question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I'd like to perform semi-supervised LDA (Latent Dirichlet Allocation) in the following sense:
I have several topics that I'd like to use, and have seed documents that relate to these topics. I'd like to run LDA to classify other documents, and potentially discover other topics.</p>
<p>I would guess there is work do... | g61740 | [
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... |
<p>How to get a random variable with a Boltzmann distribution as the probability density distribution?</p>
<p>Or more practically: In my Java program, I can easily produce a uniform random variable U(0,1) or a uniform distributed integer from the integer value range. </p>
<pre><code>Random rnd = new Random();
double ... | g18482 | [
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... |
<p>I have been looking for computer game datasets, but so far I've only been able to find the 'Avatar History' dataset for WoW.</p>
<p>Are there any other interesting datasets out there, possibly for other genres?</p> | g61741 | [
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... |
<p>I have R data frame like this:</p>
<pre><code> age group
1 23.0883 1
2 25.8344 1
3 29.4648 1
4 32.7858 2
5 33.6372 1
6 34.9350 1
7 35.2115 2
8 35.2115 2
9 35.2115 2
10 36.7803 1
...
</code></pre>
<p>I need to get data frame in the following form:</p... | g61742 | [
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0... |
<p>I am testing the robustness of a predictive model that I have previously established. I used to withdraw multiple random samples to see how robust the model is. Few days ago I came across bootstrap sampling technique, which is claimed to "to improve the stability and accuracy of machine learning algorithms". The tec... | g61743 | [
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<p>I want to test whether segment series explains anything in additional to the full series. </p>
<p>Let's say y and ts_full are time series with same length. And I divide ts_full to 3 non-overlapping sub time series with same length: ts_1 - ts_3. For example, ts_1 has valid values in first time segment and 0 in the r... | g61744 | [
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<p>I'm examining some proportions in some CPS data. Here's my output:</p>
<pre><code>Survey: Proportion estimation Number of obs = 208562
Population size = 293834358
Subpop. no. obs = 10268
Subpop. siz... | g61745 | [
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<p>I have an iid sample $x_1, ..., x_n$ from a random variable $X$ which itself is a convolution $X = Z + \mathcal{N}(0, \sigma^2)$. Neither distribution of $Z$ nor parameter $\sigma^2$ are known (we only assume that $Z$ has no normal divisors). My question is: how can I estimate this $\sigma^2$ based on the sample? </... | g18485 | [
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<p>Let us say I would like to adjust for centre effects in the analysis of data from a multicentre clinical trial.</p>
<p>In the fixed effects approach one simply chooses one centre as reference and
includes a dummy variable for each of the remaining centres.</p>
<p>A problem with that method is that the number of pa... | g61746 | [
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... |
<p>In these days I'm working with <strong>Breusch-Pagan</strong> to test homoscedasticity.</p>
<p>I've tested the prices of two stocks with this method. This is the result:</p>
<pre><code>> mod <- lm(prices[,1] ~ prices[,2])
> bp <- bptest(mod)
> bp
studentized Breusch-Pagan test
data: prices[, ... | g61747 | [
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... |
<p>Is it sensible to convert standard error to standard deviation? And if so, is this formula appropriate?
