question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have many datasets representing different populations. Each dataset contains values of an independent variable along with (0/1) representing the occurrence of an undesirable event. I analysed each of the datasets separately by using univariate logistic regression.</p>
<p>The goal was to calculate and compare the ... | g66558 | [
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<p>I am reading a pdf about Dirichlet Process, and it said "A Dirichlet Process is also a distribution over distributions."</p>
<p>anyone could explain this in plain English what does it mean by that?</p>
<p>thanks a lot!</p> | g66559 | [
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<p>I ran a HLM analysis (One Way ANOVA with random effects model). I calculated my ICC and it is very small (00.1%). I understand this means that there is basically no meaningful level-2 variability in the level-1 variable.</p>
<p>I have to run an analysis on the data still (it was a hypothesis). Do I still use HLM an... | g275 | [
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<p>I have two dimensional spatial (x,y - coordinates of meteo stations) data for small region (so I could neglect the shape of earth globe), for each (x,y) I have one observation of wind direction and speed I need to design metric for clustering problem of such data. It's simple to do when we consider only directions ... | g66560 | [
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<p>I have a question about the effects of shifting the intercept in a logistic fit on the mean of a particular transformation of the scores.</p>
<p>Here is the notation I will be using for the question. The logistic regression model is
$$
\begin{align}
\mathbb{P}[Y_i =1 \mid \boldsymbol{X}_i] &= \dfrac{1}{1+\exp(-... | g66561 | [
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<p>I have $\Pr(A)=29\%$ and $\Pr(B)=10\%$, where $A$ and $B$ are two events which are not independent.</p>
<p>In fact, a correlation measure suggests they're correlated by $\rho=0.8$.</p>
<p>I would like to calculate $\Pr(A \cap B)$, that is the probability both of them occur.</p>
<p>Here is what I've done in R:</p>... | g66562 | [
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<p>I'm not a statistician but do work with large datasets and have a problem I'd like to use a predictive model for. </p>
<p>I have two datasets that I'd like to use together to build predictions. The first set is of a list of categories:</p>
<p>A, B, B, A, C, D, A, B, D , etc. </p>
<p>I have turned this into a tabl... | g66563 | [
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<p>I am running the Jonckheere-Terpstra in place of Kruskal-Wallis test, as my factor is in ordinal scale (i.e. groups can be ordered).</p>
<p>The Asymptotic significance (2-tailed) is 0.000, so it seems there is a trend in the response variable, according to the trend of the factor.</p>
<p>However, if I look at the ... | g66564 | [
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<p>The classical (OLS) regression model is:
$$
y_i = \beta_1 x_{i1} + \cdots + \beta_p x_{ip} + \varepsilon_i
$$
For this linear model we have many instruments to estimate model's fit. But how can I estimate the fit of model like this:
$$
y_i = \beta_1 x_{i1} * \cdots * \beta_p x_{ip} * \varepsilon_i
$$
or other model... | g66565 | [
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<p>Quality assessment in trauma has for > 25 years been done with the US derived logistic regression model, the TRISS model. DV: survival/death and IVs: physiologic derangement (continuous), anatomic injury (continuous), age (dichotomous, >= 55, <55). Probability of survival (Ps) are calculated for each patient: </... | g4253 | [
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<p>I am working on classifying video frames into two classes, positive and negative. e.g. if a particular pattern appears in a frame that frame will be classified into positive, otherwise negative.</p>
<p>But in some cases it is not clear whether that pattern appears in a particular frame (let's say i) or not. But obs... | g66566 | [
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<p>I am studying the Dickey Fuller test. The book of reference is Introductory Econometrics for Finance by C. Brooks. I firstly consider the zero mean Dickey Fuller test that uses the "random walk" type of regression:</p>
<p>$\Delta Y_t = \delta Y_{t-1} + u_t$</p>
<p>The null hypothesis is that $\delta$ is zero and t... | g66567 | [
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<p>I am trying to understand how scikit-learn uses input data to train and build a classifier. Please note that i am both a Python and scikit-learn newbie.</p>
<p>From what i understand so far, scikit-learn does not handle categorical features as with other Software (IMHO a serious drawback if this actually holds) su... | g66568 | [
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<p>I'd like to get some real practice with hypothesis testing that is above what's in textbooks (plug and chug, usually). I was hoping someone could suggest some good data sets and problems to work on. Problems that I could show others that I've worked on. Along those lines, I'd very much appreciate any top notch refer... | g66569 | [
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<p>Firstly, please forgive my lack of statistics knowledge, but I am hoping someone can clear up my misunderstandings.</p>
<p>I am taking a sample of a physical quantity, (for example: temperature). To take this sample I average the measurements over a time duration (for example: 1 sec). This gives me a sample mean an... | g46006 | [
