An experiment investigated the effect of length and repetition of tv ads on students choosing to eat at del taco. all 60 students watched a 40-minute television program that included ads for del taco. some students saw a 30-second commerical; others a 90-second commerical. the same commerical was shown either 1, 3, or 5 times during the program. after the viewing, each student was asked to rate their craving for del taco on a scale of 0 to 10. what is the response variable? a. 1, 3, or 5 commercials during the 40-minute television program b. 40-minute television program c. 60 students d. 30-second and 90-second commericials e. craving for del taco on a scale of 0 to 10

60 students

Explanation:

In experiments, the subject refers to the participants that will be exposed to different type of treatments or  variables controlled by the researchers.

In the case above, the 60 students are required to watch ads with different length from del taco. We consider watching this acts as 'treatments' by the researchers They make the subjects do it in order to find out their behaviors and provide the information for Del taco's marketing team.

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.        

using the scientific method.