$$SE = \frac{SD}{\sqrt{N}}$$ </p> | g49743 | [
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0.... |
<p>I am a biologist by training and have started a project assessing “variability” using microarray data. The microarray takes a measurement (expression level) of ~20,000 genes for each sample, and I have 40 samples comprising 18 replicates of one condition and 22 replicates of a second condition. Methods have been ex... | g61748 | [
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<p>How can you estimate the upper bound of $y$ in this situation? Given: </p>
<ol>
<li>a function $y=f(x_1,x_2,x_3,x_4,x_5)$ with 5 parameters ($y=f(\cdot,\cdot,\cdot,\cdot,\cdot)$ can be any function). </li>
<li>for each $x_i$ there are $k_i$ possible values.</li>
</ol>
<p>I want to estimate the upper bound of $y$ ... | g61749 | [
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0.002102290978655219,
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0.03565071150660515,
0.020559178665280342,
... |
<p>I know how to use PDFs to calculate probabilities, but I don't think I understand them. For example, at $X=0$ the PDF of the standard normal distribution is $\approx 0.4$. Does this have any useful meaning?</p> | g61750 | [
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0.007532178424298763,
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0.02100876346230507,
-... |
<p>In <em>Bayesian Data Analysis</em>, chapter 13, page 317, second full paragraph, in the modal and distributional approximations, Gelman et al. write:</p>
<blockquote>
<p>If the plan is to summarize inference by the posterior mode of $\rho$
[the correlation parameter in a bivariate normal distribution], we
wou... | g61751 | [
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<p><strong>What are the methods to minimize the effect of boundaries in a wavelet decomposition?</strong></p>
<p>I use R and the package <a href="http://cran.r-project.org/web/packages/waveslim/index.html" rel="nofollow">waveslim</a>.</p>
<p>I have found for instance the function </p>
<pre><code>?brick.wall
</code><... | g61752 | [
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0.07... |
<p>I'm running an EFA using orthogonal/varimax rotation, and assigning variables to a factors based on maximum load (so only each variable only gets one factor). I then want to validate the model using SEM... since the rotation I used to determine the variable<->factor loads was orthogonal, is it "wrong" to let the ... | g61753 | [
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0.024612419307231903,
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0.00... |
<p>I have a single model (e.g generalized Pareto distribution) to test with a different data set (I have a set of different increasing threshold and fit the same model with a data above these threshold). I want to know which set of data will give me the best model fit. Can i use likelihood ratio test in this case or an... | g61754 | [
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<p>I have a multinomial logistic regression with dependent variable valued in {-1,0,1} (reference category is 0) and a number of continuous and discrete predictors. After running the regression a continuous predictor of interest ('size') has a Type 3 analysis of effects p-value of 0.0683, and the two coefficients (corr... | g61755 | [
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<blockquote>
<p>Let $X_1,\dots,X_{k+1}$ be mutually independent random variables, each having a gamma distribution with parameters $\alpha_i,i=1,2,\dots,k+1$ show that $Y_i=\frac{X_i}{X_1+\cdots+X_{k+1}},i=1,\dots,k$, have a joint ditribution as $\text{Dirichlet}(\alpha_1,\alpha_2,\dots,\alpha_k;\alpha_{k+1})$</p>
</... | g61756 | [
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<p>I have a learning algorithm that classifies points as 0 or 1 (haven't settled on which one to implement yet). Of the points I classify as 1, I want to ensure that the number of points correctly classified as 1 is between 40% and 60% (or generalizing, between any such threshold). This would mean that I want the same ... | g61757 | [
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<p>Does anyone have experience with approaches for selecting the number of sparse principal components to include in a regression model?</p> | g61758 | [
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<p>I have read a lot about gbm in <em>Greedy function Approximation: A Gradient boosting Machine</em> (<a href="http://www.google.fr/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&cad=rja&ved=0CDsQFjAA&url=http://www-stat.stanford.edu/~jhf/ftp/trebst.pdf&ei=r2MXU5u2HKHsywPUnoGgAw... | g18493 | [
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<p>I am creating a mixed model and including a spatial correlation. My data points include lat long values although some are duplicated. I have two questions about dealing with these.</p>
<ol>
<li>To specify the spatial correlation there must not be any distances of 0. Therefor, I jittered my coordinates to ensure tha... | g34305 | [
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<p>I have the following 2 questions about log-likelihood computation in semi-supervised Naive Bayes.</p>
<ol>
<li><p>I have read on several documents online that, in every EM iteration of the semi-supervised Naive Bayes, log-likelihood is positive. <strong>Is this always true?</strong> In my text classification proble... | g61759 | [
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0.0381... |
<p>I have a DEM (cellsize 10x10 and cells.dim 450x300)
and I need to create 100 random error grids
that have the same dimensions as the DEM.</p>
<p>The values in the error grids are generated from a
normal distribution that has mean of zero and
a standard deviation equal to the RMSE of original DEM ~ (0, +-3). </p>
... | g61760 | [
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<p>I am looking for packages (either in python, R, or a standalone package) to perform online learning to predict stock data. </p>
<p>I have found and read about Vowpal Wabbit (<a href="https://github.com/JohnLangford/vowpal_wabbit/wiki" rel="nofollow">https://github.com/JohnLangford/vowpal_wabbit/wiki</a>),
which see... | g61761 | [
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<p>I have a question for using caret and ctree for prediction with data containing NA.</p>
<p>Here's code.</p>
<pre><code>library(caret)
library(party)
x <- data.frame(sex=c("male", "male", "male", "female", "female", NA, "female"),
output=as.factor(c(T, T, T, F, F, F, F)))
model <- train(output... | g61762 | [
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<p>I understand that a good way to see if the covariate should be transformed is to do a linear model and plot the residuals. if there is a pattern, a log-transformation may be needed.
but.. I am right now trying to find the best model for a relationship with several possible predictor variables. So I don't know how to... | g61763 | [
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... |
<p>How does one prove the mistake bound of Winnow is O(log(n)/gamma^2) where gamma is the margin of the linear classifier? I see several papers citing this, however I do not see a single proof of the same.
