Problem
The Stata data file "cellphone_billing_student.dta" contains customer-level monthly billing records from a cellular phone service company and information about the promotions that this company sent to its customers. The billing data is from September, 2001 to May, 2003. New customers join between August, 2001 and December, 2001. There is no left truncation in the data, i.e. you have data for each customer from their first month onwards. However, the data stream of customers who do not leave the company before May, 2003 is right truncated or is not observed by us.
The monthly billing data provides information on the service plan a customer is currently using and his/her monthly consumption of minutes. This dataset is restricted to four types of service plans that differ in their included peak number of minutes - 200, 300, 350 and 500 minutes. These service plans are available with many different features. For example, a 200 peak minutes plan can either include Short Messaging System (SMS) service or not.
Variable
Na me Description
cust_id
Customer identification number of phone service subscriber
bill_year
Year of customer billing record
bill_month
Month of customer billing record
churn
Indicator value 1 if customer defects at the end of month; 0 otherwise
plan_chosen
Plan number chosen by customer for a billing month
plan1
Indicator value 1 if customer chooses Plan 1; 0 otherwise
plan2
Indicator value 1 if customer chooses Plan 2; 0 otherwise
plan3
Indicator value 1 if customer chooses Plan 3; 0 otherwise
plan4
Indicator value 1 if customer chooses Plan 4; 0 otherwise
total_minute_peak
Total peak-period phone minutes used by customer in a month
promo_lag1
Indicator value 1 if a marketing promotion was sent to customer in the past month; 0 otherwise
Perform a descriptive data analysis on this data set only in Stata, and answer these questions:
1. What is the average number of months a customer stays with the cellular phone service company from the start till the end of a phone service subscription?
2. How many customers are there for each type of phone service plan?
3. For each type of phone service plan, what is the number and percentage of customers who churned?
4. For each type of phone service plan, what is the average number of months a customer stays with the company from the start till the end of a service subscription?
5. What is the average number of peak minutes used in a month under each type of phone service plan?
Keep a log of Stata commands you used in a Stata .do script file. In your answer submission, please include the Stata .do script file.