Question

to test the effectiveness of energy bars on working adults, researchers selected a simple random sample of 100 people (all of whom were working adults) for an experiment. the subjects were instructed to come to a lab before work. the first 50 people who arrived were given energy bars and ate them there before going to work. the last 50 people who arrived were given fake energy bars and ate them before going to work. researchers then called the respondents at noon and 5:00 p.m. to ask them how energetic they felt. this experiment was repeated multiple times with different samples. are there any flaws in the design of this experiment?

Explanation:

The assignment of energy - bars (treatment) and fake energy - bars (placebo) is based on arrival order, not random assignment. This may introduce bias as early - arrivers could have different characteristics (e.g., more energetic, more organized) compared to late - arrivers that could affect the perception of energy levels. Also, there is no blinding. If participants know whether they received a real or fake bar, it can influence their reported energy levels due to the placebo effect or expectations.

Answer:

Yes, there are flaws. The non - random assignment based on arrival order and lack of blinding are issues.