Cross Validated Community Digest

Top new questions this week:

The probability of making a Type S error, and the average amount of magnification (type M error) as a function of power

When you filter on only viewing results with p<alpha, some of those "statistically significant" results go in the wrong direction. This is called a Type S error ("S" for sign). ...

hypothesis-testing type-i-and-ii-errors research-design reproducibility  
user avatar asked by Harvey Motulsky Score of 6
user avatar answered by Sextus Empiricus Score of 0

Can statistical units measured per thousand inhabitants be bigger than 1000?

I found some data on the number of self-employed people per one thousand inhabitants in Europe here. However, in the year 2020, for instance, some statistical units have over one thousand self-...

distributions correlation units  
user avatar asked by Anc45 Score of 6
user avatar answered by J-J-J Score of 30

What is the adequate regression model for bounded, continuous but poisson-like data?

I am trying to compare the lodging resistance scores of different wheat cultivars in an agronomic trial. Lodging is the phenomenon in which wheat plant can bend and lean closer to the ground as a ...

generalized-linear-model poisson-regression bounds  
user avatar asked by Dangerbuee Score of 6
user avatar answered by EdM Score of 8

Obtaining the chi-squared test statistic via geometry

I’m trying to informally derive the chi-squared test statistic using a combination of basic geometry and algebra. I’m successfully able to obtain a system of equations that contain Karl Pearson’s chi-...

probability chi-squared-test multinomial-distribution  
user avatar asked by Rez99 Score of 5
user avatar answered by Sextus Empiricus Score of 1

dispersion parameter in Poisson models

When using a Poisson GLM, its dispersion parameter can be estimated as "residual deviance/degrees of freedom". But when analyzing Poisson data with a Poisson model (i.e., not overdispersed), ...

generalized-linear-model overdispersion dispersion  
user avatar asked by quibble Score of 5
user avatar answered by Thomas Lumley Score of 7

Is there a clean way to derive the start parameters for running the `fitdist()` function for the Gumbel distribution?

I've begun working with the Gumbel distribution and started with the example in the package documentation at For the Gumbel ...

r survival gumbel-distribution  
user avatar asked by Village.Idyot Score of 5
user avatar answered by EdM Score of 10

References on how to interpret significant but dubious results (i.e. small numbers, plus borderline p-value)

I'm comparing two groups of people on a binary variable. The number of successes is really small for the two groups (which wasn't expected, due to a lack of previous quantitative research on the ...

statistical-significance chi-squared-test references  
user avatar asked by Coris Score of 5

Greatest hits from previous weeks:

What's the difference between multiple R and R squared?

In linear regression, we often get multiple R and R squared. What are the differences between them?

regression r-squared  
user avatar asked by RockTheStar Score of 19
user avatar answered by Nick Stauner Score of 19

What is the intuition behind beta distribution?

Disclaimer: I'm not a statistician but a software engineer. Most of my knowledge in statistics comes from self-education, thus I still have many gaps in understanding concepts that may seem trivial ...

distributions beta-distribution intuition beta-binomial-distribution  
user avatar asked by ffriend Score of 553
user avatar answered by David Robinson Score of 795

What is the difference between pooled cross sectional data and panel data?

They seem so similar. Are they the same thing but just referred to as different names?

regression econometrics panel-data dataset cross-section  
user avatar asked by Kyle Score of 26
user avatar answered by Corey Sparks Score of 21

In linear regression, when is it appropriate to use the log of an independent variable instead of the actual values?

Am I looking for a better behaved distribution for the independent variable in question, or to reduce the effect of outliers, or something else?

regression distributions data-transformation logarithm faq  
user avatar asked by d_2 Score of 214
user avatar answered by whuber Score of 217

How to interpret a QQ plot

I am working with a small dataset (21 observations) and have the following normal QQ plot in R: Seeing that the plot does not support normality, what could I infer about the underlying distribution? ...

r data-visualization inference qq-plot faq  
user avatar asked by JohnK Score of 236
user avatar answered by Glen_b Score of 410

Relationship between SVD and PCA. How to use SVD to perform PCA?

Principal component analysis (PCA) is usually explained via an eigen-decomposition of the covariance matrix. However, it can also be performed via singular value decomposition (SVD) of the data matrix ...

pca dimensionality-reduction matrix svd faq  
user avatar asked by amoeba Score of 572
user avatar answered by amoeba Score of 701

Bagging, boosting and stacking in machine learning

What's the similarities and differences between these 3 methods: Bagging, Boosting, Stacking? Which is the best one? And why? Can you give me an example for each?

machine-learning boosting ensemble-learning bagging model-averaging  
user avatar asked by Bucsa Lucian Score of 298
user avatar answered by Alexander Galkin Score of 286

Can you answer these questions?

Testing signifiance of random effects on large dataset

I want to do a mixed linear model, with two hierarchical random effects. I want to determine wether if these random effects are worth including in the model. I have tried so far doing : ...

r mixed-model model-selection  
user avatar asked by Dimitri Score of 1

Inferring a random walk from noisy "images"

I'm interested in the following inference / filtering problem in a hidden Markov model setting. Suppose we have a simple random walk $x_t\in\mathbb{Z}$ and observations are "images" ...

bayesian hidden-markov-model kalman-filter particle-filter filter  
user avatar asked by Austen Score of 1

Is there a name for a normalized, powered distribution from the exponential family?

Suppose that $f(y|\boldsymbol{\theta})$ is a distribution belonging to the exponential family (e.g., a normal distribution). I'm wondering if there is a name for the following distribution, which is ...

distributions normalization distribution-identification  
user avatar asked by Ron Snow Score of 1
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