Question

A researcher took water samples in a forest with a stream running through it. The samples were collected over the course of a year. Some samples were collected from the stream itself (called the “surface” group), some were groundwater samples collected from organic soils (called the “organic” group), and some were groundwater samples collected from mineral soils (called the “mineral” group). Each sample was analyzed for the concentration of dissolved organic carbon (mg/l). The researcher wants to test the claim that the mean concentration of dissolved organic carbon is the same in each group. The Minitab printout for this test is given below, you may assume that the normal probability plots for the groups are okay.

             Source   DF      SS     MS     F      P
             Factor    2   471.4  235.7  9.43  0.000
             Error   119  2973.8   25.0
             Total   121  3445.1

What is your conclusion?

1. a) There is not evidence to support the claim that at least one of the means is different because

   the p-value is greater than the level of significance.

2. b) There is not evidence to support the claim that the means are the same because the p-value is

   greater than the level of significance.

3. c) There is evidence to support the claim that at least one of the means is different because the p-

   value is less than the level of significance.

4. d) There is evidence to support the claim that the means are the same because the p-value is less

   than the level of significance.

Answer 1

P value = 0

c) There is evidence to support the claim that at least one of the means is different because the p-

value is less than the level of significance.