question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>I am experimenting with a recommendation systems for articles (news, magazines etc). Is there any dataset available for the same which includes the demographic information of users as well? </p>
<p>I am actually trying to incorporate demographic information as well in recommending, hence looking for such a dataset.... | 73,626 |
<p>I have a problem that I can't seem to solve:</p>
<p>The prior: $\beta_h \sim \mathcal{N}(\bar{\beta},D)$.</p>
<p>Somehow the posterior is $\beta_h \sim \mathcal{N}(M, \Omega)$, where $M=(D^{-1}+X'X)^{-1}(D^{-1}\bar{\beta}+X'p)$ and $\Omega=(D^{-1}+X'X')^{-1}$, where $X$ is a data matrix and $p$ is a data vector.</... | 73,627 |
<p>From what I understand hot deck imputation involves 2 parts</p>
<p>1) Choosing the donor pool: This based on variables related to the missing variable.
Maybe using a regression technique to test for association or just ask a subject matter expert.</p>
<p>2) Choosing the value to be imputed from the donor pool bas... | 73,628 |
<p>Are there many features in Eviews that R misses? I have heard that especially when dealing with time series R is less extensive than Eviews. Is this true? Which of the two packages contains most statistical tools (or are they comparable?)?</p> | 73,629 |
<p>I'm afraid that related questions didn't answer mine. We evaluate the performances of >2 classifiers (machine learning). Our Null hypothesis is that performances do not differ. We perform parametric (ANOVA) and non-parametric (Friedman) tests to evaluate this hypothesis. If they're significant, we want to find out w... | 73,630 |
<p>First off, I know little about statistics, so some of this question may seem naive.</p>
<p>I'm trying to perform linear regression to model the relationship between x and y where:</p>
<p>-x is a company's daily stock volume on a date</p>
<p>-y is variable that is taken from the same date, however is something unr... | 73,631 |
<p>I have data sets of the returns of two indexes in the same market (two different sets of stocks constituting each index), with 496 observations for each. I want to compare if the means are statistically different. I believe the variances are different, so I think I have to check if the variances are statistically di... | 36,032 |
<p>I don't really have a motivation for this - but I was thinking about this and couldn't work it out. </p>
<p>Suppose I have a random variables $X$ and $Y$ which are correlated. Is it possible that the partial correlation between $X$ and $X\cdot Y$ is zero after taking into account Y? In other words, would a regressi... | 36,033 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/298/in-linear-regression-when-is-it-appropriate-to-use-the-log-of-an-independent-va">In linear regression, when is it appropriate to use the log of an independent variable instead of the actual values?</a> </... | 49,325 |
<p>Let's say I have 1 success in 4 bernoulli trials, and I wish to plot the distribution of the parameter $p$ of the corresponding binomial distribution. I'm using R.</p>
<p>The probability of seeing 1 sucess and 3 failures in 4 tests for $p=0.25$ is, for these parameters:</p>
<pre><code>> n <- 4
> p <- 0... | 47,532 |
<p>Is it possible to do discriminant analysis with random effects?
Is there an R package for this?</p>
<p>Context: </p>
<p>I have habitat use data for two species of frogs from radio telemetry, but nested within 'species' the data is for individuals with highly autocorrelated data. </p>
<p>For example, I have ~280 ... | 29,245 |
<p>I have a time series data set of photon arrival times from a detector and need to know whether the arrival time is uniform.It is a continuous distribution?</p>
<p>I have calculated the maximum $D$ between the normalized CDF of the photon arrival times. Then what should I do? There is a "$Pr(k\le x)$" in the <a href... | 73,632 |
<p>I have conducted a survey which asks respondents to indicate the informational sources regarding a product. There are 8 information sources (e.g., internet, newspaper, brochure and so on) and people can choose more than one source.</p>
<p>I want to use information source a predictor variable in a multiple regressi... | 73,633 |
<p>I am developing a physiological test using R that requires some parameters optimised. In comparing the new method against the existing method, the values of individual readings correlate in a linear way but are very heteroscedastic - the variance approximately proportional to the mean. </p>
<p>I would like to com... | 39,335 |
<p>Given a hierarchical model $p(x|\phi,\theta)$, I want a two stage process to fit the model. First, fix a handful of hyperparameters $\theta$, and then do Bayesian inference on the rest of the parameters $\phi$. For fixing the hyperparameters I am considering two options.</p>
<ol>
<li>Use <strong>Empirical Bayes (EB... | 73,634 |
<p>I am developing a method to do something with permutation testing. I have two permutation / randomization schemes and do not know which one is better than the other. Can I find the confidence interval for each permutation scheme? If so, is the one with the narrower confidence region better?</p> | 29,254 |
<p>I need to calculate the sample size required for an observational study in which incidence of disease is 19-29%. Population affected is 600,000 people.</p>
<p>The study has two samples similar on baseline characteristics treated
with two different drugs.</p>
<p>Statistical analysis will be chi-square and Fisher'... | 47,538 |
<p>Lets say for example a class of students and their grades are the data set.
