Was it a blind study?
The purpose of this should be obvious. This removes expectation bias of
both patients and those who interpret test results.
Read carefully to ensure that it was double blind and that the placebo was
appropriate. A good placebo should be indistinguishable from the real
medication in appearance and taste. Another factor to consider is if the
medication may have had significant side effects compared to placebo that
would enable the participants to guess what they were taking.
Application to Pollock et al's
thyroxine paper
In this study, it is stated in the title that this is a double-blind, placebo-controlled
trial.