question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Notation: $\dot{Z}_t = Z_t - E(Z_t)$, so that it is centered at 0. $a_t$ stands for the residual and we assume the $a_t$ are independent and normally distributed with mean 0 and constant standard deviation $\sigma_a^2$. And, when I say stationarity, I mean weak stationarity and not strict stationarity.</p>
<p>In ... | g58288 | [
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<p>I have built a multivariate regression model where $\mathbf x$ is the variable vector. Now I am asked to calculate the confidence interval for the number to treat (NNT) at $\mathbf x=\mathbf {x_0}$ which in turn requires to build the confidence interval for $p=Pr(1|\mathbf x=\mathbf {x_0})$. I'm using JMP which, to ... | g42159 | [
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<p>I just started taking survival analysis class and I'm stumped on this question.</p>
<p>We need to show that when there are no censored observations $\hat{S}(t)=\prod_t_{(i)\le t}(n_i-d_i)/n_i$ equals to the empirical survival function $S_n(t)=\# \{ t_{(i)} \ge t \}/n $</p>
<p>It looks pretty obvious to me so I'm ... | g13299 | [
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<p>I am working with four survey datasets, two of them without a certain variable which I impute using multiple imputation techniques. Afterwards, I use the complete data to estimate a set of logit models for which -to my understanding- there is no substantive interpretation for their log-likelihood. This is an importa... | g58289 | [
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<p>I just started taking survival analysis class and I'm stumped on this question.</p>
<p>Let $T_1,...,T_n$ random independent continuous variables, with hazard function of $h_1(t),...,h_n(t)$.
$T=min(T_1,...,T_n)$.
And we need to show that the hazard function of T is $\sum_j{h_j(t)} $</p>
<p>Any help or direction ar... | g49446 | [
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<p>This is a general question. I have a task that is composed of 3 independent events: A, B, and C. All are mutually exclusive and don't happen at the same time. So first A, then B, then C. I know the probability of completing each event with respect to time, I have the pdfs. How can I calculate the probability of... | g58290 | [
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<p>I am comparing images for correlation. The images are all correlated, but I would like to determine when one pair is much more highly correlated, relative to another pair. I am using as a statistic the difference in the logs of p-values produced by a Spearman rank correlation test. If this is difference is small, th... | g42164 | [
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<p>Why is it dangerous to initialize weights with zeros? Is there any simple example that demonstrates it?</p> | g42165 | [
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<p>What is the exact definition of <em>precision</em> of a statistical estimator? Any references to textbooks are appreciated.</p> | g13304 | [
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<p>Is it possible to conduct a regression if all dependent and independent variables are categorical variables?</p> | g58291 | [
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<p>I've created a model with <code>lme4</code>'s <code>lmer</code> and wanted to create a prediction interval around my model fit. I figured I could do it Bayesian-style and simulate from the model to do this. My model looks like:</p>
<pre><code>b3 <- lmer (dollars ~ 1 + I(refund/days) + (1 | month) + (1 | regime),... | g58292 | [
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<p>Is it valid (reliable etc.) to compare a small sample with a large sample (which is made up of several small samples) when both samples are from the same population?</p>
<p>There are 3 firms. Each firm specialises in the manufacture of a particular product, hence it is classified in that way. </p>
<p>Firm A manufa... | g58293 | [
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<ol>
<li><p>Isn't the test statistic for both tests identical? The only difference I see is that the alternative hypothesis is different. Since you don't need to know the function h in the Breusch-Pagan test, what exactly is the difference between the two tests? </p></li>
<li><p>When would you use the White test, and w... | g58294 | [
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<p><strong>First a little background:</strong></p>
<p>I'm a college paintball coach and I have two populations of players:</p>
<p>I. Players that have a lot of experience/skill prior to joining the team e.g. playing for amateur non college teams but who don't often play together for various reasons.</p>
<p>II. Playe... | g42171 | [
