strength is that other studies have demonstrated the influence of situation variables on obedience
in a field experiment, psychologist had three confederates dress in different outfits
The Confederate individually stood in the street and asked passers-by to perform tasks, such as picking up litter, or handing over a coin for the parking meter.
People were twice as likely to help the assistant dressed as the security guard, than the one dressed in jacket and tie.
This suggests that situational variables such as uniform, does have a powerful effect on obedience