question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have fitted the ARIMA models to the original time series, and the best model is ARIMA(1,1,0). Now I want to simulate the series from that model. I wrote the simple AR(1) model, but I couldn't understand how to adjust the difference within the model ARI(1,1,0).
The following R code for AR(1) series is:</p>
<pre><... | g64521 | [
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<p>I'm trying to reproduce <a href="http://rocr.bioinf.mpi-sb.mpg.de/" rel="nofollow">this plot from the ROCR website</a>:</p>
<p><img src="http://i.stack.imgur.com/0ufkA.png" alt="enter image description here"></p>
<p>I can get something similar as follows:</p>
<pre><code>library(ROCR)
data(ROCR.simple)
pred <- ... | g22696 | [
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<p>What are some real-world applications where I can leverage Chebychev's inqueality? All the examples I find are either related to coin tosses or some school scores related problems. Are there any slightly-more complex use cases where this inequality "saves" the day?</p> | g42945 | [
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<p>I'm running a logistic regression model where anecdotally I expected age to be a very large factor. If you see from the charts I made in Excel before running the model through R, this is how the support lines up by age:</p>
<p><img src="http://i.stack.imgur.com/oEVZQ.jpg" alt="enter image description here"></p>
<p... | g49700 | [
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<p>I understand the coefficients of a logistic equation can be interpreted as odd ratio. If a regularization term is added to control for over-fitting, how does this change the interpretation of the coefficients? </p> | g64522 | [
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<p>What is the relation between estimator and estimate?</p> | g64523 | [
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<p>I'm trying to judge the performance of my perceptron linear discriminant. In one instance I'm training on a sample size of 150 and on another I'm training on a sample size of 1500. I test both of these on the same testing set. Yet, the peceptron that is trained on the larger set performs more poorly. I'm not sure ho... | g22700 | [
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<p>Greetings,
I need to determine the trend for barometric pressure based on measurements taken at 15-minute intervals over a 3 hour period. A rise or fall trend occurs if the the pressure changes more than 0.1 kPa, and rapid rise or fall if pressure changes more than 0.2 kPa over a three hour period. Measurements are ... | g42343 | [
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<p>I need to compute the confidence intervals (CI) for a multinomial proposition. I am not a statistician but I can understand basic stuff...</p>
<p>Looking around I have found this resource that explain how to do it:
Glaz, J. and C.P. Sison. 1999. "Simultaneous confidence intervals for multinomial proportions". Journ... | g64524 | [
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<p>We say a model overfits when classification error increases on the test data. The reason behind this is that the training data is not a representative of the distribution from which data is sampled.</p>
<p>Can we <strong>ever</strong> say that a model with a given set of parameters does not overfit?</p>
<p>My ques... | g98 | [
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<p>I have a sample of 5 numbers from known interval [0, 10].
Is 5 numbers is enough to make some conclusions about whether these numbers are drawn from uniform distribution or not?</p> | g22704 | [
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<p>Suppose $X_1,...,X_n$ are iid from $N(\mu,\sigma^2)$ with $\mu$ unknown and $\sigma = 2$ known. Letting $T(X) = \sum{(X_i-\mu)^2}$ from i = 1 to 40, how can I use the central limit theorem to approximate $P(T(X)>200)$?</p>
<p>I found that $E(T(X))=40$ and $Var(T(X))=160$ and $T(X)$ ~ Chi square with n=40 df. </p... | g22303 | [
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<p>I am working on a dataset that ranges between 0 - 100 and typically is centered around 50 for the most part. It seems like the dataset shows a triangular distribution given its bound between 0 - 100. I wasn't sure and just wanted to double check if this would be a triangular distribution? </p>
<p>Can we compute z-s... | g64525 | [
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<p>Folks who work with logistic regression are familiar with the issue of perfect separation: if you have a variable specific values of which are associated with only one of the two outcomes (say a binary $x$ such that all observations with $x=1$ have outcome = 1), the likelihood blows up, and the maximum likelihood es... | g64526 | [
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<p>I have a database of patients with their heart rate before and after surgery. I would like to do a few analyses: </p>
<ol>
<li>Define a threshold value for an optimal heart rate (i.e., above which there is a significant risk of post operative complications).</li>
