question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Normally when somebody finds an association in an epidemiological study people are quick to point out that it doesn't prove causality, that there are problems of missing co-founders, that it is at best hypothesis generating and at worst spurious. This leads to people not putting much weight on associations found in ... | g19174 | [
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<p>I am looking for advice on circular statistics. In particular, I'd like to know if any one had any advice/ references that deal with regression models for circular variables and whether it is possible to include random effects as well. </p>
<p>At the moment I can fit very simple models in WinBUGS using wrapped cauc... | g62201 | [
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<p>I'm using the <a href="http://cran.r-project.org/web/packages/randomForest/index.html" rel="nofollow">randomForest</a> package in R and using the iris data, the random forest generated is a classification but when I use a dataset with around 700 features (the features are each pixel in a 28x28 pixel image) and the l... | g19176 | [
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<p>I have fit a simple binary logistic GAM model in R and have used the plot() function to plot the results of this model. The outputted graph shows a fitted line and a confidence interval, but the scale is clearly not 0-1. Does anyone know what is being plotted? Ideally I would like to get a graph of the predicted pr... | g19177 | [
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<p>I have a series of repeated measurements of light intensity at different points on a grid. I have made a histogram for each point showing the relative difference between modelling and measurement. My histograms are fairly close to normal with a mean of zero. I am using the standard deviation of this distribution to ... | g19179 | [
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<p>I am trying to estimate the alpha parameter of a supposed $\alpha$-stable distributed set of data. I have tried from the Hill estimator to more <a href="http://stats.stackexchange.com/questions/25007/fitting-the-parameters-of-a-stable-distribution">advanced fitting method</a>, but they are or too approximated or too... | g62202 | [
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<p><img src="http://i.stack.imgur.com/JOzkC.jpg" alt="enter image description here">I am looking at state-wide data (entire population) of a school's grade as a function of the school's poverty index. The data appears to me to be an unconditional heteroskedastic distribution. I am drawing a line of best fit (LBF) throu... | g644 | [
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<p>suppose $X$ has an F distribution with $\nu_1$ and $\nu_2$ degrees of freedom . it is well known that as $\nu_2$ approaches infinity. how can show limiting distribution of $Y=\nu_1X$ is chi-square with $\nu_1$ degrees of freedom</p> | g62203 | [
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<p>I have a coworker who wants to create his own independent variable to add to a time series regression model because he believes that his variable will encapsulate more information. Is this advisable? His variable is essentially a weighted average, but I have concerns about the variable's interpretation (it is kind o... | g62204 | [
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<p>If $X\sim\mathcal{LN}({\mu,\sigma^2})$, then $\mathrm{E}[X]=e^{\mu+\sigma^2/2}$. My question is: what right do we have to add a mean and variance together? If $X$ has physical dimensions, then the expression $\mu + \sigma^2/2$ is incoherent. So what gives?</p>
<p>Thanks in advance!</p> | g62205 | [
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<p>I have data from raters who each provided two ratings for a large set of categories. They were asked to rate how coherent each category was on a scale of 0 (members totally dissimilar) to 9 (members highly similar) and they did this twice: first, deciding if the category members had similar sizes, and, second, wheth... | g62206 | [
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<p>Dear statistics experts, </p>
<p>I am looking for correlations between certain measures of brain structural integrity (fractional anisotropy, given as ratio between two hemisphere ==> rational data range 0-1, normally distrubuted) and behavioral parameters from stroke patients which are not normal but in part extre... | g62207 | [
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<p>In statistics, the moving average is usually defined for discrete data sets. Is there a moving average concept for continuous randomly fast-oscillating functions? I am seeking for the moving average determined in terms of integrals rather than sums.</p> | g62208 | [
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<p>I ran regression analyses using SAS with two different data sets containing <em>different individuals</em> but <em>exactly the same IV and DV</em>: let's call them "low_deviance" and "high_deviance" and I would like to assess, whether there is a significant difference in the predictive power of the IV.</p>
<p>Proba... | g62209 | [
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<p>Any help for solving the attached question (b), (c), (d) and (e) is appreciated.<img src="http://i.stack.imgur.com/O2kCE.png" alt="enter image description here"></p> | g62210 | [
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<p>I'm interested in well-known examples of Big Data misinterpreted, poorly analysed, or wrongly employed to unscientific and incorrect ends. Would appreciate any examples or observations. Thanks a lot!</p> | g19183 | [
