Answer:
Field experiment direct observation method
Step-by-step explanation:
This is the method in which the researcher observes and manipulates the one and more independent variables. It occurs in natural settings to observe the effect of behavior.
This is the extreme form of intervention observation in the method. When field experiments conducted it makes casual inferences from the observation.
Confounding in the experiments may decrease the validity of the research method. Due to con-foundation, ethical issues occur related to a high risk of low internal validity.