Thanks!</p> | g61764 | [
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<p>I am interested in comparing levels of insight between a bipolar group and a schizophrenia / schizoaffective group. I am assuming I will have to use "current mood state" as a covariate because it could influence self-reported levels of insight in these psychiatric populations. I have 4 instruments that measured diff... | g61765 | [
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0.030833685770630836,
0.017768532037734985,
-0.0322175957262516,
-0.019907597452402115,
0.00042375159682706,
-0.010887560434639454,
-0.04628625139594078,
... |
<p>Linear model in matrix form is</p>
<p>$
\mathbf{y}=\mathbf{X}\beta+\epsilon\textrm{ where }\epsilon\sim\mathbb{N}\left(0,\sigma^{2}\mathbf{I}\right).
$</p>
<p>If
$
\mathbf{K}^{\prime}\left(\mathbf{X}^{\prime}\mathbf{X}\right)^{-} \mathbf{K}
$
is nonsingular, then</p>
<p>$
\textrm{rank}\left[\mathbf{K}^{\prime}\l... | g18499 | [
-0.03388090804219246,
0.003039990086108446,
-0.02951083518564701,
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0.03434141352772713,
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0.04393487051129341,
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0.00... |
<p>I'm not sure where to post this, so I thought I'd post it here. If there is another better place to ask this question then please could you let me know. </p>
<p>Let
$\beta$ = rate of infection, and $\gamma$ = rate of recovery.</p>
<p>I don't understand how the basic reproduction number (BRN) is $\frac{\beta}{\gam... | g18500 | [
0.042904358357191086,
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0.003914861008524895,
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0.02898607961833477,
-0.01... |
<p>I have a population with a mean (mean_1) (which was calculated through many trials and so have a very very small uncertainty in the mean). The standard deviation of the population is 'S'.</p>
<p>I have a second population with mean_2 (which again has a very very small uncertainty) and a standard deviation which is ... | g49870 | [
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<p>I am a medical student and I'm a rookie in the field of statistics but I was searching and digging for a long time to do a simple (for most of people involved in the field) analysis all by myself, and I'm exhausted so please help me on this. I have a data of subcortical structure volumes for three different groups, ... | g18502 | [
-0.010805176571011543,
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0.02296796627342701,
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0.... |
<p>Suppose that in a linear regression, some of the continuous variables (such as number of pills taken each day) have small discrete values. For e.g. the number of pills taken each day can take values 0,1,2,3. </p>
<p>Would it be better to treat these continuous variables as categorical or ordinal variables? What sho... | g61766 | [
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... |
<p>I'm currently working on bond return data. I've data for 5,10,20 and 30 years. I've performed PCA, EFA. I also created an AR(11) model to forecast the return for the next month that's due. Now I want to extend my model to ADL with $X_{t-1}$ as a covariate. Here, Xt-1 is the lag of the first principal component from ... | g61767 | [
0.008209588006138802,
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0.00... |
<p>Let $X$ have a gamma distribution with $\alpha = 4$ and $\beta = \theta > 0$. Find the Fisher information $I(\theta)$. I have found the second derivative of the log of the likelihood function and then to find the information, I did:$E((-4/o^2)+(x/o^2))^2$. The answer is $\frac{4}{o^2}$ but I don't know how to get... | g61768 | [
0.014835734851658344,
0.002955426461994648,
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-0.02136470191180706,
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0.04162236675620079,
0.011208013631403446,
0.01... |
<p>Let's say I'm trying to cluster $n$ points in $\mathbb{R}^p$, and I know in advance that only $s$ many of these $p$ dimensions determine the differences between the clusters. Of course, I don't know which of these dimensions are the important ones.</p>
<p>All in all, I have an unsupervised learning problem (cluster... | g98 | [
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... |
<p>From a meta analysis, I have a distribution of probabilities that are not p-values (i.e., they are not uniformly distributed when H0 is true). I am using these probabilities for an intersection-union test. Is it legitimate to do an FDR calculation (e.g., p.adjust(method="BH") in R) on these probabilities even though... | g11061 | [
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<p>How does one calculate the derivative of a multivariate normal CDF with respect to a given correlation coefficient?</p>
<p>I have started with the bivariate case but couldn't work it out.</p> | g18503 | [
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... |
<p>I have read the excellent slides <a href="http://lme4.r-forge.r-project.org/slides/2009-07-21-Seewiesen/4PrecisionD.pdf" rel="nofollow">"Assessing the precision of estimates of variance
components"</a> from Douglas Bates. </p>
<p>I'm looking for some references about these <em>profiled deviance components</em> (fo... | g61769 | [
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0.07576415687799454,
-0.00... |
<p>A signal is corrupted with white gaussian noise, or colored noise. Why is gaussian noise considered to be high dimensional?? (REfer paper : <a href="http://www.eurasip.org/Proceedings/Eusipco/Eusipco2000/SESSIONS/THUAM/OR1/CR1473.PDF" rel="nofollow">http://www.eurasip.org/Proceedings/Eusipco/Eusipco2000/SESSIONS/THU... | g18505 | [
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0.070221446454525,
0.06319649517536163,
0.04840... |
<p>I now introduce the problem:</p>
<p>Let assume $\mathbf{z} = (z_1, z_2,z_3)$ be a trivariate normal variable. I want to find the covariance matrix of $\mathbf{z}$.