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<p>I'm attempting to generate approximately even-sized clusters of a PCA'd feature set in Scikit-learn, but I'm not having any luck. I'm only familiar with KMeans clustering, and with that algorithm the largest cluster contains the majority of the examples (in the case of K=2 it's 80%, in K=4 it's 65%, etc...). I've do... | g49637 | [
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<p>In my situation, one of two sources is not invoked if the confidence reported by the first source is higher than a threshold and hence it is missing in some examples. How can account for such missing data?</p> | g19185 | [
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<p>Gaussian MRF in Gaussian information form:</p>
<ul>
<li>edge potential: $exp(\frac{-1}{2} y_s\Lambda_{st} y_t)$ </li>
<li>node potential: $exp(\frac{-1}{2} y_t\Lambda_{t} y_t+\eta_ty_t)$</li>
</ul>
<p><strong>Why:</strong> </p>
<blockquote>
<p>precision parameter $\Lambda_{st}=0$ <=> $x_s \bot x_t | rests$. ... | g62211 | [
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<p>I am using the gls function from nlme to fit a fixed-effects model yet correct for spatial autocorrelation. My dataset has about 100,000 unique geographic observations, and running the following functions takes days on a R 64-bit edition installed on a quad-core Intel i7 3.4GHz CPU:</p>
<pre><code>fit <- gls(frm... | g62212 | [
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<p>I will have data not too dissimilar from this:</p>
<p><img src="http://i.stack.imgur.com/E9sas.png" alt="enter image description here"></p>
<p>I'd like to match the density with a set of (truncated) normal distributions and one underlying uniform distribution. I know where the spikes are, these are my means for th... | g62213 | [
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<p>The density of the Laplace distribution is given by:</p>
<p>$$f(x;\mu,\sigma)=\frac{1}{2\sigma}\exp\left(-\frac{\vert x- \mu\vert}{\sigma}\right).$$</p>
<p>It is easy to see that this function is not differentiable at $\mu$. However, I am interested on some asymptotic normality results of the MLE $(\hat{\mu},\hat{... | g19187 | [
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<p>I've been working for months on short-term load forecasting and the use of climate/weather data to improve the accuracy. I have a computer science background and for this reason I'm trying to not make big mistakes and unfair comparisons working with statistics tools like ARIMA models. I'd like to know your opinion a... | g34415 | [
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<p>I just got to apply multiple kernel learning to my data recently. I have data from three sources, so I want to learn three RBF kernels for each data source. But the MKL algorithms so far I know assume that the kernel parameters and the cost are fixed. When I used SVM with single RBF kernel before, I need to make a g... | g62214 | [
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<p>I am interested in utilizing caret for making inferences on a particular data set... Is it possible to do the following:</p>
<ol>
<li><p>produce coefficients of a glmnet model I trained in caret. I would like to use glmnet because of the inherent feature selection as I do not believe glm has it?</p></li>
<li><p>oth... | g62215 | [
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<p>The dataset comprises bandwidth usage for each customer. There is also a hybrid metric based on the distance covered by each traffic flow and aggregated to obtain 'Bit-Miles' for each customer (sum of traffic $\times$ miles for each flow).</p>
<p>Clearly, there is some (causal) dependence among the above features b... | g62216 | [
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<p>I am currently using a stochastic method for prediction that only reports my parameter of interest $\widehat{T}$ and does not report confidence intervals, though I would like them. I understand that nonparametric bootstrapping involves</p>
<ol>
<li>Resampling</li>
<li>Running a new estimate on the resampled data.</... | g62217 | [
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<p>Given a matrix $V^{m \times n}$, <a href="http://en.wikipedia.org/wiki/Non-negative_matrix_factorization" rel="nofollow">Non-negative Matrix Factorization</a> (NMF) finds two non-negative matrices $W^{m \times k}$ and $H^{k \times n}$ (i.e. with all elements $\ge 0$) to represent the decomposed matrix as:</p>
<p>$$... | g19194 | [
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<p>We are doing some testing of a major queue in our software system. During the entire testing, we have a "helper" that ensures that our queue stays full. Our intention is to figure out how quickly we are able to process the entries in the queue.</p>
<p>We can vary the number of processors that are processing the ent... | g62218 | [
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<p>I have a classification problem. My classes are 0 and 1. The dataset is a bit big, the training is done on 7 million lines and 100 + variables so I choose to use scikit learn and the logistic regression method (with weighted class). </p>
<p>This performs rather well. My AUC is around 95 % with which I am satisfied ... | g62219 | [
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<p>Often as a result of several simulations which are themselves intensive a huge amount of information i.e., points/line/plane depending to the subject of investigation are available. Although there are extensive list of multivariate analysis and data-mining techniques to summarize the results however I am often amaze... | g45548 | [
