Confidence interval for a 2-group median ratio

Source: R/statpsych1.R

Computes a distribution-free confidence interval for a ratio of population medians of ratio-scale measurements in a 2-group design.

ci.ratio.median2(alpha, y1, y2)

Arguments

alpha

alpha level for 1-alpha confidence

y1

vector of scores for group 1

y2

vector of scores for group 2

Value

Returns a 1-row matrix. The columns are:

  • Median1 - estimated median from group 1

  • Median2 - estimated median from group 2

  • Median1/Median2 - estimated ratio of medians

  • LL - lower limit of the confidence interval

  • UL - upper limit of the confidence interval

References

Bonett DG, Price RM (2020). “Confidence intervals for ratios of means and medians.” Journal of Educational and Behavioral Statistics, 45(6), 750--770. doi:10.3102/1076998620934125 .

Examples

y2 <- c(32, 39, 26, 35, 43, 27, 40, 37, 34, 29, 49, 42, 40)
y1 <- c(36, 44, 47, 42, 49, 39, 46, 31, 33, 48)
ci.ratio.median2(.05, y1, y2)
#>  Median1 Median2 Median1/Median2       LL       UL
#>       43      37        1.162162 0.927667 1.455933

# Should return:
# Median1 Median2 Median1/Median2       LL       UL
#      43      37        1.162162 0.927667 1.455933