question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>My research generates raw data from titrations that needs a substantial number of calculations before I get the numbers in a form that I can analyze. Most of these calculations are relatively simple unit conversions etc... Typically I create a spreadsheet in Excel to perform all of these calculations and then only... | g37938 | [
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<p>I'm trying to find which type of statistical test I need for the study below (inputting into SPSS). I was thinking it could be repeated measures ANOVA or numerous paired t-tests??? Thoughts please...</p>
<p>Title: A study into the effects of acute creatine supplement on cognitive function of sleep deprived subjects... | g65394 | [
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<p>The RMS for the regression line is: $\sqrt{(1-r^2)}\cdot sd(y)$ where $sd(y)$ is the standard deviation of $y$ -- let's call this eq 1.<br/>
Another way of calculating it is: $\sqrt{(\sum(residuals^2))}\cdot 2$; let's call this eq 2.</p>
<p>When I run eq2 in R I get different results vs when I hand calculate using ... | g65395 | [
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<p>We know that $X\sim {\mathrm {GEV}}(\alpha ,\beta ,0)$ and $Y\sim {\mathrm {GEV}}(\alpha ,\beta ,0)$ then $X+Y\sim {\mathrm {Logistic}}(2\alpha ,\beta )$. </p>
<p>I am wondering, what will be $X+Y+Z$ like, if $Z\sim {\mathrm {GEV}}(\alpha ,\beta ,0)$ also. And more generally what will $\sum X_{i}$ be if $X_{i}\... | g23928 | [
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<p>Simple question with no simple answer.</p>
<p>Let's say I compute 100 p-values from 100 hypotheses that have similar power (i.e. similar sample size). Now let's say I produce 1000 p-values from a series of hypotheses that are relatively under-powered (i.e. have a smaller sample size for each test). How does one con... | g23929 | [
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<p>I am doing time series analysis using R. I have to decompose my data into trend, seasonal and random component. I have weekly data for 3 years. I have found two functions in R -- <code>stl()</code> and <code>decompose()</code>. I have read that <code>stl()</code> is not good for multiplicative decomposition. Can any... | g65396 | [
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<p>I am rather ignorant about nonparametric bootstrap. Assume the same context as in <a href="http://stats.stackexchange.com/questions/29906/nonparametric-confidence-interval-about-the-difference-of-means-for-unpaired-dat">this question</a>: ${(x_i)}_{i=1}^m$ and ${(y_i)}_{i=1}^n$ are independent data samples, the $x_... | g65397 | [
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<p>Is there a software package that supports, or could support, through operator overloading or extensions, code such as the following;</p>
<pre><code>x = rand_arr(10) ; array 10 elements long
y = rand_arr(10)
z = x + y ; elemental addition (z[0]=x[0]+y[0];z[1]=x[1]+y[1],...)
print z
</code></pre>
<p>If the above, or... | g65398 | [
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<p>I am studying Variational Methods and decided to code a simple matlab implementation of the famous image denoise example:</p>
<p>$E(u) = \displaystyle\frac{1}{2}\sum_{i=1}^N (u_i - f_i)^2 + \displaystyle \frac{\lambda}{2}\sum_{i=1}^N | \nabla u_i|^2$</p>
<p>where the first term (data) measures how close the denois... | g65399 | [
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<p>I'm reading "<a href="http://www-stat.stanford.edu/~hastie/local.ftp/Springer/ESLII_print4.pdf" rel="nofollow">The Elements of Statistical Learning</a>" and early on there are references to <strong>p-vectors</strong> (page 10) and <strong>K-vectors</strong> (page 12). </p>
<p>What exactly is meant by a p-vector and... | g65400 | [
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<p>I have a small sample (n = 8), and I have calculated the mean and standard error of the mean. I don't know the underlying distribution of these observations, and I cannot assume it to be normal.</p>
<p>I want to derive the 95% confidence interval of the mean, and I have seen that people use Student's t distribution... | g65401 | [
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<p>I'm doing ordinal logit/probit only to analyse the direction of causality (e.g. if some variable makes it more likely to observe a low scale or a high scale). No interpretation is needed beyond this.</p>
<p>I can only report either (i) odds ratios, (ii) coefficients, in my table. </p>
<p>Is there a standard one I ... | g65402 | [
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<p>Will I be breaking the logic of supervised training if I check generalisation error in the process of NN training to see if it increases, and then do something to the NN if it does? Generalisation error is the only indication of overfitting. On the other hand, using generalisation error for training purpose implicit... | g65403 | [
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<p>I am working with a dataset with 12 covariates(categorical). The covariates have different Levels, some are from 0-5, and one has as much as 0-11 categories.</p>
<p>I started with a univariate analysis to choose significant
covariates. After that I test for interaction between covariates, so I later on can include ... | g23937 | [
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<p>I'm a newbie in cluster analysis so please excuse me if my question seems to be very basic.
