This study utilizes the crossover study design in examining the variability in responses by individuals to placebo treatment. Crossover study design has a number of advantages when used in the research process. This is especially for early stage trials. A major strength of crossover design is that the interventions that are being investigated are usually evaluated within the same patients. Therefore, between-subject variability is eliminated. At the same time, the design allows trials that are head-to-head and patients that receive multiple treatments are able to express their preferences for and against certain treatments. Another strength in this study is the recruitment and selection of the sample. Recruitment was done by use of flyers and postings and as such the sample was totally random eliminating any possibility of researcher bias in sample selection. The same participants used in experiment 1 were also used in experiment two. 48 participants completed experiment one and of these, 45 participated in the second experiment. This enhances the validity of the findings.
One of the limitations of the crossover design is that may have carryover effects. As such, this design might have led to effects of carryover from the first study visit to the second one. Second, the placebo outcome of sham acupuncture was not superior statistically to no-treatment control. If the placebo effect was larger, then a relationship between sham device and pill could have probably been established. Third, since the research was conducted on healthy subjects in a fairly small sample size, then it is not clear if the same results could be replicated in patient populations. However, despite these limitations, the crossover study managed to establish that individuals have different responses to different types of placebo treatments.