After stinging its victim, the honeybee leaves behind the barbed stinger, poison sac and muscles that continue to pump venom into the wound. visscher et al. (1996) compared the effects of two methods of removing the stinger left behind: scraping off with a credit card or pinching off with thumb and index finger. a total of 40 stings were induced on volunteers. twenty were removed with the credit card method and 20 were removed with the pinching method. the size of the subsequent welt by each measurement came from two volunteers (both authors of the study), each of whom received one treatment 10 times on the one arm and the other treatment 10 times on the other arm. pinching led to a slightly smaller average welt, but the difference between the methods was not significant. does this study include a control group? enter the number of the best answer choice from the options below