditional logistic regression for the main analysis. My question is, for the "descriptive" or "univariate" table wher... | g66081 | [
0.05223210155963898,
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0.01615307107567787,
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0.024486903101205826,
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0.03423212468624115,
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0.04811302572488785,
0.024171266704797745,
0.06150156259536743,
0.0... |
<p>As I say in the subject, How can I put the model
$d x_t = \eta\, (\overline{x} - x_t)\,d t + \sigma\, x_t\,d W_t$ into state space form? I mean, which are the observation and transition matrices?</p> | g66082 | [
-0.06861124187707901,
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0.05930982902646065,
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0.04122273251414299,
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0.06784713268280029,
... |
<p>I know that
$$\hat{\beta_0}=\bar{y}-\hat{\beta_1}\bar{x}$$
and this is how far I got when I calculated the variance:</p>
<p>\begin{align*}
Var(\hat{\beta_0}) &= Var(\bar{y} - \hat{\beta_1}\bar{x}) \\
&= Var((-\bar{x})\hat{\beta_1}+\bar{y}) \\
&= Var((-\bar{x})\hat{\beta_1})+Var(\bar{y}) \\
&= (-\bar... | g66083 | [
-0.03730404004454613,
0.042181551456451416,
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0.07666536420583725,
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0.11618785560131073,
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0... |
<p>I hope you are very well. I have a big dataset (~9 million registries) and I have 2 variables $X$=purchase amount and $Y$=frequency of purchase. I would like to know what distribution should I use for each variable and fitting its distribution with <code>R</code>. For example, for $X$ I'm testing with package 'mixto... | g66084 | [
0.008475521579384804,
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0.0008400036604143679,
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0.00013348371430765837,
0.010922638699412346,
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0.021419089287519455,
... |
<p>I have some data which I want to use for interpolation and extrapolation. I would (very much) prefer a function that I can plug values in instead of using cubic splines or some such technique so I resorted to least squares fitting. Here are some plots with explanation interspersed.</p>
<p><img src="http://i.stack.i... | g66085 | [
0.027329687029123306,
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0.0013851479161530733,
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0.008180576376616955,
0.06144703924655914,
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-0.02516564168035984,
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0.06326215714216232,
0.013... |
<p>I am computing the sample correlation between two vectors of uncorrelated and uniformly distributed samples using MATLAB. More precisely, I compute
$$
r_N=\frac{1}{N}\sum_{i=1}^N x_{i}\, y_{i},
$$
where $E(X)=E(Y)={\rm cov}(X,Y)=0$, and $x_{i}, y_{i}$ are drawn from a uniform distribution in $[-A/2,A/2]$.
It is cl... | g66086 | [
0.031823962926864624,
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0.04581623524427414,
0.03494676202535629,
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-0.024240562692284584,
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0.013032359071075916,
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... |
<p>I'm working on an online category learning model which uses stochastic gradient descent to fit a gaussian mixture model. The model is based on the online learning model used in Toscano & McMurray (2010).</p>
<p>While gradient descent seems to be working fairly well to estimate the means and frequencies/mixing p... | g66087 | [
-0.02986777201294899,
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0.02626621164381504,
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0.06068677082657814,
0.065811887383461,
0.04412592574954033,
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0.021198004484176636,
0.020108576864004135,
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0.04271463677287102,
0.04051926... |
<p>I have a question on calculating the threshold value or value at which the quadratic relationship turns. The formula for calculating the turn is at $x = -b/2a$, following from $ax^{2}+bx+c$.</p>
<p>My question is this: when using the mean centered quadratic terms, do you add the mean value back to calculate the thr... | g66088 | [
0.037059783935546875,
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0.019864540547132492,
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0.07322731614112854,
0.053176697343587875,
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<p>I have a dataset of gene-phenotype association in this <a href="http://pastebin.com/nkEmGsFv" rel="nofollow">format</a>.
I am looking at some combination of phenotypes and genes shared between combination.
