zelazo: Age at walking
In ISwR: Introductory Statistics with R

The zelazo object is a list with four components.

zelazo

This is a list containing data on age at walking (in months) for four groups of infants:

active: test group receiving active training; these children had their walking and placing reflexes trained during four three-minute sessions that took place every day from their second to their eighth week of life.
passive: passive training group; these children received the same types of social and gross motor stimulation, but did not have their specific walking and placing reflexes trained.
none: no training; these children had no special training, but were tested along with the children who underwent active or passive training.
ctr.8w: eighth-week controls; these children had no training and were only tested at the age of 8 weeks.

When asked to enter these data from a text source, many students will use one vector per group and will need to reformat data into a data frame for some uses. The rather unusual format of this data set mimics that situation.

P.R. Zelazo, N.A. Zelazo, and S. Kolb (1972), “Walking” in the newborn, Science, 176: 314–315.

ISwR documentation built on Jan. 20, 2020, 5:07 p.m.