Statistical Analysis

1. Suppose that a researcher wished to learn if a certain drug slows the growth of tumors. She obtained mice with tumors and randomly divided them into two groups. She then injected one group of mice with the drug and used the second group as a control. After 2 weeks, she sacrificed the mice and weighed the tumors. The mean weight of tumors for each group of mice is below.

   Drug group      = 0.39 g

   Control group = 0.42 g

   She used a t-test. The probability (p) = 0.012.

   Use a mathematical equation to state her null hypothesis.

   Use a mathematical equation to state her alternative hypothesis for a 1-tailed test.

   What should she conclude? Why?

2. Suppose that a researcher wished to learn if a particular chemical is toxic to a certain species of beetle. She believes that the chemical might interfere with the beetle’s reproduction. She obtained beetles and divided them into two groups. She then fed one group of beetles with the chemical and used the second group as a control. After 2 weeks, she counted the number of eggs produced by each beetle in each group. The mean egg count for each group of beetles is below.

   Chemical group           = 32 eggs

   Control group             = 43 eggs

   She used a t-test. The probability (p) = 0.072.

   Use a mathematical equation to state her null hypothesis.

   Use a mathematical equation to state her alternative hypothesis for a 1-tailed test.

   What should she conclude?