<li>Test this hypothesis: Does increasing heart rat... | g28929 | [
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<p>Is the semantic differential rating scale below considered a scale of intensity? This is a sample of 7 items contained in a group PQ.</p>
<p>Legend:
1 and 7: (extremely), 2 and 6: (moderately), 3 and 5:(fairly), 4: (Neutral)</p>
<pre><code> 1 2 3 4 5 6 7
</code></pre>
<p>people centric | O ... | g64527 | [
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<p>I am wanting to find the correlation between two variables: a categorical vegetation variable (with categories 1-4) and a continuous variable of erosion (with values anywhere between 0.2 and 9). I think I would be required to use a non parametric test to find the correlation, but bit of a newby to stats so could an... | g22716 | [
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<p>I have 8 sets of variables, taken from another study, each set related to either an intrinsic or extrinsic motivational construct (e.g. "challenge" or "recognition"). I want to see which construct is strongest over a number of participants. Can I add the mean of each variable (over participants) within a set of vari... | g64528 | [
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<p>We are using a Likert scale questionnaire and need to be able to identify the rate of the students. What is the best way we identify this rate? What statistical methods are typically used?</p>
<p>We based our motivation questionnaire on the <a href="http://indiana.edu/~p540alex/MSLQ.pdf" rel="nofollow">MSLQ (pdf)</... | g64529 | [
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<p>I would like to calculate the confidence interval for my autocorrelation function. Does this calculation differ in any way from the normal way of calculating confidence intervals? How would I calculate the CF for cross correlation between two time series?</p>
<p>Thank you for any help =) </p> | g49323 | [
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<p>I am currently doing a True/False exercise. One of the questions as follows:</p>
<blockquote>
<p>A marine drill instructor recoded the time in which each of 20 recruits completed an obstacle course both before and after training. To test whether any improvement occurred, the instructor would use a t-distribution ... | g64530 | [
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<p>I was looking at howto figure out the optimal lag order for an ADF-test when I came across <a href="http://homepages.strath.ac.uk/~hbs96127/mlecture12.ppt" rel="nofollow">this</a> PPT presentation. There are two examples of a ADF-test model reduction, one on p23 and one on p36.</p>
<p>I have two questions:</p>
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<p>I'm working with LibSVM and Matlab but am running into some issues. Specifically, I think I'm misunderstanding some theory. </p>
<p>I've read here and there about the support vector coefficients, but I don't understand them. Are the support vector coefficients the ||w|| to that support vector?? Specifically, my lon... | g22720 | [
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<p>Good evening,</p>
<p>I was reading a stats textbook where I came across the following statement:</p>
<blockquote>
<p>In order to reduce the portfolio risk of a portfolio involving two risky investments, we should choose their covariance to be negative, rather than positive</p>
</blockquote>
<p>I don't really ge... | g22721 | [
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<p>I use bnlearn package in R to learn the structure of my Bayesian Network and its parameters. What I want to do is to "predict" the value of a node given the value of other nodes as evidence (obviously, with the exception of the node whose values we are predicting). </p>
<p>I have continuous variables. </p>
<pre><c... | g22722 | [
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<p>Good evening everyone,</p>
<p>I am currently doing a self-study on CLT and was working on an exercise which asks if the following statement is true or false </p>
<blockquote>
<p>CLT guarantees that the population mean is normally distributed whenever sample size is sufficiently large. </p>
</blockquote>
<p>I ca... | g11 | [
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<p>I'm a frequentist but have been exploring Bayesian techniques lately. One thing that bothers me is that I'm never completely sure that I've implemented them correctly. To be specific, I'm not talking about convergence, burn-in time, or autocorrelation. I'm talking about, 'did I code the formulas correctly?'.</p>
<p... | g22723 | [
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<p>I am working on problem solution where I am collecting social feeds from twitter and Facebook for a product X . I am labeling these posts,comments or tweets using five labels</p>
<pre><code>--Positive
--Negative
--Campaign
--Reply
--Queries
</code></pre>
<p>I have a training set of around 5000 which includes twe... | g64531 | [
