question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have one simple model and one more complex model (both are PDEs that describe displacement, when different kind of forces and thermal effects take place). From those, given some data, I calculate through PyMC the posterior distribution of a parameter (elasticity). Now I want to calculate the Bayes' factor, and I a... | g18128 | [
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<p>Rookie here -- I have a a large data set with about 75,000 observations, and 2000 unique IDs. Therefore, each unique ID has about 37 observations. I'm trying to draw a random sample of unique IDs, say 4, so that I have a new data frame of 4 random unique IDs and roughly 150 observations. Any insight?</p> | g61527 | [
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<p>I use a hexplot to visualize data in R. I'm wondering if I can make the number of the colors of the bins grow. </p>
<p>Let me give you an example:</p>
<pre><code>library(hexbin)
plot(hexbin(rnorm(1000000),rnorm(1000000)))
</code></pre>
<p>This creates the following plot: </p>
<p><img src="http://i.stack.imgur.c... | g18129 | [
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<p>Firstly, excuse my naivity but I am just starting out in research.</p>
<h3>Overview of study</h3>
<p>I am doing a project looking at Social anxiety in adolescence and using social network analysis (SNA). I argue that negative peer relations accounts for variance in social anxiety above and beyond individual level ... | g61528 | [
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<p>I have three different methods that I would like to compare using ANOVA. The variable to compare is method accuracy that I get trough cross-validation. This means that the same data set (N=60 subjects) is divided into training and test sets, and into placebo and treatment groups (every subject has taken part to both... | g18133 | [
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<p>Eight rooks are placed in distinct squares of an 8 x 8 chessboard, with all possible replacements being equally likely. Find the probability that all the rooks are safe from one another.</p> | g61529 | [
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<p>I know that for panel data RE probit model we should average out the individual effects and in order to do that we do the following:
$$f(y_1,...,y_T|x_i, \theta) = \int[\prod_{t=1}^T f(y_t|x_{it},c;\beta)\frac{1}{\sigma_c}\phi(\frac{c}{\sigma_c})]dc
$$
I would be very grateful if someone could explain how an assump... | g18135 | [
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<p>I'm sure this is a very straightforward question but it came up in my work today and I could not think of the reasoning behind it.</p>
<p>I had two sets of numeric values (A & B) and was looking at the median of their ratio and noticed that median(A)/median(B) is not equal to median(A/B) and I was wondering if ... | g61530 | [
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<p>Is $f(x)=e^{x^Tx'}$ a suitable kernel to be choosen? If so, to what dimension does it transform the data?</p> | g47961 | [
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<p>I was always under the impression that regression is just a more general form of ANOVA and that the results would be identical. Recently, however, I have run both a regression and an ANOVA on the same data and the results differ significantly. That is, in the regression model both main effects and the interaction ar... | g61531 | [
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<p>I am trying to cross validate a logistic regression model with probability sampling weights (weights representing number of subjects in the population). I am not sure how to handle the weights in each of the 'folds' (cross-validation steps). I don't think it is as simple as leaving out the observations, I believe ... | g61532 | [
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<p>I would like to predict the number of flu cases in the future using predictive modeling. I am very new to statistics, so I'm not sure which classifier to use in this case.</p>
<p>For the attributes, I'm using historical data (2 years) as well as geographical location and age groups.</p>
<p>Are these attributes eno... | g18138 | [
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<p>I'm looking at measures from different studies (for a meta-analysis) and hoping to provide an aggregate effect size. I'm trying to identify hetero-/homo-geneity to determine whether I should use a random or fixed effects model.
I do not have the original data - but rather effect sizes calculated from the individual... | g61533 | [
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<p>Suppose we have factor X with n levels, factor M with p levels, then $\hat{Y} = X+M+X\cdot M$ and $\hat{Y} = X \cdot M$ will give us two parametrizations of the same model, since we can only get $np-1$ estimates for the coefficients. What, if anything, is gained by including the main effects directly in the model?</... | g61534 | [
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<p>I'm trying to run a 3 level hierarchical regression in lmer in R.
