question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have a regression model that looks like this: $$Y = \beta_0+\beta_1X_1 + \beta_2X_2 + \beta_3X_3 +\beta_{12}X_1X_2+\beta_{13}X_1X_3+\beta_{123}X_1X_2X_3$$</p>
<p>...or in R notation: <code>y ~ x1 + x2 + x3 + x1:x2 + x1:x3 + x1:x2:x3</code></p>
<p>Let's say $X_1$ and $X_2$ are categorical variables and $X_3$ is n... | g783 | [
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<p>I have a small number of samples (5) of a large population (~10,000). The samples are percentages and hence I know from the context that no answers are possible below 0% or above 100%. From this one set of samples I've calculated my t statistic and confidence intervals; however, for anything above 95% confidence my ... | g6621 | [
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<p>I'm working with some data and I used R to the a linear regression model <code>Y = aX + b</code>.
The code I used was
<code>summary(lm(Y~X))</code>
What I got was</p>
<pre><code> Estimate Std. Error t value Pr(>|t|)
(Intercept) -0.3884045 0.0260232 -14.93 <2e-16 ***
X 0.006209... | g66939 | [
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<p>I am a little confused about what p-values mean under Fisher's signficance testing & Neyman-Pearson's hypothesis testing.</p>
<p>Fisher uses p-values as a continuous measure of evidence against a null hypothesis? So a p-value of 0.06 would indicate that there is no difference and the null hypothesis is true?</p... | g66940 | [
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<pre><code>library(BRugs)
library(coda)
...
output = BRugsFit("model.bug", data, inits, numChains = 1, nThin = 5,
seed=6, parametersToSave, nBurnin = 9, nIter = 50,coda = T,digits = 5)
# computes the effective sample sizes.
effectiveSize(output)
HPDinterval(output,prob=.9)
# diagnostics
geweke.diag(output... | g66941 | [
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<p>Does anyone know of a statistical approach/method that lets you model linear regressions between 3-5 explanatory variables that are categorical or continuous and 3 continuous response variables that have interaction effects?
Thanks in advance.</p> | g66942 | [
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<p>I cannot understand what I'm doing wrong with an F-test for the regression - I get completely different answers using SSE and R2 formulas.
Unrestricted model:
<img src="http://i.stack.imgur.com/aVWhX.png" alt="enter image description here"></p>
<p>Restricted model:
<img src="http://i.stack.imgur.com/4dxNO.png" alt... | g46681 | [
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<p>I'm trying to explore (rather than formally test) relationships for various subgroups between a continuous X and a binary Y (0 or 1). A good shortcut would seem to be to graph a smoothed X-Y fit for each subgroup. But even when, at various levels of X, the mean of Y ranges from .1 to .3, R's smoothed fitline often ... | g46682 | [
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<p>Given a regression model on interval $[0,1]$
$$
Y_{i}=f(x_{i})+\epsilon_{i},\ i=1,\ldots,N
$$
with fixed design and standard error assumptions $E(\epsilon_{i})=0;\ E(\epsilon_{i}\epsilon_{j})=\delta_{i,j}\sigma^{2}$.
The regression function $f$ is from Sobolev space
$$
f\in W^{q}\left[0,1\right]=\left[f,\ldots,f^{(q... | g26252 | [
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<p>I have seen that in constructing indices by PCA the scores of only the first component is used. Although the first principle component explains the most variation contained in the data, often the VAF is too small (10% or even less). Then why do we use only the first component score instead of combining the scores of... | g66943 | [
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<p>I have this problem where I am given a matrix A of size nxp. I run svd on this matrix A. Then I am supposed to plot this matrix using imagesc in matlab where rows are sorted by the first row eigenvalue and columns are sorted by the first column eigenvalue</p>
<p>I didn't get what it means by "rows are sorted by the... | g66944 | [
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<p>I have been experimenting with gamm4 to derive GAMMs of some repeated measures data.</p>
<p>The models looks very nice and seem to give more flexibility than my LMMs.</p>
<p>Ultimately I want to compare models not by the quality of their fit (also the reality of comparing LMM and GAMM fits seems complex?), but in ... | g66945 | [
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<p>My problem is as follows:
I drop 40 balls at once from a certain point, a few meters over the floor.