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<p>Suppose that we have independent binomial variates with differing sizes and probabilities $X_i \sim Binomial(n_i,p_i)$, and $Z = \sum_iX_i$ is the sum. I understand that $Z$ is distributed poisson-binomial, and approximations to this distribution have <a href="http://stats.stackexchange.com/questions/5347/how-can-i-... | g62220 | [
0.0228556077927351,
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-0.0019074951997026801,
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0.017664942890405655... |
<p>OK, I have been reading around on how to interpret transformed models, ... including this thread:</p>
<p><a href="http://stats.stackexchange.com/questions/24467/analysing-log-and-square-root-transformed-variables">Analysing log and square-root transformed variables</a></p>
<p>I am interested in the OP's (of the li... | g62221 | [
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0.020245330408215523,
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-... |
<p>I have a classic linear model, with 5 possible regressors. They are uncorrelated with one another, and have quite low correlation with the response. I have arrived at a model where 3 of the regressors have significant coefficients for their t statistic (p<0.05). Adding either or both of the remaining 2 variables ... | g62222 | [
0.03786487877368927,
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-0.027838479727506638,
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-0.004965725354850292,
... |
<p>I have some 2d data that I believe is best fit by a sigmoid function. I can do the fitting with the following python code snippet. </p>
<pre><code>from scipy.optimize import curve_fit
ydata = array([0.1,0.15,0.2,0.3,0.7,0.8,0.9, 0.9, 0.95])
xdata = array(range(0,len(ydata),1))
def sigmoid(x, x0, k):
y = 1 / (1... | g19196 | [
0.016144363209605217,
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0.015011024661362171,
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0.08749314397573471,
... |
<p>I have a set of pre and post treatment scores on 8 measures. I'd like to test which of these show significant improvement after treatment. If I use within-subjects t tests it will mean carrying out 8 t tests, and risking type I error. </p>
<p>My textbooks all say that repeated subjects ANOVA is for more than two me... | g62223 | [
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0.00016516038158442825,
0.007133702281862497,
0.054698359221220016,
-0.04234721511602402,
... |
<p>I have a kind of data and want to find the equation(poly coeff) of given data. For example equation for given sample data is simple <code>a^2*b+10</code> </p>
<pre><code>a\b 5 10 15
________________________
3| 55 100 145
4| 90 170 250
5| 135 260 385
6| 190 370 550
</code></pre>
<... | g22352 | [
0.060080889612436295,
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0.019253406673669815,
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0.02387002855539322,
0.035372912883758545,
-0... |
<p>I'm having a little trouble early on using the convert() function in RTAQ to convert .csv taq intraday trade data into an .RData format. I type this:</p>
<pre><code>> from <- "2012-02-01"
> to <- "2012-02-29"
> ###convert data to .RData format
> convert(from, to, datasource = "/home/taylor/Deskto... | g19199 | [
-0.0244744885712862,
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0.06056831777095795,
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0.07434309273958206,
-0... |
<p>How is it possible to identify quickly (without doing many tests) an approximative number of clusters from a dataset which is not vary large, even if this value is not the correct number of clusters, I just want to identify a reasonable value representing the number of clusters from this small dataset.</p>
<p>Note1... | g49115 | [
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0.0028350946959108114,
-0.00019369406800251454,
0.031806617975234985,
0.05955462530255318,... |
<p>I intend to use a hierarchical binomial model which would look like the following in BUGS language :</p>
<pre><code>model{
for(i in 1:I){
y[i] ~ dbin(theta[k[i]],n[k[i]])
}
for(j in 1:J){
theta[j] ~ dprior(alpha, beta)
}
alpha ~ dhyperprior.alpha
beta ~ dhyperprior.beta
}
</code></pre>
<p>I wonder about the ... | g38225 | [
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0.03165066987276077,
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0... |
<p>I am taking a theoretical approach to my multiple regression but the R squared and Adjusted R squared are both really low. I assume this means I can't improve my values with existing data and that the model is invalid? Can I do anything about it?</p>
<p>I am trying to test the causes of the intensity of organised v... | g62224 | [
0.013454129919409752,
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0.01528070867061615,
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-0.... |
<p>I just did a survey and I'm pretty sure some people just filled in the bubbles on the survey without reading the questions. A pretty obvious indicator are responses to items that are negatively coded (e.g. answering "strongly agree" to related items like "I'm a moron" and "I am not a moron"). Are there any methodolo... | g62225 | [
0.005580608267337084,
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0.028815947473049164,
0.04367038980126381,
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0.0560... |
<p>I wanted to know what is the mathematical justification for using ICM as an approximation for the E step in an EM algorithm.</p>
<p>As I understand in the E step the idea is to find a distribution that is equal to the posterior distribution of the latent variable, which guarantees that the likelihood increases or f... | g62226 | [
