What method is often used to control for experimenter bias effects in research

A)  non-representative sample 
B)  placebo control group 
C)  socially desirable procedure 
D)  double-blind procedure

The double-blind procedure is a commonly used method to control for experimenter bias effects in research. This procedure involves both the experimenter and the participants being unaware of which group is receiving the treatment or the placebo, thus minimizing the risk of bias in the data collected. Non-representative sampling, placebo control groups, and socially desirable procedures may be useful for other purposes but are not specifically designed to control for experimenter bias effects.