Skip to contents

Confidence interval for a 2-group mean ratio

Source: R/statpsych1.R
ci.ratio.mean2.Rd

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.

Usage

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

Details

For more details, see Section 2.5 of Bonett (2021, Volume 1)

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.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