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<p>I've written a user defined splitting function to use with rpart, its returning a 'vector of goodness', but the tree that is returned never has any splits, just one node. </p>
<p>using the anova method on the same data provides a tree with many nodes.</p>
<p>I've been interrogating the code, but rpart feels like a... | g37738 | [
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<p>I am working for two signals. One is a dataset with 10 equally spaced impulses. Another is a dataset with randomly spaced impulses of identical length. The higher order moments, such as kurtosis, skewness or standard deviation are not sensitive to the two signals. Who can help look for an indicator to identify it?</... | g58295 | [
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<p>I am having a problem using MICE, where it generates the following warning:</p>
<pre><code>Warning message:
In var(data[, j], na.rm = TRUE) : NAs introduced by coercion
</code></pre>
<p>This seems to be related to the presence of a unique alphanumeric ID variable in the data. For example:</p>
<pre><code>require(m... | g58296 | [
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<p>Imagine we have a potentially biased coin and a potentially biased six-sided die and we want to know which is more biased than the other.</p>
<p>Firstly, is this a reasonable goal? Could it make sense to say, for example, that the coin is more biased than the die?</p>
<p>Secondly, assuming the goal is reasonable, ... | g13310 | [
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<p>I've obtained a multiple linear regression model in the form
$$
\mathrm{log}(Y) = \beta_0 + \beta_1x_1 + \dots + \beta_4x_4 + \beta_5x_1x_2 + \dots + \beta_{10}x_3x_4 + \beta_{11}x_1^2 + \dots + \beta_{14}x_4^2
$$
from the model I've obtained some contour plots that, for a more immediate interpretation, I've back t... | g13311 | [
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<p>Regarding p-values, I am wondering why 1% and 5% seem to be the gold standard for "statistical significance". Why not other values, like 6% or 10%?</p>
<p>Is there a fundamental mathematical reason for this, or is this just a widely held convention?</p> | g49911 | [
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<p>I have two unequal groups (94 and 52) and want to run a Mann-Whitney U-test to see whether their scores on a measured variable differ. I see that it is OK to do with Kruskall-Wallis, does the same apply to Mann-Whitney? </p> | g58297 | [
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<p>My study involves studying the seasonal variations (premonsoon, monsoon, postmonsoon) in river at 5 different sampling points. The water quality study involved eight water parameters. To check the reliability of data, I had run reliability analysis and got Cronbach's value = 0.187..which is very very low.
But my qu... | g58298 | [
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<p>I need to calculate some integrals using MCMC with Metropolis Random-Walk Algorithm. To decide the value I will accept as my integral, I will calculate 5 simulations of MCMC with size 2000, but I won't use the first 500 obtained values (Burn-in step). So, my doubt is:</p>
<p>$$ SE = \sqrt{\frac{1}{N} \sum_{i=1}^N (... | g58299 | [
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<p>Is there a closed-form expression for the distribution of the Sample Kurtosis of data sampled from Gaussian distribution? i.e., </p>
<p>$P(\hat{K}<a)$ where $\hat{K}$ is the sample kurtosis.</p> | g13317 | [
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<p>Objective: I want to test the effect of a regulatory change using a classical pre-post/treatment-control DiD design (Y = POST + TREAT + POSTxTREAT + e).</p>
<p>Problem: Treatment & control obs. are from different countries. Although these countries are similar with respect to many relevant aspects, a visual che... | g58300 | [
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<p>Whilst studying likelihood methodologies, I've come across some results that I haven't been able to work out.</p>
<ol>
<li><p>If $X$ and $Y$ are Poisson with means $\mu_{X}$ and $\mu_{Y}$, then the conditional distribution of $X$ given $X+Y$ is binomial with parameters $n = X+Y$ and $\pi = \frac{\mu_{X}}{mu_{X}+mu_... | g13318 | [
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<p>I have a 2x2 between-subject design with (slightly) unequal cell sizes. Hence I chose to use the <code>anova(lm(...))</code> function so that Type 1 SS are used:</p>
<p><code>anova(lm(prob ~ utility * imagination, data = e2data))</code></p>
<p><code>prob</code>is the numerical DV and <code>utility</code> and <code... | g58301 | [
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<p>I have a vector (V1) with which I need to calculate the similarity of other vectors (ex V2,V3 ... ) which may be of different lengths.
