i. Stratify the daily mortality data into 4 groups by season using the season variable. Calculate the mean PM10 level and mean daily mortality by season. Some helpful Stata commands: sort season by season: summarize pm10 death by season: summarize pole death -3 season = Winter Variable Obs Mean 5td. dev. Min Max pn10 551 -2. 933133 14. 86471 -35. 12752 94 . 87246 death 1, 715 20.7516 5. 280917 -3 season = Spring Variable Obs Mean 5td. dev. Min Max pn19 563 .7402965 14. 72493 -28.89937 76.87037 death 1, 729 18.24407 4. 708456 35 - season = Summer Variable Obs Mean 5td. dev. Min Max pn19 571 4.577036 15 . 11759 -31. 32692 78 . 72392 death 1, 748 17.74943 4.926608 46 Season - Autumn Variable Mean 5td. dev. Min Max pn19 559 -2. 96526 14. 4843 -33.37838 78 . 86962 death 1, 748 19.15389 5. 284551 38Data Set: The Baltimore PM10 data set is located in the State file named balt621 . dta. This data comes from the National Morbidity and Mortality Air Pollution Study (NMMAPS) which looked at the relationship between pollution and health outcomes for 100 U.S. cities. Refer to your Class Dataset Code Book (in CoursePlus Content for each Problem Set) for the file format. The variables of interest for this project are: . death: daily mortality count for Baltimore City * pm1 0: PM10 level on the preceding day. PM10 is particulate matter less than 10 micrometers in diameter. These I'M10 levels have been standardized so that values greater than ( are "above average" pollution days and values less than 0 are "below average" pollution days. " season: 1=Winter, 2-Spring, 3=Summer, 4=Autumn