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<p>I have a doubt, I need to check the homogeneity of variances on the residuals of a linear regression. I read that Kruskal is also good without assuming a normal-distribution. But I don't know if it's good in my case. I'm doing a linear regression of two vectors of prices(stock prices). I also checked the "normality"... | g49778 | [
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<p>I am running Cox regressions in a large dataset to determine effects of individual and area characteristics on mortality outcomes. (My model is not a multilevel model, as the initial significant variation (random intercepts) between areas disappeared once SES variables have been adjusted for).</p>
<p>I have three c... | g22726 | [
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<p>i'm quite new here!</p>
<p>I have a problem - set of time series with different lengths each. And i need to measure some similarity among them through metrics. </p>
<p>I tried to use <a href="http://en.wikipedia.org/wiki/Dynamic_time_warping" rel="nofollow">DTW metric</a>, but it seems to take into account length.... | g64532 | [
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<p>I am analysing signals from 5 sensors and comparing what they pick up between day and night. Each sensor records a time series and this is compared to a reference time series to determine whether what the sensor is picking up is significantly different to the reference signal. This is done a number of times (represe... | g64533 | [
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<p>acoording to paper <a href="http://cameron.econ.ucdavis.edu/research/Cameron_Miller_Cluster_Robust_October152013.pdf" rel="nofollow">http://cameron.econ.ucdavis.edu/research/Cameron_Miller_Cluster_Robust_October152013.pdf</a> on page 4 the “failure to control for within-cluster error correlation can lead to very mis... | g4553 | [
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<p>I've got a data set looking at how different groups change over time. </p>
<pre><code>#High Abundance, Low Change
HALC<-c(100,99,101,98,99,100,100,101,99,100)
#Low Anundance, Low Change
LALC<-c(1,2,1,2,2,2,1,2,1,2)
#High Abundance, High Absolute Change
HAHAC<-c(100,99,98,91,86,50,45,30,21,9)
#High Abund... | g64534 | [
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<p>I am searching for some algorithms for feature extraction from images which I want to classify using machine learning . I have heard only about [scale-invariant feature transform][1] (SIFT), I have images of buildings and flowers to classify . Other than SIFT what are some good algorithms . </p> | g64535 | [
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<p>Consider this model:</p>
<pre><code>summary(lm(mpg ~ hp*wt, mtcars))
Call:
lm(formula = mpg ~ hp * wt, data = mtcars)
Residuals:
Min 1Q Median 3Q Max
-3.0632 -1.6491 -0.7362 1.4211 4.5513
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 49.80842 3.60516 ... | g49701 | [
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<p>My girlfriend and I were having a debate about a magic trick that could be used to pick up women on the street.</p>
<p>I am a magician and I have a coin. I walk up to a complete stranger with the coin in my hand and know which side is up. I ask her to state heads or tails. If she picks the correct one I tell her, "... | g64536 | [
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<p>I am struggling with this question, which I thought it should be easy: suppose we have a method of sampling from the joint distribution of a collection of (discrete ordinal) random variables. We do not know the density. We need to find a way to sample from the <strong>conditional</strong> distribution of a subset of... | g64537 | [
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<p>I've been testing PCA via SVD to decompose a simple time series data matrix, $X$. I have two signals $x_1(t)$ and $x_2(t)$ in a data matrix where $M$ rows represents each timepoint sample and each column represents $x_1$ and $x_2$.</p>
<p>The mean signal, $\hat{x}$, is defined as the mean along the row axis (avera... | g42378 | [
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<p>I am currently helping a friend with some statistical analysis.</p>
<p>There is a main hypothesis, for which a significant relationship can be shown. Lets call the predictor variable A and the predicted variable B. Her sample size is 200 people. However the distribution of the sexes is very uneven, i.e. there are 1... | g22738 | [
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0.036... |
<p>I am working with an image X, I apply the "adaptive median filter" in it and I get the image Y. I'd like to measure the SNR in both in order to evaluate the quantity of noise deleted. </p>
<p>I know the formula to calculate the SNR is: </p>
<p>SNR = Psignal / Pnoise</p>
<p>but I don't know how to get these values... | g49732 | [
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... |
<p>I've been wracking my brain trying to come up with a test to do something similar to a paired wilcoxon rank sum test for more than two samples. I've explored the Friedman and Kruskal-Wallis tests, but neither of those do quite what I want (I think). The particular case in the data set I'm dealing with is the follo... | g64538 | [