I would like to use a statistical test to show that the genes shared between two phenotypes are statistically... | g45168 | [
0.027722546830773354,
0.028521521016955376,
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0.005351155996322632,
0.001205753767862916,
0.020410671830177307,
0... |
<p>I am sorry for a more basic question, but I was unable to find any good sources on google.
How is a bifactor IRT model different from a factor analysis?</p>
<p>How would you describe their key differences?</p>
<p>Any references you could direct me to would be very helpful.</p>
<p>Thank you for sharing your knowle... | g66089 | [
0.025152752175927162,
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0.003058402566239238,
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0.04888652637600899,
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0.052797187119722366,
0.027055557817220688,
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0.04533293470740318,
0.060336388647556305,
-0.... |
<p>Let $X_1,X_2,...,X_n$ be $n$ iid random variables following some distribution family $A$ (beta, gamma, normal, etc.).</p>
<p>Does the mean $\bar{X}=\frac{1}{n}\sum{X_i}$ also follow a $A$-like distribution (with different parameters)?</p>
<p>I know it is approximately normal due to the Central Limit Theorem, but d... | g10374 | [
-0.0124688521027565,
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0.01842895895242691,
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0.021980078890919685,
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0.... |
<p>Attempting to replicate the results from the recently published article,</p>
<blockquote>
<p>Aghion, Philippe, John Van Reenen, and Luigi Zingales. 2013. "Innovation and Institutional Ownership." American Economic Review, 103(1): 277-304.</p>
</blockquote>
<p>(Data and stata code is available at <a href="http://... | g24953 | [
0.027612170204520226,
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0.0015808396274223924,
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0.002192521234974265,
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0.015869826078414917,
0.026426980271935463,
-0... |
<p>Some colleagues are using 'normalized' K-L divergence to measure deviation of unit-area histogram (pseudo discrete pdf) from corresponding uniform distribution ($N$ equal-length bins). Maybe it is better to use true metric like sqrt of J-S?</p> | g24954 | [
0.024794718250632286,
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0.02652878314256668,
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0.05754662677645683,
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<p>t-test for testing whether the mean of a normally distributed sample equals a constant is said to be a Wald test, by estimating the standard deviation of the sample mean by the fisher's information of the normal distribution at the sample mean. But the test statistic in the t test has a student t distribution, while... | g66090 | [
0.014865468256175518,
0.0024125403724610806,
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0.03724638745188713,
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0.02192334271967411,
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<p>We're trying to model two time series: a random walk (independent variable) vs. the sum of this random walk and a mean-reverting process. For example: coffee bean 100kg prices (EU) vs. coffee bean 100kg prices (US). The difference between these two can be seen as costs in the transportation process, seen as the mean... | g66091 | [
0.0015826100716367364,
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0.033094536513090134,
0.010875881649553776,
0.06295518577098846,
0.06731708347797394,
-... |
<p>This is probably a blindingly obvious answer for any seasoned statistician, but I am still confused as to how correlation differs to regression, technically.</p>
<p>I understand that one is a measure of association and one a measure of causation, but how can you actually measure causation mathematically, without ac... | g66092 | [
0.08365067839622498,
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0.009175200946629047,
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0.03525889292359352,
0.06775753945112228,
0.03599310666322708,
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0.0028217134531587362,
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0.05733140930533409,
0.0... |
<p>Mboxcox in Stata suggests transforming my variables using a power of 0.1 for the independent variable, and 0.4 for the dependent variable.</p>
<p>I have run the model, and it fixes problems associated with the assumptions of OLS. But certainly, it complicates matters in terms of interpretations.</p>
<p>Please outl... | g24961 | [
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0.03657187148928642,
0.051064226776361465,