I now that the density of $(z_1, z_2)$ is a bivariate normal with mean vector $(\mu_1, \mu_2)$ and covariance matrix
$$
\left(
\begin{array}{cc}
\sig... | g18509 | [
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0.0057399338111281395,
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0.006577570457011461,
0.039353642612695694,
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0.01892220228910446,
0.04823080077767372,
0.038369473069906235,
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0.... |
<p>I am performing a meta-analysis and I have several papers that measure compound X in the blood of patients with a given disease. These papers have classified patients into groups based on disease severity (i.e. mild/moderate/severe). I hypothesize that X is positively correlated with disease severity.</p>
<p>For ... | g61770 | [
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0.038857780396938324,
0.... |
<p>I want to fit logistic regression model for a binary outcome variable to see the impact of other explanatory variable on it. What are selection criteria for selecting variables in the adjusted logistic regression model? What is the basic difference between unadjusted and adjusted logistic regression model?</p> | g61771 | [
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0.02473841793835163,
0.05... |
<p>Someone asked me questions about his outcomes from Xlstat. Since I do not know this software at all, here is the question:</p>
<p>How are p-values for Pearson correlation coefficients calculated ($H_1: \rho \neq 0$)? Does Xlstat just calculate Steiger's z-test? </p>
<p>I can not find this info. The Xlstat help doe... | g18510 | [
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0.03850443288683891,
0.041741229593753815,
-0... |
<p>This might be a stupid question - but can data samples have constant means even if they are from different distributions?</p> | g61772 | [
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... |
<p>I am working on a graph clustering algorithm (mcl). It gives the opportunity to give weights to the edges. The weights must be similarities, but I have a distance. The values of this distance range from 0 to infinity. I am looking for ways to convert this distance to a similarity. So far, my main idea is to use s = ... | g61773 | [
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<p>I was given a question as part of the interview process for a job and I was looking for some advice. In this question I was given some (x,y) data (both univariate) and was asked to construct a mathematical model. Literally no other information was given. So I'm wondering what to do here. I could fit the data with... | g61774 | [
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0.004503862001001835,
0.008394633419811726,
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0.029566023498773575,
... |
<p>For the purpose of model selection, I am using the Bayes' factor to compare different combinations of predictors in a linear regression model.</p>
<p>I have used the function <code>regressionBF()</code> from the <code>library(BayesFactor)</code>, and I got the following results:</p>
<pre><code># > regressionBF(... | g61775 | [
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-0.07632987201213837,
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0.020920176059007645,
0.042452048510313034,
-... |
<p>For two stochastic variables <em>x</em> and <em>y</em>, the rule for independence is given as
$$
p(x,y) = p(x) \, p(y)
$$
On the left hand side of this equation is a 2D quantity, and on the right hand side are two 1D quantities. In order for this equality to work, the product must therefore have the form of an <... | g49345 | [
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0.044228456914424896,
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0.013895844109356403,
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0.009215337224304676,
0.028250427916646004,
0.025477103888988495,
0.00906367227435112,
0... |
<p>From the slides <a href="http://www.csie.ntu.edu.tw/~cjlin/talks/kuleuven_svm.pdf" rel="nofollow">http://www.csie.ntu.edu.tw/~cjlin/talks/kuleuven_svm.pdf</a>,
$$\min \frac{1}{2}w^Tw $$
subject to $$y_i(w^T\phi(x_i)+b)\ge 1,i=1,\cdots,n$$</p>
<p>I think most people are very familiar with this equation.