The model is specified:</p>
<pre><code>model <- lmer(dependent ~ ind1 + ... + (1|level3/level2), data=data)
</code></pre>
<p>However, when I enter this code, R starts processing it for 20 minutes and doesn't respond. Am I doing something incorrec... | g28203 | [
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<p>I am currently working in remote sensing. It is quite common to find that the beginning of the statistical descriptions of techniques used in satellite image processing begin with defining the initial images in question as random vectors. Would this be solely for the purpose of this data to be compatible with the pr... | g61535 | [
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<p>It seems universal that demographic statistics are given in terms of 100,000 population per year. For instance, suicide rates, homicide rates, disability-adjusted life year, the list goes on. Why?</p>
<p>If we were talking about chemistry, parts per million (ppm) is common. Why is the act of counting people look... | g61536 | [
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<p>I wonder if it possible to include a mediation effect in multinomial logistic regression. I have a categorical (3 categories) outcome variable and four predictors (all continuous). I expect one of the predictors (X1) to mediate the relationship between the outcome variable and another predictor (X2). I also expect d... | g61537 | [
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<p>I've been using the <code>MCMCglmm</code> package recently. I am confused by what is referred to in the documentation as R-structure and G-structure. These seem to relate to the random effects - in particular specifying the parameters for the prior distribution on them, but the discussion in the documentation seems ... | g61538 | [
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<p><strong>The case:</strong> I am investigating the impact of various predictors on the odds of migration using a discrete-time event history model within a multilevel framework. The outcome variable is dichotomous (0=not migrated; 1=migrated). The predictors are largely time varying covariates operating at the indivi... | g61539 | [
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<p>I am trying to run a model to describe the rate of water table drawdown in the soil. The predicted variable is rate, and I am interested in the effect of two categorical variables: (1) if the water table is above a certain threshold (yes, no) and (2) if the rate is different between seasons (summer / fall). I have m... | g61540 | [
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<p>Consider you have a binary classifier which you tested on dataset AB=A union B.</p>
<p>Assume that the several Area Under the Curve metrics for the three datasets are: AUC(A), AUC(B), and AUC(AB). Without loss of generality, assume AUC(A) <= AUC(B).</p>
<p>Is the expression AUC(A) <= AUC(AB) <= AUC(B) gua... | g61541 | [
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<p>I know that one if one is trying to perform linear regression, multicollinearity can be an issue because it can "lead to unreliable and unstable estimates of regression coefficients." Suppose for a second that I have the following correlation matrix for potential continuous predictor variables I want to regress aga... | g61542 | [
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<p>We have conducted a repeated measures experiment in which we have registered the response time (RT) of each subject in 21 trials in each of 2 conditions. I have some questions related to the best analysis we can conduct...