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<p>I am using <a href="http://lavaan.ugent.be/" rel="nofollow">R lavaan package</a> to estimate a structural equation model. Let's say the model consists of 1 endogenous manifest variable with 1 latent and 2 manifest explanatory variables: </p>
<pre><code>group = {0,1}
attitude1 = latent,scale
age = respondent's age
<... | g24963 | [
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0.016973940655589104,
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-0.05461447313427925,
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0.01525022927671671,
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... |
<p>I fitted a one-parameter gamma shared frailty model with Weibull and exponential baseline hazards for recurrent event data (the dataset contained 80 subjects of which 16 patients had events (13 subjects with just one event, 2 subjects with 2 events and one subject with 3 events)) and I found:</p>
<ol>
<li><p>The W... | g66093 | [
0.003516433062031865,
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-0.017821313813328743,
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0.04208134859800339,
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-0.006058611907064915,
-0.00961988139897585,
0.02964141219854355,
0.050815291702747345,
0.0... |
<p>I've got more than 20 (10 point likert scale) variables with more than 1000 entries each. What I want to do is compare the means of the answers on the questions.</p>
<p>A one-way anova seems suitable for this, but you can only categorize by the values of a variabele. I want to categorize by question, the variable i... | g37902 | [
-0.012849440798163414,
-0.013947837054729462,
-0.00935224536806345,
-0.036180246621370316,
0.05632428079843521,
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-0.004765427205711603,
-0.02204921841621399,
0.026190314441919327,
0.007165249437093735,
... |
<p>I was recently exposed to some statistical hypothesis testing methods (e.g. Friedman test) at work, and I would like to increase my knowledge on the topic.</p>
<p>Can you suggest a good introduction to statistical significance / statistical hypothesis testing for a computer scientist? </p>
<p>I am thinking of a PD... | g24966 | [
0.08374153077602386,
0.037947215139865875,
0.011989112943410873,
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0.014404023066163063,
0.048477642238140106,
0.010809939354658127,
0.08264464884996414,
0.0... |
<p>I have 2 genes (tf1 and tf2), which are affecting a third gene (tg). By affecting a gene I mean the changes in the value of tf1 and tf2 changes the value of tg. what we measure in the whole experiment is this value. We want to see if the values of tf1 and tf2 are dependent (which means they are regulating each other... | g66094 | [
-0.0013208482414484024,
0.007653659209609032,
-0.005953236483037472,
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0.0018229542765766382,
0.0177779421210289,
0.02999795414507389,
0.013057706877589226,
0... |
<p>I'm analyzing a set of news articles and user libraries. User library is the set of news articles shared by one user. Obviously, the rating is 1 (the article is in user's library) and 0, otherwise. I hypothetically present every user with M articles sorted by their predicted rating and evaluate based on which of the... | g11021 | [
-0.04272446408867836,
0.028408849611878395,
-0.016092339530587196,
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0.03903794288635254,
-0.008693549782037735,
0.04986419156193733,
-... |
<p>I need to fit a GLS model, with some known regressors, and where the errors follow an <strong>unknown</strong> ${\rm ARIMA}(1,0,1) \times (1,N,1)$ model. It seems like the main tool out there for such models is the <code>gls</code> function in the <code>nlme</code> package for <code>R</code>. </p>
<p>In <code>gls</... | g47303 | [
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0.02150837704539299,
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0.... |
<p>In a linear model (regular OLS regression) I am exploring various models of a continuous dependent variable.</p>
<p>When adding some variables, the Akaike Information Criterion (AIC) improves (sometimes dramatically) even though the variable is not close to significant (e.g. p = .49 or even higher).</p>
<p>One rea... | g66095 | [
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0.01289921160787344,
-0.010686608962714672,
0.07027444243431091,
... |
<p>I was wondering if anyone could enlighten me on the current differences between these two functions. I found the following question: <a href="http://stats.stackexchange.com/questions/5344/how-to-choose-nlme-or-lme4-r-library-for-mixed-effects-models">How to choose nlme or lme4 R library for mixed effects models?</a>... | g24970 | [
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0.026803957298398018,
-0.008802838623523712,
0.02207605168223381,
0.0... |
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