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<p>I have performance review data and scores (ranging from 1 to 4) for employees of a company. I need to show the company average over the past year. However, the employees were only ever reviewed for a few weeks in a row at a time.</p>
<p>For example:<br>
Roger was reviewed from Jan 1 through March 1<br>
Steve was re... | g66570 | [
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<p>Please bear with me, as I'm trying to better understand these aspects. My understanding is that <em>(finite) mixture models (MM)</em> are characterized by a presence of a number of sub-populations in a population or sample. It can be argued that this <em>heterogeneity</em> might represent effects of some known or un... | g9645 | [
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<p>I have a problem where I am given an initial prior or proportion for the number of occurrences per some unit with known standard deviation (an example is 3 per mile). </p>
<p>I wish to test if this proportion is valid given a live exhaustive sampling of the area. So I would plan to use all the sampled information... | g3150 | [
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<p>The <a href="http://en.wikipedia.org/wiki/Soliton_distribution">Soliton distribution</a> is a discrete probability distribution over a set $\{1,\dots, N\}$ with the probability mass function</p>
<p>$$
p(1)=\frac{1}{N},\qquad p(k)=\frac{1}{k(k-1)}\quad\text{for }k\in\{2,\dots, N\}
$$</p>
<p>I'd like to use it as pa... | g66571 | [
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<p>I need to simulate a price series based on a GARCH(1,1) specification for the returns (price changes). I currently have this:</p>
<pre><code> d_price = diff(price) #the price changes
garch.model = garch(d_price) #a GARCH(1,1) model
specs = garchSpec(model = list(omega = garch.model$coef[1],
alph... | g66572 | [
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<p>The second question is that I found in a discussion somewhere on the web talking about "supervised clustering", as far as I know, clustering is unsupervised, so what is exactly the meaning behind "supervised clustering" ? What is the difference with respect to "classification" ?</p>
<p>There are many links talking ... | g25649 | [
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<p>I'm in my first days of learning <code>R</code> and hit a roadblock with a small use case from finance.</p>
<hr>
<p>(EDIT) Basically I want to know how to test sample fitness against any distribution. Say, find the degree of freedom of a t-distribution which would have the best fit with the given list of asset ret... | g46014 | [
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<p>I came across this study as part of a mock exam paper and was confused to say the least.</p>
<h3>Context:</h3>
<p>The study investigates cognitive and behavioural factor related to the experience of anxiety in MRI scanners.</p>
<p>Participants completed the following questionnaires 5 mins after the scan:</p>
<ul... | g46017 | [
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<p>I have a more general question. Could somebody please explain what is the general difference between OLS and FE (Fixed Effects) in a very simple way? In terms of use in panel data and in general. </p>
<p>Thank you! </p> | g66573 | [
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<p>I have been asked to assist in a study based on samples of records from registers of dental care patients. My problem is that I would like to be sure that my proposed approach for the analysis is sufficiently common, but due to my own limited experience in the field, I do need advice. One aspect is the final analysi... | g25654 | [
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<p>When conducting a t-test we can always use a Welch approximation of the df, and let go of the assumption of equal variances.</p>
<p>Is there something similar for (even one way) anova? (any R implementation of that?)</p> | g25655 | [
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<p>Sometimes in reports I include a disclaimer about the p-values and other inferential statistics I've provided. I say that since the sample wasn't random, then such statistics would not strictly apply. My specific wording is usually given in a footnote: </p>
<blockquote>
<p>"While, strictly speaking, inferentia... | g66574 | [
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<p>Let us say this is an output of a model I ran in Stata, where <code>int_ret</code>is a continuous variable and <code>time1</code>-<code>time17</code> are time dummy variables. Reference is <code>time0</code>. I notice that the coefficients are significant at alpha=0.05 up til time 5 after which it stops being signif... | g66575 | [
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<p>I observe a certain system with a rectangular array of sensors, that can be either triggered or not. I know the system behavior can be well described by the sequence of triggering events and by the time difference between them. The system is not deterministic so it cannot be fully captured by a finite state machine ... | g66576 | [
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<p>I would like to build the relationship between the dose given and two outcomes (one acute toxicity and one late toxicity). The model I used was binary logistic regression. For the acute toxicity outcome, the estimated dosage and its 95% confidence interval was 20 (15~35), while for the late toxicity outcome, the est... | g25661 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/949/when-is-logistic-regression-solved-in-closed-form">When is logistic regression solved in closed form?</a> </p>
</blockquote>
<p>Why is there no analytic solution for logistic regression?