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0... |
<p>I've been trying to code an algorithm to suggest bets in 1X2 (weighted) games.</p>
<p>Basically, each game has a set of matches (home vs away teams):</p>
<ul>
<li><code>1</code>: home wins</li>
<li><code>X</code>: draw</li>
<li><code>2</code>: away wins</li>
</ul>
<p><img src="http://i.stack.imgur.com/mD1w8.jpg" ... | g64539 | [
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-0.03... |
<p>I have a MINITAB printout I was hoping someone could help me with. My question is- from the table below <strong>how do I distinguish between a main effect and an interaction</strong>?</p>
<p>Study: Three drug treatments are compared at three sites. The treatments consist of two dosages (low and high dose) of an ex... | g64540 | [
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0.020304230973124504,
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... |
<p>In a two-way ANOVA, from Kutner's Applied Linear Statistical Models:</p>
<p><img src="http://i.stack.imgur.com/8teDH.png" alt="enter image description here"></p>
<p>What differences are between testing if two factors interact and testing if their interaction is important?</p>
<p>I know that testing if two factors... | g64541 | [
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0.... |
<p>This is Problem 4(c), Chapter 2 from <a href="http://rads.stackoverflow.com/amzn/click/0262201623" rel="nofollow"> Thrun's Probabilistic Robotics </a>. Note that this is self-study and <em>not</em> homework.</p>
<p>Suppose I know my position $x$ to be a normal distribution with density $N(\mu_1=1000,\sigma_1^2=900)... | g22745 | [
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0.053490374237298965,
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... |
<p>Let $X_1, \dots, X_n$ denote a random sample of size n from the probability distribution with pdf:</p>
<p>$$ f_X(x|\theta_1, \theta_2) = \frac{1}{\theta_2 - \theta_1} \ I(x)_{[\theta_1,\theta_2]} \ I(\theta_1)_{(-\infty,\theta_2)} \ I(\theta_2)_{(\theta_1,\infty)}\;.$$</p>
<p>(1) Find a pair of sufficient statisti... | g64542 | [
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0.031896043568849564,
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... |
<p>I’m writing some code <em>(JavaScript)</em> to compare benchmark results. I’m using the <a href="http://frank.mtsu.edu/~dkfuller/notes302/welcht.pdf" rel="nofollow">Welch T-test</a> because the variance and/or sample size between benchmarks is most likely different. The critical value is pulled from a T-distribution... | g64543 | [
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<p>A recent question about <a href="http://stats.stackexchange.com/questions/2234/alternatives-to-logistic-regression-in-r">alternatives to logistic regression in R</a> yielded a variety of answers including randomForest, gbm, rpart, bayesglm, and generalized additive models. What are the practical and interpretation ... | g64544 | [
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<p><a href="http://stats.stackexchange.com/questions/61266/why-is-dependence-a-problem">The answer to this question</a> discusses problems associated with calculating P-values for dependent observations. Let's say you have observations from two different groups that are dependent. You consider carrying out a t-test to ... | g64545 | [
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... |
<p>First, the expected survival time when time is time to event is treated as a continuous r.v. is given as the following:</p>
<p>$$\int_0^{\infty} S(t)\, dt$$</p>
<p>The formula for the mean residual survival time $\text{mrl}(u) = E(T -u | T>u)$ is given by </p>
<p>$$\frac{1}{S(u)}\int_u^{\infty} S(t)\, dt.$$</... | g64546 | [
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... |
<p>First of all, I would like to describe some common layouts that Data Mining books use explaining how to deal with <em>Unbalanced Datasets</em>. Usually the main section is named Unbalanced Datasets and they cover these two subsections: Cost-Sensitive Classification and Sampling Techniques. </p>
<p>It seems that fac... | g43181 | [
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0.013748... |
<p>This is a naive question from someone starting to learn machine learning. I'm reading these days the book "Machine Learning: An algorithmic perspective" from Marsland. I find it useful as an introductory book, but now I would like to go into advanced algorithms, those that are currently giving the best results. I'm ... | g37755 | [
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<p>How to calculate confidence interval for this mix of independent(different subjects) and dependent (data of same subject from two sessions) observations?</p>
<p>There are 12 subjects and the mean is calculated from these 12 subjects with data from two sessions, so 24 values go into the mean.</p>
<p>Any ideas? </p>... | g64547 | [
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-... |
<p>there is a question i can not answer. </p>
