What must a researcher do if she is particularly concerned about making sure that her results will generalize to the population as a whole

A)  ensure that all the variables have been operationally defined 
B)  conduct a meta-analysis 
C)  use a double-blind procedure 
D)  draw a representative sample from the population of interest

Operationally Defined

The process of strictly defining variables into measurable factors, defining how a concept will be measured in a specific study.

Meta-analysis

A statistical technique that combines the results of multiple scientific studies to arrive at a conclusion that has greater statistical power.

Double-blind Procedure

An experimental procedure in which neither the subjects of the experiment nor the persons administering the experiment know the critical aspects of the experiment, thus ensuring that neither the expectations of the subjects nor those of the experimenters influence the results.