question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>In Honglak Lee's definition of a Probabilistic Max Pooling Convolutional RBM, the probabilities are formulated as: </p>
<p>$$
P(h_{i,j}|v) = \frac{exp(I(h_{i,j}))}{1 + \sum\limits_{(i',j')\in B_\alpha}{exp(I(h_{i',j'}))}} \\
P(p_{\alpha}|v) = \frac{1}{1 + \sum\limits_{(i',j')\in B_\alpha}{exp(I(h_{i',j'}))}}
$$</p>... | 29,983 |
<p>I have some variables that I would like to run regressions on, to create a model, but I am unsure about how to actually AIC (or the BIC). Unfortunately I have not yet taken a mathematical statistics course, so if someone could direct me to a nontechnical resource, or a resource that can explain how to use the method... | 69,495 |
<p>Suppose I have a large data set with lots of features(attributes). And I'm tasked to build some kind of scoring model to rank certain objects with all these features.
How do I go about doing this?</p>
<p>From my understanding so far, I like to think of this as a supervised learning problem. But the problem is there... | 69,496 |
<p>I'm trying to compute the variance of an average of forecasts. But I'm not sure on how to get the covariances required to compute the variances.</p>
<p>Here is the situation:</p>
<p>Three ARMA(p,q) models for a variable are estimated and using each model forecasts for 12 months ahead are produced. In all three mod... | 69,497 |
<p>I am using the <code>penalized</code> package in r for fitting a Cox model with a lasso penalty. </p>
<p>Does the Cox model + lasso need to test proportionality?</p>
<p>How do you get the p-value for the nonzero coefficients in the model?</p>
<p>Thanks for any response.</p> | 69,498 |
<p>I have been working on fitting Cox model for prediction by using the <a href="http://cran.r-project.org/web/packages/rms/index.html" rel="nofollow">rms</a> package. I want to measure model calibration and discrimination.
Discrimination was measured by using <code>rms::validate()</code>; <code>Dxy</code> can be trans... | 69,499 |
<p>I am attending a data analysis class and some of my well-rooted ideas are being shaken. Namely, the idea that the error (epsilon), as well as any other sort of variance, applies only (so I thought) to a group (a sample or whole population). Now, we're being taught that one of the regression assumptions is that the v... | 40,214 |
<p>I am an economics student just starting out with R, and while I'm beginning to be somewhat comfortable with it, I also realize I need to strongly brush up my basic statistics. </p>
<p>I have individual level admin data (in the form of a rotating panel) documenting a reform which was implemented as a pilot project i... | 29,996 |
<p>I understand two-tailed hypothesis testing. You have $H_0 : \theta = \theta_0$ (vs. $H_1 = \neg H_0 : \theta \ne \theta_0$). The $p$-value is the probability that $\theta$ generates data at least as extreme as what was observed.</p>
<p>I don't understand one-tailed hypothesis testing. Here, $H_0 : \theta\le\theta_0... | 46,720 |
<p><a href="http://books.google.com/books?id=tVIjmNS3Ob8C&lpg=PA116&ots=ELDeO7K3V2&dq=elements%20of%20statistical%20learning%20sphering&pg=PA113#v=onepage&q&f=false" rel="nofollow">The Elements of Statistical Learning</a> says on page 113:</p>
<blockquote>
<p>Sphere the data with respect to t... | 29,997 |
<p>Given a random number generator to produce random variables with a probability density function $f(x)$, how to generate random variables with probability density function $g(x)?$</p> | 69,500 |
<p>Just moments ago, I asked this <a href="http://stats.stackexchange.com/questions/26329/what-is-a-unit-information-prior">question</a> because I've been reading Wagenmakers <a href="http://www.brainlife.org/reprint/2007/Wagenmakers_EJ071000.pdf" rel="nofollow">2007</a>. I now have a better understanding of what a uni... | 30,001 |