<p>Suppose the numbers in the following random number table correspond to people arriving for work at a large factory. Let 0,1,and 2 be smokers and 3-9 be nonsmokers. After each ten arrivals, calculate the total relative frequency of smokers and graph the results... | g22750 | [
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<p>When the survey design is complex, say, a 3-stage stratified cluster sampling design, then we have to use sampling weights. When I use SPSS then I see that the sampling weight it uses is the raw weight. By default it uses Taylor's linearization method for variance approximation. If I want to use relative or normaliz... | g64548 | [
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... |
<p>I'm no mathematician, so please consider the whole explanation as a subject to criticism and optimization. </p>
<p>I'm trying to build a model and calculate an estimate of error variance for the following problem.<br>
Consider a point in 3D, a ray coming out of it towards some plane, and the point of intersection ... | g64549 | [
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0.006... |
<p>This post provides an excellent example of the inner workings of a mixed effects model: <a href="http://emhart.github.com/blog/2012/11/16/making-sense-of-random-effects/" rel="nofollow">http://emhart.github.com/blog/2012/11/16/making-sense-of-random-effects/</a></p>
<p>In a hypothetical study, I have measured the w... | g64550 | [
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... |
<p>I have multiple survey questions that give respondents 4 Likert-type options for a response to qualify their knowledge/skill in a particular area. I have calculated a weighted average (and divided by the sample size of each group) for the two groups and would like to determine whether there is a significant differe... | g64551 | [
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0.025311557576060295... |
<p>I am interested in testing if linear models are statistically different, so I would like to know what I can assume about the distribution of linear parameter models, like the slope for example.</p>
<p>More specifically, assume I randomly sample n $(x,y)$ pairs from a random source, and perform a linear regression o... | g22754 | [
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... |
<p>I'm currently trying out the <code>pbkrtest</code> package. The test of the fixed effect (<code>f1</code>, in the example below) doesn't pose any problem.</p>
<pre><code>## Not run:
library(lme4)
library(pbkrtest)
# large model:
m1 <- lmer(x ~ f1 + (1|ID) + (0 + f1|ID), data)
</code></pre>
<p>When I want to ob... | g64552 | [
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0.04804329574108124,
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... |
<p>We have hourly time-series data of the status of a system: number of people present at different train stations. We collected it for a year, and we want to use it to train a model to predict the status of this system in future.</p>
<p>We know that several parameters influence the system status, such as: temperature... | g316 | [
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<p>I just fit a model in lme4, and I'm wondering what the heck I fit...</p>
<p>I have individuals <code>id</code>, and each is measured pass/fail on items that can be described using two factors, <code>f1</code> and <code>f2</code>. My theory says that <code>id</code> and <code>f2</code> can interact. So I want to com... | g64553 | [
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<p>I'm a beginner to Bayesian belief network (BBN). I read a few articles on introduction to BBN. So I know a general idea of BBN. But I'm struggling to construct a graphical network and conditional probability table (CPT) with my data set. A main aim of my research is to find any combinatory (synergistic, additive, an... | g64554 | [
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<p>I want to assume that the sea surface temperature of the Baltic Sea is the same year after year, and then describe that with a function / linear model. The idea I had was to just input year as a decimal number (or num_months/12) and get out what the temperature should be about that time. Throwing it into lm() functi... | g49404 | [
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<p>I am asking this questions for clarifications on the terms between "null distribution" and "sampling distribution". I find that when some one says <strong>null distribution</strong>, actually they mean the same thing as when others say <strong>sampling distribution</strong>. </p>
<p>In this hypothesis testing artic... | g64555 | [
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<p>I'm reading about the Linear Discriminant Analysis by Fisher and I have a couple of questions about its usage.</p>
<ol>
<li><p>If you have k>2 classes in a two-dimensional space you find k−1 vectors that you need to use to project the sample data. Is it possible that one sample is closer to different means along di... | g22761 | [
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<p>Assume I have an outcome like this:</p>
<pre><code>x<-c(rep(2.83,3),
rep(3.17,4),
rep(3.83,4),
rep(4.17,5),
rep(4.83,8),
rep(5.5,3),
rep(7.17,5),
rep(8.17,7),
rep(8.83,12),