I'm using SPSS and Matlab for performing cluster analysis in a variety of datasets.
Dendograms are great for visualising the results.
However, they are not helpful for comparing the results produced by different clustering me... | g23939 | [
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<p>I once stumbled across a type of plot for categorical data (i.e., contingency tables) on the internet, which I really liked, but I've never found it again, and I don't even know what it's called. It was essentially like a sieve plot, in that the row heights and column widths were scaled relative to the marginal pro... | g23940 | [
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<p>Consider the following figure from Faraway's Linear Models with R (2005, p. 59).</p>
<p><img src="http://i.stack.imgur.com/rtn7e.png" alt="enter image description here"></p>
<p>The first plot seems to indicate that the residuals and the fitted values are uncorrelated, as they should be in a homoscedastic linear mo... | g65404 | [
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<p>The particle physics community tends to report the <a href="http://arxiv.org/abs/1207.7214" rel="nofollow">significance of a discovery</a> by first calculating the p-values over a range of hypotheses (i.e. values of mass for the hypothetical particle), and then correcting for the "<a href="http://www.springerlink.co... | g43947 | [
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<p>I am trying to build a model to correct the class probability given by a classifier with a priori probabilities. Here are the probabilities that I have for that model:</p>
<ul>
<li>predicted probabilities from the classifier</li>
<li>a priori probabilities</li>
<li>probability of a class</li>
</ul>
<p>Any suggesti... | g65405 | [
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<p>I apologize in advance for the vague title, but I couldn't think of anything better.</p>
<p>I have two datasets, where one is a very small subset of the other. The percentage of people who have a specific attribute in the large dataset is x%. The percentage of people who have the same attribute in the subset is y%.... | g23944 | [
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<p>I'm fitting a model using R's <code>glm</code> and I would like to add a term with a particular interaction of variables:</p>
<p>$$
a\frac{K+0.6b}{T+b}
$$</p>
<p>where $K$ and $T$ are columns of data and $a$ and $b$ are constants to be fitted.</p>
<p>The overall model, then, looks like</p>
<p>$$
p=a\frac{K+0.6b}... | g65406 | [
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<p>I'm a beginner to statistics (taken only one college course), but I have a background in programming. </p>
<p>I just started playing with a Bayesian classifier library for Ruby and I am looking for ideas for things to analyze.</p>
<p>Right now I'm messing around with Tweet categorization, but do you have any ideas... | g65407 | [
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<p>I have a confusion related to the calculation of autocovariance </p>
<p>Suppose</p>
<p>$X_t = \phi X_{t-1} + \epsilon_t$</p>
<p>Then how the autocovariance </p>
<p>$E(X_{t+n}X_t) - \mu^2 = \frac{\sigma_{\epsilon}^2}{(1-\phi^2)}\phi^{|n|}$</p>
<p>I am referring to this wiki article <a href="http://en.wikipedia.... | g37540 | [
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<p>I'm a bit stuck on the general concept and calculations of iterated expectations. A simple example:</p>
<p>$$E[E[Y|X]] = E[Y]$$</p>
<p>I'm not sure how or why this is the case? I have a 3 line proof in my notes using densities and stuff but is there no 'quicker' way. Especially in longer cases like (below) writin... | g65408 | [
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<p>Can someone explain in as clear a (formalish mathematical) way as possible why the KS test in original form with parameter estimates is unreliable?</p> | g65409 | [
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<p>There are several methods to make forecasts of equidistant time series (e.g. Holt-Winters, ARIMA, ...). However I am currently working on the following irregular spaced data set, which has a varying amount of data points per year and no regular time intervals between those points:</p>
<p>Plot:
<img src="http://i.im... | g65410 | [
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<p>OK, I feel stupid asking this, but I am positive you all will know exactly what I should do here. </p>
