Two pivotal elements to consider when selecting the design of a clinical study are:
- Should the study include a placebo group?
- Should the study be performed as double-blinded or single-blinded?
Let’s explore this in more details.
Firstly, when designing a clinical study you should always consider the claim you wish to make.
- If you wish to claim that your product is better in providing X than a leading product on the market… you must include two groups in the design: your product versus leading product.
- If you wish to claim that your ingredient does X… you must include two groups: test your ingredient containing-formulation versus a placebo formulation.
- If you wish to claim that your formulation does X… a single group is sufficient: you compare to the baseline or to the regular skin care routine of study participants.
Next, a crucial element is the level of “blinding” needed in the clinical study. Double-blinded studies are generally accepted as a stronger design by the scientific community since they remove the bias of knowing which group received the treatment. This design ensures that both the study investigator and the participant are unaware of the nature of the product they are testing. This scenario is readily applicable in case when a placebo group is used or when a comparison between competition products is carried out.
On the other hand, if the manufacturer of a cosmetic product wants to evaluate the performance of the product itself, a single-blinded study is justifiable because the study participant knows that he/she is applying a product. Nevertheless, the participant is kept blinded to the exact nature of the product (brand name) to avoid a preference bias.
Hope this helps clarify some of your questions! Send me an email if you wish to have more details!
Wiechers J.W. (2013) Memories of a Cosmetically Disturbed Mind, Carol Stream, IL: Alluredbooks