Hi everyone,
I am relatively new to stata. For my thesis, I am working on a dataset that lists patents and cited patents with their respective filing date and industry classification, see an example below.
Now I would like to identify how often the industry classification of each patent (cpc_p) has been used 5 years before the filing of each individual patent (date_p), and what percentage of these citations have been referring to other patents of the same industry class (cpc_c). Optimally I could thus create a new variable that expresses this percentage for each observation.
I would imagine this could be achieved by counting the occurrences of equal and unequal industry classifications (i.e. cpc_p = or ≠ cpc_c). However, I can not figure out how to express these for a limited but shifting timeframe (i.e. 5 years before date_p).
Any help would be much appreciated.
Thank you for your support!
Best,
Paul
Example of data:
I am relatively new to stata. For my thesis, I am working on a dataset that lists patents and cited patents with their respective filing date and industry classification, see an example below.
Now I would like to identify how often the industry classification of each patent (cpc_p) has been used 5 years before the filing of each individual patent (date_p), and what percentage of these citations have been referring to other patents of the same industry class (cpc_c). Optimally I could thus create a new variable that expresses this percentage for each observation.
I would imagine this could be achieved by counting the occurrences of equal and unequal industry classifications (i.e. cpc_p = or ≠ cpc_c). However, I can not figure out how to express these for a limited but shifting timeframe (i.e. 5 years before date_p).
Any help would be much appreciated.
Thank you for your support!
Best,
Paul
Example of data:
| patent_id | citation_id | date_p | date_c | cpc_p | cpc_c |
| 6523634 | 4779697 | 1998-04-09 | 1996-06-11 | B62K | B62K |
| 6732830 | 4779697 | 2002-03-12 | 1996-06-11 | B62K | B62K |
| 5514171 | 4784151 | 1994-07-07 | 1992-03-30 | A61B | A61B |
| 6591143 | 4784151 | 2000-05-24 | 1992-03-30 | A61N | A61B |
| 5271392 | 4784151 | 1997-01-27 | 1992-03-30 | A61N | A61B |