<p>I have a simple regression situations (small sample sizes; n=13-18), and a few observations that are different with respect to a suite of characteristics that can be generalized by a single dummy variable (ex.... | g65411 | [
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<p>How, and should I, use KL-divergence to improve a naive Bayes classifier?</p>
<p>I have a Naive Bayes Classifier working on a number of datatypes (real, boolean and categorical). Each variable is weighted identically. But from inspecting my data I know
that some variables contribute more to my overall classificatio... | g39707 | [
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<p>I found this question on the open MOOC from Stanford, however the answer is not present. </p>
<p>I think the median $\leq$ mean.</p>
<p>Is this the case?</p> | g65412 | [
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<p>I have results from three archaeological populations in which I found that the prevalence of a certain disease was:</p>
<p>65% (13/20) in population A, </p>
<p>31.25% (5/16) in population B and </p>
<p>46.60% (48/103) in population C </p>
<p>I did a chi-squared test and found that while population A was signific... | g65413 | [
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<p>I have the following generalized linear model. Object <code>glmDV</code> is modeled as a proportion of successes over total trials. Objects <code>x_i</code> are continuous variables.</p>
<p>How does this look in math notation?</p>
<p><code>winp.glm = glm(glmDV ~ x1 + x2 + x3 + x4 + x5 + x6 + x7, data=myData, famil... | g65414 | [
-0.0022767477203160524,
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<p>I am working on a model that predicts gestation period of new hires. By gestation period, I mean the period between when they completed their training and the time they start working on their first real live project. I have data for gestation period in months. I classified the time into two parts - "0 - 3 months" an... | g21719 | [
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0.0... |
<p>I am currently developing a mathematical symbol classifier (see <a href="http://write-math.com" rel="nofollow">http://write-math.com</a>) for my bachelors thesis in computer science. To evaluate what type of classifiation / features / parameters work, I calculate from the labeled dataset with $n$ instances of $m$ ma... | g65415 | [
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<p>In analyzing panel data is it important to see the correlation matrix?if so then should we have to drop those variables which has higher correlation?Is there any rule of thumb?How do I decide which variables to take as my independent and control variable?</p> | g65416 | [
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<p>For a meta-analysis I'd like to calculate and aggregate ES-values from studies reporting F-values for mixed model-ANOVA-s. Can you recommend any literature specifically on this topic?</p>
<p>+++</p>
<p>After posting the question I realized it is related to <a href="http://stats.stackexchange.com/questions/41861/ca... | g23957 | [
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<h1><strong><em>Background and experiment details</em></strong></h1>
<p>We have just completed data collection for an experiment. The experiment was a long term study which involved assessing the effect of a drug on behavioural attributes.</p>
<p>Behavioural data involved collection of over 22 attributes/characterist... | g65417 | [
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<p>I am trying to create a plot in R which gives me boxplots (and/or distributions) of one column ranked by quantiles (and/or equally spaced groups) of another column in a dataframe.</p>
<p>An example would be the following plot:</p>
<p><img src="http://i.stack.imgur.com/Jg8SM.png" alt="enter image description here">... | g65418 | [
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<p>I'm training a bunch of SVM models to do one-against-all multiclass classification (a test instance is classified as the class which produces the largest positive SVM response).</p>
<p>What's the best way to do cross-validation for selection of the regularization parameter?</p>
<p>Should I do cross-validation sepa... | g65419 | [
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<p>I need to fit a generalised extreme value distribution to my data but I want the ability to perform generalised linear modelling of the parameters, particularly the location. Can anyone recommend the best method/R package for doing this?
