ci.2x2.mean.mixed: Computes tests and confidence intervals of effects in a 2x2...

In statpsych: Statistical Methods for Psychologists

Computes tests and confidence intervals of effects in a 2x2 mixed design for means

Description

Computes confidence intervals and tests for the AB interaction effect, main effect of A, main efect of B, simple main effects of A, and simple main effects of B in a 2x2 mixed factorial design with a quantitative response variable where Factor A is a within-subjects factor, and Factor B is a between-subjects factor. A Satterthwaite adjustment to the degrees of freedom is used and equality of population variances is not assumed.

Usage

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

Arguments

alpha	alpha level for 1-alpha confidence
y11	vector of scores at level 1 in group 1
y12	vector of scores at level 2 in group 1
y21	vector of scores at level 1 in group 2
y22	vector of scores at level 2 in group 2

Value

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

• Estimate - estimate of effect

• SE - standard error

• t - t test statistic

• df - degrees of freedom

• p - p-value

• LL - lower limit of the confidence interval

• UL - upper limit of the confidence interval

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.mean.mixed(.05, y11, y12, y21, y22)

# Should return:
#            Estimate        SE         t       df            p         LL        UL
# AB:      -3.8333333 0.9803627 -3.910117 8.346534 0.0041247610 -6.0778198 -1.588847
# A:        2.0833333 0.4901814  4.250128 8.346534 0.0025414549  0.9610901  3.205577
# B:        3.7500000 1.0226599  3.666908 7.601289 0.0069250119  1.3700362  6.129964
# A at b1:  0.1666667 0.8333333  0.200000 5.000000 0.8493605140 -1.9754849  2.308818
# A at b2:  4.0000000 0.5163978  7.745967 5.000000 0.0005732451  2.6725572  5.327443
# B at a1:  1.8333333 0.9803627  1.870056 9.943850 0.0911668588 -0.3527241  4.019391
# B at a2:  5.6666667 1.2692955  4.464419 7.666363 0.0023323966  2.7173445  8.615989

statpsych documentation built on July 9, 2023, 6:50 p.m.