I was trying t... | g49498 | [
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-0.037540532648563385,
-0.008075046353042126,
0.04285668581724167,
0.06697161495685577,
0.00418... |
<p>I am trying to compute the KL-distance between two columns in a data-frame. Whats the best way to implement this? </p>
<p>I have seen FNN and FLEXMIX packages and their examples, but it is implemented for random samples. How can I do it on two data frame columns?</p>
<pre><code> V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 ... | g66577 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/12386/machine-learning-cookbook-reference-card-cheatsheet">Machine learning cookbook / reference card / cheatsheet?</a><br>
<a href="http://stats.stackexchange.com/questions/20040/machine-learning-self-learn... | g49363 | [
0.029343828558921814,
0.01087886095046997,
0.01274900697171688,
0.01717095822095871,
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0.02099967747926712,
0.04176434874534607,
-0.04400634765625,
0.06519147753715515,
0.028791921213269234,
0.03596106544137001,
0.11667680740356445,
0.04616834595... |
<p>I'm trying to analyse data from a factorial design, but I don't have all combinations of factor levels, and I have repetition for the combination. As this configuration differs from book's examples I'm wondering how it would impact the results. An example of what I'm saying:</p>
<pre><code>F1 2 levels
F2 3 level... | g46028 | [
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<p>If $X$ has a beta distribution $ \beta(\alpha,b)$, $Y$ has a gamma distribution $\Gamma (K,\theta)$ and $X$ is independent of $Y$. What is the distribution of the product $P=XY$ .</p>
<p>Thanks! </p> | g66578 | [
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<p>I'm beginner in R, Could you please explain how to use ses in forecast package of R <a href="http://cran.r-project.org/web/packages/forecast/forecast.pdf" rel="nofollow">forecast</a>?
I'd like to choose the number of initial periods and smoothing constant.</p>
<pre><code>d=[3 4 41 10 9 86 56 20 18 36 ... | g25667 | [
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0.005929823964834213,
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0.02438600... |
<p>I have two sets of data. The first is multivariate linear regression data consisting of betas and standard errors. It was log(e) transformed before the linear regression model was applied. </p>
<p>The second set is also multivariate linear regression data, consisting of betas and standard errors, but it was z-score... | g66579 | [
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<p>Given the distribution:</p>
<p>$f(x;\theta) = \frac{3}{\theta}x^2e^{-x^3/\theta}$ if $x>0$</p>
<p>the MLE for $\theta$ is $\frac{1}{n}\sum_{i=1}^n x_i^3$. It's an unbiased estimator with variance $\theta^2/n$. The Fisher information number is $1/\theta^2$.</p>
<p>Now, I am supposed to check whether or not this... | g47260 | [
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<p>I am running a logistic regression in R and am attempting to determine if multicollinearity is a problem with my model.<br>
When I run <code>vif()</code> on my final model, I get <code>GVIF</code> and <code>GVIF^1/(2*Df)</code> columns. From what I have read <code>GVIF^1/(2*Df)</code> is what I should use to assess... | g66580 | [
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<p>In a Logistic Regression with linear and quadratic terms only, if I have a linear coefficient $\beta_1$ and quadratic coefficient $\beta_2$, can I say that that there is turning point of the probability at $-\beta_1 / (2\beta_2)$?</p> | g66581 | [
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<p>Asked this previously <a href="http://math.stackexchange.com/questions/148860">on Math.Stackexchange</a>, maybe this fits here. </p>
<p>I would like to understand the relation (if any) between the Cramer-Rao Lower Bound of estimation theory and the following simple definition of "reconstruction accuracy" which does... | g41032 | [
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<p>I am currently using Viterbi training for an image segmentation problem. I wanted to know what the advantages/disadvantages are of using the Baum-Welch algorithm instead of Viterbi training. </p> | g66582 | [
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<p>How to adapt this piece of code but for:
- gamma distribution
- 3 parameter log normal</p>
<p>More specifically, where can I find the specification of the parameter (lmom) for pelgam() and pelln3()? </p>
<p>Lmom package info just gives: pelgam(lmom), lelln3(lmom), where lmom is a numeric vector containing the L-mo... | g39938 | [
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<p>As part of my graduate thesis (area: psychology) I have gathered preference data. The data includes approximately 50000 heads-up comparison between elementX and elementX. I have a total of 15 elements. The participant would be shown 36 comparisons in random order, of which he/she would then choose the preferred elem... | g66583 | [
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<p>Am I missing something? When I use SVMLight, there's always a lot of vectors in the model file.</p>
<p>But when I create one with SVMPerf - there's only one vector in the file? (?)</p>