Thanks</p> | g29134 | [
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<p>I am faced with the following problem : I have binomial data, ie. data of the form trials/successes, with a list of features. </p>
<p>What I need is to sample without replacement from that data, ie. take a fraction $p$ (in my case 50%)of the examples. Since the data is aggregated, this is tricky.</p>
<p>So far my ... | g11335 | [
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<p>I have implemented a constraint-based random number generator producing 3 columns with the constraint that each row sums to 1:</p>
<pre><code>0.4 0.3 0.3
0.5 0.2 0.3
0.5 0.3 0.2
0.6 0.1 0.3
0.6 0.3 0.1
0.8 0.1 0.1
0.6 0.2 0.2
0.3 0.4 0.3
0.2 0.5 0.3
0.3 0.5 0.2
0.1 0.6 0.3
0.3 0.6 0.1
0.1 0.8 0.1
0.2 0.6 0.2
0.3 0.... | g65420 | [
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<p><strong>Question:</strong> Is anyone aware of a consistent, non-parametric estimator of the expected value of an asymmetric distribution that is robust to fat tails? What if we constrain ourselves to the class of continuous (on the real number line) uni-modal distributions?</p>
<p><strong>Note:</strong> There are s... | g65421 | [
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<p>I have seen two different representations of the quantile regression estimator which are</p>
<p>$$Q(\beta_{q}) = \sum^{n}_{i:y_{i}\geq x'_{i}\beta} q\mid y_i - x'_i \beta_q \mid + \sum^{n}_{i:y_{i}< x'_{i}\beta} (1-q)\mid y_i - x'_i \beta_q \mid$$</p>
<p>and
$$Q(\beta_q) = \sum^{n}_{i=1} \rho_q (y_i - x'_i \bet... | g65422 | [
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<p>I would like to determine the variance explained by random factors and slopes in a mixed model but am unsure if the analysis I use and my interpretation are correct. Furthermore, comparing models and analysing a mixed model with random slopes seem to give opposite conclusions, therefore I would like to know when to ... | g23963 | [
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<p>I am exploring hierarchical logistic regression, using glmer from the lme4 package. To my understanding, one of the first steps in multilevel modeling is to estimate the degree of clustering of level-1 units within level-2 units, given by the intraclass correlation (to "justify" the additional cost of estimating par... | g23964 | [
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<p>Can anyone show me how gradient boosting works for a binary classification problem (the process) using Bernoulli loss function? What is the format of the loss function and how to calculate the gradient?</p> | g23965 | [
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<p>I have a simple contingency table with two nominal variables. Let's say Age and Gender. The software that I'm using reports the relationship between the two variables using Pearson's Chi-Square Test of Independence, to which I understand.</p>
<p>But when I select only two cells in the table and try to do a test for... | g65423 | [
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<p>I am currently running some mixed effect linear models. </p>
<p>I am using the package "lme4" in R. </p>
<p>My models take the form:</p>
<pre><code>model <- lmer(response ~ predictor1 + predictor2 + (1 | random effect))
</code></pre>
<p>Before running my models, I checked for possible multicollinearity betwee... | g23966 | [
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<p>I kinda have a another question and solved it but I'm unsure if I did it right.</p>
<p>I first attempted to find the posterior density of the parameter using this formula</p>
<p><img src="http://i.imgur.com/lSxWfix.png" alt="a busy cat"></p>
<p>However if the X is observed to be 2 is it fair to assume n=1 and tha... | g65424 | [
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<p>I'm using kernel utilization distributions to describe bird territories and also to estimate overlap between multiple territories. There are several ways to calculate overlap and one of the published methods is called a UDOI. The equation is
$$UDOI = V1,2 \iiint UD1 (x,y,z) \times UD2 (x,y,z) dxdydz$$</p>
<p>where... | g65425 | [
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<p>Not sure if I should ask this at math or here but anyway. I am wondering what we as people could do if we were asked to produce a random sequence of numbers (let's say between 1 and 1000). I'd say it would normally be really easy to prove that people are bad at producing random numbers. How could we try to avoid it?... | g65426 | [
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<p>I have a longitudinal dataset-- a series of measurements were collected each individual in the study, and the individuals fall into several treatment groups (normal untreated, mutant untreated, normal treated, mutant treated).</p>
<p>I am fitting a models where the fixed terms include a spline function of each indi... | g65427 | [
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<p>I have a series of data looking like this, and I wonder if this can be considered to close to normally distributed, even if it has a tail to the right? Can I use t-tests and define "large" being over 1 standard deviation and such, or would that be wrong?</p>
<pre><code>Count 1 536
Mean 27,8
Median 26,0
Mod... | g43980 | [
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... |
<p>Can discrete wavelet trasform be used for feature extraction from time series in order to cluster them? Any R code how to do this will be appreciated.</p> | g65428 | [
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<p>Questionaires are often used in social sciences.