<p>I want to simulate a binary response variable which depends on two normally distributed continuous variables, and I want to have more 1s than 0s in the response variable. I wonder how this can be done such that a logistic regression will not identify a significant interaction term.</p>
<p>My current approach in R l... | 49,831 |
<ol>
<li>what is the clear model for truncated negative binomial regression model with brief explanation about the parameters?</li>
<li>what is the clear difference between truncated negative binomial regression model and zero-truncated negative binomial regression model?</li>
</ol> | 69,501 |
<p>I was sent here from Stackoverflow because this is more a statistics question. I hope I am in the right place now!</p>
<p>The summary command of a plm regression with the (factor="twoways") argument reports the same coefficients as a plm regression with manual time dummies (and the default factor="individual") but ... | 30,005 |
<p>I need to do a backward elimination on my glmer model, but I have no idea to do that ?</p>
<p>It seem that a lot of thing do no work with glmer ...</p>
<p>thank you </p> | 69,502 |
<p>I am xyz organization. I have recruit entry level engineers from 100 colleges. I have their performance, attrition & promotion data for last 3 yrs. I have 4 parameters performance, promotion, attrition and volume intake. I want to rank these colleges based on the above parameters using any statistical model or ... | 69,503 |
<p>I'm working with a dataset that has accelerometer (tri axis) readings, magnetometer (also tri axis) readings, readings for colour etc. All the values are numerical. This data was collected by wearable camera technology.</p>
<p>I am trying to find repeating patterns in this data, but I'm new to data mining and not s... | 69,504 |
<p>Given a testing set of nodes which can be either +,-, or 0,
I use an incomplete classifier which allows me to predict if a node is +, -, 0, not +, not -, or not 0, and sometimes it cannot predict anything.</p>
<p>How are precision, recall, and accuracy defined for such a classifier?</p> | 30,008 |
<p>I have a question about outlier detection in my system. I’m designing a system (in Matlab) that optimize both features and parameters of a classification method (like mlp) together with optimization algorithms. My input data are financial statement and some these statements have strange and unusual values. (For exam... | 69,505 |
<p>I’m designing a system (using Matlab) that I can optimize parameters of a support vector machine (SVM) with genetic algorithm, harmony search and another optimization algorithms to find the best structure of SVM for a specific data. My problem is binary classification with 0 and 1 output and I normalize data (mapmax... | 30,009 |
<p>I am intending to explain the variation in dependent variable Y through a number of ratios that, combined, sum to 1 in each period <code>t</code></p>
<p>Hence,
$$
Y_t = \alpha + \beta_i^I * X_t + \epsilon_t
$$
Where $X_t$ is a vector of ratios that sum to 1 (say 1/3, 1/6 and 3/6 in t = 1) and $\beta_i^I$ a vector ... | 69,506 |
<p>I'm particularly interested in plotting residuals against fitted values, and residuals against predictors. Often times I need to make boxplots of the residuals conditional on predictors.</p>
<p>I'd be interested in functions that include other/multiple diagnostics as well, e.g. ceres plots, qqplots.</p>
<p>The ca... | 30,013 |
<p>It seems to me that rather than using non robust
estimation methods with robust standard errors it would be better to use
robust estimation from the outset. I wonder what other people think.</p> | 69,507 |
<p>Let us assume we have two parameters, $p_1$ and $p_2$. We also have two maximum likelihood estimators $\hat{p_1}$ and $\hat{p_2}$ and two confidence intervals for these parameters. Is there a way to build a confidence interval for $p_1p_2$?</p> | 49,890 |
<p>I am new to time series modelling and I am trying to build a simple time series model using ARIMA methodology and forecast. I could write an R program to do the same, but I am more interested in writing my own <code>arima(1,1,0)</code> and <code>predict()</code> functions that R provides in Java / C++ / Python. Whi... | 40,235 |