<p>But still, it works fine. Am I missing something? </p>
<p>Also the number of documents that it supposedly used is way smaller ... | g25673 | [
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<p>What is confidence interval and why it is useful. </p>
<p>I am trying to compare two classification models. </p>
<p>I came to know I have to use confidence interval of true predictions in order to compare two classification models.</p>
<p>I have googled the term confidence interval. But I could not understand wh... | g49464 | [
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<p>I'm analysing paired data for equivalency and it's not normally distributed, i.e., the difference of the paired result is not normally distributed due to, amongst other things, outliers. If it were normally distributed I would use a Two One Sided T-test (TOST).</p>
<p>My questions are:</p>
<ol>
<li>Can two one-sid... | g66584 | [
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<p>I'm familiar with the concept of a mean value of data and the variation around the mean. Is it possible to quantify variation around maximum values? </p>
<p>For example, take the below data collected across 10 years. I want to present the maximum value for each month, but I also want to quantify the variation aroun... | g66585 | [
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<p>This may as well go down as the silliest questions ever asked on this forum, but having received sound and meaningful answers to a previous question, i thought i will stretch my luck again.</p>
<p>I have been very confused for some time on the importance of statistical distributions especially as they relate to ass... | g66586 | [
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<p>What are some common methods of making distribution predictions? I have a set of features $x_1,x_2,x_3$ which map to Gaussian distributions ($\mu,\sigma^2$). That is, the feature vector of a single example $X_1$ can be defined by a distribution with ($\mu_1,\sigma^2_1$).</p>
<p>What are some ways to go about buildi... | g25677 | [
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<p>In a training center, a new strategy was implemented. After the implementation of this new strategy the training center claimed that on an average $80\%$ of the students passed. In order to find out whether this claim can be justified, we take a random sample of $30$ students and see that $60\%$ of the students pass... | g66587 | [
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<p>Is it ok to generate a classifier by collecting all association rules so that the conclusion part refers to the target variable? does it perform better than decision tree or rule learning?</p> | g66588 | [
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<p>For a counter example, I am searching for random variables $Y$ such that for a independent normal random variable $X$ the distribution of $Z=Y+X$ is known parametrically. Ideally, the Shannon entropy of $Z$ should also be known. </p>
<p>The obvious case is when $Y$ is normal as well. </p>
<p>Another example would ... | g25679 | [
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<p>I'd like to perform a cluster analysis on ordinal data (Likert scale) by using SPSS. I have around 140 observations and 20 variables that are scaled from 1 to 5 (1: I strongly agree, 3: neutral, 5: I strongly disagree). As a result, I want to assign one cluster to each person, such as person 1 belongs to the group o... | g66589 | [
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<p>I am a beginner in SAS. I have a data set called cars with 25 variables and 93 observations. I have attached the image of the data set.<img src="http://i.stack.imgur.com/YO4Fl.png" alt="enter image description here"></p>
<p>Here you can see that there is a variable <code>Model</code>: all values are different. The... | g66590 | [
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<p>A market research firms conducts studies regarding the success of new products. The company is not always perfect in predicting the success. Suppose that there is a 50% chance that any new product would be successful (and a 50% chance that it would fail). In the past, for all new products that ultimately were succes... | g66591 | [
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<p>I feel this may be a slightly dumb question but I ran a regression with 4 variables, and all are very statistically significant, with T values $\approx 7,9,26$ and $31$ (I say $\approx$ because it seems irrelevant to include the decimals) which are very high and clearly significant. But then the $R^2$ is only .2284.... | g39269 | [
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<p>I've read papers comparing them, but never seen a study that used them
together. Is this done? Why or why not? Suppose you use
ANCOVA to analyze a reduced sample of matched pairs generated using
propensity scores (assuming the propensity scores are estimated from
the complete set of confounders X that jointly effec... | g66592 | [
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<p>I need to automate time-series forecasting, and I don't know in advance the features of those series (seasonality, trend, noise, etc). </p>
