Computes confidence intervals of standardized effects in a 2x2 mixed design

Source: R/statpsych1.R

Computes confidence intervals for the standardized AB interaction effect, main effect of A, main effect of B, simple main effects of A, and simple main effects of B in a 2x2 mixed factorial design where Factor A is a within-subjects factor, and Factor B is a between-subjects factor. Equality of population variances is not assumed.

ci.2x2.stdmean.mixed(alpha, y11, y12, y21, y22)

Arguments

alpha

alpha level for 1-alpha confidence

y11

vector of scores at level 1 of A in group 1

y12

vector of scores at level 2 of A in group 1

y21

vector of scores at level 1 of A in group 2

y22

vector of scores at level 2 of A in group 2

Value

Returns a 7-row matrix (one row per effect). The columns are:

  • Estimate - estimated standardized effect

  • adj Estimate - bias adjusted standardized effect estimate

  • SE - standard error

  • LL - lower limit of the confidence interval

  • UL - upper limit of the confidence interval

References

Bonett DG (2008). “Confidence intervals for standardized linear contrasts of means.” Psychological Methods, 13(2), 99--109. ISSN 1939-1463, doi:10.1037/1082-989X.13.2.99 .

Examples

y11 <- c(18, 19, 20, 17, 20, 16)
y12 <- c(19, 18, 19, 20, 17, 16)
y21 <- c(19, 16, 16, 14, 16, 18)
y22 <- c(16, 10, 12,  9, 13, 15)
ci.2x2.stdmean.mixed(.05, y11, y12, y21, y22)
#>             Estimate adj Estimate        SE         LL         UL
#> AB:      -1.95153666  -1.80141845 0.5424100 -3.0146407 -0.8884326
#> A:        1.06061775   1.01125934 0.2780119  0.5157244  1.6055111
#> B:        1.90911195   1.76225718 0.5743510  0.7834047  3.0348192
#> A at b1:  0.08484942   0.07589163 0.4649598 -0.8264549  0.9961538
#> A at b2:  2.03638608   1.82139908 0.2964013  1.4554502  2.6173219
#> B at a1:  0.93334362   0.86154796 0.5487927 -0.1422703  2.0089575
#> B at a2:  2.88488027   2.66296641 0.7127726  1.4878717  4.2818889

# Should return:
#             Estimate  adj Estimate        SE         LL         UL
# AB:      -1.95153666   -1.80141845 0.5424100 -3.0146407 -0.8884326
# A:        1.06061775    1.01125934 0.2780119  0.5157244  1.6055111
# B:        1.90911195    1.76225718 0.5743510  0.7834047  3.0348192
# A at b1:  0.08484942    0.07589163 0.4649598 -0.8264549  0.9961538
# A at b2:  2.03638608    1.82139908 0.2964013  1.4554502  2.6173219
# B at a1:  0.93334362    0.86154796 0.5487927 -0.1422703  2.0089575
# B at a2:  2.88488027    2.66296641 0.7127726  1.4878717  4.2818889