the study measures what it intends to measure, the effects on the DV are caused by the IV, meaning the findings are accurate.
external validity
whether the study paints a true picture of real-life behaviours (mundane realism,) and would apply to different places, times or people (population validity.)
researcher bias
double-blind procedure will prevent researcher bias as the researcher does not know the aim and therefore cannot give hints or tips to ppts.
also reduces demand characteristics, as the ppts won't change their behaviour accordingly.
changes to the location of the research and nature of the task can improve validity - ensuring that research is conducted in the field rather than the lab.
changes to the sampling technique and target population can also improve external validity.
