Left-handed people have an advantage in many sports, and it has been suggested that left-handedness might have been advantageous in hand-tohand fights in early societies. (Left-handed people can get a lot of practice against right-handed opponents, whereas right-handers are less experienced against lefties.) To explore this potential advantage, Faurie and Raymond (2005) compared the frequency of left-handed individuals in traditional societies with measures of the level of violence in those societies. The following table lists the data for one index of violence, the rate of homicide, measured in number/1000 people/year.

a. Use a graph to illustrate the association between the two variables.

b. What assumption of linear correlation analysis is violated by these data? Explain.

c. Before resorting to a nonparametric method, what strategy is available to test for a correlation between percent left-handedness and homicide rate?

d. Carry out this strategy, using a scatter plot to assess your success in meeting assumptions.

e. Using your results from part (d), test whether the two variables are correlated.

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Society DioulaDioula Ntumu Ntumu KreyolKreyol Inuit Inuit Baka Baka Jimi Jimi EipoEipo Yanomamo Yanomamo Percent left-handed 3.5 3.5 8.2 8.2 6.6 6.6 6.4 6.4 10.210.2 13.013.0 20.420.4 22.722.7 Homicide rate 0.010.01 0.020.02 0.030.03 0.170.17 0.500.50 5.375.37 3.023.02 3.983.98