The balls roll, and comes to a rest.
Using computer vision, I calculate the center of mass in the X-Y plane.
I am only interested in the distance from the center of mass to each ball, which is calculated using simple... | g26256 | [
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<p>I'm involved in sample size calculation for an oncology clinical trial. Our Primary outcome is quality of life (quantitative, normal).
There are two treatment regimes. Therefore I started with a simple t-test sample size calculation. With an effect size of 0.55, pow=.8, alpha=.05 we need overall 106 participants. C... | g66946 | [
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<p>I have monthly data for about the last 2.5 years for an economic index as well as external regressors for each month. Is it feasible to treat the months as independent and just fit a multiple regression model regressing the external data (3-5 variables) on the index? I have tried fitting an ARIMA (1,0,0) and with ex... | g26257 | [
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<p>In Brockwell and Davis' Introduction to Time Series and Forecasting, </p>
<p>a linear process is <a href="http://books.google.com/books?id=VHB4OSAmwcUC&lpg=PP1&pg=PA51#v=onepage&q&f=false" rel="nofollow">defined to be</a></p>
<p><img src="http://i.stack.imgur.com/FHA9V.png" alt="enter image descrip... | g66947 | [
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<p>Suppose $X_i, i \in \mathbb N $ is a white noise. Given $X_1,\dots, X_n$, what is the best one-step linear predictor for $X_{n+1}$, best in the sense of mean square error?</p>
<p>What if the question is changed to the following case:</p>
<p>Suppose $X_i, i \in \mathbb N $ are uncorrelated, and they have identical ... | g66948 | [
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<pre><code>Dickey-Fuller test for unit root Number of obs = 21
---------- Interpolated Dickey-Fuller ---------
Test 1% Critical 5% Critical 10% Critical
Statistic Value Value ... | g49602 | [
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<p>This is my first time at stack exchange, hence please pardon me if I miss something. I have multiple questions and I am tearing myself as curve-fitting and estimation is foreign land to me, I am ready to learn given directions and ideas.</p>
<p>I am trying to model liquidity (ease of trading) of a security. In my c... | g66949 | [
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<p>I'm using demographic variables (age, number of children, gender, socioeconomic status, educational status) as moderating variables between Self differentiation (independent variable) and Marital Satisfaction (DV). I'm planning to use hierarchical regression is it correct? if in case I would not follow random sampli... | g26261 | [
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<p>I want to test whether the breeding periods of several closely related birds is significantly separated in time. What statistical test should I use?</p>
<p>My data consists of several observations per species with the date of breeding initiation (i.e. egg laying dates).</p>
<p>Could I just simply do an ANOVA on th... | g66950 | [
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<p>I'm trying to model correctly the data of a research were doing.</p>
<p>We have many indicators measured along a day in n patients. For example, we have heart rate recorded once per minute for every patient. The patients belong to 4 groups. </p>
<p>We want to estimate the effect of the group they belong to on the ... | g66951 | [
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<p>In local news [1] comes with information that 58% of people is for something. This information is based on option pool that ask 500 people from 10.5 million about that question. What is confidence interval for people that are for that something?</p>
<p>To solve this I try following. The $n$ people from $10^7$ is fo... | g49351 | [
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<p>The problem I am working on not only requires me to use several levels but also identify, from a set of attributes, which ones could be treated as levels. </p>
<p>What is a good resource to understand Mixed Models? Also, what are the concepts that one must understand before putting such models to use? And what are ... | g49763 | [
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<p>I have learned several classifiers in Machine learning - Decision tree, Neural network, SVM, Bayesian classifier, K-NN, Markov process...etc.</p>
<p>Can anyone please help to understand when I should prefer one of the classifier over other - for example - in which situation(nature of data sets, etc) I should prefer... | g49363 | [
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<p>I would like to know how about the differences between hidden markov model and neural network.</p> | g66952 | [
