Question: In a study on the health and development of a bird species, Yellow Robin, two different sites were compared: one in The Dandenong Ranges (East of Melbourne) and another in the drier area of the Grampians (in western Victoria).
Samples of mature birds were taken at each site: 10 in The Dandenong Ranges and only 8 in the Grampians. They were trapped safely, weighed and then returned to the wild. The data on these sites is given in the following table:
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Mass of Yellow Robin in Dandenong Ranges (g) 10.3 11.4 10.9 12.0 10.0 11.9 12.2 12.3 11.7 12.0
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Mass of Yellow Robin in Grampians (g) 12.2 12.1 13.1 11.9 12.1 12.0 12.9 11.4
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Consider the difference between the masses of the birds in the two regions.
a) Is this a paired or unpaired situation?
b) Calculate the summary statistics relevant to this problem.
c) Test whether there is evidence of any difference between the mean mass of the birds in the two regions. State clearly the null and alternative hypotheses and show all steps in the hypothesis test. Use long-hand calculation and check your answer using the Excel/Data Analysis appropriate tests.