First, to reduce individual variability between subjects, we have standardize "within subject... | g18147 | [
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<p>I have the following linear model:</p>
<p>$$w^*=\text{arg min}_w\sum_{i=1}^N \bigg(Y_i-\sum_{j=1}^M X_{i,j}\times w_j\bigg)^2$$</p>
<p>Let $T \in N^*$ and $e_i=|Y_i-\sum_{j=1}^M X_{i,j}\times w_j|$. </p>
<p>It's possible using logistic regression to predict which errors will be less than $T$ (i.e., $e_i<T$) an... | g18148 | [
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<p>I am using "smooth.spline" in R. Here is a snippet from the documentation:</p>
<p><a href="http://stat.ethz.ch/R-manual/R-patched/library/stats/html/smooth.spline.html" rel="nofollow">http://stat.ethz.ch/R-manual/R-patched/library/stats/html/smooth.spline.html</a></p>
<p>smooth.spline {stats} R Documentation </p>
... | g18149 | [
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<p>Ok, almost all applications I have seen that use HoG features use linear svm as classifier. Can someone explain for me why linear svm are chosen and why they give good performance?</p>
<p>Are linear svm chosen because it more simple and easier to train than svms that use polynomial or gaussian kernel and using thes... | g61543 | [
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<p>I’m reading <em><a href="http://rads.stackoverflow.com/amzn/click/081764055X" rel="nofollow">A Probability Path</a></em> by S. Resnick, and I got stuck on one problem:</p>
<blockquote>
<p><strong>Problem 1.16</strong> (<em>pp. 22-23</em>) Suppose $C$ is a class of subset of $\Omega$ such that $\Omega \in C$,
... | g22188 | [
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<p>I have two random variables: $x = N(0, \sigma^2)$ and $y =U[0, b]$. I need to compute $E(x/(1+y))$. How does one go about doing this? They are independent so the joint pdf is just the product of the two pdfs but can the integral be computed in closed form or is this something that should just be done numerically?... | g61544 | [
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<p>I'm starting to want to advance my own skillset and I've always been fascinated by machine learning. However, six years ago instead of pursuing this I decided to take a completely unrelated degree to computer science. </p>
<p>I have been developing software and applications for about 8-10 years now, so I have a goo... | g18156 | [
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<p>My question is how can different anomaly detection algorithms be compared for my specific dataset. Essentially, I have multivariate timeseries (physical quantities such as temperature, pressure) and a label in one of the time stamps saying that my physical system reached some critical state (e.g. had to shutdown, fa... | g61545 | [
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<p>I do not know much about statistics as you could notice below.
I need to calculate the significance of change in land cover in two periods of time. The problem is I have two equal by surface territories with different by territory land cover territories so when using two-tail t-test I get p=1: Is it because the cha... | g18158 | [
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<p>Suppose I have massive data set (think Terabytes) is available to train a learning algorithm. Which one of the following conditions must be true to obtain good performance (low error rate)</p>
<p>a. Using a complex model with many parameters, including high order polynomial features
of the original space (e.g x^1... | g61546 | [
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<p>I have ran a nested ANOVA on a data set and the results suggest that there is an association for the higher level with an insignificant P-value but also an association for the lower level with a significant P-value. Is this even possible, or have I done something completely wrong?</p>
<p><em>Details</em></p>
<p>I ... | g18160 | [
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<p>I an trying to perform a multivariate linear regression in R. </p>
<p>I have two dependent variables (outcomes) and one independent variable (predictor).
The model would be something like: </p>
<pre><code>y1,y2~x
</code></pre>
<p>I did not find any way to implement this in R.
Any help?</p> | g61547 | [
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<p>Is there a way to calculate the optimal sample size for a balanced panel over 8 years from a population of approximately 30,000 and involving 10 variables being studied, say for 95% degree of confidence?</p> | g18161 | [
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<p>Can anyone help explain some of the mathematics behind classification in CART? I'm looking to understand how two main stages happen. For instance I trained a CART classifier on a dataset and used a testing dataset to mark its predictive performance but:</p>
<ol>
<li><p>How is the initial root of the tree chosen?</p... | g49521 | [
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<p>Assume I have $N$ samples $x_1, \cdots, x_N$ from a Gaussian random variable $X\sim N(\mu, \sigma^2)$ where both $\mu$ and $\lambda = 1/\sigma^2$ are unknown.</p>
<p>If I apply MLE, I have $\mu_{MLE} = \frac{1}{N} \sum_i x_i$, and $\lambda_{MLE}^{-1} = \frac{1}{N} \sum_i (x_i - \mu_{MLE})^2$.
