Answer:
Step-by-step explanation:
Bob's research strategy has several flaws:
1. Lack of control group: Bob did not include a control group in his study. A control group is essential to compare the results of the experimental group (friends who drank coffee) with a group that did not consume caffeine. Without a control group, it is difficult to determine whether any changes in reaction time were solely due to caffeine or other factors.
2. Small sample size: Bob only included five friends in his study. A small sample size may not be representative of the larger population, and the results may not be generalizable. To obtain more reliable results, a larger sample size is typically required.
3. Lack of randomization: Bob did not randomly assign his friends to the experimental and control groups. Randomization helps ensure that any differences observed between the groups are due to the treatment (caffeine) rather than pre-existing differences among individuals.
4. Lack of blinding: Bob's friends were aware that they were consuming coffee, which could introduce bias into their performance on the learning task. To minimize this bias, it is important to conduct double-blind studies where neither the participants nor the researchers know who is receiving the treatment.
5. Single measurement point: Bob only measured his friends' reaction time once after consuming coffee. It would be more reliable to measure their reaction time multiple times before and after consuming coffee to account for individual variations and potential confounding factors.