Prediction interval for difference of scores in a 2-level within-subjects experiment

Source: R/statpsych1.R

For a 2-level within-subjects experiment, this function computes a prediction interval for how the response variable score for one randomly selected person from the study population would differ under the two treatment conditions.

pi.score.ps(alpha, m1, m2, sd1, sd2, cor, n)

Arguments

alpha

alpha level for 1-alpha confidence

m1

estimated mean for measurement 1

m2

estimated mean for measurement 2

sd1

estimated standard deviation for measurement 1

sd2

estimated standard deviation for measurement 2

cor

estimated correlation of paired scores

n

sample size

Value

Returns a 1-row matrix. The columns are:

  • Predicted - predicted difference in scores

  • df - degrees of freedom

  • LL - lower limit of the prediction interval

  • UL - upper limit of the prediction interval

Examples

pi.score.ps(.05, 265.1, 208.6, 23.51, 19.94, .814, 30)
#>  Predicted df       LL       UL
#>       56.5 29 28.05936 84.94064

# Should return:
# Predicted df       LL       UL
#      56.5 29 28.05936 84.94064