Note that $\lambda_{ML... | g18163 | [
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<p>I have simulated one possible path of a variance gamma process by the following code:</p>
<pre><code>vektor<-c(1:23)
S0=20
theta=0.01
v=5
sigma=0.1
vektor[1]<-S0
for (i in 2:23){
randomgamma<-rgamma(1, shape=1/v, scale = v)
randomnormal<-rnorm(1,mean=0,sd=1)
vektor[i]<-vektor[i-1]+theta*randomgam... | g18164 | [
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<p>(This is part-2 of my long question, you can have a look at part-1 <a href="http://stats.stackexchange.com/questions/1099/how-to-handle-count-data-categorical-data-when-it-has-been-converted-to-a-rate">here</a>)</p>
<p>I am going to do a quasi-experiment, with measuring the base line of a sample (actually not quite... | g47998 | [
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<p>If I have a (financial) time series, and I sample it with two different periods, at 5 and at 60 minute intervals, can I create an exponential moving average on the 5 minute sampled data which is the same as an exponential moving average on the 60 minute sampled data?</p>
<p>Something like this:<br>
e1 = EMA(a1) app... | g61548 | [
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<p>I have approximately 1200 input parameters that I am trying to whittle down with the following rough process:</p>
<p>1) Fit rbf SVM with n = 1200 parameters and calculate Matthews Correlation Coefficient(cross validation with 10 partitions)</p>
<p>2) Fit linear SVM, find the lowest weight (absolute value) paramete... | g61549 | [
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<p>I have a set of data which consists of many different types (measurable, categorical)
For example:
name measurable_attribute_1 categorical_attribute_1 measurable_attribute_2 categorical_attribute_2 ...</p>
<p>Number of attributes may grows quite quickly during my study: into my spreadsheet, I can as many ne... | g61550 | [
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<p>[0,1,0,2,4,1,0,1,5,1,4,2,1,3,1,1,1,1,0,1,1,0,2,0,2,0,0,1,0,1,2,2,1,2,4,1,4,1,0,0,4,1,0,1,0,1,1,2,1,1,0,0]</p>
<p>What is the best way to convince myself that these data are correlated? that no univariate discrete distribution would approximate them well? that a time series model is necessary to better estimate the ... | g61551 | [
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<p>In the absence of good a priori guesses about the number of components to request in Independent Components Analysis, I'm looking to automate a selection process. I think that a reasonable criterion might be the number that minimizes the global evidence for correlation amongst the computed components. Here's pseudo... | g18170 | [
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<p>I have made a very simple questionnaire that asks questions that are independent of each other. Every question can be answered with a rating between 1 and 5 where 1 means I strongly disagree and 5 I strongly agree.</p>
<p>Now I was wondering with statistical methods I could use to evaluate the results. I know maybe... | g61552 | [
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<p>I am a bit lost in the process of WLS regression. I have been given dataset and my task is to test whether there is heteroscedascity, and if so I should run WLS regression.</p>
<p>I have carried out the test and found evidence for heteroscedascity, so I need to run the WLS. I have been told that WLS is basically OL... | g61553 | [
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<p>I ran a mixed model using lme4::glmer for a logistic regression and consistently got these warning messages. I noticed there are still regular results even so, but are they accurate estimates?</p>
<pre><code> > glmm.ms1<-glmer(as.formula(paste(paste(y[1], x, sep="~"), mix[1], sep="+")),
+ d... | g18171 | [
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<p>The best way I can think to describe this question is by example: Imagine there is a ship sailing around the pacific ocean on an unknown path (possibly random.) Other ships passing by sometimes see this ship and radio in its location to me. Some of these scout ships have better instruments or a more trustworthy crew... | g48011 | [
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<p>Suppose I have a non-stationary limited data. Do I have to make it stationary before making forecasts? Can I use exponential smoothing, moving averages or even Holt Winters methods without making my data stationary? I've read that time series should be stationary to use such methods? Is that correct?</p> | g61554 | [
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<p>If you flip a coin and get 268 heads and 98 tails, you can calculate the probability that coin is fair several ways. A simple, heuristic observation would have most likely conclude that such a coin is unfair. I've calculated the p-value in R with:</p>
<pre><code>> coin <- pbinom(98, 366, 0.5)
> coin*2
[1] ... | g48014 | [
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<p>I've made a little questionnaire where participants can rate an answer between 1 and 5. I calculated the mean value, the average value and the standard deviation.</p>
<p>Now I was asking myself if it is possible to calculated a confidence interval for these results and if yes, if this would tell me anything. So I j... | g18175 | [
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<p>Can anyone help me understand the Pearson correlation formula?