Lets say there are around 35 students.</p>
<p>Here is what you know:</p>
<pre><code>Your mark
The class average
The median mark
The standard deviation
</code></pre>
<p>Are there any other conclusions about this data that can be made given... | 996 |
<p>I have some data which works nicely with JMP's canned linear discriminant analysis (LDA), but after <a href="http://en.wikipedia.org/wiki/Linear_discriminant_analysis" rel="nofollow">reading about LDA</a> I'm not sure if the analysis is valid. The Wiki article notes a fundamental assumption of LDA is that independe... | 73,635 |
<p>I apologize in advance if the question is rather simple, but I have been having a difficult time figuring it out. </p>
<p>I am an experimental scientist interested in modeling human disease with induced pluripotent stem cells. The disease is fairly common, but doesn't have a common genetic basis. It is mainly drive... | 73,636 |
<p>I am new to R and I have run the <code>lmer</code> in lme4. In the model summary, there is no any warning message, but when I ask for <code>confint(lmer)</code>, R gives me this message at the bottom of the output:</p>
<pre><code>Warning messages:
1: In profile.merMod(object, signames = oldNames, ...) :
non-monot... | 73,637 |
<p>I recently read a <a href="http://blog.echen.me/2012/03/20/infinite-mixture-models-with-nonparametric-bayes-and-the-dirichlet-process/" rel="nofollow">fascinating article</a> describing methods for clustering data without assuming a fixed number of clusters.</p>
<p>The article even includes some sample code, in a m... | 25,062 |
<p>I have some trouble with score functions in likelihood calculation. I'm not good at statistics or probability, so I'm still confused on formalism and mathematical-probabilistic language.</p>
<p><strong>Some background:</strong> I'm on particle filter, so inferring a pdf that is analytically intractable by a Monte C... | 36,045 |
<p>I'm trying to wrap my head around mixture modelling, and I've come across a small matlab script that seems relevant. In order to familiarize myself with pymix, I've decided to try rewriting the matlab script in python. I appear to have successfully fitted/decomposed the data with the expectation maximization algor... | 36,046 |
<p>I would like to compare the data of a community of species between two years. I used to compare communities based on different levels of a factor (for example, a treatment). The case of a treatment is easy because each site has a corresponding level of the treatment. </p>
<p>However, if the factor is a year, we fac... | 47,551 |
<p>I have a time series dataset that reports the hourly page views and social media shares of online news stories. What I hope to obtain is the relationship between the two variables. I would imagine that the more shares a story gets, the more page views it will attract, and vice versa. That means the two variables wou... | 73,638 |
<p>I am trying to build sparse coefficient time series models but couldn't find a good resource/book to learn from. Can anyone share with me a good resource/book? It will be great if it comes with R codes.Can anyone use this kind model? Thanks.</p> | 36,048 |
<p>I am using <code>R</code> and <code>e1071</code> package to tune a C-classification SVM.</p>
<p>My question is: regardless of the kernel type (linear, polynomial, radial basis or sigmoidal), is there any good criterion to choose the range in which cost and $\gamma$ parameters should range over and/or to choose what... | 73,639 |
<p>Suppose I am doing random forest classification of labels $A$,$B$,$C$,$D$. There is some theoretical ordering to this output such that when $A$ is more likely than $B$, $B$ is also more likely than $C$, etc. Also, if $P(D) > P(C)$, we also have that $P(C) > P(B) > P(A)$. There are other such conditions that... | 73,640 |
<p>I have two <em>finite</em> samples $s_1$ and $s_2$ and two distributions $p_1(s_1)$ and $p_2(s_2)$ that are associated to these samples. I'm essentially interested to measure the distance or similarity between these two distributions. I'm currently using the Jensen-Shannon (JS) distance, which involves in calculatin... | 73,641 |
<p>I was wondering if you could share your experience in reporting chi-square tests for complex survey data in journal publications. Normally Chi-square tests are reported as $\chi^2_1(2,\text{ N} = 90)= 0.89, \text{ p} = .35$. (for example, although I guess there can be some variations). However the concept of N becom... | 73,642 |
<p>I'm looking to use a multivariate regression for prediction, but making use of (possibly) superior estimates of variance for both the independent and extraneous variables.</p>
<p>My approach is to standardize the dependent and extraneous variables (by dividing their respective standard deviations derived from the f... | 39,441 |
<blockquote>
<p>Let $X$ be a random varaible from a distribution with pdf
$$
f(x) = \theta x^{\theta-1}, \quad 0< x < 1.
