In a study of parents’ perceptions of their children’s size, researchers Kaufman etal. (Current Biology, 2013) asked parents to estimate their youngest child’s height. The researchers hypothesized that parents tend to underestimate their youngest child’s size because the youngest child is the baby of the family and everybody else is the family appears bigger compared to the baby. Th e sample of 39 parents who were surveyed underestimated their youngest child’s height by 7.50 cm, on average; the standard deviation for the difference in actual heights and estimated heights was 7.20 cm and the data are not strongly skewed.

a. Which of the following is an appropriate null hypothesis for this study?

A. Parents’ estimate of their youngest child’s height is accurate, on average.

B. Parents tend to overestimate their youngest child’s height, on average.

C. Parents tend to underestimate their youngest child’s height, on average.

b. Which of the following is an appropriate alternative hypothesis for this study?

A. Parents’ estimate of their youngest child’s height is accurate, on average.

B. Parents tend to overestimate their youngest child’s height, on average.

C. Parents tend to underestimate their youngest child’s height, on average.

c. Identify the observational units in this study.

A. Children

B. Parents

C. Actual heights

D. Estimated heights

d. Identify the parameter in this study.

A. The probability that parents will overestimate their youngest child’s height, ????

B. The probability that parents will underestimate their youngest child’s height, ????

C. The probability that parents will correctly estimate their youngest child’s height, ????

D. The average amount by which parents’ guess of their youngest child’s height will diff er from the actual height, ????

e. Explain why the simulation-based method cannot be used to analyze the available information, to investigate whether parents tend to overestimate their youngest child’s height.

f. Explain why a theory-based approach is valid.