Question

The mean crying time of infants during naptime at a local preschool is 12 min. The school implements a new naptime routine in a sample of 25 infants and records an average crying time of 8 ± 4.6 (M±SD) min. Test whether this new naptime routine reduced crying time at a .05 level of significance.

Provide the following:

(1) Null and alternative research hypotheses

(2) Criteria

(3) Compute test statistic

(4) Decision - accept or reject null hypothesis. Explain meaning.

(5) Calculate confidence interval

(6) Calculate effect size and proportion of variance. Explain meaning.

Answer 1

(1-4)

(5)

The 95% confidence interval is :

(6)

Cohen's d effect size is

And effect size r2 is