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1
vote
2answers
94 views

Statistical test to find variable causing failure

I have a database with tests that are either a pass or fail and around 25 description fields. Each description field is either a boolean or has between 3 and 10 options. I'd like to hook into my ...
5
votes
1answer
3k views

What are the rules / guidelines for downsampling?

I have a data set with ~ 7 million rows, of which ~ 100k are positives. I'm looking to shrink the data by keeping all the ...
4
votes
1answer
686 views

Absent categorical data levels in Bootstrap samples

I have a huge dataset ($n$ around five million, $p$ around three thousand) for a classification problem, where my interest is predictive class probabilities for test data, not the target. I shall be ...
4
votes
2answers
446 views

How to reconstruct database from cross-tabulated data?

I am given a set of almost 100 crosstabulations (most 2D, but some three dimensional) based on a single, yet unavailable dataset. My task is to perform basic statistical tests ($\chi^2$, Mann-Whitney, ...
11
votes
3answers
12k views

How to resample in R without repeating permutations?

In R, if I set.seed(), and then use the sample function to randomize a list, can I guarantee I won't generate the same permutation? ie... ...
7
votes
2answers
7k views

How do I sample without replacement using a sampling-with-replacement function?

I vaguely recall from grad school that the following is a valid approach to do a weighted sampling without replacement: Start with an initially empty "sampled set". Draw a (single) weighted sample ...
4
votes
2answers
2k views

A robust R package to do MCMC and Gibbs sampling

I need to make linear model for which I need to do Gibbs sampling in MCMC simulations. The model needed to be fitted is a linear mixed model. Please suggest me for a robust R package for this task.
7
votes
2answers
2k views

How to calculate sample size for comparing the area under the curve of two models?

Because I would like to calculate the sample size for comparing the area under the curve (AUC) of 2 models (cross-sectional study, predictor = continuous variable). Can you point me which function in ...
4
votes
2answers
828 views

Incidence density sampling in R

I was wondering if there is an R package to perform incidence density sampling for a case-control design. That is, for matching in a case-control design; accounting for multiple matching covariates.
16
votes
1answer
31k views

Generating random samples from a custom distribution

I am trying to generate random samples from a custom pdf using R. My pdf is: $$f_{X}(x) = \frac{3}{2} (1-x^2), 0 \le x \le 1$$ I generated uniform samples and then tried to transform it to my custom ...
6
votes
3answers
2k views

Multistage sampling in R

I've got a dataset similar to this: ...
3
votes
1answer
279 views

Sample selection and variation in the variable of interest when using panel data

I wonder how to reason when selecting samples. I am doing a panel data regression analysis about how the euro membership correlates with the budget deficit in the member countriues. Using R that is: ...
9
votes
3answers
6k views

How to re-sample an XTS time series in R?

I have an irregularly spaced XTS time series (with POSIXct values as index type). How can I build a new time series sampled at ...
1
vote
2answers
880 views

Should I use an average ECDF?

This relates to a previous question of mine which didn't gain many responses, perhaps because it wasn't very clear nd well written. I hope this time I will be more accurate and get your much ...
13
votes
3answers
589 views

Estimate the size of a population being sampled by the number of repeat observations

Say I have a population of 50 million unique things, and I take 10 million samples (with replacement)... The first graph is I've attached shows how many times I sample the same "thing", which is ...