<p>My aim is not to get the best possible model for each series, but to avoid pretty bad models. In other words, to get small errors every time is not a problem, but to get big... | g46048 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/18599/pacf-manual-calculation">PACF manual calculation</a> </p>
</blockquote>
<p>I am trying to find a formula for how to calculate partial autocorrelation between variables. We know that aucorrealtion be... | g49754 | [
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<p>Suppose I have $n=100$ observations of ordinal data and get threshold coefficients $b_1, \dots, b_3$ and probit slope $b_4$. I want to test the hypothesis $H_{0}: \frac{b_{3}}{b_{4}} = \frac{1}{2}$ vs. $H_a: \frac{b_{3}}{b_{4}} \neq \frac{1}{2}$. So I want to count the proportion of times we fail to reject the null ... | g41798 | [
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... |
<p>What happens if you reject normality of residuals when estimating with least squares? </p>
<p>Is it too important to have normality on the residuals? </p> | g66593 | [
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-0.005686791148036718,
0.02501220628619194,
-0.008691573515534401,
-0.012530980631709099,
-0.0061878724955022335,
0.03928988054394722,
-0.04475688934326172,
0... |
<p>It is often argued that the bayesian framework has a big advantage in interpretation (over frequentist), because it computes the probability of a parameter given the data - $p(\theta|x)$ instead of $p(x|\theta)$ as in the frequentist framework. So far so good.</p>
<p>But, the whole equation it is based on:</p>
<p>... | g25684 | [
0.04984993860125542,
-0.013279533945024014,
0.0038882282096892595,
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0.004613065160810947,
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0.023935886099934578,
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-0.046390727162361145,
0.06677516549825668,
-0.0006707619177177548,
0.013817531056702137,
0... |
<p>So we have a regression equation with one explained variable and 10 explanatory variables.</p>
<p>What I have read so far:</p>
<ol>
<li><p>Multicollinearity doesnt affect the regression of the model as a whole.</p></li>
<li><p>But if we start looking at the effect of individual predictor variable Xs on the explain... | g66594 | [
0.01498529501259327,
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0.04035668820142746,
0.0... |
<p>I keep seeing this in class and I don't understand why we add the log in there from time to time. For example we have regression model 1: $$1:\hat Y=-14.37+.321X_1+.043X_2-.0051X_3+.0035X_4$$ and then it says that we reestimate the model using the log form of $X_3$ and $X_4$ to get model 2: $$2:\hat Y=-36.30+.327X_1... | g49416 | [
-0.025013137608766556,
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0.05816774442791939,
0.04135613515973091,
0.0172... |
<p>I was looking for the proof of convergence for <a href="http://en.wikipedia.org/wiki/Perceptron" rel="nofollow">perceptron</a> algorithm with margin. I was not able to find it in any pattern classification text book or over the internet.</p>
<p>Can anyone here please point to a text or reference for the above?</p> | g46054 | [
0.07296153903007507,
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0.0027499645948410034,
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<p>Based on a simulated empirical distribution of $Z$, find $\mu^*_X$, the smallest $\mu_X$ such that $P(Z > c) = p$, where $Z$ is given by $Z = \prod^5_{i=1}(aX_i + bY_i)$ where the $X_i$'s are i.i.d $LN(\mu_X,\sigma_X^2)$, the $Y_i$'s are i.i.d $LN(\mu_Y,\sigma_Y^2)$ and $LN(,)$ is the Log-Normal distribution. (Me... | g66595 | [
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0.04164513945579529,
0.003726877039298415... |
<p>I am trying to create a mediation model for:</p>
<p>X1=employee capability;
X2 (Mediator)=Company capability;
Y= employee earnings</p>
<p>Although, I am not sure if I can still say that this will be a mediation model when I believe and support that X1 and X2 have reciprocal relation. Where, employee capability (... | g3380 | [
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0.006920070853084326,
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<p>I have a batch of(~200) velocity data of celestial bodies that I know they are either type A or B, supposedly with respective normal distribution of velocity. I want to use these observed data to decide the mean and variance of the two, as well as ratio between 2 types of stars. Any suggestion?</p>
<p>PS I'm quite ... | g66596 | [
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0.03640514984726906,
0.036259956657886505,
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... |
<p>Has anyone attempted to use Empirical Mode Decomposition(EMD)-Support Vector Regression(SVR) in nonstationary time series forecasting? It seems quite interesting. As I observed it has high performance compared with single SVR. But I didn't find it as a real approach for time series. </p> | g25695 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/5504/normal-distribution-probability">Normal distribution probability</a> </p>
</blockquote>
<p>Issues getting to the bottom of a HW problem, but I am not looking for the answer, just some guidance.</p>
<... | g49755 | [
0.007415015250444412,
0.0193405132740736,