rep(9.5, 12),
rep(9.83,17),
rep(10.17,50))
hist(x)
hist(log(x))
</code></pre>
<p>I ... | g64556 | [
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<p>There are different methods for prediction of ordinal and categorical variables.</p>
<p>What I do not understand, is how this distinction matters. Is there a simple example which can make clear what goes wrong if I drop the order? Under what circumstances does it not matter? For instance, if the independent variabl... | g22762 | [
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<p>I am doing a static panel analysis: four independent variables, seven cross sections and $T = 13$ years. I want to include a variable (exchange rate) which varies over time but is identical (has the same value) for each of the cross section members. </p>
<h3>Question:</h3>
<p><strong>Is it possible to use a variab... | g1012 | [
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<p>I'd like to hear your opinions on the following:</p>
<ul>
<li>What parameters would you report when estimating different likelihood based regression? AIC, BIC, Pseudo $R^2$? </li>
<li>What is the standard to report? </li>
</ul>
<p>It should be a parameter which answers the question of how good the specified model ... | g22763 | [
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<p>I have a multitree that represents the lineages of all the fishgroups in a breeding program. It's stored as a double adjacency table with <code>fish_id</code>, <code>sire_id</code> and <code>dam_id</code>. This means a particular fishgroup is only directly aware of its parents (if any) and knows nothing about descen... | g42397 | [
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<p>I am conducting a non-linear least squares regression fit using the python scipy.optimize.curve_fit function, and am trying to better understand the weights that go into this method.</p>
<p>I have a distribution of raw data points that I wish to fit to a Gaussian cumulative distribution function. I created a functi... | g64557 | [
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<p>My understanding is that a sample can be adjusted based on a known population using the "Weight Cases" function in SPSS. What is the proper procedure for weighting by multiple factors? Let's say I have WEIGHT_SEX and WEIGHT_ETHNICITY. Can I compute a WEIGHT_COMPOSITE by taking their product? Are there any downsides ... | g64558 | [
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<p>I've done a test using ARMA model on some financial series. It turns out the prediction rate is really very bad – close to half time correct and half time wrong…</p>
<p>I am new to ARMA model so what I tried is very simple, following the textbook of deciding (p,q) for ARMA model by ACF and PACF first, and then use... | g64559 | [
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<p>I am trying to use machine learning on some peculiar (at least for me) data.
Usually, when I do machine learning I am use to have the data in this format:</p>
<pre><code> Feat1 Feat2 Feat3 Feat4 Class
I1 | .0 | .0 | .2 | .3 | TRUE |
I2 | .5 | .0 | .1 | .3 | TRUE |
I3 | .0 | .0 | .1 | .3 | FALSE |
... | g64560 | [
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0.016195783391594887,
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0.02605040930211544,
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0.005537217948585749,
0.004820330534130335,
0.09118971973657608,
0.0... |
<p>My problem can be summarized very simply: I'm using a linear mixed-effects model and I am trying to get p-values using pvals.fnc(). The problem is that this function seems to have some trouble estimating p-values directly from the t-values associated with model coefficients (Baayen et al., 2008), and I don't know wh... | g22767 | [
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0.03049011342227459,
0.0... |
<p>Let $p$ be a matrix, where each row represents an observation of a 4-variate normally distributed random variable $\mathcal{N}_4(\mu,\Sigma)$. </p>
<ul>
<li><p>Is there any Bootstrap methode to get a good estimation for Σ?</p></li>
<li><p>If not, is the number of the following sample enough to bootstrap the distrib... | g64561 | [
0.0007641123957000673,
0.0035739613231271505,
0.013890847563743591,
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0.0021207088138908148,
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0.0403401218354702,
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0.03185288980603218,
0.02901497483253479,
0.00983500387519598,
0.... |
<p>Is it possible to obtain a Gamma distribution from knowing the pessimistic, most-likely and optimistic value of a random variable? The values are known with a 90% confidence, i.e. nine times out of ten, the actual value of the random variable will fall within the pessimistic-optimistic bound while it will be skewed ... | g64562 | [
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0.004699569195508957,
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... |
<p>I'm facing a problem with a binomial <code>glmer</code> model. I want to find if differences in flower presence in pine trees is due to procedence of the tree.