I assume $w... | g61776 | [
0.0011804073583334684,
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0.017017414793372154,
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0.012943229638040066,
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0.015498356893658638,
0.07743646204471588,
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0... |
<p>I have a formulation of a statistical problem in mind and haven't been able to find any literature/references about it. As professors that I asked also couldn't help, I thought I'd ask here.</p>
<p>Consider the problem of performing statistical analysis on patient records from several hospitals. For example, we wan... | g61777 | [
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0.013730056583881378,
0.0271130483597517,
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0.06493739783763885,
... |
<p>Is there a way to run a linear regression with upper and/or lower limits
on the coefficients in R?</p> | g61778 | [
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0.05356529355049133,
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... |
<p>I want to compare two dependent variables. </p>
<p>I have two groups of data.</p>
<p>Model 1
$$Y_1 = \beta_1 *x_1 + \beta_2 *W_1 + error$$ </p>
<p>Model two
$$Y_2 = \beta_3 *x_1 + \beta4 *Z_2 + error$$ </p>
<p>How different are $Y_1$ and $Y_2$?</p>
<p>Suppose $\frac{Y_1-Y_2}{Y_1}$. How confident am I that thes... | g18514 | [
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0.006859299726784229,
0.01823139563202858,
0.047540083527565,
-0.0224768053740263,
-0.0059... |
<p>I try to minimize mean squared error function defined as:</p>
<p>$E\left[Y - f(X)\right]^2$</p>
<p>I summarized the minimization procedure from different online sources (e.g., <a href="http://scholar.harvard.edu/files/danielyewmaolim/files/api-208section1.pdf" rel="nofollow">URL 1</a> (p. 4), <a href="http://www.e... | g61779 | [
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0.005807321052998304,
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... |
<p>I am working on a word sense disambiguation task and I have a dataset consisting of labelled sentences for two meanings of the word 'line'. I am trying to find 'trigger' words that are good at determining the sense of the ambiguous word if it occurs with it in the sentence. So, for each word in my training data (e... | g61780 | [
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0.0027632825076580048,
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0.0... |
<p>I'm working on a predictive cost model where the patient's age (an integer quantity measured in years) is one of the predictor variables. A strong nonlinear relationship between age and risk of a hospital stay is evident:</p>
<p><img src="http://i.stack.imgur.com/Oh5Ul.jpg" alt="enter image description here"></p>
... | g61781 | [
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0.0027601562906056643,
0.03241642564535141,
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<p>I have conducted a series of tests on a single, dichotomic variable (presence/absence of a personality disorder in a neurological illness) in order to compare several things (i.e. presence of anxiety or depression, disease duration, gender, etc) between subjects who show the personality disorder and subject who don'... | g61782 | [
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0.043772488832473755,
... |
<p>I have been struggling with a panel data analysis that measures the significance of the determinants of Foreign Direct Investment in a host country.
I have data for a period of ten years, and FDI flows from 8 countries into one country (France). I have taken France's macroeconomic indicators, labour statistics and ... | g10597 | [
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0.010141677223145962,
... |
<p>I am looking for a proof that omitted variable bias (OVB) in OLS regression may lead to endogeneity. I have found many examples here and out there on how to prove that a given parameter $b_{j}$ (where $j=1,...,J$ parameters in the model) gets biased, for instance these two threads:</p>
<ul>
<li><a href="http://stat... | g18519 | [
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... |
<p>I want to fit a model with two crossed random factors that also allow heteroscedasticity. Whereas <code>nlme4</code> allows non-constant error variance, I was not sure how to fit a model with crossed random effects. Recently I found the example in Pinheiro and Bates (2000), p. 163, that suggest the syntax (I fitted ... | g61783 | [
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<p>If I have a data set with $n$ patients and I have a categorical variable $X$ for each patient, I want to drop all patients whose $x$ is a particular value. </p>
<p><strong>Question 1</strong>: what is the term (preferably the epidemiological term) for variable $X$? (Is it an <em>exclusion criteria variable</em> [I'... | g18520 | [
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... |
<p>Is it possible to interpret coefficients from a quantile regression on standardized data? </p>
