Cross Validated Community Digest

Top new questions this week:

Can increasing the amount of training data make overfitting worse?

Suppose I train a neural network on dataset A and evaluate on dataset B (that has a different feature distribution than dataset A). If I increase the amount of data in dataset A by a factor of 10, is ...

machine-learning neural-networks validation overfitting train  
asked by asdfaefi 12 votes
answered by Frans Rodenburg 12 votes

How to calculate number of sets in Sigma Algebra

The example 1.2.2 of the book Statistical Inference by Casella and Berger states: if S has n elements, there are 2^n sets...(please see attached). Could you please explain how the authors derived ...

probability mathematical-statistics subset  
asked by Nemo 7 votes
answered by gunes 14 votes

How are PQL, REML, ML, Laplace, Gauss-Hermite related to each other?

While learning about the Generalized Linear Mixed Models, I often see the above terms. Sometimes it seems to me these are separate methods of estimation of (fixed? random? both?) effects, but when I ...

mixed-model glmm glmmtmb reml laplace-approximation  
asked by humbleasker 6 votes
answered by Dimitris Rizopoulos 5 votes

The distribution of the p-values under the null hypothesis is uniform(0, 1)

I have seen this, and this and a few YouTube videos, and I'm still stuck. I understand how the probability integral transform gives rise to the result that the CDF of the p-values will have a ...

distributions p-value  
asked by StatsSorceress 6 votes
answered by ryu576 2 votes

When can't Cramer-Rao lower bound be reached?

The Cramer-Rao lower bound (CRLB) gives the minimum variance of an unbiased estimator. One sentence in the wiki page says "However, in some cases, no unbiased technique exists which achieves the ...

estimation unbiased-estimator estimators point-estimation efficiency  
asked by Tony B 6 votes
answered by StubbornAtom 4 votes

Comparison of statistical tests exploring co-dependence of two binary variables

Suppose we observe data $(X_i,Y_i)_{i=1,...,n}$ on two binary variables: $X\in\{0,1\}$ and $Y\in\{0,1\}$. We would like to test if $X$ and $Y$ are co-dependent (related). Standard suggestions in ...

hypothesis-testing logistic generalized-linear-model binary-data power  
asked by stans - Reinstate Monica 5 votes

What exactly is model instability due to multicollinearity?

I've read that model parameters become unstable in case of multicollinearity. Can some one give an example situation of this behavior, and explain why this is happening? Please use the following ...

regression machine-learning multiple-regression linear-model multicollinearity  
asked by Eric Kim 5 votes
answered by Demetri Pananos 6 votes

Greatest hits from previous weeks:

Is it possible to find the combined standard deviation?

Suppose I have 2 sets: Set A: number of items $n= 10$, $\mu = 2.4$ , $\sigma = 0.8$ Set B: number of items $n= 5$, $\mu = 2$, $\sigma = 1.2$ I can find the combined mean ($\mu$) easily, but how am ...

asked by kype 32 votes

What is your favorite "data analysis" cartoon?

This is one of my favorites: One entry per answer. (This is in the vein of the Stack Overflow question What’s your favorite “programmer” cartoon?.) P.S. Do not hotlink the cartoon without the ...

asked by Shane 343 votes
answered by Shane 208 votes

Pearson's or Spearman's correlation with non-normal data

I get this question frequently enough in my statistics consulting work, that I thought I'd post it here. I have an answer, which is posted below, but I was keen to hear what others have to say. ...

correlation normality-assumption pearson-r spearman-rho  
asked by Jeromy Anglim 114 votes
answered by Rob Hyndman 78 votes

How to 'sum' a standard deviation?

I have a monthly average for a value and a standard deviation corresponding to that average. I am now computing the annual average as the sum of monthly averages, how can I represent the standard ...

standard-deviation descriptive-statistics  
asked by klonq 69 votes
answered by Ian Boyd 67 votes

How to check for normal distribution using Excel for performing a t-test?

I want to know how to check a data set for normality in Excel, just to verify that the requirements for using a t-test are being met. For the right tail, is it appropriate to just calculate a mean ...

normal-distribution excel  
asked by Eudora 21 votes
answered by whuber 15 votes

Statistics Jokes

Well, we've got favourite statistics quotes. What about statistics jokes?

references humor  
asked by Thylacoleo 167 votes
answered by Peter Flom - Reinstate Monica 225 votes

R vs SAS, why is SAS preferred by private companies?

I learned R but it seems that companies are much more interested in SAS experience. What are the advantages of SAS over R?

r sas  
asked by Benoit_Plante 144 votes
answered by gung - Reinstate Monica 139 votes

Can you answer these questions?

Is there any advantage to using $\chi^2$ for checking linear relationship $y(x)$?

At my university (physics major), we are often forced to use $\chi^2$ for checking if $y(x)$, where $y$ and $x$ are measured, is linear. We fit a linear regression $f(x)$ and then use $\chi^2 = ...

chi-squared linear  
asked by lkky7 1 vote

Which statistical method do I need for my research (combining correlation and independent two-samples t-test?)

I need some guidance with my model, because I believe I need both correlation as well as an independent two samples t-test for my research.. is that even a thing? My model claims that firm ...

correlation t-test predictor two-sample  
asked by Alex UM 1 vote

Determining Sample Size When Low Probability Items Are Of Interest

Let's assume there are 10,000,000 Yankee fans and we want to analyze what else these 10 million people are fans of. A simple question is, what sample size do we need to be confident in the results? ...

confidence-interval sample survey-sampling  
asked by mks212 1 vote
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