heplots (version 1.8.5)

ReadingDisability: Cognitive and Achievement Test Scores by Reading Level

Description

Six cognitive/achievement test scores for children classified into four reading-achievement groups (Severe, Mild, Average, Superior), reconstructed from the group means, standard deviations, and pooled within-cells correlations reported as a worked "real data example" in Bray & Maxwell (1985), Table 2.3.

Individual rows are simulated, not the original observations: only group-level summary statistics were published, with no raw data and no per-group correlations (a single correlation matrix, pooled across all four groups, was reported). Each group was drawn from a multivariate normal with that group's reported means and a covariance matrix built from that group's reported SDs combined with the pooled correlations, then forced to match those exact moments via MASS::mvrnorm(..., empirical = TRUE). Summarizing this data frame by Group exactly reproduces Bray & Maxwell's Table 2.3 (see data-raw/ReadingDisability.R).

B&M (p.38) describe the six measures as follows: "The PPVT is a general verbal measure of IQ, whereas the VF and SIM tests are verbal criteria. The EF taps higher-order nonverbal abilities, whereas the VMI and RD are general nonverbal measures."

Usage

data("ReadingDisability")

Format

A data frame with 571 observations on the following 7 variables, a 4-level between-subjects factor (Group) with unequal n.

Group

Reading achievement level, an ordered factor with levels (worst to best) Severe (n = 93) < Mild (n = 113) < Average (n = 274) < Superior (n = 91)

PPVT

Peabody Picture Vocabulary Test score -- a general verbal measure of IQ, numeric

RD

Recognition-Discrimination Test score -- a general nonverbal measure, numeric

EF

Embedded Figures Test score -- taps higher-order nonverbal abilities, numeric

VF

Verbal Fluency Test score -- a verbal criterion measure, numeric

VMI

Beery Visual-Motor Integration Test score -- a general nonverbal measure, numeric

SIM

Similarities subtest of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) score -- a verbal criterion measure, numeric

Examples

data(ReadingDisability)
str(ReadingDisability)

rd.mod <- lm(cbind(PPVT, RD, EF, VF, VMI, SIM) ~ Group,
             data = ReadingDisability)
car::Anova(rd.mod)

heplot(rd.mod, fill = TRUE, fill.alpha = 0.1)