Many people try to complete them very quickly and very often they only "guess" answers.
Is there any statistical technique or any research in this area, how to identify which questionnaires are completed poorly?</p>
<p>I think that this is similar to detection of out... | g23973 | [
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<p>I assessed the internal reliability of a self-created scale with eight items ($N = 150$) by calculating Cronbach’s $\alpha$. It appears that one item correlates low with the overall score of the scale (item 4 in the example below). The corrected item-total correlation, i.e. the correlation of this item with the scal... | g65429 | [
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<p>Apart from some unique circumstances where we absolutely must understand the conditional mean relationship, what are the situations where a researcher should pick OLS over Quantile Regression?</p>
<p>I don't want the answer to be "if there is no use in understanding the tail relationships", as we could just use med... | g65430 | [
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<p>Do both graphical models and stochastic networks (e.g. <a href="http://people.cs.pitt.edu/~milos/networks/" rel="nofollow">http://people.cs.pitt.edu/~milos/networks/</a>) mean the same concept: there is an underlying graph, each vertex corresponding to a random variable, and the edges representing the dependence be... | g65431 | [
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<p>I was just wondering if there were any consequences to applying dummy variables to independent variables which don't need it.</p>
<p>For example, let's say I ran an OLS with income as my y variable and age and education as my x variables. Let's imagine I then used a dummy variable for every working age (instead of ... | g65432 | [
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<p>In the following second order equation $ax^2+2bx+1.5=0$ where $a$ and $b$ are given by random points $(a,b)$ in the $[0,2]\times[0,1]$ rectangle, what is the probability of having two real solutions?</p>
<p>I'm a little lost here. I tried integrating $4b^2-6a$ with $a=0\to 2$ and $b=0\to 1$ as limits but the integr... | g16938 | [
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<p>I've been tasked with performing a propensity score matching and to measure the <code>standardised difference</code> for every covariate to assess the quality of fit. Details are given <a href="http://www.ispor.org/news/articles/feb06/propensity.asp" rel="nofollow">here</a> and some SAS code <a href="http://support.... | g65433 | [
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0.009695246815681458,
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-0.01... |
<p>when dealing with missing data, filled in observations can be created for missing data and weights can be assigned to these filled in data based on Bayes theorem. <strong>I am wondering how to implement this in R for this example below.</strong></p>
<p>$$p(x_{miss}\mid y_i, x_{obs,i},\theta^s)=\frac{p(y_i\mid x_i,\... | g65434 | [
0.050880130380392075,
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<p>Do you know how can I compute out the p-value in LM statistics? (What is the command in stata?)
