Anna is within the normal range for weight, but she uses laxatives in order to control her severe overconsumption of calories. Anna has a disorder known as anorexia

Cross-sectional research by Schaie on the development of intellectual ability in adulthood was carefully controlled to account for cohort effects. This research found that

a) most people improve in basic mental ability during adulthood. b) the majority of people decline considerably in mental ability as they age. c) people are gradually becoming more intelligent in an increasingly complex society. d) individual abilities are primarily a function of genetic endowment; therefore, overall intelligence either increases or decreases as a unit.

In a single-subject experimental design, if there is low variability from one observation to the next within a phase, the data are ____

a. stable b. unstable c. statistically significant d. visually significant