<p>I am trying to replicate and hopefully improve on an analysis done in a study to find determinants of patient satisfaction after shoulder surgery. Satisfaction is heavily skewed (with over 60% of patients responding 10) The original study ran a multiple linear regression on satisfaction with a handful of predictor... | 69,508 |
<p>I am assessing the benefit of using a therapeutic intervention in a population of 80 people split evenly into two groups. The benefit is to decrease a certain complication which only has a incidence rate of 5-10%. How can I prove non-inferiority? Which statistical test is best an and how can I calculate the sample s... | 40,237 |
<p>I have calculated a z test to examine the difference between two proportions. I found differences to be significant. The formula I used was:</p>
<p>$$z = (p_1-p_2)/SE$$
where
$$SE = \sqrt{ p ( 1 - p ) ( \frac{1}{n_1} + \frac{1}{n_2} ) }$$</p>
<p>and $n_1$ is the sample size of sample 1, $n_2$ sample size of sam... | 69,509 |
<p>I understand that the probability density function, pdf, of a continuous random variable is the probability of the variable taking on a given value. I am also thought that for a continuous random variable, the probability of it taking a specific value is always 0 i.e. P(X=x) = 0.</p>
<p>Therefore, in R, I am wonder... | 69,510 |
<p>I'm new to survival analysis, but I've been reading some papers and books and I got a nice model. </p>
<p>However, one of the variables (Sit) does not met the proportionality assumption for the Cox model. Nevertheless, this got me thinking and it makes sense, since that variable should have a time-varying effect. F... | 30,029 |
<p>Take these two vectors:</p>
<pre><code>points <- c(44, 36, 33, 33, 29, 28, 28, 22, 21, 20, 18, 15, 15, 15, 12, 12, 12, 11, 10, 10, 8, 8, 8, 8, 7, 7, 7, 6, 6, 6, 6, 6, 5, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1)
hours <- c(137.000000, 58.450000, 92.250000, 94.750000, 80.00000... | 29,241 |
<p>I have a variable that has 57 kurtosis, so I decided to transform it to log. However, I have multicolleanirity problem due to interacting this variable and others with another variable so I am using z scores to reduce VIF value.
So ... </p>
<blockquote>
<blockquote>
<p>Is it ok to transform the log variable t... | 49,517 |
<p>HW question I am having trouble on:</p>
<p><img src="http://i.stack.imgur.com/qY8nh.jpg" alt="enter image description here"></p>
<p>My attempt at solving it:</p>
<p><img src="http://i.stack.imgur.com/uh9zh.jpg" alt="enter image description here"></p>
<p>I thought part (a) was pretty straight forward until I work... | 69,511 |
<p>I have been thinking about how to use regression to prove whether X factor is a necessary or a sufficient condition for Y. I am employing these terms in the traditionally logical sense, i.e.</p>
<ul>
<li>If no X, then no Y --> X is necessary for Y</li>
<li>If X, then Y --> X is sufficient for Y</li>
</ul>
<p>The r... | 49,531 |
<p>I am in the basic level of statistic...</p>
<p>I have some trouble in how to do SPSS for this statistic question.</p>
<p>So my topic is if music with or without lyric would make a impact on reading comprehension task. I have two same music but with and without lyric. And also I have two reading (A & B) compreh... | 69,512 |
<p>I'm currently just learning about Maximum likelihood estimators and I'm a bit stuck on how I should answer this question.</p>
<p><img src="http://i.imgur.com/lzlS1Xu.png" alt="a busy cat"></p>
<p>So far I know that for the function to hold, the observation 4 should be <= 2*theta. and that theta>=2 as a result r... | 69,513 |
<p>I have some data which i am trying to work on. I am pretty new to R though, but i love R. First, I fit an <code>arima</code> model to this data and used the <code>detectIO</code> function in R to detect a single influential outlier (IO). I then incorporated this IO into my model and then developed an <code>arimax</c... | 41,897 |
