166k views

### Explaining to laypeople why bootstrapping works

I recently used bootstrapping to estimate confidence intervals for a project. Someone who doesn't know much about statistics recently asked me to explain why bootstrapping works, i.e., why is it that ...
38k views

### Bootstrap vs. permutation hypothesis testing

There are several popular resampling techniques, which are often used in practice, such as bootstrapping, permutation test, jackknife, etc. There are numerous articles & books discuss these ...
44k views

### Alternatives to one-way ANOVA for heteroskedastic data

I have data from 3 groups of algae biomass ($A$, $B$, $C$) which contain unequal sample sizes ($n_A=15$, $n_B=13$, $n_C=12$) and I would like compare if these groups are from the same population. One-...
23k views

### Using bootstrap under H0 to perform a test for the difference of two means: replacement within the groups or within the pooled sample

Suppose that I have a data with two independent groups: ...
25k views

### Why would I want to bootstrap when computing an independent sample t-test? (how to justify, interpret, and report a bootstrapped t-test)

Let's say I have two conditions, and my sample size for the two conditions is extremely low. Let's say I only have 14 observations in the first condition and 11 in the other. I want to use the t-test ...
28k views

### Is Random Forest suitable for very small data sets?

I have data set comprising 24 rows of monthly data. The features are GDP, airport arrivals, month, and a few others. The dependent variable is number of visitors to a popular tourism destination. ...
4k views

### Bootstrap: the issue of overfitting

Suppose one performs the so-called non-parametric bootstrap by drawing $B$ samples of size $n$ each from the original $n$ observations with replacement. I believe this procedure is equivalent to ...
2k views

### How to calculate the mean and CI for a percentage

I have some data that is percent reduction, i.e., -%, from a study and I want to be able to summarize the average percent reduction from my n = 20 samples, and to also provide a confidence interval. I ...
802 views

### Why do hypothesis tests on resampled datasets reject the null too often?

tl;dr: Starting with a dataset generated under the null, I resampled cases with replacement and conducted a hypothesis test on each resampled dataset. These hypothesis tests reject the null more than ...
1k views

### Bootstrapping and hypothesis testing

I got a comment on a paper that I recently submitted. He said, "Pag 7: referring to the “Univariate Analysis” section, bootstrap is not mentioned. This technique is extremely useful when dealing ...
688 views

### Estimating the ratio of cell means in ANOVA under lognormal assumption

I am conducting a two-sample test (1-way ANOVA with 2 treatments), and the goal is to estimate the ratio of cell means assuming that the data are lognormal. A simple approach is to log the response ...
363 views

### Is it erroneous to double data for a larger sample size?

Is it a big no no to double data in order to increase sample size? I have a sample size of 27 which really doesn't give me much to work with when running tests. Would this be statistically incorrect? ...
581 views

### Log transform before bootstrapping?

Background: I’m exploring if hair cortisol levels (pg/mg) are related with executive functions like working memory (measured on WISC-scale), inhibition control (BRIEF-scale) and attention shifting (...
Here is a MWE of my problem: I measure the size, $S$, of 10 red apples and 32 green apples. $\bar S_\mathrm{red} = 8 \pm 1\,\mathrm{cm}$ and $\bar S_\mathrm{green} = 4 \pm 2\,\mathrm{cm}$. I want ...