Refer to Data Set 7 in Appendix B, which looks at temperature and precipitation departures from seasonal norms. Pick out the data pairs corresponding to years of strong El Ninos. Compare (a) the precipitation departure for the first spring of El Nino and (b) the precipitation departure for the second spring of El Nino. Based on the result, does there appear to be a correlation between precipitation in the first spring and that in the second spring of El Nino phenomena? If so, could researchers use this information to help predict the precipitation departures for the second spring of El Nino?
Use the rank correlation coefficient to test the claim of no correlation between the two variables. Use a significance level of α = 0.05.