<p>I understand that the $p$-value is the conditional probability of observing the test statistic or something more extreme given that the null hypothesis is true. I have read the great explanation by @user28 in this post: <a href="http://stats.stackexchange.com/questions/31/what-is-the-meaning-of-p-values-and-t-values... | 30,034 |
<p>A number of sources suggest that there are many negative consequences of the discretization (categorization) of continuous variables prior to statistical analysis (sample of references [1]-[4] below).</p>
<p> Conversely [5] suggests that some machine learning techniques are known to produce better results when cont... | 864 |
<p>I have two sets of data and need to compare mean times for a variety of situations (i.e. time of day, day of the week, different areas, etc...). Some of the situations have small samples sizes (n=8) and need to be compared against a larger sample size (n=260). Neither data set is normally distributed (both are usual... | 69,514 |
<p>I have data in the form given below, and I want to perform forecasting using multiple regression. I found definition of multiple regression from this link: <a href="http://otexts.com/fpp/5/1/" rel="nofollow">http://otexts.com/fpp/5/1/</a> . I have these questions: <strong>(1)</strong> Can we forecast value of Y (the... | 50 |
<p>I have two variables representing 1) players' predicted fantasy football points and 2) players' actual fantasy football points scored. What statistics are best for assessing the accuracy of the predictions in terms of absolute agreement (not just relative rank-order accuracy) in relation to the actual values? I'd ... | 40,252 |
<p>I'm calculating a factor analysis of several variables in R. I want to determine each case's value on the latent variable. When I run the factor analysis, I receive factor scores. The factor scores do not have the same metric as the raw data or the latent variable. How can I rescale the factor scores to correspond t... | 30,040 |
<p>I have following type of <strong>associated</strong> data. The following example step to generate associated variable. <strong>p</strong> number of variables and <strong>n</strong> is number of observations. </p>
<pre><code>p = 500
n = 200
mat <- matrix(NA, ncol = 500, nrow = 200)
for (i in 1:p){
if(i ==1){
... | 11,168 |
<p>I'm trying to compute the marginal likelihood for a statistical model by Monte Carlo methods:</p>
<p>$$f(x) = \int f(x\mid\theta) \pi(\theta)\, d\theta$$</p>
<p>The likelihood is well behaved - smooth, log-concave - but high-dimensional. I've tried importance sampling, but the results are wonky and depend highly o... | 30,042 |
<p>This question relates to situations where we apply some test to the same people at Time 1 and Time 2, and then calculate the correlation between scores at Time 1 and Time 2. </p>
<p>I am reading the book Principles & Applications of Assessment in Counseling, which states <a href="http://books.google.com.au/book... | 69,515 |
<p>I am a beginner in statistics and looking for suggestions from you all on the approach for one of my study.</p>
<p>For my study, there is a company which sells products via its online website (lets call it Desktop Website). They have recently launched a mobile app in addition to the desktop website. Both online web... | 69,516 |
<p>Put simply, I need to make a prediction interval (or confidence interval?) for the x value when y reaches a certain number given historical data for x versus y. </p>
<p>Long Version: I have data on the speed of computers in FLOPS from the 1950s up until 2012 and need to make a prediction interval for the predicted ... | 69,517 |
<p><a href="http://en.wikipedia.org/wiki/Scheff%C3%A9%27s_method" rel="nofollow">Scheffé's method</a>, when first written about by Henry Scheffé, was described as serving the purpose of identifying statistically significant contrasts in multiple-comparison's ANOVA problems.</p>