$$</p>
<p>a) Name the distribution of $U=-\ln(X)$ by first finding its density </p>
<p>b) Let $X_1, X_2, \ldots,X_n$ be independent and identically distributed random variables wi... | 16,625 |
<p>If I'm not wrong, likelihood functions are sensitive to the size of the sample, i.e. the larger the sample, the lower the likelihood value. Given a sample $x$ of a random variable $X \sim f(\theta)$, and a parameter estimate $\hat\theta$, suppose I want to test the hypothesis that the likelihoods of different subsam... | 36,056 |
<p>In a panel regression using fixed effects, is it correct to use an instrument that does not vary by year? To use an old but simple example, Angrist and Kruger 1991 use quarter of birth as an instrument for education. If one had access to similar data that was in panel form, is it still correct (and I don't mean sp... | 36,057 |
<p>I am currently working on biomass estimates using satellite imagery. I'll quickly define the background of my question, and then explain the statistical question I am working on.</p>
<p><strong>Background</strong></p>
<p><em>Problem</em> </p>
<p>I am trying to estimate biomass over an area in France. My response ... | 36,058 |
<p>I am aware that the "prediction interval", as defined in most textbooks on linear models, is focused on the uncertainty in the model being fit and is used to estimate an output prediction range for exact inputs. However, as is normally the case, what about situations where the input isn't exact? How do you calc... | 47,564 |
<p>I'm trying to assess the difference between two algorithms. They are stochastic, so I've run them multiple times against the same input files and noted their results. I want to determine whether my algorithm offers a statistically significant improvement over a previous approach. From my (potentially flawed) underst... | 47,566 |
<p>I'm familiar with using tools like SVMs and decision trees for discrete classification problems. But one detail that I have not encountered in that domain is: what do you do if your classifier must conserve some quantity when it is predicting outcomes for new input data?</p>
<p>For example, suppose that you took al... | 73,643 |
<p>I am doing multiple imputation on a database of observations on hospital patients. There is one observation of many covariates per patient. There are 2 binary outcome variables:</p>
<ol>
<li><p>Alive/Dead after 30 days</p></li>
<li><p>Died in hospital, or survived/discharged</p></li>
</ol>
<p>Two seperate analysis... | 47,568 |
<p>Suppose, the data below shows the mean response time on a task for respondents among four different groups:</p>
<pre><code>A B C D
1.2 2.3 4.5 6.7
</code></pre>
<p>In order to assess which one of the means are different from one another I do a multiple comparisons test (after an omnibus ANOVA tes... | 6,799 |
<p>I am trying to implement a test as described in a paper in R. The aim is to calculate enrichment for a particular type of mutation that occurs in a given base in a given sequence context.</p>
<p>I quote</p>
<blockquote>
<p>Statistical evaluation of the over-representation of APOBEC signature mutations in each sa... | 36,060 |
<p>I have 6,000 points for which I have all pairwise distances in a distance matrix. I want to get an idea whether these data were generated by a mixture of Gaussian distributions so I'm trying to get a visualization. I am trying to apply multidimensional scaling in 2 dimensions using sklearn in Python. </p>
<p>I have... | 73,644 |
<p>This question regards the basic statistics of a normal distribution, but I can't figure it out. I have been given the mean and 95% confidence intervals for a distribution, but would like to know the standard deviation. In my example:</p>
<p>$$
\mu=53.4\quad
95\%\ c.i.=(52.3, 54.3)
$$</p>
<p>I had thought that the ... | 49,618 |
<p>I was able to reproduce table 3.1 from ESL. However, when I tried to reproduce table 3.2, my estimated coefficients were way off (shown below):</p>
<pre><code> [,1]
[1,] 0.4292
[2,] 0.5765
[3,] 0.6140
[4,] -0.0190
[5,] 0.1448
[6,] 0.7372
[7,] -0.2063
[8,] -0.0295
[9,] 0.0095
</code></pre>
<p... | 73,645 |
<p>I am currently reviewing some work and have come across the following, which seems wrong to me. Two mixed models are fitted (in R) using lmer. The models are non-nested and are compared by likelihood-ratio tests. In short, here is a reproducible example of what I have:</p>
<pre><code>set.seed(105)
Resp = rnorm(100)... | 73,646 |
<p>I am trying to learn some statistics using the book, Biometry by Sokal and Rohlf (3e). This is an exercise in the 5th chapter which covers probability, the binomial distribution, and Poisson distribution.