0.043793898075819016,
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0.002173982560634613,
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0.04566248133778572,
0.... |
<p>If we have the tables of conditionals $p(x|y)$ and $p(y|x)$, how can we calculate the joint probability $p(x, y)$? (Let us assume $x$ and $y$ are binary variables).</p>
<p>Using these tables, how can we calculate the covariance of $x$ and $y$? Covariance of two variables are calculated using $E[xy]-E[x]E[y]$, but I... | g19203 | [
0.012105884961783886,
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0.02088622935116291,
0.013239159248769283,
0.02687939815223217,
0.0026417660992592573,
0.0283... |
<p>Why does the Okun's law, the one that measures the relationship between unemployment rate and GDP, regress the percentage change in GDP on change in unemployment rate?</p>
<p>Why cannot we just simply regress GDP on unemployment rate?</p>
<p>What is the statistical difference between the two approaches?</p> | g62227 | [
-0.012512844055891037,
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<p>In a (Bayesian in my case) inference, all observations do not contribute equally to the results. Some of them drive substantially the results while others have only negligible effects. When studying hierarchical models it is sometimes difficult to identify which data belong to the first class and to the second class... | g62228 | [
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0... |
<p>Each week, John drives to his mother's house. The amount of time required for the trip varies
and is normally distributed. On about 16% of trips, it takes him more than 54 minutes to
reach his mother's house. On about 2.5% of trips, it takes him less than 33 minutes to reach
his mother's house. Which is closest to t... | g49776 | [
-0.03382803499698639,
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0.018314072862267494,
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0.04337913915514946,
-... |
<p>How up-to-date is the assertion in <a href="http://en.wikipedia.org/wiki/Lilliefors_test" rel="nofollow">this Wikipedia article</a> that tables of the Lilliefors distribution have been computed only by Monte Carlo methods?</p>
<p>(It would seem preferable to use deterministic numerical methods if possible.)</p> | g43017 | [
0.05125029385089874,
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0.009561488404870033,
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0.10008784383535385,
0.0... |
<p>i have a different sample size <code>n</code> for every month</p>
<p>for example i have <code>13890</code> one month then <code>17756</code>, then <code>21425</code></p>
<p>the data every month for example <code>13890</code> is broken down into:</p>
<pre><code>48 chairs, 12 tables, 2 couches etc...
</code></pre>
... | g62229 | [
-0.025387974455952644,
0.027105187997221947,
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0.014313637278974056,
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0.04431706666946411,
0... |
<p>I have a question on subject chi-square test for independence.</p>
<p>I have, for example, two events A and B. If chi square test is not passed: is A dependent on B (A|B) or B on A (B|A)? Or does be valid both? (A|B and B|A).</p>
<p>Thank you in advance.</p> | g62230 | [
0.041684892028570175,
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0.041334182024002075,
-0.011352142319083214... |
<p>Using Minitab I have checked for regression assumptions. Here I can see that the residuals (errors) of x4 are distributed normally. (y is response). However, are they distributed randomly? Looking at the "Versus Fits" graph they seem to be distributed normally, however I'm not very sure. What do you think?</p>
<p><... | g48624 | [
0.0023495680652558804,
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0.003175875870510936,
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0.02523212693631649,
-0.0... |
<p>Could you inform me please, how can I calculate conditioned probability of several events?</p>
<p>for example:</p>
<p>P (A | B, C, D) - ?</p>
<p>I know, that:</p>
<p>P (A | B) = P (A intersection B) / P (B)</p>
<p>But, unfortunately, I can't find any formula if an event A depends on several variables. Thanks in... | g62231 | [
0.003916883375495672,
0.0004166784347034991,
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0.0016725900350138545,
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0.012439717538654804,
0.009772169403731823,
0... |
<p>I am performing deviance goodness-of-fit test on my model (used negative binomial regression), and the R <code>summary()</code> table of my model gives the following:</p>
<pre><code>Call:
glm.nb(formula = topPagesCount ~ DB_LEGAL_STATUS_CODE_V2 + BCORP_INDUSTRY_DENSITY +
DENSE_MSA + DENSE_MSA * BCORP_INDUSTRY_DENS... | g49638 | [
-0.008535398170351982,
-0.058360859751701355,
-0.015642860904335976,
0.025690147653222084,
0.045809898525476456,
0.004054209217429161,
0.07190770655870438,
0.018875300884246826,
-0.06467101722955704,
-0.02127441018819809,
-0.013439382426440716,
0.04676085710525513,
0.012872274965047836,
-0... |
<p>A simple sine curve could be written as $\text{amplitude}\cdot\sin(x+\text{phase})$. It can be also written in linear form as $a \cdot \sin(x) + b \cdot \cos(x)$.</p>
<p>I run my analysis with R as:</p>
<pre><code> fit.lm2 <- lm(temperature~sin(2*pi*Time/366) + cos(2*pi*Time/366))
summary(fit.lm2)
Coefficient... | g62232 | [
0.05742538347840309,
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0.01339150033891201,
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0.03156841918826103,
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0.04661010578274727,