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<p>If you are fitting a SEM and wish to add an interaction effect between two variables, I understand that you convert the variables to z-scores, multiply them together and insert this new variable into the model as the interaction effect.</p>
<p>What do you do if the interaction effect variable does not meet assumpti... | g66953 | [
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<p>I'm looking at a data set and trying to understand relationships between what is charged and what is paid.</p>
<p>First pass with a simple regression using excel's data analysis regression tool gives the following, without forcing zero intercept:</p>
<p><img src="http://i.imgur.com/IzaJJyF.png" alt="Residuals Plot... | g26266 | [
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<p>“Determine probability that a purchase is paid for by debit card OR credit card given that the customer paid over $100 for it” [2 events and 1 condition] </p>
<p>“Compute the probability that a child survives an accident given that the child is either 3 OR 4 years old.” [ 1 condition, 2 events]</p>
<p>My question ... | g66954 | [
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<p>I have a table.</p>
<pre><code> CASH CREDIT CARD DEBIT CARD TOTAL
UNDER 20 0.09 0.03 0.04 0.16
20-100 0.05 0.21 0.18 0.44
OVER 100 0.03 0.23 0.14 0.4
TOTAL 0.17 0.47 0.36 1
<... | g66955 | [
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<p>The problem I have is as follows. I have enrolment data describing the number of male and female preferences for two broad fields of education: i) Information Technology and ii) Engineering. The data reflects "first preferences", that is, the number of people who wrote down on paper that their most preferred degre... | g652 | [
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0.03415185585618019,
-0.0293014757335186,
0.008330113254487514,
0.01800175942480564,
0.013946457765996456,
0.025220081210136414,
0.06802143901586533,
0.01375187... |
<p>I have access to two large medical datasets of observational records in the UK. The first - Clinical Practice Research Datalink (CPRD) - has data on 100,000's of patients - largely dates of doctor's visits, diagnoses & prescriptions. Crucially, it has little information on hospitalisations.</p>
<p>The second ... | g66956 | [
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0... |
<p>I've been using the backbone network extraction method outlined in this paper: <a href="http://www.pnas.org/content/106/16/6483.abstract">http://www.pnas.org/content/106/16/6483.abstract</a></p>
<p>Basically, the authors propose a method based in statistics that produces a probability, for each edge in the graph, t... | g6758 | [
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0.... |
<p>Could someone please tell me, where this comes from:</p>
<p>$$
p(\beta, \sigma^2 | y, \tau) \propto p(y | \beta, \sigma^2) p(\beta | \tau) p(\sigma^2).
$$</p>
<p>Thank you!</p> | g66957 | [
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<p>I have three groups with two hundred individuals each, and each individual within a group has a pre and post treatment measurement. A single group contains individuals with similar pre measurement scores. </p>
<p>If I wanted to see which groups have had a significant change in their measurements from pre to post tr... | g26270 | [
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-0... |
<p>Why are we using the squared residuals instead of the absolute residuals in OLS estimation?</p>
<p>My idea was that we use the square of the error values, so that residuals below the fitted line (which are then negative), would still have to be able to be added up to the positive errors. Otherwise, we could have an... | g49295 | [
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<p>The following binomial test (exact binomial test) has a <em>p</em>-value of <strong>0.05698</strong>, greater than 0.05 by a bit. 95% CI is (0.5698, 0.8077).</p>
<pre><code>binom.test(x = 44, n = 63, p = 0.8, alternative = "two.sided")
</code></pre>
<p>The following proportions test (without Yates' continuity corr... | g26272 | [
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-0.02... |
<p><strong>tl;dr</strong> I can only generate samples of a random variable $X$ using MCMC. How can I find the error in the estimate of the expected value of $X$ based on this MCMC data?</p>
<hr>
<h3>The problem</h3>
<p>I have a "black box" which gives me a sequence of "random" numbers (MCMC sampler). I have record... | g66958 | [
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0.... |
<p>I have been playing with this SPSS <a href="http://rpadgett.butler.edu/ps310/datasets/LooksOrPersonality.sav" rel="nofollow">data file</a>, which is a class example from a university I am not enrolled in.</p>
<p>In the original file there are 10 men and 10 women. I did a two-way mixed ANOVA with gender as the betwe... | g26273 | [
