iqdat {umx}

Twin data: IQ measured longitudinally across 4 ages.

Description

Measures of IQ across four ages in 261 pairs of identical twins and 301 pairs of fraternal (DZ) twins. (see details). It is used as data for the [umxSimplex()] examples.

Usage

data(iqdat)

Format

A data frame with 562 rows (twin families). Nine measures on each twin.

Details

• zygosity Zygosity (MZ or DZ)

• IQ_age1_T1 T1 IQ measured at age 1

• IQ_age2_T1 T1 IQ measured at age 2

• IQ_age3_T1 T1 IQ measured at age 3

• IQ_age4_T1 T1 IQ measured at age 4

• IQ_age1_T2 T2 IQ measured at age 1

• IQ_age2_T2 T2 IQ measured at age 2

• IQ_age3_T2 T2 IQ measured at age 3

• IQ_age4_T2 T2 IQ measured at age 4

References

Boomsma, D. I., Martin, N. G., & Molenaar, P. C. (1989). Factor and simplex models for repeated measures: application to two psychomotor measures of alcohol sensitivity in twins. *Behavior Genetics*, **19**, 79-96. Retrieved from <https://www.ncbi.nlm.nih.gov/pubmed/2712815>

See Also

[umxSimplex()]

Other datasets: Fischbein_wt, GFF, docData, umx, us_skinfold_data

Examples

## Not run: 
data(iqdat)
str(iqdat)
par(mfrow = c(1, 3))  # 1 rows and 3 columns
plot(IQ_age4_T1 ~ IQ_age4_T2, ylim = c(50, 150), data = subset(iqdat, zygosity == "MZ"))
plot(IQ_age4_T1 ~ IQ_age4_T2, ylim = c(50, 150), data = subset(iqdat, zygosity == "DZ"))
plot(IQ_age1_T1 ~ IQ_age4_T2, data = subset(iqdat, zygosity == "MZ"))
par(mfrow = c(1, 1))  # back to as it was

## End(Not run)