<p>Suppose I standardize the dependent variable $y$ and the independent variable $x$ (subtract the mean and divide by the standard deviation) and then run a quantile regression for the median such as</p>
<pre><code>qreg ... | g48469 | [
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-0.0... |
<p>I am testing a model in which I have 2 independent variables (IVs) and 2 dependent variables (DVs). I am hypothesizing that both IVs will predict both DVs; however that the relationship between IV1 and DV1 will be stronger than the relationship between IV2 and DV1. Similarly, I am hypothesizing that the relationship... | g61784 | [
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<p>When you make the normal probability plot, the plot may have curved bounds. Then the plot should be roughly linear <strong>and</strong> the data must lie within the bounds provided by software. In the examples I have seen the normal was rejected because some data points were not within the bounds. Can you provide a... | g39291 | [
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<p>The lifetime of a particular brand of batteries is known to have a gamma distribution. Tests on a large sample of these batteries show a mean lifetime of 480 hours and a standard deviation of 96 hours.</p>
<p>Some questions I require help on</p>
<ol>
<li><p>Show that the moment estimators for the gamma distributio... | g44594 | [
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<p>There are several good books about machine learning and there are many mathematical explanations for several classification models (in most books personally read commonly explain Naive Bayes, Logistic Regression and SVM).</p>
<p>Besides the Naive Bayes, Logistic Regression, SVM and several decision trees for which ... | g61785 | [
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<p>Given the median is $m>0$</p>
<p>We have $n$ random variables: $Y_1,Y_2,..,Y_n$</p>
<p>If we observe a value above $m$ then $Y_i=1$ if we observe a value below $m$ then $Y_i=0$</p>
<p>The probability of getting an observation above $m$ is "$p$" </p>
<hr>
<p>$(i)$ Then what distribution is $Y_i$ describing? ... | g61786 | [
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<p>If I have disease free survival data (defined as whether or not a particular disease has been diagnosed or not along with the time to that event or loss to follow up) and also overall survival data, how do I deal with deaths that occur without the disease event? Are these censored or should I exclude such patients f... | g37671 | [
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<p>I have been studying an organisation with 58 people with a number of Likert style questionnaires. The data are not random samples but rather incomplete census's. For the 6 questionnaires I managed to get between 49 & 57 respondents. However when I come to combine questionnaire data, the number can fall to say 43... | g48476 | [
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<p>I was attempting a self-study question on Margin of Error and managed to get the answer right. The answer key states 2.77, but I managed to get at 2.76. Close enough I guess.</p>
<p>But I thought that it seems pretty weird that I did not have to use many of the provided variables such as mean or even the confidence... | g18527 | [
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<p>I'm investigating the effect of a continuous variable A on a measurement variable M stratified by another factor variable C in an observational dataset. </p>
<p>Due to heteroscedasticity I decided to use a bootstrapped regression analysis. However looking at the data, the background set of variables are not evenly ... | g15999 | [
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<p>Linear mixed-effects models aren't commonly used in my corner of biology, and I need to report the statistical test I used in a paper I'm trying to write. I know that awareness of multilevel modeling is starting to appear in some areas of the biosciences (<a href="http://www.nature.com/neuro/journal/v17/n4/full/nn.... | g61787 | [
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<p>I am analysing a study using a 4-way mixed ANOVA. It has one between-subjects factor and 3 within-subjects factors (with 2, 2, and 3 levels). My sample size is 63 - 29 in one group and 34 in the other.</p>
<p>I have 9 dependent variables, all which asked participants to choose their answer on a scale of 0 to 10. I ... | g18530 | [
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<p>I am working on my thesis project and have come across a problem with the statistics which I am looking for a bit of guidance.</p>
<p>I am running ANOVA tests to determine significance between groups but
i have come across a problem with a couple of the results which do not have equal variance (p<0.05 & p<... | g34316 | [
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<p>I have written some code that basically does the following:-</p>
<p>1: creates a matrix of binary features and a matrix of scaled features ( in the range 0 to 1 )</p>
<p>2: RBM trains separately on each of the above features matrices to get weight matrices</p>
<p>3: horizontally stacks a random row vector for bia... | g61788 | [