<img src="http://i.stack.imgur.com/T0Tth.jpg" alt="enter image description here"></p>
<p>I realize there is a ... | 73,647 |
<p>Here is an example case:</p>
<ul>
<li>I have a population of 10,000 items. Each item has an unique id. </li>
<li>I randomly pick 100 items and record down the ids </li>
<li>I put the 100 items back into the population </li>
<li>I randomly pick 100 items again, record down the ids and replace. </li>
<li>In total... | 73,648 |
<p>This is a homework question and I need suggestion how to approach it. We have given the transitions </p>
<ol>
<li>$\ i\rightarrow i+1$ with rate $\lambda(i)$ where $\ i \ge 1$ </li>
<li>$\ i\rightarrow i-1$ with rate $\mu(i)(i-1)$ where $\ i \ge 2$</li>
</ol>
<p>I am starting the forward equation like this:</p>
... | 36,067 |
<p>I've used rjags to run MCMC on a model, specified in the JAGS language. Is there a good way to extract that model and perform predictions with it (using the posterior distributions of my parameters)? I can re-specify the model in R and plug in the modes of my parameter posteriors; I'm just wondering if there's a les... | 47,486 |
<p>I've been looking at numerous questions on this site regarding bootstrapping and confidence intervals, but I'm still confused. Part of the reason for my confusion is probably that I'm not advanced enough in my statistics knowledge to understand a lot of the answers. I'm about half-way through an introductory statist... | 73,649 |
<p>I computed a feature <code>x</code> that I use to predict <code>y</code> which is a <strong>probability</strong> of being a certain class.</p>
<p><strong>Raw data in R format for (x,y) is pasted here:</strong>
<a href="http://tny.cz/a97b3fd0" rel="nofollow">http://tny.cz/a97b3fd0</a>
(500 samples)</p>
<p>plot(x,y... | 49,921 |
<p>I'm working on my final project, and it's a QUEST algorithm, and it uses the chi-square test. I have a problem where the expected value = 0. </p>
<ol>
<li>What should I do? </li>
<li>What does it imply to the chi-square test or to the QUEST algorithm?</li>
</ol> | 73,650 |
<p>I am interested in the following sampling problem, which I will try to describe by a motivating example. </p>
<p>Suppose we want to estimate how many people in a certain area, has blue eyes, how many have them has brown eyes etc.(think of a color scale) We do have an estimate on total number eye colors that the pop... | 36,070 |
<p>I am attempting to build a model to forecast attendance in a given week in the current year based on this year's attendance values up until the present, and data from two previous years. My data looks like this:</p>
<pre><code> Week 11-12 Cumulative ADA 12-13 Cumulative ADA 13-14 Cumulative ADA
1 0.99... | 36,071 |
<p><strong>Study Design:</strong><br>
Below is a clinical trial in a longitudinal dataset. All subjects (n=34) attended <code>V1</code> (baseline) and then they were assigned to either a <code>Placebo</code> (n=15) or a <code>Drug</code> (n=19), both then were investigated at visit <code>V2</code>. Based on an investi... | 73,651 |
<p>I have set of time series data tuples: {$(1,22), (2, 25), (3, 18), (4, 26), ...$ so on}</p>
<p>I want to estimate $Y_{t+1}$ using support vector machine regression technique. I have found numerous publications that mostly refer to <a href="http://alex.smola.org/papers/2003/SmoSch03b.pdf" rel="nofollow">Smola's pape... | 47,585 |
<p>I have accuracy vectors of two classifiers. How can I make a t-test for them on Matlab and is there a good plot type to show it?</p> | 36,075 |
<p>I am using Wilcoxon test to compare two paired sets of data for whether their means differ. Besides the p-value, I would also like to know the power of this test. How to compute it in R? Thank you in advance.</p> | 36,078 |
<p>I am trying to ascertain if a relationship exists between <strong>hours of play</strong> and <strong>number of friends</strong>. I have two contexts for the study: "at school" and "at a place other than the school".</p>
<p>My data set relates to the "at school" context and the correlation r=0.8766 (significant). </... | 73,652 |
<p>This may be too simple a question for this forum - it is possibly a very basic statistics question as commonly found in biomedical research. But since scientists often lack good understanding of statistics, I would appreciate a lot if I could hear the thoughts from expert statisticians on this forum and be educated ... | 73,653 |
