The participants knew what effect the researchers (the shoe company) were looking for.
The participants had clearly sympathetic feelings towards the researchers.
The participants also knew which boxes were in the test or control groups and that both types of boxes were sent out the same day.
The study relied solely on the reports of the subjects.
It seems a very real possibility that at least some of the participants could be trying to “help-out” the study, either because they want attention (albeit a small amount) or they want the study to succeed.
It also seems odd that postal employees would risk their jobs to interfere with the packages marked "atheist" but then allow packages that looked exactly the same, were going to the same address, and were coming from the same company to sail by.
Slashdot Mirror
The test also seems not very “blind" :
It seems a very real possibility that at least some of the participants could be trying to “help-out” the study, either because they want attention (albeit a small amount) or they want the study to succeed.
It also seems odd that postal employees would risk their jobs to interfere with the packages marked "atheist" but then allow packages that looked exactly the same, were going to the same address, and were coming from the same company to sail by.