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<p>I've around 3e3 two-dimensional data points, </p>
<pre><code> x, d
1 1, 0.1
2 3, 0.1
3 2, 0.2
4 1, 0.5
range(x) = [-600, 600], range(d) = [0, 1]
</code></pre>
<p>We are trying to model <code>d</code> with a probability model. I believe the distribution of <code>d</code> should be dependent on <code>x</cod... | g61789 | [
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<p>Is there a way to calculate a number that evaluates the viability of an experiment? By that I mean the probability that the observed probability is just chance.</p>
<p>I read about the $p$ value, but it doesn't seem to be that, as it doesn't take at all into account the number of experiments.</p>
<p>Let's say I ha... | g61790 | [
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<p>I know that zero-inflated models (e.g. zero-inflated Poisson or negative binomial models) can be used for dependent variables. I also know that in general there are no assumptions for the independent variables (i.e. predictors) in regression analyses. However, I have a quantitative (continuous or count) predictor wh... | g61791 | [
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<p>Is there any relationship between the draw from a Bernoulli with parameter $p$ and the Normal CDF. Specifically is the condition $p>\Phi(x)$, where $x$ is drawn from the standard normal distribution, equivalent to a draw from Bernoulli$(p)$ ?</p> | g61792 | [
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<p>SVMs for classification make intuitive sense to me: I understand how minimizing $||\theta||^2$ yields the maximum margin. However, I don't understand that objective in the context of regression. Various texts (<a href="http://kernelsvm.tripod.com/">here</a> and <a href="http://citeseerx.ist.psu.edu/viewdoc/download?... | g61793 | [
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<p>I wonder what are the better approaches to <strong>categorize continuous data</strong> (e.g. <em>age</em>) than dividing them with the use of quantiles and <code>cut</code> function (in <code>R</code>). I have heard about using trees to divide data in the way which takes into consideration how a division would diffe... | g33688 | [
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<p>What am I supposed to do when I want to interpret significances, although I know that standard errors are biased because of wrong error term assumptions? I know that there is the possibility to use White estimators, weighted OLS. But my prof told me not to do so.</p>
<p>Maybe some extra information:</p>
<p>1.) I a... | g61794 | [
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<p>I have data on grades obtained in a course over three consecutive years. The grade distribution includes the number of students who received a fail, pass, credit, distinction and high distinction. </p>
<p>I need to work out if the proportion of students who obtain a pass (or fail, credit, etc.) is the same, or diff... | g61795 | [
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<p>I have data that indicates if the computers in my network are up or down. Data is collected every minute and has a seasonality of one week, looks like this for 3 hosts.
Servers are supposed to go down less often than workstations. </p>
<pre><code>ID TIME STATE TYPE
1 60 0 workstation
2 60 1 serv... | g16002 | [
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<p>In an attempt to improve the results of Bayesian NNT, I transformed the 7 variables that I have into normal scores (subtracted the mean and divided by SD).<br>
Then I used a PCA on the transformed variables to generate new 7 PCs. I used these PCs to run the Bayesian NNT and the classification results improved a litt... | g61796 | [
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<p>Does anyone have Stata code they could share with me so that I can run a two-part model to look at health care expenditures? The first part of the model will determine whether or not an individual had any visit and the second part will determine how much individuals spent (estimated on the subset of those who had a ... | g61797 | [
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<p>The problem I'm trying to solve here is very simple but the available data is very limited. That makes it a hard problem to solve.</p>
<p>The available data are as follows:</p>
<ol>
<li>I have 100 patients and I need to rank order them in terms of how healthy they are.</li>
<li>I only have 5 measurements for each ... | g210 | [
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<p>I have the results of a meta-analysis of 10 studies that reports a combined random effects odds ratio (computed using Woolf's method) and 95% confidence interval of an event happening in one group relative to another:</p>
<p>$OR = 7.1\ (95\%\ CI\ 4.4-11.7)$</p>
<p>I'm now building a model that needs to sample arou... | g61798 | [
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<p>Not sure if this question makes sense but I have been spending a lot of time looking at information about expectation propagation and one of the key operations in it as explained by Tom Minka is the projection of product of distributions to the best Gaussian approximation.</p>