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0.00... |
<p>My fixed effect model is insignificant when I don't include the year dummies
$$\text{Prob $>$ F} = 0.7769$$</p>
<p>When I try other regressions the model is fine, for example Driscoll & Kraay fixed effect.</p>
<p>When I delete some outliers from my dependent variable, the fixed effect become signifi... | g66959 | [
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<p>Suppose I want to fit a lasso/ridge regression to a training set. Then, I need to choose $\lambda$, the regularization parameter. To choose $\lambda$, I can use two methods:</p>
<ol>
<li><p>K-fold Cross Validation (from An Introduction to Statistical Learning p. 227):</p>
<ol>
<li>Divide the training set into K fo... | g26274 | [
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<p>I'd appreciate reference books/online resources in learning how to apply A/B hypothesis testing for problems of the following type:</p>
<p>Given an initial strategy B with $X$ samples yields a success rate of $b$. Now say we are given two new strategies $B_1$ and $B_2$, one trial each with number of samples $X_1$ a... | g66960 | [
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<p>What does this statement mean: "we calculated binomial 95% confidence intervals to determine the number of weeks that were statistically-significantly outside of the bounds of error"? How can one calculate it?</p> | g26275 | [
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<p>I have some simple datasets that consist of a discrete integer-valued variable together with frequency counts. The frequencies vary a lot as does the value of the variable. For example one set has values from 1 to a little less than 15000 with frequencies from 1 to half a million. The small values have the many occu... | g26276 | [
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<p>I am trying to fit the mixed effects model and test for a variance component using RLRsim package.</p>
<p>$$
Y_{ik} = \alpha + \mu_{k} + \beta G_{i} + Z_{k}G_{i} + b_{i} + \epsilon_{ik}
$$
Random effects:
$$
Z_{k} \sim N\left(0,\psi\right) \qquad b_{i} \sim N\left(0,\tau\right) \qquad \epsilon_{ik} \sim \l... | g66961 | [
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<p>Does anyone have advice/references on choosing a minimally informative prior for the shape parameter of an Erlang distribution (gamma distribution with shape parameter restricted to integer space), or a joint prior on both parameters.<br>
My gut tells me that a discrete uniform could be a bad idea. A truncated poiss... | g66962 | [
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<p>I working on this data set with marital status and age. I want to plot the percentage of never married man versus each age. Could you please help me to figure out the way how to do it in R? So far I have created two separate arrays with men never marries and ever married. I know how many case of each I have. What i ... | g46721 | [
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... |
<p>I was wondering if I have to worry about the homogeneity of error variance assumption (which states that the predicted scores for Y should be similarly distributed about the regression line for each of the moderator based populations) when my moderator is continuous? I know you should not dichotomize a continuous m... | g66963 | [
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... |
<p>I am using simple linear regression to predict the number of days of school a single student might miss after 250 days using their cumulative daily attendance data over the first 50 days of the student's schooling--i.e., predicting how many days of school they will have missed at 250 days based on their individual c... | g66964 | [
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0.017... |
<p>From Kutner's Applied Linear Statistical Models</p>
<blockquote>
<p>In the next three sections, we shall discuss three multiple comparison
procedures for analysis of variance models that permit the family
confidence coefficient and the family a risk to be controlled. </p>
<p>Two of these procedures, the... | g66965 | [
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0.012460298836231232,
... |
<p>Consider n independent observations {($x_i, y_i$) : $1 \le i \le n$} from the model $$Y = α + βx + \epsilon,$$
where $\epsilon$ is normal with mean 0 and variance $σ^2$. Let $\hat α$, $\hat β$ and $\hat σ^2$ be the maximum likelihood estimators of $α$, $β$ and $σ^2$ respectively. Let $v_{11}$,
$v_{22}$ and $v_{12}$ ... | g66966 | [
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0.0009674721513874829,
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0.03480545058846474,
0.021102463826537132,
... |