My model is as follows: <code>FlorMas ~ Proc + (1|Blq)</code>.
Proc is a factor with nine levels, one of it (<code>TAMR</code>) presents no flower at all (va... | g64563 | [
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0.... |
<p>A researcher wants to compare 50 websites. There is 80 binary variables for each website that belong to 4 main measures.</p>
<p>Actually There is 50*80 matrix that each row represent a website and each column is a binary variable.</p>
<p>He asked me a statistical method for comparing (and ranking) the websites bas... | g64564 | [
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0.000911564682610333,
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0.0006109709502197802,
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0.014678134582936764,
0.02626812644302845,
... |
<p>I've learned sum of exponential random variables follows Gamma distribution.</p>
<p>But everywhere I read the parametrization is different. For instance, Wiki describes the relationship, but don't say what their parameters actually mean? Shape, scale, rate, 1/rate?</p>
<p>Expoenetial distribution: $x$~$exp(\lam... | g22771 | [
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... |
<p>In reviewing some market research, I came across a study which decided to weight the results/outcomes of the control group so the distribution of participants in the control sub-groups (0,1,2,3,4,5 - a measure of their pre-experiment activity of a certain activity) would equate with that of the treatment group. The ... | g64565 | [
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... |
<p>I wonder if you can help me to get the right answer to a question about structural equation modeling. Imagine someone trying to validate a questionnaire using component factor analysis that highlighted 5 subscales. Is it right to use the total score of the questionnaire in a model created by structural equation mode... | g64566 | [
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0.027655381709337234,
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0.04152070730924606,
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<p>I have performed the following experiment: Two genotype groups of two different ages were monitored in the presence of three drugs one after the other. So, each subject after a control period received drug A, then drug B and then drug C. I want to know what is the effect of every drug compared to control and between... | g64567 | [
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0.00009216434409609064,
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<p>Suppose A is a fixed factor and B is a random factor. A and B are crossed. Another random factor C is nested in B. Taking into account the AB and AC interactions, how should I fit the model using lme function in the nlme package? Thanks.</p> | g22775 | [
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0.004364148247987032,
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0.01337471604347229,
0.03080298937857151,
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<p>I'm wondering if there are any statistical issues with using a dummy variable that is a subcategory of another dummy variable.</p>
<p>For example:</p>
<p>Let's say I am trying to predict a binary outcome of whether a child goes to college.</p>
<p>If I have one dummy variable "NYC" for "lives in New York City" and... | g22939 | [
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0.0024704625830054283,
0.002489676931872964,
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0... |
<p>For the development of a new chemical process, a handful experts should be asked a few questions (4 to 6), what values they expect for several experimental parameters, i.e. temperature ranges and how confident they are regarding their guesses on a scale from 1 to 10.</p>
<p>I would like to weight their responses co... | g64568 | [
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<p>I am interested in financial time series and I have a small question regarding the use of the forecast package. </p>
<p>The time series I am interested in is a monthly one and present clear evidences of seasonality. Thus there is a need to use a lag 12 differentiation. After this step, I apply a full collection of ... | g22776 | [
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<p>Say, there are three nodes: $S$, $R$, $D$. $S$ transmits to $R$, $R$ stores the packets, and later transmits to $D$. At any time, either $S$ or $R$ is selected to transmit according to some random selection rule. The probability that $S$ is selected to transmit is $P_S$, and that of R is $P_R$. For e.g., if $S$ is s... | g22777 | [
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0.03966454416513443,
0.0005... |
<p>I know that this has been widely discussed, but even after having read many discussions on this matter, I'm still not sure if I'm understanding properly.</p>
<p>So I have a dataset of studies reporting prevalence in several settings, here is an exemple:</p>