<p>I have a waveform, for which most people will measure either a peak amplitude or a slope. I have included the area under the curve and several other measures involving the same original waveform. I now have 10 measures on such waveforms (and I have measured these waveforms in 500 patients). Is it legitimate to pu... | 73,654 |
<p>I've known that, in orthogonal rotation, if the rotation matrix has determinant of -1 then reflection is present. Otherwise the determinant is +1 and we have pure rotation. May I extend this "sign-of-determinant" rule for non-orthogonal rotations? Such as orthogonal-into-oblique axes or oblique-into-orthogonal axes ... | 73,655 |
<p>Suppose I have a random symmetric matrix W of size $n\times n$, with i.i.d. coefficients uniformly distributed in [0,1], and I set $W_{ii} = 0$.</p>
<p>Then I apply a Multidimensional Scaling of dimension $k$, which I define as minimizing the quantity:
$H=n^{-2}\sum_{i,j} (W_{ij} - ||x_i-x_j||^2)^2$
with respect to... | 73,656 |
<p>I have a data which contains several columns which I later reduced using a PCA algorithms to two different components. I then applied the k-means algorithms to the data.<br>
Now, how can I verify that my data clustered well into each group? Or how do I determine misclassification rate?</p>
<p>For instance, using... | 73,657 |
<p>I'd like to test how well my data can be modeled by an <a href="http://en.wikipedia.org/wiki/Exponentially_modified_Gaussian_distribution" rel="nofollow">Exponentially modified Gaussian distribution (Wikipedia)</a> or <a href="https://en.wikipedia.org/wiki/Normal-exponential-gamma_distribution" rel="nofollow">Normal... | 73,658 |
<p>I have $n$ dice with $m$ sides. The $i^{th}$ dice will show value $0 \leq x_i \leq m-1$ with probability $0 \leq D_i(x_i) \leq 1$. What is the probability that the sum of the dice equals $\alpha$</p>
<p>Is there some approximation for $P(\alpha)$</p> | 73,659 |
<p>I use SPSS, but am forced to use R for exact logistic regression. So I'm brand new to R (and hating it so far) and also new to logistic regression. I've read the original elrm paper and looked at examples of its use. However, I can't find information on the questions below (after the data description).</p>
<p>The... | 73,660 |
<p>I am doing a study of how legal need relates to a number of predictors.</p>
<p>Outcome Variable: Legal Need (Yes or No)<br>
Possible Predictors: Age, Gender, Race, Ethnicity, Language, Clinic, Insurance Status.<br>
Predictors based on bivariate analysis: Age, Language, Clinic, Insurance Status. All ORs were aro... | 36,086 |
<p>I have two variables measured concurrently at 3 time points, let's call them wealth (<code>W1</code>, <code>W2</code>, <code>W3</code>) and anxiety (<code>A1</code>, <code>A2</code>, <code>A3</code>). Suppose that wealth and anxiety are uncorrelated. Now, I'm interested whether <em>change</em> in anxiety is related ... | 73,661 |
<p>As a little experiment, I am extending a nice, interpretable AR/MA relationship between a security $r$ that is variably influenced by the previous $k$ time points over another security $f$. These relationships ("lags") are represented by $l$. I want to pump up the "realism" by making both securities move with stoc... | 36,087 |
<p>I have 20 years of data from observing dolphins. When a group is seen, it gets an unique number identifying it, and all identified (marked) dolphins were also registered. So I had a table like</p>
<pre><code>Group Dolphin
1 1
1 10
1 14
2 10
2 23
</code></pre>
<p>I got about 20,000 groups and 50... | 36,088 |
<p>I'm trying to help out a not-for-profit organization and made an error that I'm trying to fix. They've been doing a non scientific survey of their Board of Directors for a number of years regarding board engagement. They asked me to help them convert the survey format from an unfriendly Excel file to something web b... | 73,662 |
<p>I am looking at two populations on which I have measured 4 independent variables ($X_1$, $X_2$, $X_3$, $X_4$) and one dependent variable ($Y$) along with each measurement or observation. I suspect that the two populations are different in the sense that the second population's $Y$ shows a dependence on an additional... | 73,663 |