<p>But here in this forum I am told in a... | 69,518 |
<p>I understand the basics of confidence intervals, the central limit theorem, etc, to be able to know things like given N samples of random variable, we're 68/95/99.7 percent sure the variable is within these two values.</p>
<p>I'm wondering about how this generalizes to cases where we're trying to derive a relations... | 30,046 |
<p>Given a correlation between two sequences of numbers, I need to find to what point in one sequence the correlation is strongest. Here's why:</p>
<p>I'm tracking large numbers of pages in a knowledge base, and flagging certain pages for followup. For example, if a page is among the most frequently viewed but also ha... | 69,519 |
<p>If I have a number of statistics/information of a data set, e.g. mean, SD, skew, kurtosis, % data values within a certain range, etc, how might I go about trying to deduce a portion of the actual data. In my case, the data are not numbers, but rather subjects in a study, and therefore have more information (and thus... | 69,520 |
<p>I was wondering if there is an easy way to find sufficient conditions for the following inequality to hold</p>
<p>$$
\int f(x,y)^2 \:\mathrm{d}x \:\mathrm{d}y - \int f(x)^2 f(y)^2 \:\mathrm{d}x\:\mathrm{d}y \geq 0,
$$</p>
<p>where $f$ is the density function. Do you have any suggestions?</p> | 36,173 |
<p>I'm currently experimenting with quantile regression of a strongly right skewed outcome variable y on a 3-category exposure x (values 1,2,3). I wanted to model the .2, .5, and .8 quantile, using the interior point algorithm for estimation and bootstrapping (Markov chain marginal bootstrap method, n=1000) for confide... | 30,047 |
<p>I have two lines in a x-y plot:</p>
<ol>
<li><p>observed migration distance (y) and predicted migration distance (x)
$$Y=0.95X+0.31,$$ where 0.95 and 0.31 are the slope coefficient and the intercept (p-value = 0.001)</p></li>
<li><p>1:1 line (slope: 1 and intercept: 0)</p></li>
</ol>
<p>The null hypothesis is</... | 69,521 |
<p>I'm a student helping a professor with some research interviews done in QSR Nvivo.</p>
<p>Basically the interviews are coded in 4 outcome categories:</p>
<ol>
<li>solely positive</li>
<li>generally positive with a few considerations</li>
<li>generally positive with some considerations</li>
<li>generally negative <... | 30,049 |
<p>What is the difference between varimax rotation and direct oblimin in factor analysis? Also, I am confused the relationship among principal component analysis, varimax rotation and exploratory factor analysis in theory and SPSS? Are they have some connections? Thank you.</p> | 30,050 |
<p>Is there a statistical method to compare these density plots other than ANOVA (MANOVA)? I would like to compare the densities among year within each plot and report which of those distributions are "significantly different". The reason is that I am more interested in the spread and where on the distribution of the d... | 69,522 |
<p>I have two curves of quadratic regression models in a x-y plot</p>
<ol>
<li><p>$y=a_1\text{x}^2+b_1\text{x}+c_1$
$Y= -0.51\text{x}^2-0.88\text{x}+3.21$, $R^2: 0.12$, coefficient of the quadratic term: p-value = 0.001</p></li>
<li><p>$y=a_2\text{x}^2+b_2\text{x}+c_2$
$Y= -0.17\text{x}^2-0.13\text{x}+3.41$, $R^... | 30,053 |
<p>This <a href="https://akela.mendelu.cz/~xhavir3/ekm/Heij.pdf" rel="nofollow">book</a> states, on page page 256 ( the GMM section) that the J-test(for over-identifying restrictions) is of the following form $G_n'J_n^{-1}G_n \approx \chi^2(m-p) $, where $G_n=G_n(\theta)=1/n \cdot \sum^n_{i=1}g_i(\theta)$ which are the... | 29,317 |
<p>I am looking for a model to fit longitudinal data and opted for GLMM with a logit link.
I tried to add random effects but when both a random slope and random intercept are in the model, this does not converge.
