ii. For each of the four seasonal strata, stratify the days into 5 pollution (pm10) strata. "time pmlowinter-pm10 if season==1, ag15) xtile pm10spring-pm10 if season==2, ag15) xtime pm10summer-pm10 if season==], ng15) *the pmloautumn-pm10 if season==4, ag15) iii. Separately for your four seasonal strata, calculate the mean mortality in the lowest and highest of the five pollution strata. Winter: summarize death if pmidwinter==1 Variable obs Mean Std. dev. Min Max death 111 22. 20721 5.288267 12 37 summarize death if pmlowinter==5 summarize death if pm10winter==5 variable Obs Mean Std. dev. Min Max death 110 21. 35455 5. 35456 35 Spring: summarize death if pm10spring==1summarize death if pm10spring==1 Variable Obs Mean Std. dev. Min Max death 113 18.59292 4. 193186 33 Stammazize death if pm10wintermm5 summarize death if phlospring=-5 Variable Obs Mean Std. dev. Min Max death 112 18 . 90214 5.02961 7 33 Summer: summarize death if pmlesummer==1 Variable Obs Mean Std. dev. Min Max death 115 17. 69565 4. 193089 29 summarize death if pm10summer==5 Variable Obs Mean Std. dev. Min Max death 114 19.92902 5. 678276 41 Autumn: summarize death if pmloautumn==1 Variable Obs Mean Std. dev. Min Max death 112 19. 82143 5.352884 3 32