Early R Documentation

## Early childhood intervention study

### Description

Cognitive scores of infants in a study of early childhood intervention. The 103 infants from low income African American families were divided into a treatment group (58 infants) and a control group (45 infants). Starting at 0.5 years of age the infants in the treatment group were exposed to an enriched environment. Each infant's cognitive score on an age-specific, normalized scale was recorded at ages 1, 1.5, and 2 years.

### Usage

data(Early)

### Format

This groupedData object contains the following columns

id

An ordered factor of the id number for each infant.

cog

A numeric cognitive score.

age

The age of the infant at the measurement.

trt

A factor with two levels, "N" and "Y", indicating if the infant is in the early childhood intervention program.

### References

Singer, Judith D. and Willett, John B. (2003), Applied Longitudinal Data Analysis, Oxford University Press. (Ch. 3)

### Examples

str(Early)