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0.0012476806296035647,
0.006465088576078415,
0.026277171447873116,
0.0064245788380503654,... |
<p>Can I run multiple regression with mostly categorical independent variables? I'd appreciate some examples to cite this approach as one of my reviewers is insisting that I justify the use of multiple regression for categorical IVs.</p>
<pre><code>2 DVs (test scores) interval
IVs -
1 score (1-5 scale)
Gender dummy c... | g66597 | [
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0.01961411163210869,
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-0.018118195235729218,
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0.019365044310688972,
0.010090538300573826,
0.04... |
<p>I have a general question on fixed-effects and mixed-effects models for panel data. I am doing a logistic regression on panel data, with data measured on the individual level.</p>
<p>I understand that by using fixed-effects in my model (<code>xtlogit...,fe</code> in Stata) I basically ignore or do not look at the d... | g66598 | [
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0.015295450575649738,
0.018908396363258362,
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<p>Horrible title, so let me explain - I think this must be a very basic statistical problem, but I don't remember what little statistics I once knew. </p>
<p>I'm writing a low-level emulator of an old IBM CPU. Each machine instruction of the IBM1620 was accomplished by a sequence of various "machine cycles". On th... | g25698 | [
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0.02944117598235607,
0.04333712160587311,
0.... |
<p>Let's say I have 4 plants and I measure <code>something</code> under 2 conditions. For example:</p>
<p>The entries in the table show how many times I <code>saw something</code> under condition (C1 or C2) for plant (P1, P2, P3 or P4). </p>
<pre>
P1, P2, P3, P4
C1 0 20 0 19
C2 100 80 180 150... | g49425 | [
0.002549487864598632,
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0.013225669041275978,
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0.... |
<p>I have a time series data, see jpg. It goes straight up and then straight down, later tailing off. This seems to fit my textbook’s description of a deterministic trend being an almost exact function of time on the way up and on the way down.
Using the D-F test I found that I could reject the existence of a unit root... | g46065 | [
0.02309238351881504,
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0.04225299134850502,
0.045889485627412796,
-0... |
<p>I am wondering how to estimate the uncertainty of the fit if the coefficients in the model have uncertainties as well. for example:</p>
<p>I try to use model <strong>y=exp(-(a+b)*x)+c</strong> to fit a data set <strong>x</strong> and <strong>y</strong> to find out the value of <strong>b</strong> and <strong>sigma_b... | g66599 | [
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0.014337737113237381,
0.010702847503125668,
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-0.03159449249505997,
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0.03671054169535637,
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... |
<p>I ran a repeated design whereby I tested 30 males and 30 females across three different tasks. I want to understand how the behaviour of males and females is different and how that depends on the task. I used both the lmer and lme4 package to investigate this, however, I am stuck with trying to check assumptions for... | g66600 | [
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0.015866883099079132,
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0.029892124235630035,
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0.02051026001572609,
0.04013465344905853,
0.... |
<p>Please provide your input on what kind of sampling methodology is followed here.</p>
<ul>
<li>Data being collected for a questionnaire.</li>
<li>the sample population consists of people in employment and IT professionals</li>
<li>they were targeted by sending mails and posting messages on professional groups on soc... | g66601 | [
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0.01240466721355915,
0.00042286713141947985,
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0.0018755412893369794,
0.04024955630302429,
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0.03286060690879822,
0.0052442229352891445,
0.03545844182372093,
-0.011268535628914833,
0.043408043682575226,
... |
<p>Can somebody tell me </p>
<ol>
<li>what are and how to do <strong>pooled time series</strong>?</li>
<li>and in what way it can help me to <strong>build forecast models from clusters of time series?</strong></li>
</ol>
<p>Maharaj and Brett do this in their article <a href="http://ideas.repec.org/p/msh/ebswps/1999-9... | g66602 | [
-0.024668095633387566,
0.013048077933490276,
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0.03612419590353966,
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0.05625012516975403,
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0.020829422399401665,
0.15137450397014618,
... |
<p>My understanding of the difference between machine learning/other statistical predictive techniques vs. the kind of statistics that social scientists (e.g., economists) use is that economists seem very interested in understanding the effect of a single or several variables -- both in terms of magnitude and detecting... | g46066 | [