the sample $r$ = the mean of the products of the standard scores of variables $X$ and $Y$. </p>
<p>I kind of understand why they need to standardize $X$ and $Y$, but how to understand the products of both the z scores? </p>
<p>This formula is also cal... | g61555 | [
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<p>Hopefully a very simple question:</p>
<p>If we're told we have n observations, but the model we're evaluating is</p>
<p>$$ y_t = \alpha + \sum_{i=0}^{p}{\beta_i x_{t-i}} + \epsilon_t $$</p>
<p>And say I'm testing $ H_0: \beta_1 = \beta_2 = 0 $</p>
<p>Would the F statistic have: $F(2, n - p - 1)$ distribution, or... | g61556 | [
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<p>When looking for specific indirect effect sizes (lets say we have several series of mediators between "A" and "B"), I have runned nested models. In one model (lets call it, "happy face") I constrained to zero all the paths involved in the specific indirect effect I am not interested in. Then I get a specific indirec... | g61557 | [
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... |
<p>Is there any way to construct an expected conditional probability distribution of the form p(x|(y,z)) if I am starting with p(x|y) and p(x|z)? All variables are categorical.</p>
<p>My specific problem deals with a DNA multiple-sequence alignment. Abstractly, I have a two-dimensional dataset, where each position can... | g18177 | [
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<p>I have been working with nonlinear models whose parameters have been estimated by Maximum Likelihood. Also, I use the "Vuong" test for model selection in non-nested models, this test requires to have every single value of log-likelihood of the sample. Lately, I found the GNM function really useful for estimating mod... | g18178 | [
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<p>For a project, I've collected some basic information on weather, and some basic information on births. Both data sets are focused on a single state, Massachusetts. The weather set contains very basic information: the weather event (hail, winter storm, etc.), and the month it occurred in. Not very granular. Simil... | g18181 | [
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<p>I have measured frequency of a certain behavior on 15 individuals.
I would like to create two groups based on the amount of this behaviour that was observed (i.e., a group exhibiting high levels of the behaviour and a group exhibiting low levels of the behaviour).</p>
<p>I want to see whether this new binary varia... | g3772 | [
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<blockquote>
<p>Ben has a coin which he claims is weighted in a way so that when he flips it, heads appears more often than 50% of the time. He tries to prove it to you by flipping the coin 100 times, which results in 60 heads.</p>
<p>Test the claim that the population proportion of heads that result from flippi... | g61558 | [
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<p>I hope this is an appropriate forum for this question...if not, any pointers on a place to ask would be great. If my questions is not clear, please just let me know and I'll try to add information/explanation where I can.</p>
<p>Say I have a set of data points that I run through a <a href="http://en.wikipedia.org/... | g18184 | [
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<p>I have divided my data (a matrix of proximities expressed by cosines between 94 objects) into clusters with Ward hierarchical method, and I am very happy with the results from a visual point of view. However, I'd like to check whether the quality of the clusters is good.</p>
<p>I've been told that for Ward method, ... | g61559 | [
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0.0781305804848671,
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<p>Other then gapminder.org, could you please direct me to any good examples (interactive or static) of visualizations that compare between countries?</p>
<p>Thanks.</p> | g875 | [
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<p>I am finishing up some analysis on a large set of data. I would like to take the linear model used in the first part of the work and re-fit it using an LME. The LME would be very similar with the exception that one of the variables used in the model would be used in the random effects. This data comes from many obse... | g18186 | [
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<p>I have two cosine signals in MATLAB both having a frequency of 100 Hz and the second signal has been delayed in time by 0.003 seconds. Both signals have been sampled at 1 Khz. When I use the cross correlation function and plot it to verify the delay between the signals, I expect to see a single point in time at whic... | g61560 | [