<p>I am trying to model weekly disease counts in 25 different regions within 1 country over a ten year period as influenced by temperature. The data is zero inflated and over dispersed. </p>
<p>I am most familiar with Stata but I don't think that there is any option amongst the <code>gee</code>, <code>xtmixed</code>... | 36,091 |
<p>I'm new to both R and Bayesian statistics, and I have a problem where I have a normally distributed prior that elicits a mean and standard deviation. The introduced likelihood function is also normally distributed with a mean and standard deviation that can be drawn from a sample.</p>
<p>Now I understand that a po... | 73,664 |
<p>I am new to PCA and wanted to do a bit of experimentation on my data set just to see what it looked like (using R). I am not able to give access to the data here since it is confidential. However, if there is some other kind of statistic/visualization you would like to see that would help you answer my questions ple... | 73,665 |
<p>$\newcommand{\E}{\mathrm{E}}$
I don't understand why Baum-Welch algorithm is an instantiation of EM algorithm.</p>
<p>Indeed, why computing $\alpha_t(i)$ and $\beta_t(i)$ corresponds to Expectation step. Expectation step corresponds to compute expectation over the latent variable of log-likelihood of observed vari... | 73,666 |
<p>I'm performing a web based a/b test where there is a control and one treatment. The results are not as simple as "converted" or "didn't convert." A user can "convert" anywhere between 0-10 times. I have all of the data from both the control and the treatment (how many times each user converted from both the control ... | 36,094 |
<p>I have a vector $v=(v_1,...,v_J)$, which is jointly normal. I then need to take the expectation of this vector. This should give me something like this:</p>
<p>1)$$E(v)=(E(v_1),...,E(v_J))$$</p>
<p>However, I want to write up the integral for this expectation, but I'm unsure how to do this. My guess is something l... | 73,667 |
<p>Suppose that you are running a linear regression model with outcome $Y$ and explanatory variables $X_1$ and $X_2$. You also run a linear regression model with a quadratic transformation of $X_1$: $$E[Y] = \beta_0 + \beta_{1}X_{1}+\beta_{2}X_{1}^{2} + \beta_{3}X_{2}$$ </p>
<p>If $|\beta_2| \approx 0$ can we drop it... | 73,668 |
<p>Which method would you suggest for estimation an univariate regression ($y = a + bx + e$) which comprise a lot of $0$ values in the dependent variable (actually kind of censored data). My experience hints at the use of the <strong>Tobit model</strong>. But There is a problem connected with the normal distribution an... | 73,669 |
<p>I would like to calculate Student's t test of two normal distribution data.
However, I do not have the data at all, but only mean and standard deviation of each population.
So, how can I simulate those data in R and calculate the t.test among both?</p>
<p>These are the values (mean and SD):
Population 1: 6,62 +- 0... | 73,670 |
<p>I am new to Neural Networks and trying to implement RBM. I am stuck on initializing the visible layer's bias value. Is it supposed to initialize to some random number or there is some probabilistic distribution by which it should be initialized. In python I am seeing: </p>
<pre><code>> "vbias = theano.shared(val... | 73,671 |
<p>I have run a logistic regression using several predictor variables (call them p1 p2 p3 p4) to predict a binary dependent variable (call it y). P1 is a significant predictor of y in the regression. However, a Mann-Whitney test of p1 shows no significant difference by category of y.</p>
<p>Is it normal to have a sign... | 73,672 |
<p>I wonder if it is fair is to compare the gini coefficient of two discrete distributions with different number of elements. If not, how can I adjust the coefficients for a fair comparison. </p>
<p>In particular, I'm interested in the case when the sum of values in both distributions are equal. For example, minutes p... | 22,257 |
<p>I'm looking to test for equality of means across different sample sizes of data, but know that the data is not normally distributed and heteroscedastic.