The different angle here is that the elements inside the vectors are itself similar to each other.</p>
<pre><code>V1 = c("a","b","c")
V2 = c("a","d","e","f","g")
V3 = c("b","c","f")... | g13319 | [
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<p>I struggle with following question: </p>
<blockquote>
<p>It is now considered that house prices are rising again following the
recent slump. Given that in 2008 the average price of a standard 3
bedroom house was €215,000. A sample of 25 similar houses in 2013 gave
an average price of €275,000 with a standar... | g58302 | [
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<p>I have a model with two random effects</p>
<pre><code>> lmer(TotalPayoff~Type+Game+PgvnD*Asym+(1|Subject)+(1|Pairing),REML=FALSE,data=table)-
>m1
</code></pre>
<p>each pairing contains 2 subjects and each Subject is in 2 different pairings with different subjects. For some reason the subject random effec... | g13320 | [
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<p>I've always heard that data mining and machine learning tools/techniques are heavily used in the pharmacy sector and biology but I have never heard of companies that offer commercial applications of data ming for pharmacy and biology. Once I heard my professor saying that if you really want to know the state-of-the-... | g58303 | [
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0.052015259861946106,
-0.033... |
<p>I need to calculate the regression variance ($\sigma^2$) in order to estimate both the confidence intervals and the prediction intervals in a gls regression analysis. For the analysis, the covariance matrix ($V$) of the response variable ($y$) is known in advance, and so I use it directly as the weighting matrix (=... | g58304 | [
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<p>I am planning a seven-question Likert-type survey with a "1 to 10" scale. The questions I am asking in the survey are to assess an individual's risk factors (how much risk they present to an organization). The risk factors are compounding, meaning the more risk factors an individual exhibits, the greater risk the i... | g58305 | [
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<p>During study our of statistics in my psychology coursework, we had to teach ourselves how to use generalized linear models in SPSS (only basic knowledge). For an exam we may also use generalized linear models and I want to try it, but I have two problems:</p>
<ol>
<li><p>According to the distribution of the depende... | g58306 | [
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<p>I have measurements for daily space heating vs daily mean outdoor temperature for two different control strategies. The data is shown here:</p>
<p><img src="http://i.stack.imgur.com/c4L6Y.png" alt="enter image description here"></p>
<p>I have also performed linear regression, of the form:</p>
<pre><code>lm(Energy... | g58307 | [
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0.027137048542499542,
0.028200911357998848,
0.02548046223819256,
-0.... |
<p>I have a longitudinal data set in which my predictor/Independent Variable is dichotomous and was assessed at age 4 years, and my outcome/Dependent Variable (depressive symptoms) was assessed at 16 years. I would rather not arbitrarily dichotomize the DV, and I would prefer to avoid non-parametric stats so that I co... | g58308 | [
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0.023328788578510284,... |
<p>I am trying to fit several MLEs on a small dataset. I have managed to get it done for all my potential models except for this last one. This last one is actually the model that I expected to be the best model, because it was the best model when I did the whole thing using GLS. To start, here is the data:</p>
<pre><... | g13328 | [
0.019988249987363815,
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0.004073162097483873,
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0.013134434819221497,
0.0050233276560902596,
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0.012802577577531338,
0.031457193195819855,
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0.0... |
<p>I have a questionnaire distributed to the users with the following question from which users can select an answer</p>
<p>Q: What was the project Cost Performance Index</p>
<pre><code>Option 1 : 0 < CPI < .5
Option 2 : .5 < CPI < .75
Option 3 : .75 < CPI < 1
Option 4 : 1 < CPI < 1.5
Opti... | g13330 | [
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0.02456650137901306,
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0.03416592627763748,
0.01389001589268446,
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<p>First off, I am aware I have not enough data to be performing a regression with this number of parameters, lets overlook that for now - I'm interested only in why I get an error with one model, and not with the other:</p>
<p>I try to do a regression as follows:</p>
<pre><code>glm("y~(x1+x2+x3+...x8)^2", family=Gam... | g2566 | [
0.04704335704445839,
0.008824444375932217,
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0.03139008209109306,
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0.02791314199566841,
0.03180942311882973,
0.0... |
