Question

A researcher in environmental science is conducting a study to investigate the impact of a particular herbicide on fish. He has 60 healthy fish and randomly assigns each fish to either a treatment or a control group. The fish in the treatment group showed higher levels of the indicator enzyme.

23. Suppose a test of significance was correctly conducted and showed no statistically significant difference in average enzyme level between the fish that were exposed to the herbicide and those that were not. What conclusion can the graduate student draw from these results?

a. The researcher must not be interpreting the results correctly; there should be a significant difference.

b. The sample size may be too small to detect a statistically significant difference.

c. It must be true that the herbicide does not cause higher levels of the enzyme.

24. Suppose a test of significance was correctly conducted and showed a statistically significant difference in average enzyme level between the fish that were exposed to the herbicide and those that were not. What conclusion can the graduate student draw from these results?

1. There is evidence of association, but no causal effect of herbicide on enzyme levels.
2. The sample size is too small to draw a valid conclusion.
3. He has proven that the herbicide causes higher levels of the enzyme.
4. There is evidence that the herbicide causes higher levels of the enzyme for these fish.
5. There is evidence of association, but no causal effect of herbicide on enzyme levels.
6. The sample size is too small to draw a valid conclusion.
7. He has proven that the herbicide causes higher levels of the enzyme.
8. There is evidence that the herbicide causes higher levels of the enzyme for these fish.

Answer 1

the sample size of treatment group and control group is 30 if 60 fishes are divided equally among the groups. therefore the sample size is large enough to conduct the hypothesis test.

from the test it is revealed that there is no difference in the two groups . therefore it must be true that the herbicides doesn't cause higher level of enzymes.

option c is correct.

24.

the test shows that there is significant difference between the two groups.

there is evidence of association but no cause effect of herbicide on enzyme level.

option a is correct.

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