Confidence interval for a 2-group mean ratio

Source: R/statpsych1.R

Computes a confidence interval for a ratio of population means of ratio-scale measurements in a 2-group design. Equality of variances is not assumed.

ci.ratio.mean2(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:

  • Mean1 - estimated mean for group 1

  • Mean2 - estimated mean for group 2

  • Mean1/Mean2- estimated mean ratio

  • 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.mean2(.05, y1, y2)
#>  Mean1    Mean2 Mean1/Mean2        LL      UL
#>   41.5 36.38462    1.140592 0.9837277 1.32247

# Should return:
#
# Mean1    Mean2 Mean1/Mean2        LL       UL
#  41.5 36.38462    1.140592 0.9897482 1.314425