Which research method would best test the hypothesis that a developed vocabulary in preschoolers predicts better reading comprehension in third grade?

• A. A case study of a single child with advanced vocabulary skills
• B. An experimental study randomly assigning children to vocabulary training or control groups for one week
• C. A longitudinal study following the same children from preschool through third grade
• D. A cross-sectional study comparing preschoolers and third graders at one point in time

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the hypothesis, which is about predicting a future outcome (reading comprehension in third grade) based on an earlier characteristic (vocabulary in preschoolers). This implies a need to observe changes or developments over time.
2. Step 2: Review the research methods options: a case study focuses on one individual and is not generalizable; an experimental study involves manipulation and control but may be too short-term to observe long-term prediction; a cross-sectional study compares different age groups at one time but does not track development within the same individuals.
3. Step 3: Recognize that a longitudinal study involves following the same group of children over an extended period, allowing researchers to observe how early vocabulary skills relate to later reading comprehension within the same individuals.
4. Step 4: Conclude that the longitudinal study is best suited to test the hypothesis because it captures developmental changes and predictive relationships over time.
5. Step 5: Summarize that to test predictive hypotheses about development, research designs must track the same participants across relevant time points, which is the strength of longitudinal studies.