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-0.013699413277208805,
-0.004679359961301088,
0.06303879618644714,
0.041969917714595795,
-0.0... |
<p>I am try to evaluate a logistic regression with new data using R. I have created the logistic regression using the old data and evaluated that using chi^2 etc. i.e.</p>
<pre><code>model <- glm(outcome ~ input + 0, data = training.data, family = binomial())
</code></pre>
<p>(note I do need the intercept = 0). An... | g19211 | [
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0.00601721229031682,
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-0.06569180637598038,
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0.01512580830603838,
0.02465170808136463,
0.... |
<p>I'm an amateur statistician. I do it mostly for fun. I'm finishing up on my first semester stats class that covers up to hypothesis testing. I'm planning on beginning learning simple regression testing by myself so I can be prepared for the next level class when I have a free slot in my schedule again.</p>
<p>Anywa... | g37340 | [
0.033771779388189316,
0.0025110195856541395,
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0.007213286589831114,
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-0.04159758612513542,
0.059251051396131516,
0.020487530156970024,
0.014207765460014343,
... |
<p>I am trying to fit a multivariate linear regression model with approximately 60 predictor variables and 30 observations, so I am using the <strong>glmnet</strong> package for regularized regression because p>n.</p>
<p>I have been going through documentation and other questions but I still can't interpret the result... | g62233 | [
0.052893247455358505,
-0.04771619290113449,
-0.014571061357855797,
-0.002534998580813408,
0.055106207728385925,
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0.023425554856657982,
0.026392176747322083,
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-0.04831382632255554,
-0.010851898230612278,
0.027986373752355576,
0.021327998489141464,
... |
<p>I am conducting a systematic review to <strong>compare the effect of intervention A vs. B on outcome Y (A, B, Y binary variables).</strong> So far the collected studies are categorized as below: </p>
<ol>
<li>7 studies on both intervention A's effect on Y (A x Y) and B x Y </li>
<li>60 studies on A x Y </li>
<li>... | g62234 | [
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0.01792099140584469,
0.028875861316919327,
0.0216097142547369,
-0.007362485863268375,
0.0331837460398674,
0.0409250371158123,
-0.0046037109568715096,
0.04398... |
<p>In my industry it is common to test a sample of 20-30 and then use that data to draw conclusions about the reliability of the product with a certain confidence. We have tables for such things but it appears that for the case of 0 failures in the sample, the "Success Run Theorem" is used. In my references this appe... | g62235 | [
0.04328509047627449,
0.013317006640136242,
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0.0243311058729887,
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0.05836125463247299,
0.035234011709690094,
-0.03... |
<p>In the question <a href="http://stackoverflow.com/questions/18153450/generating-random-variables-from-the-multivariate-t-distribution">http://stackoverflow.com/questions/18153450/generating-random-variables-from-the-multivariate-t-distribution</a>, I am confused by why the answer requires we modify the <code>Sigma</... | g19214 | [
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0.013300153426826,
0.045545246452093124,
0.01... |
<p>I'm trying to build a binary 1/0 ML classification algorithm, and was thinking about how to set up the input dataset. If the event I want to predict (the 1's) occur relatively less frequently in the total data than the 0's, does it makes sense to pare the dataset in such a way to get a more equal distribution of 1's... | g62236 | [
0.029810046777129173,
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0.04459983855485916,
0.08036430925130844,
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-0.03450433909893036,
0.011557026766240597,
0.03890838846564293,
0.053476810455322266,
0.0410... |
<p>Suppose I have a sample $(X_n,Y_n), n=1..N$ from the joint distribution of $X$ and $Y$. How do I test the hypothesis that $X$ and $Y$ are <strong>independent</strong>? </p>
<p>No assumption is made on the joint or marginal distribution laws of $X$ and $Y$ (least of all joint normality, since in that case independen... | g62237 | [
0.02016141451895237,
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0.0031453196424990892,
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0.02308211289346218,
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0.004589948803186417,
... |
<p>$X'X \sim Wishart(\Sigma,n)$, however I'm having a tough time producing this in R.</p>
<p>Example:</p>
<pre><code>data=cbind(rnorm(100,10,5),rnorm(100,5,2),rnorm(100,-4,3))
X=cbind(rnorm(1,10,5),rnorm(1,5,2),rnorm(1,-4,3))
t(X)%*%X
rWishart(10,99,cov(data))
</code></pre>
<p>The data generated from rWishart is no... | g19215 | [
-0.010616662912070751,
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<p>I am building a Cox Proportional Hazards Model to predict the survival outcome of seabird faced with predation pressure. I have 6 factor variables with two or three levels each that I have predicted to affect survival. Three of which are management relevant (they can be manipulated by wildlife managers to increase o... | g62238 | [
0.011553021147847176,
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0.... |
<p>I'm working on a financial project that in the past calculated its number quarterly. It would then also have a 4-quarters ended calculation as well.