<p>I am conducting a study on a sample of 100 people in order to test whether or not education has an effect on employment status. Basically i'm running a logistic regression where education is the independent categorical variable (i.e 1= HighSchool, 2=Bachelors, 3=Masters etc...) and the dependent variable being binar... | g66967 | [
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<p>I have been checking out which diagnostics to use for a GEE analysis. It seem that influence measures are appropriate (Preisser, 1996). Does anyone know of a package that can be used in R to examine influence measures in GEE? The "stats" package does not work: it returns an error when I run</p>
<pre><code>influence... | g26280 | [
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0.023642661049962044,
0.000745088211260736,
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... |
<p>I am working my way (self-study) through E.T. Jaynes' book <em>Probability Theory - The Logic of Science</em></p>
<h2>Original Problem</h2>
<p><em>Exercise 2.1</em> says: "Is it possible to find a general formula for $p(C|A+B)$ analogous to [the formula $p(A+B|C)=p(A|C)+p(B|C)-p(AB|C)$] from the product and sum r... | g46733 | [
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0.01885506883263588,
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0.006464764941483736,
0.0... |
<p>Partly as a learning exercise, I’m attempting to reproduce a published SAS PROC MIXED analysis using R’s lme4 package. A full description of both the application and the statistical method is available in <a href="http://www.biomedcentral.com/1472-6750/11/15" rel="nofollow">http://www.biomedcentral.com/1472-6750/11... | g66968 | [
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0.022006576880812645,
0.054... |
<p>My data look like this.</p>
<p><img src="http://i.stack.imgur.com/Qi08m.png" alt="Heights of hoverers and non-hoverers"></p>
<p>The variable on the $x$ axis is height in inches. The variable on the $y$ axis is whether someone hovers when urinating at a public toilet. Each of the 103 points is a female university s... | g26281 | [
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<p>Suppose you have observations $f_1, f_2, \ldots, f_n$ which are drawn <em>i.i.d.</em> from a central F distribution, with unknown numerator degrees of freedom, $n_1$ and known denominator degrees of freedom, $n_2$. What is the preferred method for computing/estimating the MLE of $n_1$? If the likelihood is known to... | g26282 | [
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<p>I have developed a web application in which I show a picture and two captions. One of those captions is the correct and the other is randomly selected from a corpus of picture captions.</p>
<p>Next, I present the following question: "Which caption best describes the picture?" and the user casts a vote on the captio... | g109 | [
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<p>I'm needing to validate an inherited testing project correct use of confidence testing.</p>
<p>Direct mail creatives are being evaluated at month end over a 90 day campaign cycle for several unique customer groups (eg.: new, upgraded, lapsed, etc.) Here's a low volume data example for just one customer group (new) ... | g26284 | [
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<p>I am very interested in the concepts and discussions taking place here. However, I'm not entirely sure what this field of study is called or what the many branches of study are being discussed here are. It all seems to be related to finding relations and patterns in data so we can use it in a meaningful way.</p>
<p... | g66969 | [
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<p>Say I have n sets of data where each set of data has a binomial distribution. The n sets of data are then combined into one set.
If I take the combined set of data, how would I go about detecting that this set is made up from n individual sets ?</p>
<p>I have only a limited background in statistics, so here is an ... | g66970 | [
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0.026745498180389404,
... |
<p>How to reproduce MS Excel's <a href="http://office.microsoft.com/en-us/excel-help/chidist-HP005209010.aspx" rel="nofollow">CHIDIST</a> function in MATLAB?</p>
<blockquote>
<p>Returns the one-tailed probability of the chi-squared distribution. The χ2 distribution is associated with a χ2 test. Use the χ2 test to co... | g66971 | [
0.03052564151585102,
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0.029369531199336052,
0.07136761397123337,
0.0... |
<p>I would like to estimate the distribution of a very large population of known size but unknown mean and variance. I cannot assume anything about the shape of the underlying distribution (although I am relatively certain that it is not normal). However, I am certain that the values in the population are non-negative,... | g66972 | [
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<p>I've seen that multiplicative Holt-Winters requires strictly positive data points.