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<p>I'd like to modify the answer to <a href="http://stats.stackexchange.com/questions/21565/how-do-i-fit-a-constrained-regression-in-r-so-that-coefficients-total-1">this question</a> to allow weighted observations. I think all I need to do is weight the inputs X and Y. </p>
<pre><code>X = w * X
Y = w * Y
</code></pr... | g61561 | [
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<p>I need to resolve a question with the use of SPSS, but don't really know what model to use. The question talks about the environment (scale variable (from not at all concerned - very concerned)), I need to compare it to different scale variables like gender (male/female), age group, education level (no formal educat... | g61562 | [
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<p>I have used 1 DV and 5 IVs. I performed MR to test a model, entered age and gender in first block, IVs in second block, and interaction terms in third block. All the models are coming significant. How can I correct for the significance of interaction model as it is showing significant effect on DV now.</p>
<p>And b... | g18189 | [
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<p>Is it possible to have both Precision and Recall to be equal to 1.</p>
<p>If such a case may exist, does it mean the system is over-fitting the dataset?</p> | g38002 | [
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<p>I should investigate the lead-lag relationship among 2 sets of data, annual incidence of a disease and annual average data of an environmental factor for 13 consecutive years. Both sets are not normally distributed and therefore, correlation should be assessed by Spearman's correlation. But "cross-correlation analys... | g45628 | [
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<p>I've been trying to figure this one for weeks so your advise is very appreciated.
I have log returns for the past 5 yrs on the following indexes: NYSE, Communication, Growth and Large Cap. I performed PCA on those and kept 2 ‘unobservable factors’ with loadings as follows:</p>
<pre><code>NYSE Index 0.2599870 0.... | g42079 | [
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<p>Suppose a survey contained a dichotomous variable of chief interest, such as smoker/non-smoker, along with ten other dichotomous variables. Then suppose that the incidence of smokers is a rare event with an unknown population proportion. The goal is to infer differences between smokers and non-smokers from the answe... | g48042 | [
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<p>I am really new to statistics and now I have some data and I want to make a frequency table with the yearly salary (a variable in my data). In the end, I need to be able to say what is the maximum salary of the first 25% people and the minimum salary of the top 10%.</p>
<p>How should I do it in SPSS?</p> | g61563 | [
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<p>In my elementary statistics course, I learnt how to construct 95% confidence interval such as population mean, mu based on <strong>asymptotic normality</strong> for "large" sample size. Apart from <strong>resampling methods</strong>, there is another approach based on <strong>"profile likelihood"</strong>. Could som... | g61564 | [
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<p>Suppose I wanted to know a one minute average of the time it takes to make a breath. So basically I would record the number of times I made a breath during one minute (one inhale and one exhale) and divide by 60 seconds to get the 1 minute average time to make a single breath? Would this be a distribution with a sta... | g45828 | [
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... |
<p>Can somebody give me references (book/online resource) on using R for Marketing Mix Modelling?</p> | g18192 | [
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<p>I have a SPSS database with 747 patients with sickness symptoms and lab results as variables. With those symptoms and results I have generate two scoring systems. I sum the scores of all the variables to come to the final score.</p>
<p>However, on one variable I have 546 missing values. For the 201 other patients I... | g61565 | [
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<p>Do there exist any systems for symbolically solving expectations?</p>
<p>This is sort of a follow-up to my question <a href="http://stats.stackexchange.com/q/9809/3577">List of Tricks for Solving Messy Expectations?</a> Basically, I'm looking for ways to solve a messy expectation after I've exhausted all obvious r... | g18194 | [
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<p>I'm doing some research into methods for discretizing a continuous variable coupled with a binary target variable to find the optimal split points to maxamise a measure of impurity (gini/entropy).</p>
