Check Balance of Sample Sizes Among Groups

Determines whether sample sizes are approximately balanced across groups. Sample sizes are considered balanced when the smallest and largest group sizes are within the specified tolerance range relative to the average sample size.

Usage

is_balance(data, formula, buffer_ratio = 0)

Arguments

data: A data frame or a list containing observations from each group.
formula: A formula specifying the dependent variable (DV) and the independent variable (IV) in the form DV ~ IV. This argument is required when data is a data frame and is ignored when data is already a list.
buffer_ratio: Numeric value between 0 and 1 (default: 0). The allowable proportional deviation from the mean sample size. For example, buffer_ratio = 0.2 allows group sizes to differ from the mean by up to 20%. When buffer_ratio = 0, the function requires exact equality of sample sizes among groups.

Value

A logical value:

TRUE: Sample sizes among groups are considered balanced.
FALSE: At least one group has a sample size outside the specified tolerance range.

Details

The function compares each group's sample size with the mean sample size across groups. The sample sizes are considered balanced if:

$$ (1-r) \leq \frac{\min(n)}{\bar{n}} \leq \frac{\max(n)}{\bar{n}} \leq (1+r) $$

where $\bar{n}$ is the mean sample size across groups and r is buffer_ratio.

Examples

is_balance(list(rnorm(10), rnorm(13)), buffer_ratio = 0.2)
#> [1] TRUE
is_balance(list(rnorm(10), rnorm(13)), buffer_ratio = 0.1)
#> [1] FALSE