I was wondering why it does not allow zero values?</p> | g66973 | [
0.0021392074413597584,
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<h3>Context:</h3>
<p>From a question on Mathematics Stack Exchange <a href="http://math.stackexchange.com/questions/31649/can-i-build-a-program-that-will-tell-me-if-a-real-world-data-set-looks-linear-lo/">(Can I build a program)</a>, someone has a set of $x-y$ points, and wants to fit a curve to it, linear, exponentia... | g66974 | [
0.07628884166479111,
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0.017428454011678696,
0.002625880530104041,
-0.011595262214541435,
-0.03983946889638901,
0.015364253893494606,
-0.026079943403601646,
0.0641731470823288,
-0... |
<p>I am new to the use of cubic splines for regression purposes and wanted to find out </p>
<p>1) What is a good source (besides ESL which I read but am still uncertain) to learn about splines for regression? <br/>
2) How would you calculate the basis of a given natural cubic spline solution on new data? Specifically ... | g26288 | [
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<p>We have a series of experiments where we measure virus transmission to plants when exposed to virus-infected insects for different time periods, so all of the experiments have similar types of independent and dependent variables. In one experiment, there are 6 time periods (1 to 24 hours) and 25 plants were tested ... | g66975 | [
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<h3>Context:</h3>
<p>I have a series of figures for car sales that show me (a) the usual number of car sales for particular models and (b) the number of car sales by a particular car salesperson for each model.</p>
<p>Let's say the values are:</p>
<pre><code>Model | Sales by all Salespeople | Sales by Salesperson x
... | g314 | [
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0.013680851086974144,
0.009263938292860985,
0.04816367104649544,
0.0... |
<p>Repeating an experiment with $n$ possible outcomes $t$ times independently, where all but one outcomes have probability $\frac{1}{n+1}$ and the other outcome has the double probability $\frac{2}{n+1}$, is there a good approximate formula for the probability that the outcome with the higher probability happens more o... | g45408 | [
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<p>In <em>Mostly Harmless Econometrics</em>, section 5.2.1 (Regression DD), pages 233-234, equation (5.2.3) defines $Y_{ist}=\alpha + \gamma NJ_{s}+\lambda d_{t}+\delta (NJ_{s}.d_{t})+\epsilon_{ist}$, where $NJ_{s}$ is a dummy denoting observations from New Jersey and $d_{t}$ is a dummy for observations obtained in Nov... | g66976 | [
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<p>I mean something like <a href="https://github.com/glennblock" rel="nofollow">this chart</a> showing the frequencies of a user's public contributions on GitHub.</p>
<p><img src="http://i.stack.imgur.com/X9SRH.png" alt="enter image description here"></p>
<p>I really like this kind of chart, as I think that they disp... | g49546 | [
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<p>Can any one help?</p>
<p>I am trying to graph the probability of predicting a male bird based on tarsus length according to the GLM.</p>
<p>I have run a GLM and I am not sure why I can't plot the predictions.</p>
<p>My code and data follows.</p>
<pre><code>Tarsus Sex
33.49 female
36.36 female
36.61 femal... | g66977 | [
0.008177264593541622,
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0.024474719539284706,
0.048701781779527664,
0.06466203927993774,
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<p>Many textbooks and papers said that intercept should not be suppressed. Recently, I used a training dataset to build a linear regression model with or without an intercept. I was surprised to find that the model without an intercept predicts better than that with an intercept in terms of rmse in an independent valid... | g66978 | [
0.004305988550186157,
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<p>I want to investigate performance in a learning test, where my test animals have been submitted to a number of trials within test day over several test days. I want to investigate if there is an effect of trial and of test day on the performance.</p>
<p>Normally, I would use a random intercept model using <code>lme... | g45432 | [
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<p>The sample mean is the maximum likelihood estimator of $\mu$ for a normal distribution $\text{Normal}(\mu,\sigma)$. The sample median is the maximum likelihood estimator of $m$ for a <a href="http://en.wikipedia.org/wiki/Laplace_distribution">Laplace distribution</a> $\text{Laplace}(m,s)$ (also called the double ex... | g26296 | [
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<p>The correlation between two ratios with the same denominators are spurious. Similarly, the correlation between two mathematically-coupled variables could also be spurious. Are mathematically-coupled variables (e.g. age and income are used to derive two formulas, which are then used as Y and X in linear regression an... | g38387 | [