I know that to implement the LM computing procedure I have to do the following steps:</p>
<ol>
<li>Obtain the OLS estimators of the restricted model;</li>
<li>Obtain the residuals regression;</li>
<li>regress the residua... | g23975 | [
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<p>I'm currently writing a .NET library to handle various statistical/classification tasks and I am currently writing the structures to represent nominal and ordinal data.</p>
<p>In doing so, I've been debating whether or not the structures that handle ordinal data should derive from the structures that handle nominal... | g23976 | [
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<p>I have a situation where I measure something for a long time, and occasionally a seperate event of interest will occur. I want to determine if these events have a significant effect on the signal I am measuring. So I am thinking of taking the signal value at each event time, and comparing it to times when there was ... | g23977 | [
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<p>A sequence of symbols is produced as follows:</p>
<p>Some unknown mechanism mimics sequential drawns are made from a set of $N$ distinct symbols. So we have a series $\{a_j\}$ with $a_j\in \{1,2,\dots N\}$.</p>
<p>The data is now censored in the following way:
Fix some integer $k$ (let us assume, say, $3k < N$ ... | g43994 | [
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<p>Given two classes of training data (A and B), I want to fit each class' distribution using a GMM with k components, and then use Bayes Decision Model for the classification. </p>
<p>The first step was to use PCA on data set A, project the data into
a lower-dimensional subspace, and then for each class do the actu... | g43995 | [
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<p>In a simple experiment I asked participants to make acceptability judgements (9-point Likert scale) when they observed different animated virtual characters. I have two factors: character (7 levels) and motion (5 levels). </p>
<p>Two-way ANOVA showed significant interaction between the above factors, so I want to e... | g65435 | [
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<p>I hope this finds someone with the right expertise here.</p>
<p>I am currently working with a data set on product information that has
- a defined search tree structure
- product types
- synonyms for product types
- usages for product types</p>
<p>Most of the above are connected in an n:m fashion, e.g.
- a product... | g65436 | [
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<p>I have a set of $N$ bodies, which is a random sample from a population whose mean and variance I want to estimate. A property of each body is being measured $m_i$ times ($m_i>1$) and different for each body index $i$ identifies which body it is; the property is expected to be distributed around zero). I would li... | g65437 | [
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<p>I have a sample of experimentally measured survival times that are quite noisy and vary stochastically. The survival probability of these events (number of events with a survival time of t or more) is expected to decay in time as a single exponential. My experimental sample size is small (10 to 15 events) and I have... | g65438 | [
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<p>I've come across a very good text on Bayes/MCMC. IT suggests that a standardisation of your independent variables will make an MCMC (Metropolis) algorithm more efficient, but also that it may reduce (multi)collinearity. Can that be true? Is this something I should be doing as <strong>standard</strong>.(Sorry).</p>
... | g23981 | [
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<p>I am looking for freeware similar to MS Access for data mining, querying and reporting without really writing SQL (which I know very well but sometimes I feel lazy and would rather just drag and drop). I had used MS Access with ODBC connections to all sorts of external RDBMSs that create an Access pseudo-table as a... | g65439 | [
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<p>I have two continuous stochastic Markov processes: the concentration readout of two proteins in a cell over time. These are shown in this figure, where the blue line is the unbounded protein, and all other lines are zero bounded proteins, but I am interested in just one of them. (The y axis is concentration, and sor... | g65440 | [
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<p>I'm working with a mixed model for which I have several response measurements for every individual. One goal is to determine the sampling variance/covariance of the fixed effect estimates for a particular trait. This has been relatively straightforward to accomplish. However, I would also like to estimate the sam... | g23984 | [
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<p><em>Before you begin reading, I want to say thank you for helping, or attempting to help me. I really appreciate any help you can give me! Also, warning: Wall of Text approaching fast.</em></p>
<p>I've been informed that I am misusing the term Confidence Interval. I have been told that what I am actually looking fo... | g65441 | [
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<p>I am new to R, and don't see these questions answered anywhere in documentation (though I could be wrong).</p>
<ol>
