Foster explains why most literature can be called political. summarize his argument

answer: fact: italy has over 300 islands ranging from extremely small uninhabited islands to the huge island of sicily.

explanation:

opinion: italy has way to many islands

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.