<p>The duality theorem between acceptance region of testing and confidence region is about their validity (i.e. satisfying the significance level of the former and the confidence level of the latter sum up to be 1). For example, this is what is given in Casella's Statistical Inference.</p>
<p>I was wondering if there... | g42200 | [
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<p>Trying to "understand" a time series' patterns it is intuitively tempting to use STL decomposition as the concept of distinguishing between trend, season and the rest makes sense.</p>
<p>But my experience tells me that no static algorithm will lead under all circumstances to useful results. </p>
<p>So my general q... | g109 | [
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<p>I ran a mixed model regression and obtained the following output. Because I log-transformed the concentration variable, I interpreted the coefficient as follows: the mean concentration is reduced $1.5$ percent each year. The years run from 1993-2010. </p>
<p>Can say also state that the mean concentration is redu... | g42205 | [
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<p>I'm analyzing a very large, but not finite, set of survey data. I've assembled a time series crossing gender (2 categories, if there was uncertainty) with age (in 6 categories) and wish to test whether the demographic representation has changed over time. Using the chi-squared test for independence, I understand tha... | g13341 | [
0.033561836928129196,
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<p>Hi all I have a question. Suppose</p>
<p>$$X(t) = A \cos(t) + B \sin(t)$$ </p>
<p>is a weakly stationary process, where $A$ and $B$ are random variables.</p>
<p>Why is it that the mean of $A$ and $B$ are necessarily 0? As I understand it, weak stationarity only requires that the $E(X) = \mathrm{constant}$.</p> | g13342 | [
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... |
<p>Based on a sample of $n$ survival times, I would like to estimate the probability of surviving time $t$, for some specific $t$, using the Kaplan-Meier estimator. Is it possible to do this in <code>R</code>? Please, note that $t$ is not necessarily an event time. </p> | g58309 | [
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0.058746088296175,
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<p>I have done my Conjoint Analysis (fractional factorial design) but when it comes to validating the model, it shows a Kendall's tau for Holdouts of 0.33 and not significant.
But Pearson's R and Kendall's tau are high and significant which is supposed to show that the fit of my model is good...</p>
<p>How do I interp... | g58310 | [
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<p>This question is similar to the one posed here:
<a href="http://stats.stackexchange.com/questions/12164/testing-significance-of-peaks-in-spectral-density">Testing significance of peaks in spectral density</a></p>
<p>In that post, Pantera asks how to test whether a peak in a periodogram has a spike that is significa... | g42215 | [
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<p>I'm reading John Kruschke's <a href="http://www.indiana.edu/~wim/docs/1_14_2011_slides.pdf">"Doing Bayesian Data Analysis" slides</a>, but actually have a question about his interpretation of t-tests and/or the whole null-hypothesis significance testing framework. He argues that p-values are ill-defined because they... | g58311 | [
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<p>I'm trying to calculate marginal effects (and their confidence intervals) for an interaction variable. </p>
<p>I'm using Stata and have panel data (pooled cross-sectional time series). I am using the <code>xtpcse</code> command.</p>
<p>For some reason the results calculated using Stata's <code>margins</code> comma... | g42216 | [
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<p>I am quite new in the field of mixed-effect modeling. For a beginner like me, I guess I combine several levels of complication in my analysis: paired observations & bounded response variables. I hope to be clear in my description and to get some useful comments, at least on some of the challenges I face. Thanks ... | g13345 | [
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<p>(We may just assume single parameter model and single variable data for this discussion).</p>
<p>I understand that the "observed information" evaluated at the MLE measures the curvature and hence gives a gauge of how much information our data is giving us. "Observed information" here refers to having already obtain... | g58312 | [
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<p>I have created a logistic regression model in R. The dependent variable is binary whether or not a landscape transitioned to another cover class denoted by 1s and 0s, and the independent or predictor variables are some characteristics of the landscapes such as elevation, slope, distance to urban areas, etc. I need t... | g40225 | [
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<p>I'm trying to recreate some test statistics that use the infinite AR representation of normal ARMA models. I found out about the function ARMAtoMA but have not been able to find the same functionality for AR representations as well. Do you guys know of a package that would make extracting them easy? I was hopeful wh... | g42218 | [
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... |
<p>I have the following problem:</p>