Then I tried to include only one of them and both models converged but I am wondering if I can have a model... | 30,055 |
<p>I do not fully understand how to interpret the difference between two statistical models where they only differ based on whether a certain variable is included on the right hand side.</p>
<p>If the results do not change much, then do we say that that this omitted variable has little effect on the result?</p>
<p>I... | 40,266 |
<p>I am looking for a R command to test the difference of two linear regressoon betas. Lets say I have data $x_1, x_2...x_{n＋1}$.</p>
<p>$\beta_1$ is obtained from regressing $x_1$ to $x_n$ onto $1$ to $n$.</p>
<p>$\beta_2$ is obtained from regressing $x_2$ to $x_{n＋1}$ onto $1$ to $n$.</p>
<p>Is there a way in <cod... | 69,523 |
<p>I was trying to compare the volatilities of the stock market index of China and America. But I realized that a direct comparison of historical data would not be fair. The Chinese market has a rule that restricts changes in stock prices to be within $\pm$ 10% everyday. No such rule exists in the US.</p>
<p>I couldn'... | 69,524 |
<p>I am trying to learn more about how to build ensembles of predictions in R and coming to a roadblock, and am hoping one can offer guidance. </p>
<p>I often read about people automatically identifying how they should weight each model through the use of OLS. How do people do this? Do you just insert your prediction ... | 36,175 |
<p>I am conducting three-way ANOVA (A*B*C) with 2 levels each.<br>
1) I found A*B interaction.<br>
2) I moved to 2-way ANOVA (A*B) and found interaction again. I reported Eta-squared and equivalent Cohen's d.<br>
3) I moved to 1-way ANOVA (a1,a2,b1,b2) with mushed cells and bonferonni posthoc showed that b2 was lower t... | 69,525 |
<p>I have two timeseries, <code>y[t]</code> and <code>x[t]</code>. A domain expert tells me that <code>y[t]</code> should be a linear combination of past values of <code>x[t]</code> up to a certain horizon, i.e.</p>
<pre><code>y[t] = a[0]*x[t] + a[1]*x[t-1] + ... + a[n]*x[t-n]
</code></pre>
<p>How do I estimate the <... | 30,060 |
<p>Structural equation models (sem) are used to model latent variables. Renal function is a latent variable measured by serum creatinine levels (with measurement errors) expressed by many different clinical formulae derived from linear regression models. Inulin clearance is a gold standard for renal function. However, ... | 30,062 |
<p>So here's a question. lets say we have three datasets A, B, C, D(continuous, that take values within the data range [0, 5]) where C and D are actually the predicted values of A and B accordingly, taken from a model use. Both pairs (A and C, B and D) are significantly correlated and Spearman's Rho for pair (A,C) is 0... | 40,278 |
<p>I think trimean is the cat's meow. Is there a generalization of this idea to $n$-th order (central) moments?</p>
<p>Basically I live in a world where the pain of outliers vastly exceeds the pain of inefficiency. The <a href="http://archive.org/stream/atomicnucleus032805mbp#page/n925/mode/2up" rel="nofollow">refer... | 2,309 |
<p>I 'm looking to find a general formula for the following problem:</p>
<p>The events:</p>
<ul>
<li>Let each event have two possible outcomes (e.g. success and failure)</li>
<li>The events are independent</li>
</ul>
<p>Scenario: <br></p>
<ul>
<li>Let the number of trials be Y</li>
<li>Let the number of successes b... | 30,071 |
<p>I may be mixing up my time series and non time series concepts, but what is the difference between a regression model that exhibits serial correlation and a model that exhibits a unit root? </p>
<p>In addition, why is it that you can use a Durbin-Watson test to test for serial correlation, but must use a Dickey-Fu... | 69,526 |
<p>I can't seem to find this anywhere on the internet or in my books. I'm putting together a construct for an underlying variable.</p>
<p>Is it acceptable to have a construct with two variables if that produces a bigger Cronbach alpha than the construct with 3 variables in a professional statistical analysis?</p>
<p>... | 38,205 |
<p>I have a bit of a problem with the <a href="http://cran.r-project.org/web/packages/tm/index.html" rel="nofollow">tm</a> R package for cleaning text documents.</p>
<p>Here is how my code looks like:</p>
<pre><code>library("tm")
# import text files in corpus text – ok
c_txt <- Corpus((DirSource(directory = ".", ... | 39,655 |
<p>Can anybody tell me where can I find the information whether the Nyblom-Hansen test for coefficients stability has a right or left-sided critical region?
