A researcher wants to study the effects of playing video games 24-7 for a week. What type of study would be best suited to make this determination

observational study

Explanation:

the researcher cannot control the independent variable, which is the player himself as his response to playing the video game 24X7 is the purpose of the study.  this is an observational study and the researcher has to wait for 7 days to see the effects on the player.

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.