In the context of AP Psychology, which of the following best defines a longitudinal study?

• A. A research method that involves studying the same group of individuals over an extended period of time to observe changes and developments.
• B. A research method that collects data from participants at a single moment without follow-up.
• C. A research method that compares different groups of people at one point in time.
• D. A research method that manipulates variables to determine cause and effect.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the key concept of a longitudinal study in psychology, which involves observing the same participants repeatedly over a long period to track changes and developments.
2. Step 2: Recognize that this method contrasts with cross-sectional studies, which collect data from different groups at a single point in time, and experimental methods, which manipulate variables to test cause and effect.
3. Step 3: Identify that a longitudinal study is designed to observe how individuals change over time, making it ideal for studying development, aging, or long-term effects.
4. Step 4: Note that the other options describe different research methods: a single moment data collection is a cross-sectional approach, comparing different groups is also cross-sectional, and manipulating variables refers to experimental research.
5. Step 5: Conclude that the best definition of a longitudinal study is the one emphasizing studying the same group over an extended period to observe changes and developments.