0.0581236258149147,
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0.021878642961382866,
0.0029191221110522747,
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0.03171135112643242,
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0.002350532915443182,
-0.03797634690999985,
0.06260675191879272,
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0.0740528330206871,
0.020211... |
<p>In my work, we are comparing predicted rankings versus true rankings for some sets of data. Up until recently, we've been using Kendall-Tau alone. A group working on a similar project suggested we try to use the <a href="http://en.wikipedia.org/wiki/Gamma_test_(statistics)" rel="nofollow">Goodman-Kruskal Gamma test<... | g66603 | [
0.04426709935069084,
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0.009966246783733368,
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0.0425260029733181,
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-0.009081537835299969,
0.02831122651696205,
0.0020777664612978697,
0.04909089580178261,
-0.... |
<p>How do you get a confidence interval for an odds ratio between two different groups (both of which are not the reference group) in SAS?</p>
<p>Suppose $x_1$ is the reference level and $x_2,x_3,x_4$ are the other variables. Odds ratios in SAS give them for each level compared to the reference (e.g. $x_2$ vs $x_1$, $... | g66604 | [
0.024200376123189926,
-0.04097319766879082,
-0.023185990750789642,
0.003228880697861314,
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0.05690900981426239,
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-0.00148499826900661,
0.04476914927363396,
0.025715522468090057,
-0.012511872686445713,
-... |
<p>I have closed form moment-generating function and characteristic function of a distribution, which describes waiting time of a continuous univariate random process. However, I cannot analytically invert the characteristic function to get PDF.</p>
<p>Now, I have run simulations of the original process in order to ... | g66605 | [
-0.01677250675857067,
-0.03612176328897476,
-0.007790412753820419,
-0.06295870244503021,
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0.026734957471489906,
0.05295604467391968,
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0.01870560646057129,
0.014589257538318634,
-0.0022691700141876936,
0.0284136850386858,
-0... |
<p>Does it make sense to say that the odds of some risk for a person in group A is $0.4$ times lower that that of someone in group B? Or would it be better to phrase it in "higher than" language?</p> | g25706 | [
0.045844800770282745,
0.02134496532380581,
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0.001282417681068182,
0.014988694339990616,
0.002792272251099348,
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0.0075712441466748714,
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0.003920387011021376,
0.004749819170683622,
0.0180639810860157,
-0.029085872694849968,
0.016... |
<p>I want to predict a health problem. I have 3 outcome categories that are ordered: 'normal', 'mild', and 'severe'. I wish to predict this from two predictor variables, a test result (a continuous, interval covariate) and family history with this problem (yes or no). In my sample, the probabilities are 55% (normal)... | g585 | [
0.03317273408174515,
-0.08353148400783539,
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0.02689099870622158,
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0.02640674076974392,
0.0270833820104599,
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0.0076524061150848866,
0.04129336401820183,
-0.010432696901261806,
0.05539826676249504,
-0.0... |
<p>I'm looking for a way to fit several arbitrary discrete distributions to another discrete distribution using maximum likelihood, but I'm having trouble finding a function to do this in <code>numpy</code> or <code>scipy</code>. I'm ok with using another library, so long as </p>
<ul>
<li>it's in C++ or Python</li>
<l... | g25707 | [
0.0244431309401989,
0.006726016290485859,
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0.01187935285270214,
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-0.04224163666367531,
-0.011203034780919552,
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0.07028425484895706,
-0.005... |
<p>I am looking at the effect of genotype on a continuous variable. In total 16 comparisons were done involving 9 different SNPs. The number of significant events was 3 out of 16 tests (Mann-Whitney U-test). Is it necessary to correct the p-values to account for multiple comparisons?</p> | g66606 | [
0.02985047549009323,
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0.02738245204091072,
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0.0355... |
<p>For the Gaussian distribution with unknown mean and variance, the sufficient statistics in the standard <a href="http://en.wikipedia.org/wiki/Exponential_family">exponential family</a> form is $T(x)=(x,x^2)$. I have a distribution that has $T(x)=(x,x^2,...,x^{2N})$, where N is kind of like a design parameter. Is the... | g25711 | [
-0.031886160373687744,
-0.0084192780777812,
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0.015024686232209206,
