Variance ratio: a distributional balance check

The ratio of a condition's variance to the reference's, complementing the mean-based Cohen's d and TOST. Two conditions can share a mean yet differ in spread and still confound, which a mean-based statistic misses (Armstrong et al., 2012; Austin, 2009). A ratio near 1 is balanced; a common heuristic flags ratios outside roughly 0.5 to 2.

Usage

variance_ratio(cond, ref)

Arguments

cond, ref

Numeric vectors (condition and reference).

Value

The variance ratio, or NA when a variance is undefined.

Examples

variance_ratio(c(1, 2, 3, 4), c(1, 2, 3, 8))
#> [1] 0.1724138