<p>I have 100 unique items (n), and I'm selecting 43 (m) of them one at a time (with replacement).</p>
<p>I need to solve for the expected number of uniques (only selected once, k = 1), doubles (selected exactly twice k = 2), tripples (exactly k =3), quads etc...</p>
<p>I've been... | g40231 | [
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0.03731798380613327,
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0.015368134714663029,
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<p>I am trying to understand the difference between these parameters, and their application. Was hoping to get some correction/clarification to my statements. I have a training set and cross-validation set. I am using bayesian statistics, I realize AIC and BIC can't be used in this context.</p>
<p>AIC and BIC assess h... | g42221 | [
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<p>So my basic understanding is that I may end up in one of the following situations.</p>
<ul>
<li><p>I have a sample mean and therefore calculate a sample variance</p></li>
<li><p>I have a population mean sand calculate a population variance.</p></li>
</ul>
<p>Though in one book I have been reading it looks like teh... | g34903 | [
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<p>I ran a multiple regression using 10 independent variables and the single dependent variable (consumer complaining behaviour). One of those independent variables was gender. The $R^2$ for the model itself was $.157 (F= 20.50, p = .000)$ which whilst not the highest $R^2$ score was at least significant. Down in the c... | g13349 | [
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0.0281... |
<p>What cluster method would be appropriate for a study with 16 variables both categorial and quantitative? It is a repeated measures observational study. I read in a text that k-means would be best if the data was mostly quantitative although I may have interpreted that wrong.</p>
<p>Also, what methods are best for t... | g33476 | [
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... |
<p>Can anyone tell me how to obtain the 95% confidence intervals for the x and y coordinates of the vertex (peak in my case) of a quadratic fit? Is there a way to get these CIs in R? Thanks.</p> | g58313 | [
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<p>Say we have a Markov Chain with probability matrix </p>
<p>$$ P = \begin{pmatrix} 0.25 & 0.25 & 0.5 & 0 & 0 \\
0 & 0.66 & 0 & 0.33 & 0 \\
0 & 0.25 & 0.25 & 0.25 & 0.25 \\
0.5 & 0 & 0 & 0.25 & 0.25 \\
0 & 0 & 0 & 0.2 & 0.8 \end{pmatrix} ... | g58314 | [
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0.06563317775726318,
0.02462720312178135,
-... |
<p>For a distribution, let's say I know the scores at the 10th, 30th, 50th, 70th and 90th percentiles. I also know the interquartile range and range. Is it possible to get the exact percentile rank of a given score? I'll be using R if that makes things any easier.</p>
<p>As a more concrete example, I have the followin... | g13353 | [
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0.01968904212117195,
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... |
<p>I have data of the price of a product before a newer version came out and after a newer version came out. I'd like to model the slope of the product pre the new product, and post the new product. </p>
<p><img src="http://i.stack.imgur.com/ffsHQ.png" alt="enter image description here"></p>
<p>Looking at the data, i... | g58315 | [
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0.013451151549816132,
-0.02591043896973133,
0.02458002232015133,
0.07226128876209259,
-0.... |
<p>Using a large, cross-sectional survey of victims of violence, I am interested in testing the effect of alcohol intoxication (let's call it the 'treatment') on victims' subjective rating of the seriousness of the assault (outcome).</p>
<p>I have run regression analyses to explore factors associated with seriousness ... | g58316 | [
0.006113430950790644,
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0.01251091156154871,
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-0.... |
<p>I've a question regarding principal component regression (regression of a DV on principal components). I have 4 components in my PCR and the third component is non-significant as a predictor. What does that mean? It's curious that the "weaker" fourth component however is significant. Can anyone explain this to me?</... | g49526 | [
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<p>Suppose I have a function which is a solution of an ODE with varying-coefficients.Based on the simulation from the function plus Gaussian noise, I use 2nd order ODE to model the simulated data.</p>
<p>But even I got good estimate of solution function, I have a very different estimates of varying coefficients.</p>
... | g58317 | [
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0.0450... |
<p>Say some previous findings identified a curvilinear effect of X on Y, (specifically that X had a positive effect on Y, and that X^2 had a negative effect). You want to see if the same holds for your entirely different sample (although everything else between studies, constructs/measures, are exactly the same). Neith... | g42232 | [