<li><p>I am using the following nomenclature to run my mixed-effects logistic regression, based on instructions from another site: </p>
<p><code>output <- glmer(DV ~ IV1 + IV2 + (1 | RE), family ... | g23986 | [
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<p>I'm using offset for the first time (as per a recommendation from a colleague) and have a couple questions about interpreting my results. Our ultimate goal is to look at the effect of some population level treatment on disease incidence (cases/population). We've decided to use poisson models, but there are surely ... | g23987 | [
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<p>Imagine that you repeat an experiment three times. In each experiment, you collect triplicate measurements. The triplicates tend to be fairly close together, compared to the differences among the three experimental means. Computing the grand mean is pretty easy. But how can one compute a confidence interval for the ... | g65442 | [
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<p>I have two sets of data for males and females: $n=33$. I'd like to compare test results for both groups. I want to do a $t$ test, and I know my data should be normally distributed if I want to use a parametric test. I also know that if $n>30$, then the $t$ test normality assumption can be violated. Anyway, what w... | g65443 | [
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<p>I am planning to do a statistical power analysis, and I would like to know how to calculate the required sample size to detect an interaction between two continuous predictors in the presence of other covariates. The outcome I have could be analyzed continuously or categorically. I'm looking for both solutions. Is t... | g65444 | [
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<p>I have one parameter, that is, a behaviour happened or not. I have then the proportions of animals who performed the behaviour under different treatments. I want to compare if there are any difference between the treatments. Specifically if treament A differs from treatment B or C, etc. I have only GraphPad Prism an... | g65445 | [
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<p>I need to use a test for normality for a problem.</p>
<p>By calculating skewness, there is a formula, which is:</p>
<p>$$
\text{skewness} = \frac{\sum (x_i -\bar{x})^3/n}{s^3}
$$ where $\bar{x}$ is the sample mean. </p>
<p>But I don't know how to calculate $s$ in the formula. What is $s$? </p> | g65446 | [
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<p>Suppose we have $n$ observations. For example, consider $n$ people who each have their blood pressure ($x_1$), pulse ($x_2$), and blood glucose ($x_3$) levels measured. So there are are $3$ explanatory variables measured for each person. The outcome variable is presence or absence of obesity ($Y$). In this case, doe... | g23990 | [
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<p>I'm practicing MANOVA with R.
I have a data (perhaps famous) called 'rat-weight data.'</p>
<pre><code>> rat
w0 w1 w2 w3 w4
1 46 70 102 131 153
2 49 67 90 112 140
3 49 67 100 129 164
4 51 71 94 110 141
5 52 77 111 144 185
6 56 81 104 121 151
7 57 82 110 139 169
8 57 86 114 139 172
9 60 93 123 14... | g65447 | [
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<p>I have small dataset that cannot be extended (rare disease) in which I have 30 instances characterized by 20 features each. The features are concentrations from spectrometry (scale var). As I care about the difference in concentrations I feel ranking useless in this scenario. Is it justified to use parametric statis... | g65448 | [
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<p>I am trying to simulate multi-level data for repeated measurements. My design includes just one within subjects factor, no between-subject factor. Consider the case of three treatment conditions with 10 trials in each. This is what I've written so far (using R):</p>
<pre><code>##### repeated measures analysed using... | g29593 | [
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<p>First I am confused what the <code>ugarchfit</code> in the <code>rugarch</code> package means by likelihood versus loglikelihood. In the complete ugarchfit output it says "log-likelihood". But when extracting the likelihood by the function <code>likelihood()</code> we get the same number. Here <a href="http://www.in... | g65449 | [
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<p>Given a Bayesian network, if I reverse the edge from $X \rightarrow Y$,
what additional edges do I need to add to the structure of the network?</p>
<p>I know that there are some rules about linking (adding edges amongst) the parents (and/or children)
for one or both of $X,Y$, but I haven't found a good concise set ... | g23994 | [
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<p>Consider a sample of 34 pairs of values $(x,y)$ for the regression equation
$$
y_{i}=\alpha + \beta x_{i} + \epsilon_i .
$$</p>
<p>Using linear regression (OLS), I got the estimate $\hat{\beta}=2.3$.</p>
<ul>
<li>What is the probability that $\beta>\hat{\beta}$</li>
<li>or $ \beta > 2.3$ in this case?</li>
<... | g65450 | [
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<p>Wooldridge 2002 describes how to test for serial correlation in pooled OLS but I don´t get it when I have to use it in STATA. </p>
<p>Does anyone know how to test for serial correlation after pooled ols?
