Question

what is a \sample\ in psychological research? *
every person in the world
a drug
only people who agree with the psychologist
a small group studied to represent a larger population
a research study examined the intellectual growth of 20 premature children over a period of 18 years. this is best described as an example of
a longitudinal study
a case study
a cross - sectional study
a survey

Explanation:

For the first question: In psychological research, a sample is a subset of a larger population selected for study to represent that population. The other options are incorrect as they do not fit the definition of a research sample.
For the second question: A longitudinal study follows the same group of participants over an extended period of time to observe changes. This matches the description of tracking 20 premature children for 18 years. A case study focuses on a single individual or small group in depth but not over such a long, extended tracking period; a cross-sectional study compares different groups at a single point in time; a survey collects data via self-report measures, not long-term tracking.

Answer:

1. A small group studied to represent a larger population
2. A longitudinal study