1. For each of the following case, describe the best possible data structure (e.g., array, data

frame, list, table etc.) for representing the data. Also, use appropriate R codes to

answer the questions that follow, treating the data as if it is given.

(a) Data: A study of health effects of air quality in 10 major cities of the world involves

daily measurements on the four variables: average temperature (temp), total pre

cipitation (precip), maximum PM10 concentration (PM10) and number of deaths

among elderly population (death). Measurements are available for five years.

(i) What is the average number of deaths for each of the cities on days where the

PM10 concentration is greater than 20 ?

(ii) What is the average PM10 concentration for each of the cities on days with no

precipitation and average temperature above 80 degrees F ?

(b) Data: The data consist of records of patients' visit to a clinic. The measurements

for each patient are: date of visit (visit), age of patient in years (age), gender with

values M or F (gender), weight in lb (weight), systolic blood pressure (BP.sys),

diastolic blood pressure (BP.dia), blood glucose level in mg/dl (glucose). For blood

pressure levels, the unit is standard and the value is numeric with range between 0

and 600.

(i) How many times did each patient visit the clinic ?

(ii) What is the average systolic blood pressure level for each of the patients with

maximum weight (during the study period) greater than 180 lb ?

(iii) What is the average blood glucose level for each of the patients with age at

least 40 years at the fifirst visit ?