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<p>I want to learn the statistics package <a href="http://gretl.sourceforge.net/gretl_and_R.html" rel="nofollow">gretl</a>.</p>
<p>My first attempt to do so is to calculate a linear regression model of a set of data:</p>
<p>$$y_i = \alpha + \beta x_i + u_i$$</p>
<p>First I want to create a crossplot of the data and ... | g41162 | [
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<p>I have been trying to understand a method of finding parameter uncertainties resulting from maximum likelihood estimation. Unfortunately the document I have is not in the public domain however I have found what I think is exactly the same method used in a paper from medicine. Having found it somewhere else has made ... | g26298 | [
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<p>could anybody define what is meant by stochastic drift?</p>
<p>I <em>think</em> I have a rough idea, say on a random walk X(n)= a + X(n-1) + Z(n) where Z(n) are iid zero mean and constant variance, then E[X(n)] = na. Is this stochastic drift?</p>
<p>Many thanks </p> | g26299 | [
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<p>When studying math / stats or reading a academic paper often there are theorems, concepts, hypotheses and ideas are inter-connected to each other. These relationships can be a combination of hierarchical and flat network ones. </p>
<p>From my own experience the best way to study is to taking notes. So, I am seeking... | g556 | [
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<p>I am working on a study where I have a sample of 86 students. I have tests for 5th grade, 6th grade, 7th grade, and 8th grade. I think I can run a Repeated Measures ANOVA since I have observations for 4 different occasions. </p>
<p>However, I am unsure what my independent and dependent variables are in this set up.... | g26300 | [
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<p>If we know that random variables $X$ and $Y$ are positively correlated, do we know that the random variables $Z = \log(X)$ and $W = \log(Y)$ are positively correlated?</p> | g37482 | [
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<p>Beginner questions:</p>
<p>I want to test whether two discrete data sets come from the same distribution. A Kolmogorov-Smirnov test was suggested to me.</p>
<p>Conover (<em>Practical Nonparametric Statistics</em>, 3d) seems to say that the Kolmogorov-Smirnov Test can be used for this purpose, but its behavior "con... | g66979 | [
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<p>I wish to do a principal component analysis (PCA) with a few features (variables). While most of the features have a single numerical value, one feature is an <em>unordered</em> vector of 5 numbers.</p>
<p>For example:</p>
<pre><code>#observation value_feature1 value_feature2 value_feature_3
obsv1 ... | g66980 | [
0.01738438941538334,
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0.030741466209292412,
0.0029511393513530493,
0.043... |
<p>I want to estimate the distribution function of the random variable. Due to the complicate nature of this function, I can be calculated only the first and second order moments(mean and variance) of this variable. Given these circumstances, how can I estimate the approximate distribution function? Thanks to all who h... | g24033 | [
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<p>I'm working on a multi-armed bandit problem where we do not have any information about the reward distribution. </p>
<p>I have found many papers which guarantee regret bounds for a distribution with known bound, and for general distributions with support in [0,1]. </p>
<p>I would like to find out if there is a way... | g49557 | [
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<p>What should I do if I am getting negative results for Cronbach's alpha? Is there anyway to adjust it?</p> | g66981 | [
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0... |
<p>Suppose I model a data generating process as a hierarchal model and have made some training observation from the process. To learn about the process, with the observations I run the bayesian machinery to calculate posterior for the stochastic parameters of the model. Now I would like to be able to throw out the ... | g66982 | [
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0.026748422533273697,
0.046094... |
<p>I calculated a negative lower inner fence value. I've double checked my work but I can't figure out what's wrong. I was under the impression that these values couldn't be outside of the min and max (duh).</p>
<p>My values range from 0.06188 to 1.90957 and when I plot them in Graphpad it looks fine. I'm plotting wit... | g26303 | [
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<p>I stumbled accross <a href="http://stats.stackexchange.com/questions/2611/how-to-combine-confidence-intervals-for-a-variance-component-of-a-mixed-effects">this</a> related question from 2010, and I wonder if there has been any progress on using multiple imputation for mixed effects models ? I prefer to use R, though... | g66983 | [
