Dr. franklin wants to assess the intelligence of 1,000 people ages 20, 30 and 40. if he does this as a cross-sectional study, he has some concerns that since these people were all born at different times and have had different experiences and opportunities, there may be

The given blank can be filled with cohort effect.

Explanation:

A cohort effect refers to the specific influence of a group bonded by common life experiences or time. Cohorts in an organization are generally illustrated by entry date and retain some common features like cohesiveness, size, and competition, which can influence the organization.  

A cohort refers to a group of individuals who shares common experiences or features like the region where they were born, their years of birth, and others. Cohort effects are a concern for the scientists working in the fields like epidemiology, sociology, and psychology.