The mating habits of three- spined stickleback (a fish) have been studied intensively ...

The mating habits of three- spined stickleback (a fish) have been studied intensively. One experiment examined whether fish are re likely to mate with a member of the opposite sex that was similar in body size, rather than with fish that were different in size (McKinnon et al. 2004). The mating preferences were measured in nine different populations, and the preference was measured by an index that is zero if the population shows no preference for mating by size, positive if the population contains fish that prefer to mate with fish of a different size, and negative if the fish mate preferentially with individuals of the same size. Notice that the independent data points here are indices for each fish population.

The nine indexes are as follows: -32.0,-29.8,-40.6,-90.8,-29.2,-28.8,-78.4,-59.2,-74.3 

Assuming normality, test the hypothesis that, on average, sticklebacks do not mate differently by size. What can you conclude mom these data?