Can anyone suggest anything?</p> | 49,583 |
<p>Let's say I have two models. One has cumulative lift on test data 4.322578, second 2.84488. The only advantage of the second over the first consists in the quality of having the cumulative lift curve nearly identical for both train and validate sets. </p>
<p>For the first model the curve of cumulative lift looks as... | 36,103 |
<p>I did some research and didn't find what I was looking for: I have a data set x = 10,100,1000 and y1, y2, y3 respectively, and I want to plot those points. </p>
<p>But what is happening is that in the x axis the values that are appearing are 10, 200, 400, 600, 800 and 1000. How can I set the scale so that it only a... | 73,673 |
<p>Please help me proving this:</p>
<p>Suppose that $Y_1,\ldots,Y_n$ are i.i.d. nonnegative RV's with CDF $F$ and $E(Y_i)=\mu<\infty$. Let $y_1,\ldots,y_n$ be a realization from which an EDF $\hat{F}$ is defined:
$$
\hat{F}(y)=\frac{1}{n}\sum_{i=1}^nI(y_i\leq y).
$$
<strong>Want to show</strong>:
$$
\text{plim}_{n\... | 73,674 |
<p>149 students each sat two tests. My null hypothesis is that the product-moment correlation coefficient is 1, because each test should be an accurate indicator of current attainment. The actual PMCC for the data is 0.912152856.</p>
<p>Please could you show (and explain) how to test if this is a significant result?</... | 73,675 |
<p>I recently came across a predicting problem (0-1 outcome, with more than 80 variables), I decided to use GBM (Gradient Boosting Machine by Friedman)to handle this job. I let the GBM use only 70% of the dataset, and within this training set, 60% are used at each iteration. </p>
<p>During this process I found a big p... | 36,513 |
<p>I have to validate the data in one database by comparing it to data from a validated application system. The solution I came up with was (at least in theory) creating a statistical method that would define the number of random samples needed to check on a table of the database, in order to say, that with a 95% chanc... | 73,676 |
<p>I am applying a linear model to my data:
$$
y_{i}=\beta_{0}+\beta_{1}x_{i}+\epsilon_{i}, \quad\epsilon_{i} \sim N(0,\sigma^{2}).
$$</p>
<p>I would like to estimate the confidence interval (CI) of the coefficients ($\beta_{0}$, $\beta_{1}$) using bootstrap method. There are two ways that I can apply the bootstrap me... | 73,677 |
<p>Presumably this has been discussed already, but I wanted to get some sense of how prevalent is the use of R for biostatistics publications. On PubMed I did find a number of research papers that were conducted using R (as mentioned in the Methods or Statistical Analysis sections of the documents). However, the majori... | 73,678 |
<p>Hi i am trying to use AIC value for comparing logit and probit model where in each model the data and the number of covariates are same (say, covariate= 3 for each model)</p>
<p>Does AIC value increases while increasing sample size?</p>
<p>Which one better to use as a tool for comparing logit and probit, AIC or MS... | 73,679 |
<p>Logistic regression essentially means taking the logit of your response proportions, p, and then doing standard regression. Consider the case where one p is 1. </p>
<p>logit(1) = log(1/(1-1)) = infinity. How can you do regression with infinity?</p>
<p>That is, if one of your observed proportions p is 1, then you a... | 36,114 |
<p>I have a data set of recorded elephant locations for the span of 6 years (elephantdata). Some of the entries are duplicates of the same day. I want to create a subset of my 'elephantdata' and create a new matrix that only has one data point before noon and one data point after noon for each day. I would like that da... | 73,680 |
<p>Good evening everyeone,</p>
<p>I am currently working on a set of self-study questions which relate to true/false answers. I am currently faced with a question where the answer claims for it to be false, but I find it true. Not sure if there is an error in the answer. Appreciate some help and advice please.</p>
<b... | 36,116 |
<p>According to the <a href="http://en.wikipedia.org/wiki/Approximate_Bayesian_computation" rel="nofollow">Wikipedia article</a>, we have the scenario shown below, but how can ABC generate simulation datasets from samples of $\theta$ without knowing or evaluating the likelihood function?</p>
<p>For example, how would ... | 36,117 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.