Question

1. You are interested in the effect of copper sulfate on mucus cells in the gill filaments of eastern mosquitofish. You wish to determine whether a 24 hour exposure to copper sulfate will reduce the number of mucus cells. Select an appropriate statistical test to determine whether the number of mucus cells/mm² differs between the gill filaments of separate treatment and control mosquitofish. Use the Mosquitofish Dataset and assume all data are normally distributed.

1. What type of test did you perform? Why did you choose this test?
2. How many df are there for this test? Why is this the appropriate df?
3. Write a complete sentence (as you would in a lab report) that summarizes the results of your test. Be sure to include all relevant statistical parameters.

Answer 1

*Since the dataset is not available here, I am highlighting the test that can be performed in the given scenario.

A. We wish to test the null hypothesis, Ho: There is no significant difference in the number of mucus cells/mm2 in the gill filaments of treatment and control mosquitofish.

We use independent t-test in the given situation because the two groups of mosquitofish are independent samples.

B. The DFs should ideally be equal to n1+n2 - 1 where n1 is the sample size of control group and n2 is the sample size of the treatment group.

C. If the p-value < level of significance, we may reject H0 at alpha% level of significance and conclude that there is significant difference in the number of mucus cells/mm2 in the gill filaments of treatment and control mosquitofish. i.e. 24 hour exposure to copper sulphate will reduce the no. of mucus cells.