It is impossible to select for study adults who are similar to ...

[Garrulous]

It is impossible to select for study adults who are similar to each other in every aspect except age; for this reason, cross-sectional research can easily be distorted by ______.
 
  Fill in the blank with correct word

Question 2

Schaie found that ______ research shows a gradual decline in intellectual ability, while ______ research, which may not be applicable to other cohorts, shows an increase in intellectual abilities throughout most of adulthood.
 
  Fill in the blank with correct word

[mistyjohnson]

Answer to Question 1

cohort differences

Answer to Question 2

cross-sectional; longitudinal

[Garrulous]

Wow, this really help

[ultraflyy23]

Thanks for the timely response, appreciate it