<p>So, I have a setup where my joint d... | g18541 | [
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0.024962682276964188,
-0.0010551403975114226,
0.0143919130787253... |
<p>I have model where coefficient is of different powers:</p>
<p>$$\mbox{log} ( \mu_{i} ) = \alpha + \beta x_1 + \beta^2x_2 + \beta^3x_3 + ... + \beta^nx_n \\
\\
N_{i} \sim \mbox{Poiss} ( \mu_{i} )
$$</p>
<p>$N_i$ and $x_i$ is the data, $\alpha$ and $\beta$ are model coefficients.</p>
<ol>
<li><strong>Can this prob... | g61799 | [
-0.00911763682961464,
-0.034776657819747925,
-0.007932592183351517,
-0.004787088837474585,
0.056215282529592514,
-0.06636711955070496,
-0.000037309888284653425,
0.010269423946738243,
-0.04792141914367676,
0.002050188137218356,
-0.044400654733181,
0.016022704541683197,
0.018178557977080345,
... |
<p>I am trying to predict the result of an experiment (binary dependent variable) based on a number of continuous independent variables. When I do this using a largish model (9 main effects + 2 factor interaction) it seems to "work" meaning I get a plot where the predicted values are 0/1. However, if I reduce the model... | g36266 | [
0.06432502716779709,
-0.032745204865932465,
-0.011753331869840622,
-0.020620113238692284,
0.007243988569825888,
-0.009302778169512749,
0.04958264157176018,
-0.00583930779248476,
-0.0608106330037117,
-0.06438314914703369,
0.0007660709670744836,
0.040641240775585175,
0.0467047318816185,
0.02... |
<p>I tried to create a neural network for predicting temporal data. Having selected a different nuber of inputs (number of previous known values), number of hidden units and regularization parameter value, I calculated and visualized the training and test values.</p>
<p>As I haven't managed to tune network structure a... | g61800 | [
0.043135177344083786,
0.010445090010762215,
-0.015481974929571152,
-0.010995283722877502,
0.006443241145461798,
-0.07850116491317749,
0.05022021755576134,
0.039575785398483276,
-0.022285746410489082,
-0.006378985475748777,
-0.06318503618240356,
0.0581657774746418,
0.03497245907783508,
0.01... |
<p>I always thought $\alpha_i \neq 0$ implied that $i$ was a support vector. However, now that I think about it, I am confused. If a training point is incorrectly classified, it will have a non-null $\alpha$, does it make sense to use it for classifying new points? Do we use it to compute the optimal separating hyperpl... | g61801 | [
-0.0013692417414858937,
-0.012569599784910679,
0.027977587655186653,
0.023164156824350357,
-0.0034998853225260973,
-0.02903095632791519,
0.013078058138489723,
0.05607374384999275,
-0.036843955516815186,
-0.062072232365608215,
-0.00785107258707285,
0.004660014528781176,
0.03374851495027542,
... |
<p>I am trying to figure out how can I create an optimization function that will select from a data.frame or matrix, the row with the most drawn value (the numbers are not integer, so I need to maybe look for the number with the highest probability of occurrence) and at the same time minimize the second column (that re... | g61802 | [
0.015819834545254707,
-0.019239826127886772,
-0.008774816058576107,
-0.012490443885326385,
0.03423722833395004,
-0.08116283267736435,
0.04503144323825836,
-0.0034777687396854162,
-0.06466899812221527,
-0.04765504598617554,
-0.04315151646733284,
0.03914638236165047,
0.07480552792549133,
0.0... |
<p>I am performing logistic regression and would like some help with interpretation.
My data was collected at 2 time points; baseline and follow-up.</p>
<p>My outcome variable is a psychosocial functioning variable (as an example working or not working) at follow-up.</p>
<p>In step 1 I entered the functioning variabl... | g61803 | [
-0.0004101976228412241,
-0.03448124974966049,
0.014925671741366386,
-0.04083651304244995,
0.0015591970877721906,
-0.01591610722243786,
0.06863173097372055,
0.05552057549357414,
-0.05512839928269386,
-0.04559502378106117,
-0.016071980819106102,
0.007769902236759663,
0.022338809445500374,
-0... |
<p>I have an idea to use ECDF conversion of data to their uniform distribution of equal sample sizes. So, for say 1000 pieces of data, each value should more or less correlate with a .1% representative value, if a value is repeated, that repeated value is translated into another correlated 1/1000%.</p>
<p>So if the n... | g61804 | [
0.00024189033138100058,
-0.034529995173215866,
0.0027673859149217606,
-0.06356154382228851,
0.027601975947618484,
-0.02052314765751362,
-0.03259965404868126,
0.029660539701581,
-0.03930116072297096,
-0.01263957004994154,
0.033782631158828735,
0.0028451778925955296,
0.03455081209540367,
0.0... |
<p>I am working in text clustering. I would like to find a way to identify the number of classes for the clustering process automatically rather than proving the number of class manually. Is their any proof or model for this? </p> | g18547 | [
0.013143508695065975,
0.0024771858006715775,
0.02517375536262989,
-0.04446585103869438,
0.035737741738557816,
-0.09836829453706741,
0.017128540202975273,
0.019653767347335815,
0.013060014694929123,
-0.012331834994256496,
-0.022237244993448257,
0.001983487978577614,
0.0802278146147728,
0.08... |
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