I mean I have computed the test statistics and I found the critical values for this test, but do I reject the null hypothesis if the test statistic is below the cr... | 29,490 |
<p>I am assessing how good different features are for unsupervised classification of a set of objects. For each different feature I test, I have computed a feature vector that describes the object. I then want to get a metric out for how 'good' this vector is at separating the objects into their respective classes.</p>... | 69,527 |
<p>How can one test the significance of the clusters obtained after a clustering procedure?</p>
<p>Are there separate tests for the distance/similarity/dissimilarity measure used to get the distance matrix and the clustering procedure used subsequently?</p>
<p>For example I am using Gower/Euclidean/Mahalanobis distan... | 30,075 |
<p>As I understand it, Pearsons residuals are ordinary residuals expressed in standard deviations.</p>
<p>I've ran this poisson regression:</p>
<pre><code>library(ggplot2)
glm_diamonds <- glm(price ~ carat, family = "poisson", data=diamonds)
</code></pre>
<p>I then saved the Pearsons residuals and fitted values ... | 69,528 |
<p>I want to learn how to generate a random field with long-range spatial correlations and the underlying distribution being a beta distribution.</p>
<p>EDIT:
Is it possible to take a random Gaussian field, look up the CDF value for each point and then map the distribution on $[0,1]$ with onto the beta with its invers... | 69,529 |
<blockquote>
<p>$R\sim Bi(n,\theta)$</p>
<p>i. The MLE of $\theta$ is $t_1(R) = R/n$. Find the MSE of the estimator</p>
<p>ii. prove that $t_2(R) = R/(n+1)$. Show that the $t_2$ has a lower MSE for $0<\theta<$ $2n+1\over 3n+1$</p>
<p>iii. Explain which estimator is better</p>
</blockquote>
<p>I ... | 69,530 |
<p>I have multiple observations from <code>n</code> groups\treatments. How to test the equivalence of <code>n</code> groups using all the variables? </p>
<p>Something like <code>MANOVA</code>, but for testing equivalence and not differences.</p> | 69,531 |
<p>This question is related to frequentist properties of p-values and their relation to type I error and why the results from an online simulation differ from what I would have expected.</p>
<p>Assume that I perform an experiment and do hypothesis testing at a significance level of 0.05. Next, I compute the p-value. I... | 30,076 |
<p>I am currently reading up on assumptions for Pearson correlations. An important assumption for the ensuing t-test seems to be that both variables come from normal distributions; if they don't, then the use of alternative measures such as the Spearman rho is advocated. The Spearman correlation is computed like the Pe... | 69,532 |
<p>Suppose we have a data set with a binary outcome variable $y$. The predictor variables are $x,w$ and $z$. This is the training data set. We obtain a logistic regression model from this training data set. Now suppose we have a test data set and want to predict $y$. In R, we use the <code> predict </code> function to ... | 30,078 |
<p>I was reading this paper <a href="http://comjnl.oxfordjournals.org/content/20/4/359.full.pdf" rel="nofollow">http://comjnl.oxfordjournals.org/content/20/4/359.full.pdf</a> and in the last paragraph of the first page, Rule 1 is given as $\alpha_{j+1} > \bar{\alpha} + k s_{\alpha}$. Here, $\bar{\alpha}$ and $s_{\al... | 69,533 |
<p>I am building a random forest model to make predictions. </p>
<p>Response variable is treated as continuous but not really continuous, e.g., integers from 0 to 10. </p>
<p>I have problems in constructing prediction interval for new observation. </p>
<p>Here are my questions:</p>
<ol>
<li><p>If prediction error i... | 30,079 |
<p>I work in a problem domain where people often report <strong>ROC-AUC</strong> or <strong>AveP</strong> (average precision). However, I recently found papers that optimize <a href="https://www.kaggle.com/c/criteo-display-ad-challenge/details/evaluation" rel="nofollow">Log Loss</a> instead, while yet others report <a ... | 282 |