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<p>I'm interested in learning how to create the type of visualizations you see at <a href="http://flowingdata.com">http://flowingdata.com</a> and informationisbeautiful. EDIT: Meaning, visualizations that are interesting in of themselves -- kinda like the NY Times graphics, as opposed to a quick something for a report.... | g58318 | [
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<p>All of my variables are continuous. There are no levels. Is it possible to even <em>have</em> interaction between the variables?</p> | g49605 | [
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<p>Unlike other articles, I found the <a href="http://en.wikipedia.org/wiki/Regularization_%28mathematics%29">wikipedia</a> entry for this subject unreadable for a non-math person (like me).</p>
<p>I understood the basic idea, that you favor models with fewer rules. What I don't get is how do you get from a set of rul... | g13360 | [
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<p>I have conducted a one-way ANOVA on 8 groups. I understand that the degrees of freedom for that test is 7, but I don't understand how to ascertain the degrees of freedom for the post hoc tests:</p>
<p>I conducted a series of t-tests as the multiple comparison post-hocs using the Holm-sidak method of familywise err... | g1003 | [
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<p>From <code>?combine</code> in <a href="http://cran.r-project.org/web/packages/randomForest/" rel="nofollow">randomForest</a>:</p>
<blockquote>
<p>The confusion, err.rate, mse and rsq components (as well as the
corresponding components in the test compnent, if exist) of the
combined object will be NULL.</p>
</... | g58319 | [
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<p>I have used <strong>aplpack</strong> package <code>faces()</code> method in R for drawing a Chernoff graph of the following data. I would like to draw a face with only four variables <code>a</code>, <code>b</code>, <code>c</code>, and <code>d</code> in order to explain why program <code>A</code> is better than progr... | g58320 | [
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<p>Suppose you had a method for estimating the population covariance of a vector-valued random variable given observations of that random variable, say $f(Z) \rightarrow C$, where the rows of $Z$ are observations of the random variable. Can one abuse this process to perform a least squares regression $y = x^T\beta + \e... | g13365 | [
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<p>I have a few (5-6) data sets, each is a function of time, with the time span the same between datasets. These datasets are all statistics of various perspectives of something (the partitions of a graph), and I am trying to find points in time which show interesting changes across the different datasets. Normally t... | g58321 | [
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0... |
<p>I am about to help teach statistics to medical students this semester.</p>
<p>I've heard many horror stories about the fear of these students from learning statistics.</p>
<p>Can anyone suggest what to do with this fear? (Either links to people who are discussing this, or offer suggestions from your own experience... | g13366 | [
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<p>I have around ten groups (of companies). Each group is connected with each other group. The data I have is representing the strength of the connection. Imagine it's the number of times someone from group A sent an email to group B.</p>
<p>The strength of a connection can be 0. There are two connections between two ... | g58322 | [
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<p>Let's say I have a point $P_1$ on a 2D scatter plot. The coordinates of $P_1$ are $(x_1, y_1)$. $x_1$ has a standard deviation of $\pm u_1$ and $y_1$ has a standard deviation of $\pm v_1$.</p>
<p>I also have a point $P_2$. The coordinates of $P_2$ are $(x_2, y_2)$, with standard deviations of $\pm u_2$ and $\pm v_2... | g58323 | [
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<p>I have a problem with a number of inputs and one binary output, which I have tried to train several classifiers to solve. Unfortunately, none of the classifiers (MLP, SVM, bagging) have achieved the required level of accuracy. </p>
<p>I am thinking of subdividing the problem by splitting the dataset into two, and u... | g58324 | [
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<p>I am correlating two features in the leaves of a dendrogram for a given tree distance (2,3,...). </p>
<p>When i find the pair "A-B" at distance x I will also have the duplicate "B-A" in the same set for distance x along the tree branches. The result is that for every two leaves i will have for example a pair of (x=... | g58325 | [
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<p>I am quantifying a measure of correlation in a graph/network under two different experimental conditions to determine whether there is a significant difference in the measure given by the change of condition. I am repeating this computation for a number (N=5) of heterogeneous graphs/networks in the sense that they m... | g58326 | [
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<p>Working on a problem of extracting a minimal sub-set of criteria in a siting problem, I resorted to PCA, I have only 26 individuals (measures), I naturally thought it would be wise to ask whether that number is sufficient or not.