However, now we need to run the calculations on a rolling quarter basis, in other words every month we run the data for the previous 4 months.
Does it make sense to do... | g62239 | [
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<p>I compute a statistic s using two methods, X and Y. In order to measure the reliability of X and Y, I found split half reliability measures (alpha) using a bootstraping technique. So, for each of method X and method Y, I found the split half alpha value N times, where N is the number of bootstraps.</p>
<p>Now, I ha... | g19218 | [
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0.004595826379954815,
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... |
<p>I searched many websites to know what exactly lift will do? The results that I found all were about using it in applications not itself.</p>
<p>I know about the support and confidence function. From Wikipedia, in data mining, lift is a measure of the performance of a model at predicting or classifying cases, measur... | g49616 | [
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-0.05155140906572342,
-0.027365420013666153,
0.0008285439107567072,
0.05337967723608017,
-... |
<p>Are standard deviation estimates calculated via:</p>
<p>$
s_N = \sqrt{\frac{1}{N} \sum_{i=1}^N (x_i - \overline{x})^2}.
$</p>
<p>(<a href="http://en.wikipedia.org/wiki/Standard_deviation#Sample_standard_deviation">http://en.wikipedia.org/wiki/Standard_deviation#Sample_standard_deviation</a>)</p>
<p>for prediction... | g19221 | [
-0.0023206062614917755,
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0.0017155124805867672,
0.0018669440178200603,
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0.03606062009930611,
0.015633031725883484,
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-0.0024482414592057467,
0.03989596664905548,
-0.02834445796906948,
0.02330719120800495,
-... |
<p>I have two surveys of business owners. One is a sample (sample 1) of business owners who were <em>not</em> members of the association, done using a random digit dialing approach. The other is a sample (sample 2) of business owners who were members of an association (used the list of members for the frame). Both s... | g19223 | [
-0.004152522422373295,
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-0.0351574681699276,
0.05196526274085045,
0.00995407160371542,
0.055364564061164856,
0.04... |
<p>This is the result I've got after running linear regression analysis in SPSS:
<img src="http://i.stack.imgur.com/GtViC.jpg" alt="enter image description here"></p>
<p>I am a bit confused why the sum of squared part correlations is not equal to (or less than) R squared, but rather exceeds the value of R squared (R s... | g62240 | [
0.05144409090280533,
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-0.025905171409249306,
0.012172450311481953,
-0.0017552436329424381,
0.014671515673398972,
... |
<p>I can't seem to get my head around "<strong>iterations</strong>" in <strong>Adaboost</strong>.</p>
<p>Are they analogous to <strong>weak classifiers</strong> that are used for <strong>Boosting</strong>?</p>
<p>I've seen many examples of <strong>Adaboost</strong> where a programmers use a</p>
<ol>
<li><strong>Sing... | g19225 | [
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0.017057131975889206,
0.03887305036187172,
0.0... |
<p>There is an easy way to test the linearity hypothesis for a simple regression model $y \sim {\cal N}(\alpha+\beta x,\sigma^2)$: calling $H_0$ this model, perform a test against the ANOVA model $H_1$ obtained by considering the (numeric) covariate $x$ as a (qualitative) factor. Of course this requires to have several... | g62241 | [
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0.002379500074312091,
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0.028233841061592102,
0.012786577455699444,
... |
<p>I have a project in which I am looking at the correlation betwen fortnightly income and the amount saved each fortnight by low income workers.</p>
<p>I am reporting the effect size and the confidence interval. One of my results is as follows: r (214) = 0.34, p < 001, 95% CI [0.22, 0.45]</p>
<p>I know it is acce... | g62242 | [
0.02342093549668789,
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0.04597897455096245,
0.0016327355988323689,
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-0.0689462274312973,
0.017409728839993477,
0.02175622433423996,
0.005017245188355446,
-0.020... |
<p>We have a data set that looks like a lognormal distribution when we plot it.</p>
<p>We would like to convert/normalize the distribution into normal distribution and see what feature weight got enhanced.</p>
<p>It there a way to do it in python/java/scala?</p> | g44157 | [
0.007883042097091675,
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0.06880371272563934,
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-0.0... |
<p>Hi all I'm trying to do one step ahead forecast. Lets say I have 1000 data and fit an ARIMA model with it and then I do a forecast for one period ahead. When I get more data I would like to forecast another step using the new data without having to reestimate all coefficients and so on...</p>
<p>This is my code but... | g49242 | [
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0.00892794132232666,
0.044198885560035706,
... |
<p>I 'm new to the CV and not very good at statistic:) I would much appreciate some help on a non parametric ANCOVA in R <a href="http://cran.r-project.org/web/packages/sm/index.html" rel="nofollow">sm</a> package.