<p>I am a graduate student in Business. Fortunately, I found a DLMCAPM code (<a href="https://github.com/VSRonin/DLMCAPM/blob/master/Final%20Work.R" rel="nofollow">https://github.com/VSRonin/DLMCAPM/blob/master/Final%20Work.R</a>) for a bivariate case in GitHub regarding on the Dynamic Regression and "Seemingly Unrelat... | 30,081 |
<p>I have a dataset which includes 4 separate measures of intelligence. To simplify my analysis, I wanted to express them as "g" a variable based on the shared variation of the 4 measures. A paper I read (Behav Genet. 2014; 44: 91–96.) did this by: </p>
<blockquote>
<p>General intelligence was assessed by extracting... | 30,082 |
<p>I'm trying to understand better Johansen method so I developed an example 3.1 given by the book <a href="http://www.amazon.in/Likelihood-Based-Inference-Cointegrated-Autoregressive-Econometrics/dp/0198774508%22Likelihood-Based-Inference-Cointegrated-Autoregressive-Econometrics%22" rel="nofollow">Likelihood-Based-Inf... | 69,534 |
<p>I have a <a href="http://stats.stackexchange.com/q/28041/8207">multilevel logistic regression</a> (Rasch), fit in JAGS. Specifically, </p>
<p>$\text{logit} (P(\text{Win})) = \alpha_p + \gamma_w + \delta_{p,w}$</p>
<p>The prior on $\alpha_p$ is partially pooled, $\alpha_p \sim N(\mu_\alpha,\tau_\alpha)$, and the re... | 69,535 |
<p>There has a data set with several features. One feature is of the type of continuous numerical values; another feature is of the type of categorical values, such as A, B and C. If I want to build a classification model with SVM, do I have to pre-process those different feature types? </p> | 69,536 |
<p>I've generated a user test to compare two methods: M1 and M2. I generate 40 test cases and show the result of each method on test case to 20 individuals, side by side, the individuals don't know what result came from which method. For each test case each person has to say if the result computed by M1 is better or M2... | 69,537 |
<p>I am using the R package <code>boot</code> to bootstrap Harrel's C Index with different Cox models. My sample consists of about 700 cases with 90 events.</p>
<pre><code>> boot.ci(boots[[2]], type="bca")
BOOTSTRAP CONFIDENCE INTERVAL CALCULATIONS
Based on 10000 bootstrap replicates
CALL :
boot.ci(boot.out = bo... | 40,312 |
<p>Is there a simultaneous test for the equality of two proportions when $k$ binomial properties are being tested? </p>
<p>Example:</p>
<p>Two groups of large size $n_1$ and $n_2$ are asked if they agree or disagree on 10 different questions. For any one particular question you can do a $Z$-test for the equality of p... | 69,538 |
<p>I would like to find the distance between two points locaion1 and location2.
In 2D, location1 is represented by a Gaussian distribution with mean m1 and co-variance matrix P1. Similarly location2 is represented by a Gaussian distribution with mean m2 and co-variance matrix P2.</p>
<p>Here m1= [m_x1; m_y1] and P1 = ... | 30,088 |
<p>We have been given the following for home work and I have calculated the OR however I am confused with the next 3 questions on percentages. Can someone help and explain and also what is the significance of only women in the study?</p>
<blockquote>
<p>You have brought to the attention of the Alcohol and Tobacco c... | 69,539 |
<p>Say, I had a sample of discrete counts from a random phenomenon, with two categorical factor variables $T$ and $G$, where , $T$ has three levels $T_1$, $T_2$ and $T_3$ and $G$ has three levels $G_1$, $G_2$ , $G_3$. </p>
<p><strong>What is a good way to estimate the effect of the individual levels, within each categ... | 69,540 |
<p>I want to model the case where a particular message is forwarded from a source to multiple nodes with transmission radius r (in multiple hops), until the message reaches a particular destination. The source and the destination are fixed. The other nodes move with known speed and direction of movement (those quantiti... | 40,316 |
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