Dear All,
How do I generate a variable which equals 1 for the first month the company
enters the dataset, equals 2 for the second month the company enters the
dataset etc...
It is an unbalanced panel, so every company starts from a different date.
I have an example of the dataset below,
companyname companyid date date_s variable
Agra and Masterman's ltd 1 01-03-1965 -1138 1
Agra and Masterman's ltd 1 01-04-1965 -1137 2
Agra and Masterman's ltd 1 01-05-1965 -1136 3
Agra and Masterman's ltd 1 01-06-1965 -1135 4
Agra and Masterman's ltd 1 01-07-1965 -1134 5
Agra and Masterman's ltd 1 01-08-1965 -1133 6
Agra and Masterman's ltd 1 01-09-1965 -1132 7
Agra and Masterman's ltd 1 01-10-1965 -1131 8
Agra and United Service ltd 2 01-03-1959 -1210 1
Agra and United Service ltd 2 01-04-1959 -1209 2
Agra and United Service ltd 2 01-05-1959 -1208 3
Agra and United Service ltd 2 01-06-1959 -1207 4
Agra and United Service ltd 2 01-07-1959 -1206 5
Agra and United Service ltd 2 01-08-1959 -1205 6
Agra and United Service ltd 2 01-09-1959 -1204 7
Agra and United Service ltd 2 01-10-1959 -1203 8
Agra and United Service ltd 2 01-11-1959 -1202 9
Agra and United Service ltd 2 01-12-1959 -1201 10
Agra,ltd a 3 01-04-1967 -1113 1
Agra,ltd a 3 01-05-1967 -1112 2
Agra,ltd a 3 01-06-1967 -1111 3
Agra,ltd a 3 01-07-1967 -1110 4
Agra,ltd(do b) 4 01-02-1968 -1103 1
Agra,ltd(do b) 4 01-03-1968 -1102 2
Agra,ltd(do b) 4 01-04-1968 -1101 3
Agra,ltd(do b) 4 01-05-1968 -1100 4
Agra,ltd(do b) 4 01-06-1968 -1099 5
Agra,ltd(do b) 4 01-07-1968 -1098 6
Agra,ltd(do b) 4 01-08-1968 -1097 7
Agra,ltd(do b) 4 01-09-1968 -1096 8
Agra,ltd(do b) 4 01-10-1968 -1095 9
Agra,ltd(do b) 4 01-11-1968 -1094 10
Albion 5 01-04-1965 -1137 1
Albion 5 01-05-1965 -1136 2
Albion 5 01-06-1965 -1135 3
?Variable? is the variable that I want to generate from the date.
Many Thanks for your help.
Best Wishes
Wenwen
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