This exercise is based on summary statistics rather than raw
data. This information is typically all that is presented in
published reports. You can calculate inference procedures by hand
from the summaries. Use the conservative Option 2 (degrees of
freedom the smaller of n₁ ? 1 and
n₂ ? 1) for two-sample t confidence
intervals and P-values. You must trust that the authors
understood the conditions for inference and verified that they
apply. This isn’t always true.

Do education programs for preschool children that follow the
Montessori method perform better than other programs? A study
compared 5-year-old children in a certain city, who had been
enrolled in preschool programs from the age of 3.

A.)  In all, 57 children were assigned to the
Montessori school and 119 to other schools at age 3. When the
children were 5, parents of 39 of the Montessori children and 31 of
the others could be located. Those who were located agreed to and
subsequently participated in testing. This information reveals a
possible source of bias in the comparison of outcomes. Explain why.
(Round your answers to the nearest whole number.)

About ____ % Montessori parents participated in the study,
compared to about _____ % of the other parents.