I do a pre post analysis on a set of pre/post variables of two groups (so <code>group</code> is a factor... | g19233 | [
-0.014530237764120102,
-0.01204652152955532,
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0.09143799543380737,
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0.04091821238398552,
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0.02775939740240574,
-0.001319797127507627,
0.... |
<p>I have 260 teacher conferences to score using a rubric. How do two raters need to score these for rater agreement? Do we need three raters?</p> | g62243 | [
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<p>Let's say I have a dataset with scores on a bunch of questionnaire items, which are theoretically comprised of a smaller number of scales, like in psychology research.</p>
<p>I know a common approach here is to check the reliability of the scales using Cronbach's alpha or something similar, then aggregate the items... | g62244 | [
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0.048942744731903076,
... |
<p>Which options are there to test, whether two contingency tables of the same variables, say $X$ and $Y$, are equal across the levels of a third discrete variable, say $Z$?</p>
<p>I can think of a log-linear model with terms $+X,+Y,+Z,+XY,+YZ,+XZ$. If it is significant against the saturated model, there is evidence o... | g62245 | [
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0.0030520318541675806,
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<p>My question is simple. Which are the general conditions for which a Monte Carlo simulation can be used to represent a statistical system? Or conversely, which are the statistical system that cannot be represented, even in principle, by a Monte Carlo simulation? </p> | g19238 | [
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0... |
<p>Coming back to degrees of freedom for chi squared, I have found a wonderful answer here:
<a href="http://stats.stackexchange.com/questions/16921/how-to-understand-degrees-of-freedom">How to understand degrees of freedom?</a></p>
<p>However it is hard for me to apply it to my particular case. Let's say we observed c... | g62246 | [
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0.003146413480862975,
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0.025460923090577126,
-0... |
<p>From Tsay's <em>Analysis of Financial Time Series</em>, </p>
<p>For a univariate weakly stationary time series $r_t$,
its sample autocorrelation function $\hat{\rho}_l$ is defined as:</p>
<p><img src="http://i.stack.imgur.com/eU17a.png" alt="enter image description here"></p>
<p>and the Ljung-Box test is </p>
<... | g62247 | [
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0.... |
<p>I have been running ANN (Neural network) on my data set, until last week that I figured out I will get more robust model using Cross validation, So That's why I have started using ANN with the aid of cross validation.</p>
<p>For example using a 10-fold cross validation, all the dataset will be divided into 10 sunse... | g19239 | [
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0.0... |
<p>I have a plot of a GAM which models deforestation severity.</p>
<p><img src="http://i.stack.imgur.com/A9tXG.png" alt="Component smooth functions of a GAM"></p>
<p>The explanatory variables are transformed, with log10, inverse, and square root. Is it meaningful to interpret a gradient like this: 'Deforestation seve... | g62248 | [
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<p>Currently I am using rfe function in the "caret" package to do feature selection. There are 380 variables as input candidates. I have done many trials and I noticed that something weird always happens, as the rfe tends to output all candidate variables as the best subset while I have set the parameter size to be 5 t... | g108 | [
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0.040186602622270584,
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0.0... |
<p>I have two random variables:</p>
<p>(1) With standard normal distribution. Confidence interval $I_1$, which is centered and has probability of $(1-\alpha)$</p>
<p>(2) With T-distribution. Confidence intervall intervall $I_2$, also centered and has prob. $(1-\alpha)$.</p>
<p>First I had to compute the length of bo... | g19243 | [
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... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/7165/a-resource-on-concepts-underlying-statistics-not-the-techniques-used-in-applied">A resource on concepts underlying statistics, not the techniques used in applied stats</a> </p>
</blockquote>
<p>I am i... | g49639 | [
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0.007099... |
<p>Hope I'm able to find someone who can answer this question. The previous one didn't get answered!</p>
<p>Proc ucm is the SAS implementation (using state space concepts) to isolate the unobserved trend, seasonality & estimate the coefficients of regressors simultaneously. </p>
<p>Documentation/research on proc ... | g62249 | [
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0.041... |
<p>I'm having difficulty figuring out the difference between (typically referred to as S.E):</p>
<p>A. The Standard Error</p>
<p>And</p>
<p>B. The Standard Deviation of the Sample Mean (typically referred to as s)</p>
<p>Are they the same thing?</p>
<p>OR</p>
<ol>
<li>S.E is the standard deviation of the the mean... | g49377 | [
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0.0016747084446251392,