I know that there are various methods when using the FE and RE models but it is not the same? </p> | g65451 | [
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<p>I ran into little trouble transforming a set of data I need for analysis. I have been trying to analyze results of a lab test as Z-scores. I have an output field with a reading and unit field. Data are shown in the figure below. </p>
<p><img src="http://i.stack.imgur.com/bdnas.png" alt="Data Set"></p>
<p>The appro... | g65452 | [
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0.06015099957585335,
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0.0014538443647325039,
0.009965666569769382,
0.02675933577120304,
0.03697016090154648,
-0.0... |
<p>My problem this time concerns sampling size-related errors, resample-based confidence intervals and a possible way to control for this error. My dataset consists of 50 measurements of certain cranial dimensions, from several groups (populations). <strong>My aim is to calculate a certain index based on a correlation ... | g65453 | [
-0.0061283353716135025,
0.009121960960328579,
-0.004610536620020866,
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0.007429676596075296,
0.03562312200665474,
0.024334019050002098,
0.012119142338633537,
... |
<p>I have a nested question of sorts. My first question, is that I am wondering if it is possible to 'convert' a Rayleigh random variable into a uniform random variable, and how one may do this. </p>
<p>Strongly related and dependent on this question though, is: if such a conversion was possible, would 'corrupt data',... | g36561 | [
-0.0019505389500409365,
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0.01244709175080061,
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0.00427806144580245,
0.0053738998249173164,
0.0504244901239872,
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<p>I am doing survival analysis using ridge regression. I'm using this R command:</p>
<pre><code>coxph(Surv(time, status) ~ ridge(x1, x2, x3), data=DATA)
</code></pre>
<p>As far as I know, <code>lambda</code> (the regulation parameter) is estimated using cross validation, but then this R code should result in differe... | g65454 | [
0.036046192049980164,
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0.05105166137218475,
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<p>I have a dataset where I am trying to enforce normality on positively-skewed variables. I've found that consecutive log transformations help in achieving normality but am wondering if there is any statistical or theoretical violation that is breached when consecutive log transformations are performed.</p>
<p>Thanks... | g24003 | [
-0.04841316118836403,
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0.005872122012078762,
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0.004206840414553881,
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0.02623533271253109,
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-0.007... |
<p>I've got a study, a before-and-after controlled design.</p>
<p>I have pre-intervention data and post-intervention data, the intervention is an educational intervention, given to general practitioners and the outcomes (a continuous outcome and a binary outcome) are measured on patients. Therefore, the pre-intervent... | g65455 | [
-0.03994600102305412,
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<p>I'm really intrigued by Lasso Regression, and it seems like a potential candidate for estimating “objective” ratings for items based on the users who watched them. The user data is sparse, and the estimation of the overall rating can be a regression problem.</p>
<p>To be clear: I would be using this for a Netflix-p... | g65456 | [
0.009481046348810196,
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0.012660483829677105,
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0.004277720581740141,
0.006661491934210062,
0.08989289402961731,
0... |
<p>There is a web service where I can request information about a random item.
For every request each item has an equal chance of being returned.</p>
<p>I can keep requesting items and record the number of duplicates and unique. How can I use this data to estimate the total number of items?</p> | g24005 | [
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0.04... |
<p>When it comes to compare a new clustering algorithm, one always wants to show the advantages of his/her method over existing and well known methods. Going this way may mislead one to ignore disadvantages proposed method.</p>
<p>For clustering results, usually people compare different methods over a set of datasets ... | g24006 | [
-0.002715262584388256,
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0.062121327966451645,
-0.012271600775420666,
0.08213105797767639,
0.05... |
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