statpsych (version 1.7.0)

ci.2x2.prop.mixed: Computes tests and confidence intervals of effects in a 2x2 mixed factorial design for proportions

Description

Computes adjusted Wald confidence intervals and tests for the 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 with a dichotomous response variable where Factor A is a within-subjects factor and Factor B is a between-subjects factor. The 4x1 vector of frequency counts for Factor A within each group is f00, f01, f10, f11 where fij is the number of participants with a response of i = 0 or 1 at level 1 of Factor A and a response of j = 0 or 1 at level 2 of Factor A.

Usage

ci.2x2.prop.mixed(alpha, group1, group2)

Value

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

• Estimate - adjusted estimate of effect

• SE - standard error of estimate

• z - z test statistic

• p - two-sided p-value

• LL - lower limit of the adjusted Wald confidence interval

• UL - upper limit of the adjusted Wald confidence interval

Arguments

alpha

alpha level for 1-alpha confidence

group1

vector of frequency counts from 2x2 contingency table in group 1

group2

vector of frequency counts from 2x2 contingency table in group 2

Examples

group1 <- c(125, 14, 10, 254)
group2 <- c(100, 16, 9, 275)
ci.2x2.prop.mixed (.05, group1, group2)

# Should return:
#              Estimate          SE          z          p          LL           UL
# AB:       0.007555369 0.017716073  0.4264697 0.66976559 -0.02716750  0.042278234
# A:       -0.013678675 0.008858036 -1.5442107 0.12253730 -0.03104011  0.003682758
# B:       -0.058393219 0.023032656 -2.5352360 0.01123716 -0.10353640 -0.013250043
# A at b1: -0.009876543 0.012580603 -0.7850612 0.43241768 -0.03453407  0.014780985
# A at b2: -0.017412935 0.012896543 -1.3502018 0.17695126 -0.04268969  0.007863824
# B at a1: -0.054634236 0.032737738 -1.6688458 0.09514794 -0.11879902  0.009530550
# B at a2: -0.062170628 0.032328556 -1.9230871 0.05446912 -0.12553343  0.001192177