I do obtain results, that's not the issue, I just wonder if I can trust them or not. <... | g58327 | [
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<p>I have a list of numeric vectors, not necessarily all the same length.</p>
<p>I'd like to get a plot where each vector in the list is plotted vertically above a label for that vector on the x-axis.</p>
<p>Is there an "automatic way" to do that in R?</p>
<p>Here's an example set of data: </p>
<pre><code> yl = str... | g58328 | [
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<p>What is the appropriate (or the advantages of disadvantages for each) measure for weighting mortality rates across countries: total population or total number of deaths?</p>
<p>For example, if you have age-standardized cardiovascular disease mortality rates for 5 different-sized but otherwise comparable countries a... | g58329 | [
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0.0... |
<p>Lets say I have multiple table representing 10 countries, and tables contains <code>user_id</code>, and <code>user_score</code>.</p>
<p>Example:</p>
<pre><code>Table CountryA Table CountryB
user_id | user_score user_id | user_score
--------------------- -----------------... | g58330 | [
-0.00905750971287489,
0.022016026079654694,
-0.028096184134483337,
-0.02480020932853222,
0.030856674537062645,
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0.028488516807556152,
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-0.018883485347032547,
0.007437625899910927,
0.015873601660132408,
0.07354222238063812,
-... |
<p>I have several discrete datasets with a small range (-2 to +2) which I want to test against the null hypothesis "the distribution is centred around zero".</p>
<p>The Wilcoxon signed-rank test was suggested to me as an appropriate choice, and some answers on this site back this up. The issue is that, for some datase... | g58331 | [
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-0... |
<p>I would like to ask what is the specific objective function that Scikit-learn's Random Forest classifier is optimizing at each node for the "Entropy" option.</p>
<p>My understanding is that entropy is used as a measure here to split the training data reaching a particular node to the left and right subtree by ensur... | g58332 | [
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... |
<p>I'm trying to identify numeric properties of a text message that make it a spam or, more specifically, a bad question on sites like this one. For example, would things like capital letter density matter? Can anyone make any suggestions based on experience?</p> | g58333 | [
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0.00... |
<p>Suppose I have an $m$ by $n$ table $X_{ij} \in \{0,1\}$, where in each row, $r$ randomly chosen entries are set to 1 (the rest are 0), i.e. $\sum_j X_{ij}=r$.</p>
<p>I know that e.g. the column sum $\sum_i X_{i1} $ has a binomial distribution $\mathrm{Bin}(m, r/n) $. But what is the joint distribution of all column... | g58334 | [
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... |
<p>In the Poisson binomial distribution each trial is either yes (1) or no (0). Is there a distribution where each trial is either yes (N) or no (0)? </p>
<p>I'd like to model a situation where I have, for example, 10 workers. Each worker can produce $N$ units of good in one day or fail with known probability and pro... | g58335 | [
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... |
<p>I clustered my dataset of several thousand first-order Markov chains into about 10 clusters.</p>
<p>Is there some recommended way how I can evaluate these clusters and find out what the items in the clusters share and how they differ from other clusters? So I can make statement like "Processes in cluster A tend to... | g58336 | [
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<p>I have a study in which participants facebook profiles were rated by a group of students. The participants were then randomly allocated into one of three groups: the <strong>uncertain condition</strong> (where they could have been assigned either a liked-best or liked-least rating but they are not told which one), t... | g58337 | [
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... |
<p>I'm working on a problem to predict/classify overall sentiment of a large amount of text, which I can verify on the next day. Each data point is a day and is composed of multiple articles. I bin the words by frequency in those articles to train a Bayesian classifier.</p>
<p>I tried predicting the sentiment using al... | g58338 | [
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0.... |
<p>What is the canonical example which show situation when robust linear regression has advantage over least square linear regression ? I was trying to simulate situation when some errors (20% of them) are generated from t-student distribution and 80% are from normal - both distribution with the same variance ! on data... | g58339 | [
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0.05199472978711128,
-0.0... |
<p>It is well known that confidence intervals and testing statistical hypothesis are strongly related. My questions is focused on comparison of means for two groups based on a numerical variable. Let's assume that such hypothesis is tested using t-test. On the other side, one can compute confidence intervals for means ... | g49439 | [
0.013512291945517063,
0.011071999557316303,
0.0047018569894135,
-0.010551583021879196,
-0.030571933835744858,
0.05850841477513313,
-0.017830656841397285,
0.00644141249358654,
-0.059253063052892685,
-0.03290729969739914,
0.02056102268397808,
0.006015352439135313,
0.010256612673401833,
0.013... |
<p>Common data-based variable selection procedures (for example, forward, backward, stepwise, all subsets) tend to yield models with undesirable properties, including:</p>
<ol>
<li>Coefficients biased away from zero.</li>
<li>Standard errors that are too small and confidence intervals that are
too narrow.</li>
<li>Tes... | g58340 | [
0.019287897273898125,
-0.03548102825880051,
0.006043128203600645,
-0.011278786696493626,
0.006834722589701414,
-0.016846826300024986,
0.03058052994310856,
0.048373471945524216,
0.012423274107277393,
0.010852701961994171,
0.03308963403105736,
-0.017805811017751694,
-0.01426706276834011,
0.0... |
<p>I have a set of data, each element has a weight.
