Final answer:
To ensure reliability in this experiment, random assignment, double-blind procedure, and inclusion of a control group should be implemented.
Step-by-step explanation:
In this experiment, there are several factors that could be evaluated to ensure reliability. First, the groups should be randomly assigned to ensure that each group has an equal chance of receiving a certain dose of caffeine. This helps to eliminate any bias in the selection process. Second, the experiment should be double-blind, meaning that neither the researcher nor the participants know which group received which dosage. This helps to eliminate any bias in the observations and measurements.
Lastly, the experiment should include a control group that receives a placebo, such as plain water in this case. This allows for comparison between the different dosage groups and the control group, and helps to account for any external factors that may influence the results.