<p>First off I'm having some trouble coming up with google-able terms. "Optimal Split" seems to relate to choosing ... | g61566 | [
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<p>I have a device which rotates on a stepper motor through a belt and pulley system. I would like to know both the positional accuracy and precision of this movement.</p>
<p>It is of my opinion that this should be determined by taking a large number of measurements to random angles to give a bell curve then using the... | g18195 | [
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<p>I am trying to understand how CNN works. I want to use them in object recognition task. I thouhgt that CNN is unsupervised networks. My main question is how can I implement the back propagation without using image targets (pre-defined labels), in order to calculate the error function which will affect the weights of... | g61567 | [
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<p>What does "X" stand for in "XARMAX"? I searched online but couldn't find it.</p>
<p>Is there "XARMA"?</p>
<p>Thanks!</p> | g61568 | [
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<p>I have a log of customer call data, and would like to know what kind of statistical test I could use to test for statistical significance. Customers call with a unique call reason, and fit into either one customer type, young customers or elderly customers.</p>
<pre><code>Call Reason Young customers Elder... | g61569 | [
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... |
<p>Let $X$ be an integer-valued $rv$ with $\mathrm{pgf}$ $P(s)$ (probability generating functions) and suppose that $\mathrm{mgf}$ $M(s)$ (moment generating functions) exist for $s∈(-s_0,s_0),s_0>0$. How can we proof that $M(s)$ and $P(s)$ are related??</p> | g61570 | [
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<p>Just wondering what you call a regression undertaken with robust variance estimators for clustered data. </p>
<p>Is it ok to say you have used OLS regression with robust variance estimators for clustered data, or is this fundamentally not the case (i.e. once you are using robust variance estimators for clustered da... | g61571 | [
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... |
<p>I read at <a href="http://www.unesco.org/webworld/idams/advguide/Chapt5_2.htm" rel="nofollow">http://www.unesco.org/webworld/idams/advguide/Chapt5_2.htm</a> that this was the degrees of freedom I should use, but I don't understand why. My understanding was that t-tests generally had n-1 degrees of freedom.</p> | g929 | [
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<p>Will software eventually make statisticians obsolete? What is done that can't be programmed into a computer?</p> | g61572 | [
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<p>I've been working for almost a year on electricity load forecasting in collaboration with some climate scientists, using temperature data obtained from models. Instead of using directly temperature values, we use the 'anomaly' from the annual average (called 'climatology'). It seems, in climate sciences, that is goo... | g18200 | [
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<p>I am using the <code>homals</code>-package in R to optimally quantify my data that contains categorical (nominal and ordinal) as well as numerical variables. My goal is to quantify the categorical variables using optimal scaling. To achieve this, I use the rank constraint <code> rank = 1</code>, since this "reduces ... | g31601 | [
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<p>I'm looking for common standards (file formats) for how most statistics software packages import data. </p>
<p>The reason is that I'm going to make an export function for a simulation software package.</p>
<p>The data to be exported consists of time-series of (1 or more) values for all members of a population. The... | g624 | [
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<p>I am looking for a KNN imputation package. I have been looking at imputation package (<a href="http://cran.r-project.org/web/packages/imputation/imputation.pdf">http://cran.r-project.org/web/packages/imputation/imputation.pdf</a>) but for some reason the KNN impute function (even when following the example from the ... | g61573 | [
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<p>Here are some simulated data:</p>
<pre><code> library(mvtnorm)
I <- 3 # positions (fixed factor)
J <- 4 # tubes (random factor)
K <- 4 # repeats
n <- I*J*K
set.seed(123)
tube <- rep(1:J, each=I)
position <- rep(LETTERS[1:I], times=J)
Mu_i <- 3*(1:I)
Mu_ij... | g18209 | [
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<p>I am undertaking a study which has the following aims:</p>
