A Researcher Does a Series of Studies to See What

Essay

A researcher does a series of studies to see what affects motor development. In Study 1, preterm infants are compared to full-term infants on their motor development at one year of age.
In Study 2, the motor development of two groups is compared: one-year-olds whose parents
had enrolled them in "baby gymnastics" versus one-year-olds without this experience. In
Study 3, six-month-olds are randomly assigned to a group that receives extra large-motor
stimulation (in "walkers") versus no enrichment; the two groups' large-motor skills are
compared at twelve months.
Assuming that the test of motor development is at the interval level, which type of statistical
test is most appropriate for each study?
Study 1:
Study 2:
Study 3:
t test^{(for all)}
What type of approach is used in each study?