Imagine that a researcher performs an experiment examining the effects of nutrition on memory. each subject is randomly assigned to one of three groups: high-protein diet; high-fiber diet; standard diet (control). after a month on this diet, each subject undergoes a memory test. the experimenter finds that memory performance is somewhat better for the high-protein and high-fiber groups than for the control group, but the effect of nutrition is not statistically significant. thus, the experimenter accepts the null hypothesis. the experimenter hypothesizes that the effect was weak because the experiment was only 1 month long. a new experiment is then conducted that is identical to the first, except with 3 months on the diet. now a significant effect of nutrition is found. from these two experiments, the experimenter is justified in concluding that: [click all that are correct]a. nutrition impacts memory when people are on the diet for three monthsb. nutrition has a bigger impact on memory when people are on the diet for three months than when they are on the diet for one monthc. there is not sufficient evidence to conclude that nutrition impacts memory when people are on the diet for one monthd. nutrition has no impact on memory when people are on the diet for one month

Options A, B and C are correct.

Explanation:

A. Nutrition impacts memory when people are on the diet for three months

This option is correct because it was found that being on a high- protein or high-fiber diet for three months resulted in a significant improvement on memory performance tests. Note that "significant" here refers to statistical significance- which means the result is not due to random chance.

B. Nutrition has a bigger impact on memory when people are on the diet for three months than when they are on the diet for one month

This option is correct because when subjects were on a month long diet of either a standard diet, high- protein or high-fiber diet, it was found that memory performance is somewhat better for the high-protein and high-fiber groups than for the control group, but the effect of nutrition is not statistically significant. This means that the subjects on the high-protein and high-fiber groups did not conclusively do better on memory tests, and the result could be attributed to chance or other extraneous factors.

On the other hand, when subjects were on a high- protein or high-fiber diet for three months, it resulted in a significant improvement on memory performance tests- which means the result was not due to random chance.

C. There is not sufficient evidence to conclude that nutrition impacts memory when people are on the diet for one month

This option is correct because as stated above, it was found that memory performance is somewhat better for the high-protein and high-fiber groups than for the control group, but the effect of nutrition was not statistically significant- which means the results could be attributed to chance.