autism data in Chapter 6

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Description

The data comes from researchers at the University of Michigan as part of a prospective longitudinal study of 214 children.

Usage

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Format

A data frame with 612 observations on the following 4 variables.

age

: Age in years (2, 3, 5, 9, 13); the time variable

vsae

: Vineland Socialization Age Equivalent: parent-reported socialization, the dependent variable measured at each age

sicdegp

: Sequenced Inventory of Communication Development Expressive Group: categorized expressive language score at age 2 years (1 = Low, 2 = Medium, 3 = High)

childid

: Unique child identifier

References

Oti, R., Anderson, D., Risi, S., Pickles, A. & Lord, C., Social Trajectories Among Individuals with Autism Spectrum Disorders, Developmental Psychopathology (under review), 2006.

West, B., Welch, K. & Galecki, A, Linear Mixed Models: A Practical Guide Using Statistical Software, Chapman Hall / CRC Press, first edition, 2006.

Examples

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attach(autism)
sicdegp.f <- factor(sicdegp)
age.f <- factor(age)
detach(autism)

# Add the new variables to a new data frame object.
autism.updated <- data.frame(autism, sicdegp.f, age.f)
dim(autism.updated)
names(autism.updated)