<p>The main aim of the current study is to investigate the effects of food messages about the healthiness of foods on actual food intake. </p>
<p>Additionally, a secondary aim is to discover the extent to which impulsivity/sensation seeking, taste prefere... | g61574 | [
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<p>In my experiment in which participants make a yes-no decision, I use two measures of empathy because I predict these to be both of influence. The two questionnaire scales are weakly correlated but do not measure exactly the same. Can I include these two scales in my mixed model ANOVA or will they sort of average eac... | g61575 | [
-0.0061222100630402565,
-0.06219615787267685,
-0.0005776393809355795,
-0.06406207382678986,
0.03974979370832443,
0.03296084329485893,
0.009393799118697643,
0.015460132621228695,
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-0.001273644040338695,
0.027484452351927757,
-0.006905221380293369,
0.012912622652947903,
... |
<p>Does vector autoregression (<a href="http://en.wikipedia.org/wiki/Vector_autoregression" rel="nofollow">VAR</a>) model require data to be of normal distribution? What are the pitfalls if the residuals are not of normal distribution?</p> | g61576 | [
0.010187376290559769,
-0.020017176866531372,
-0.025595733895897865,
-0.029567034915089607,
-0.038791920989751816,
-0.004092477727681398,
0.05810653790831566,
-0.011547479778528214,
-0.04265069589018822,
-0.017202353104948997,
-0.022874930873513222,
0.009038612246513367,
0.008958271704614162,... |
<p>I am assessing a bunch of risk factors related to HIV infection by logistic regression.
First I will conduct a couple of chi square tests or t-tests to see if each factor is associated with HIV infection or not.</p>
<p>Then I will pick those factors with p value less than 0.1 out of the bivariate analysis above and... | g61577 | [
0.01967621222138405,
-0.028963550925254822,
0.013884189538657665,
-0.010411955416202545,
0.013612356968224049,
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0.006365322042256594,
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-0.005021954420953989,
0.009451414458453655,
0.028740383684635162,
-0.04190345108509064,
0... |
<p>As I understand it, the definition of the hazard ratio is the ratio of two hazard rates. Often the exp(coef) from a Cox model is also used as an estimate of the hazard ratio. These methods give two different, although similar, results. Are there circumstances in which it's appropriate to use one method vs. the other... | g587 | [
0.05066918954253197,
-0.015635529533028603,
0.013286576606333256,
-0.0058067794889211655,
0.06256810575723648,
-0.017440523952245712,
-0.021734017878770828,
0.017896683886647224,
0.012354742735624313,
0.0013408255763351917,
0.018792765215039253,
-0.009769640862941742,
0.0818546786904335,
0... |
<p>I am wondering what is the best way to extract knowledge about periodic time series data?</p>
<p>In my case, I am trying to analyse <a href="https://www2.ameren.com/RetailEnergy/rtpDownload.aspx" rel="nofollow">historical hourly electricity prices</a> to get information about its volatility, when the peaks occur, w... | g61578 | [
0.029109526425600052,
0.0039009132888168097,
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-0.008759872056543827,
-0.01322266086935997,
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0.02500610426068306,
-0.014842000789940357,
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0.03213287517428398,
0.052406251430511475,
-0.029496369883418083,
0.02918313816189766,
0.0... |
<p>I am trying to do nonlinear regression on a dataset obtained from full factorial design (2 and 3 levels) with the help of genetic programming. </p>
<p>Is there something fundamentally wrong with trying to construct a nonlinear regression model with full-factorial design? My background is not in statistics, and I di... | g61579 | [
0.015164823271334171,
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0.008940601721405983,
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0.04473573714494705,
0.029... |
<p>This is a follow up to <a href="http://stats.stackexchange.com/questions/55301/best-process-for-randomly-drawing-an-odd-and-an-even-number">my previous question</a>.</p>
<p>Assume I want to randomly draw two numbers from the numbers 1 to 8, one even number and one odd number. I would create two urns, one with the e... | g61580 | [
-0.03032735362648964,
0.02462327666580677,
0.019661452621221542,
-0.053738512098789215,
0.019509892910718918,
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0.011690116487443447,
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-0.06694366037845612,
-0.020746540278196335,
-0.011500558815896511,
0.04716234281659126,
-... |
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