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0.018568014726042747,
-0.011640901677310467,
-0.010074116289615631,
0.028091810643672943,... |
<h2>Background</h2>
<p>I am generally interested in learning appropriate methods of using data to specify priors. A <a href="http://stats.stackexchange.com/q/1/1381">previous question</a> asks how to elicit priors from experts and received some good recommendations. Here, I am interested in learning how to specify a p... | g66607 | [
-0.00499756122007966,
-0.016570953652262688,
-0.003585888771340251,
-0.09535810351371765,
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-0.03739705681800842,
0.019465535879135132,
0.013605024665594101,
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-0.04457229748368263,
-0.016369013115763664,
-0.024235928431153297,
0.06283484399318695,
... |
<p>I have found some distributions for which BUGS and R have different parameterizations: Normal, log-Normal, and Weibull.</p>
<p>For each of these, I gather that the second parameter used by R needs to be inverse transformed (1/parameter) before being used in BUGS (or JAGS in my case). </p>
<p>Does anyone know of a ... | g46070 | [
0.024495961144566536,
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0.0009602190111763775,
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-0.006818943191319704,
0.021746382117271423,
-... |
<p>New to the site and to stats here! This may be a silly question, but I haven't been able to find a satisfactory answer on the procedure for a power analysis (or general guidelines about sample size) with a quantile regression. I plan on looking at 3 predictors along a single outcome. What would a recommended sample ... | g66608 | [
-0.0254594124853611,
-0.02317359484732151,
0.006536869797855616,
-0.024857761338353157,
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-0.020643414929509163,
0.06845235079526901,
-0.04036302864551544,
0.005471943877637386,
0... |
<p>Apologies if this is a little confusing. If anything needs clarifying, I'll edit the question as best I can. Thanks.</p>
<hr>
<p>If we take a sample of, say, 100 people, we could measure their heights, and find the mean and standard deviation. We can calculate an estimate of the standard error from this single sam... | g66609 | [
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... |
<p>I am constructing a Vector autoregression model and I have used AIC to find how many lags I should use. Does 7 lags seem unreasonable? I am trying to find the impact the property market has had on the economy and my variables are GDP, inflation, employment rates, housing prices, number of housing complete, long-term... | g46075 | [
0.040517911314964294,
0.049442190676927567,
0.0005320251802913845,
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0.00796988420188427,
0.05109155550599098,
0.0... |
<p>What approaches exist to observe the time lag between two variables?</p>
<p>I need to analyze the relationship between blood pressure and some other factor, such as exercise. The data set I am drawing from has around 1800 individuals, with an average of 100 entries a piece. It is generally known that there is a str... | g66610 | [
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0.0004398691817186773,
0.032761428505182266,... |
<p>If you have 3 separate models in a multiple regression problem (and 3 ANOVA tables), which would be best given that you have the coefficient of determination, $R^2$, and mean-squared error values?</p>
<p>So you have 1 table, with just $X_1$, another with just $X_2$ and a third with $X_1$, $X_2$ combined. Which is b... | g3488 | [
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0.0106083843... |
<p>Consider these two grayscale images:</p>
<p><img src="http://i.stack.imgur.com/2ndLs.png" alt="river">
<img src="http://i.stack.imgur.com/3nWSz.png" alt="random"></p>
<p>The first image shows a meandering river pattern.
The second image shows random noise.</p>
<p><strong>I am looking for a statistical measure tha... | g66611 | [
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-0.022980032488703728,
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0.017224235460162163,
0.06884803622961044,
0.03694842755794525,
0.050... |
<p>I´m trying to learn generalized mixed models in SAS and I have now bumbed into a situation that I cannot figure out by myself. So I was thinking that maybe some of you could help me forward.</p>
<p>I´m running a model where I have normally distributed measurements of traits like tarsus etc in birds from different p... | g66612 | [
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0.... |
<p>Estimate 3 parameters of beta exponential distribution in the case of censored type 1 samples via L-moments</p> | g66613 | [
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... |
<p>I am trying to optimize the hyperparameters for a Gaussian process. As a starter I choose the squared exponential function for covariance where iI have to optimize 3 parameters $\sigma_f$, $\sigma_n$ and the length parameter $l$.</p>
<p>$$k_y(x_p,x_q) = \sigma^2_f \exp\left(-\frac{1}{2l^2}(x_p-x_q)^2\right) + \sigm... | g46078 | [
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-0.018317116424441338,
0.018855461850762367,
0.04066045954823494,
0.075642831... |
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