I need to estimate the mean of this data.
I found that there are two ways:
A weighted geometric mean and a weighted mean.
When should I use each of them and what are the advantages of using each of them?</p> | g49829 | [
0.04042490944266319,
-0.004620418418198824,
0.01335606537759304,
-0.04410769045352936,
0.05204690620303154,
0.0042167347855865955,
-0.025479134172201157,
-0.0010579071240499616,
-0.08905825018882751,
-0.010630699805915356,
0.003778024110943079,
0.037185847759246826,
0.02479463815689087,
0.... |
<p>Weekly's demand of a product has a probability function</p>
<pre><code>Demand, x Probability (fx)
------------------------
0 0,1
1 025
2 0,4
3 0,15
4 0,10
5 or more 0
</code></pre>
<p>I have difficult to find out the </p>
<ul>
<li>expected value, </li>
<li>va... | g58341 | [
0.0036226059310138226,
0.04595405235886574,
-0.023965738713741302,
-0.0589531809091568,
-0.03433483839035034,
-0.018730031326413155,
0.03130413219332695,
0.027480684220790863,
-0.016154538840055466,
-0.07445032149553299,
-0.013899609446525574,
0.0013022619532421231,
0.017301594838500023,
-... |
<p>Consider the plot attached as the histogram of the outcome ($Y$) that is going to be the outcome in a linear regression. Clearly, the histogram shows the outcome is not normally distributed. How can I come up with a transformation that makes the data be normal so that I can fit a linear regression?</p>
<p>My goal i... | g58342 | [
0.006251172162592411,
-0.030144046992063522,
-0.024383779615163803,
-0.07756026089191437,
0.008729245513677597,
-0.02617599256336689,
0.0202639140188694,
0.05554413050413132,
-0.025816254317760468,
-0.019548607990145683,
0.01876058615744114,
-0.011949817650020123,
0.04855592921376228,
-0.0... |
<p>I've looking around Google Scholar for the earliest mention of this particular classifier and have not had much luck finding a definitive source. I've seen some sources cite as late as the 1980s and other as early as the 1930s. Does anyone know when the Naïve Bayes Classifier was developed and/or first used as a cla... | g2876 | [
0.06978937238454819,
-0.022300459444522858,
0.031011493876576424,
-0.033994074910879135,
-0.04609550163149834,
-0.019432229921221733,
0.036681756377220154,
0.004094122443348169,
-0.053590431809425354,
-0.05095479637384415,
-0.00030044338200241327,
0.041716642677783966,
0.08510997146368027,
... |
<p>Let ${(x_1,x_2,z_1,z_2)}$ be real-valued vectors of equal length with </p>
<p>$${\hat{r}_p(x_1,x_2) \approx \hat{r}_p(z_1,z_2) > 0}$$</p>
<p>$${\hat{r}_p(x_1,z_1) \approx \hat{r}_p(x_2,z_2) > 0}$$</p>
<p>where $\hat{r}_p$ denotes the estimated Pearson correlation coefficient.
Now perform two simple linear r... | g58343 | [
0.01114614773541689,
-0.06566845625638962,
-0.0017414519097656012,
-0.017777016386389732,
0.0035601549316197634,
-0.023441120982170105,
0.04300471395254135,
0.04836072772741318,
-0.04993231222033501,
0.0011190478689968586,
-0.01165042631328106,
0.019383462145924568,
-0.011104644276201725,
... |
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