Short Answer 
Dr. Jamal’s research links being an only child to cognitive development, but the reliance on survey data limits his ability to assert causation. The use of correlational data and the lack of random assignment introduce biases and alternative explanations, indicating a need for more rigorous studies to support his claims.
Step 1: Understanding Dr. Jamal’s Claim
Dr. Jamal’s research examines the link between being an only child and cognitive development, specifically focusing on the transition to concrete operational thinking. However, his findings are limited due to the reliance on survey data, which primarily shows correlation rather than causation. This makes it difficult for him to definitively state that being an only child directly results in faster cognitive development.
Step 2: Issues with Surveys
Surveys typically yield correlational data, meaning Dr. Jamal cannot draw firm conclusions about cause and effect from his results. The critical points here include:
- The data may suggest a relationship but fail to indicate whether one factor causes the other.
- Without a controlled experiment, alternative explanations remain possible.
- The specific choice about causation captures the inherent limitations of survey conclusions.
Step 3: Importance of Random Assignment
Another significant flaw in Dr. Jamal’s approach is the absence of random assignment in his research. Not having a randomized participant list can lead to biases that skew results, as factors influencing the cognitive development could be unaccounted for. Key considerations include:
- Random assignment enhances the validity of research findings.
- It helps ensure that differences in cognitive development are due to the being an only child, not other variables.
- Ultimately, more rigorously designed studies are needed to substantiate Dr. Jamal’s assertions.