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0.02537723258137703,
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0.03384990617632866,
0.01720... |
<p>I am relatively new to machine learning and I have a data classification problem where each sample has ~1500 features (continuous) and the category is binary.</p>
<p>I want to apply logistic regression, for learning purposes. I have done a vectorized implementation in Python, which works very well and is fast on ot... | g66984 | [
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0.020237425342202187,
0.05... |
<p>R's multcompView package offers a seemingly useful set of tools to visualize the results of multiple comparisons, e.g. Tukey HSD analysis, including boxplots and 'letters' to identify significantly-different groups. It also provides a "t" depiction, in which groups are labeled with either a box, a sort of pyramid, o... | g66985 | [
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0.00011373042070772499,
0.10972856730222702,
0... |
<p>Say I want to predict whether or not a project will be profitable. In my sample data, the response variable is actually a continuous variable: the $ profit/loss of the project. </p>
<p>Because my ultimate goal is just a binary classification (profitable project or unprofitable project), should I use a classificat... | g66986 | [
0.05642066150903702,
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0.017711492255330086,
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0.017533309757709503,
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0... |
<p>How can you separate a group of points in 3 dimensions into two groups with labels A and B?</p>
<p>My approach:<br>
If we draw a plane through the cloud of points, the group A can be the points above the plane, and the group B can be the points below the plane.</p>
<p>I am not sure if this a legitimate approach. I... | g66987 | [
-0.01759641058743,
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0.05382371321320534,
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-0.0004926149849779904,
-0.0011... |
<p>I am building an interactive forecast tool (in python) as an aid to forecasting that is done in my organisation. To date the forecast process has been largely human driven, with forecasters assimilating the data in their natural neural networks and using their learned gut feel to make predictions. From a long term f... | g66988 | [
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0.053... |
<p>I'm reading web pages for goodness of fit tests, when I came to the <a href="http://en.wikipedia.org/wiki/Anderson%E2%80%93Darling_test" rel="nofollow">Anderson–Darling test</a> and the <a href="http://en.wikipedia.org/wiki/Cram%C3%A9r%E2%80%93von_Mises_criterion" rel="nofollow">Cramér–von Mises criterio... | g26309 | [
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0.0162739809602499,
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0.0349... |
<p>Suppose $T$ is a set of transactions containing some paths taken from a set of undirected graphs $G$ whose nodes are all taken from the same finite alphabet $A$. I would now like to extract all frequent cycles (strongly connected components) from $T$ by using the Apriori algorithm. </p>
<p>The idea is that since th... | g66989 | [
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0.022269248962402344,
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0.0030811550095677376,
-0.03446... |
<p>Below is a question on a recent actuarial exam, Exam 3L of the CAS. I didn't know whether or not to use the continuity correction when using the normal approximation to do hypothesis testing involving a bernoulli trial. The answer is vastly different (based on the answer choices given in the exam) depending on whe... | g66990 | [
0.08456582576036453,
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0.02401505410671234,
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0.0172... |
<p>I have a nonlinear model with residuals that are negatively autocorrelated at short distances. </p>
<p>I can find no spatial correlation structures in <code>nlme</code> that can easily handle negative autocorrelation as most have bounds on parameter values so that the correlation is between 0 and 1. </p>
<p>Firs... | g66991 | [
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<p>How to derive the following formula:</p>
<p>where $\sigma(y)$ is the standard deviation of $y$ (dependent variable), and $\rho(x,y)^2$ is correlation between $x$ and $y$ squared, $\sigma(\epsilon)$ the standard deviation of the error. </p>
<p>$$ \sigma(\epsilon) = \sigma(y) \sqrt{1-\rho(x,y)^2} $$ </p>
<p>if $y =... | g26310 | [
0.044580891728401184,
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0.07596905529499054,
-0.00542852096259594,
... |
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