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Confidence interval for a 2-group median ratio

Source: R/statpsych1.R
ci.ratio.median2.Rd

Computes a distribution-free confidence interval for a ratio of population medians of ratio-scale measurements in a 2-group design. Tied scores within each group are assumed to be rare.

For more details, see Section 2.12 of Bonett (2021, Volume 1)

Usage

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 for group 1

  • Median2 - estimated median for 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 .

Bonett DG (2021). Statistical Methods for Psychologists https://dgbonett.sites.ucsc.edu/.

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