0.05235328525304794,
... |
<p>What is the preferred model to analyze firms' R&D decision and intensity?<br>
Normally the questionaires include two steps: </p>
<ol>
<li>firms are asked whether they engage in R&D (binary variable (yes/no))<br>
(around 70 % answer no) </li>
<li>If yes, firms report how much they invest.</li>
</ol>
<p>... | g19249 | [
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<p>Exploring the work of ET Jaynes, <em>Probability Theory</em> (11th Printing 2013) has led to consideration of the technique he identifies as <strong>Sequential Inference</strong> (p. 96); where the <em>evidence</em>, in decibels, accumulates until the investigator either (1) stops with acceptance, (2) stops with rej... | g62250 | [
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-0.05116782337427139,
0.021781252697110176,
0.0... |
<p>I am running a conditional logit model and it will not converge! The DV has 6 levels of vote choice, essentially parties one can vote for, and I've got one predictor, individual level economic perception. Because the independent variable does not vary across alternatives, I created interaction terms by multiplying... | g62251 | [
-0.005939815659075975,
0.030657196417450905,
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0.0156815536320209... |
<p>Trying to build a predictive model for attrition prediction at service desk/call center.</p>
<p>Have daily data on the following parameters:</p>
<p>1.Call quality - QTM (0-100%),
2.No. of calls - Calls(Number)
3.Attendance
4.Customer feedback(1/0) Q1,Q2 (0-100%)
for both, agents who left the job and for the ones w... | g19253 | [
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0.045525047928094864,
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-0.0070557426661252975,
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0.017515745013952255,
0.017764268442988396,
0.06588337570428848,... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/48696/generalized-linear-mixed-model-in-r-with-repeated-measures">Generalized Linear Mixed Model in R with repeated measures</a> </p>
</blockquote>
<p>I am trying to investigate how four variables (var1=co... | g49652 | [
-0.021991262212395668,
-0.0633559376001358,
-0.003648612415418029,
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0.001793103525415063,
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0.026012951508164406,
0.0016076569445431232,
0.0... |
<p>I am trying to analyze multiple variables of our student population as it comes to assessment outcomes. I have the assessment change score and demographic information such as (race, sex, age, program, # of programs, time of service, # of services). I am trying to ascertain which variables are significant to the chan... | g62252 | [
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0.0509052574634552,
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0.... |
<p>I just read about the deviance measure for the logistic regression. However, the part that is called saturated model is not clear to me. </p>
<p>I did an extensive Google search but none of the results answered my question. So far I found out that a saturated model has a parameter for each observation which as a co... | g62253 | [
-0.030818214640021324,
-0.00827712006866932,
0.010553129017353058,
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0.05150994285941124,
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0.01842176541686058,
0.03392824903130531,
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0.004153505899012089,
-0.022418107837438583,
0.019023744389414787,
0.07847963273525238,
0.01... |
<p>I have our company's daily revenue data in multiple markets. The essence of the project is to see how different markets compare to each other based on a few variables, namely the age of the market and its population.</p>
<p>I've created 30 day rolling means for each market and plotted them,
<img src="http://i.stac... | g62254 | [
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0.06408563256263733,
-... |
<p>I think I need to use a Poisson-family regression or negative binomial regression. My variables are as follows: Y is an integer value ranging from 0 to ~1200. It represents sums (number of species summed over an areal unit). There are in fact many zeroes but no negative values. X1 is a categorical variable, x2 is co... | g62255 | [
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0.001204008935019374,
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... |
<p>Lets say I have the following JAGS model, what are the proper terms for the three parts and 1/tau?</p>
<pre><code> model{
#Term???
for(n in 1:Ndata){
y[n] ~ dnorm( mu[ subj[n] ], tau[ subj[n]] )
}
#Term???
for(s in 1:Nsubj){
mu[s] ~ dnorm( muG, tauG)
tau[s] ~ dgamma( 5, 5)
}
#Term???
muG ~... | g19257 | [
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0.06594111025333405,
... |
<p>This question is regarding the weighted Euclidean distance. I have three features and I am using it as three dimensions. I need to place 2 projects named A and B in this 3 dimensional space and measure the distance among them.</p>
<p>But the case is I need to give them separate weights.</p>
<p>if first feature is ... | g62256 | [
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0.015250088647007942,
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0.01302871573716402,
0.023398922756314278,
0.02850823663175106,
0.0017928429879248142,
-0.01... |
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