A Researcher Tests All the Students in One College and Finds

Multiple Choice

A researcher tests all the students in one college and finds that the first-borns have higher GPAs than later-born children, on the average. One possible explanation is that the results reflect the influence of birth order. The other explanation is that the results depend on differences between

A) motivated students and unmotivated students.
B) one-child families and larger families.
C) longitudinal studies and cross-sectional studies.
D) left-handers and right-handers.