<pre><code>data<-data.frame(id_study=c("UK1","UK2","UK... | g22778 | [
0.014864466153085232,
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0.00435613514855504,
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0.025394994765520096,
0.05131835117936134,
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0.018394652754068375,
0.03388040512800217,
-0.... |
<pre><code>ridge.fit1 <- glmnet(x,y, alpha = 0)
ridge.fitt <- coef(glmnet(x, y, alpha = 0, lambda = 3))
ridge.pred <- predict(ridge.fit1, s = 3, type = 'coefficients')
</code></pre>
<p>What's the difference between ridge.fitt and ridge.pred?</p> | g22779 | [
0.06264032423496246,
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-0.0372026227414608,
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0.06221577152609825,
0.0183528084307909,
-0.0207... |
<p>I'm trying to generalise a formula that takes the mean of some variances to it work with vectors.</p>
<p>I'm not sure it makes sense to take the variance between a bunch of vectors, rather it is more suited to generate a covariance matrix.</p>
<p>So, is there a way to take the mean of a bunch of covariance matrice... | g22780 | [
-0.018362004309892654,
0.02729301154613495,
-0.013539548963308334,
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0.028515996411442757,
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0.0010749408975243568,
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0.01661839708685875,
0.0221210028976202,
-0.02932754158973694,
0... |
<p>I have an ascii dataset which consists of three columns, but only the last two are actual data. Now I want to create a dotchart of the data by using <code>read.csv(file = "result1", sep= " ")</code>. R reads all three columns. How do I avoid this?</p> | g64569 | [
0.0035760272294282913,
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0.06523758918046951,
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<p>I am looking for the equation for the se.fit values when using logistic regression in R.
I have seen this answer - <a href="https://stats.stackexchange.com/questions/66946/how-are-the-standard-errors-computed-for-the-fitted-values-from-a-logistic-regre/66947#66947">How are the standard errors computed for the fitted... | g64570 | [
0.026417357847094536,
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0.0674959048628807,
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<p>I have a collection of matrices $A_1,\ldots,A_n$, and I want to do joint Schur decomposition on them (they all have the same unitary matrices in their decomposition). I couldn't find any implementation of this (I was looking for Python, but I would be happy to find anything at the moment). The closest I found was an... | g64571 | [
0.000754773966036737,
-0.05199068412184715,
0.023185329511761665,
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0.02594941109418869,
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0.017495788633823395,
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0.0... |
<p>What is a Gaussian Discriminant Analysis (GDA)? What materials should one read to understand how a GDA works and where it comes from? Try to explain this for someone at a high-school level.</p> | g22785 | [
0.02757219970226288,
0.005483522545546293,
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0.0740973949432373,
0.11075909435749054,
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<p>I have two groups (G1, n=10; G2, n = 10) each representing a separate condition.
Participants in each group answered 20 questions and each question is a dichotomous variable coded 0 and 1 (VDD).</p>
<p>I want to compare the group 1 with group 2.
I am having some trouble understanding if I have it right, for every ... | g64572 | [
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0.... |
<p>I am planning to perform an online behavioral survey across a nationwide sample, and I expect several thousand responses. I expect to have not that many questions (perhaps 3 pages, 8 qs each), require skip logic, and would like it to redirect back to a page of my choice. I also need it to be hosted, as local webho... | g64573 | [
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0.061902739107608795,
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0.010580469854176044,
0.014020255766808987,
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0.006323528476059437,
-0.... |
<p>I have some data which is clearly truncated on the left. I wish to fit it with a density estimation that will handle it in some way instead of trying to smooth it down.</p>
<p>What known methods (as usual, in R) can address this?</p>
<p>Sample code:</p>
<pre><code>set.seed(1341)
x <- c(runif(30, 0, 0.01), rno... | g64574 | [
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0.004933384712785482,
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0.00048686264199204743,
-0.028271155431866646,
0.0478980615735054,
0.001... |
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