Wharton Research Data Services Using WRDS to access

Wharton Research Data Services Using WRDS to access CRSP and Computstat data

Three Ways to Access • Web – Accessible to all UWindsor users through IP authentication • SAS-Connect and Server via SSH – Only available with an account (Faculty, RAs, grad students)

Web Interface • Access through a browser • Simple query using lists of company identifiers • Compustat also allows simple conditional queries • Download limit: 2 GB • Query limit: do not start a second query while the first is still running

Unix & SAS-Connect • Both: – More flexible and powerful data download – Run and save customized programs. – Pull data from several sources at the same time and merge them – More than 1 TB of temprary processing space available • SAS-Connect: – Need to be running SAS on your PC • Unix: – Access via a SSH program and use Unix commands and SAS or Fortran programming

PC SAS-Connect

Important Identifiers: CRSP • Primary identifiers: – Permno: Permanent security identifier – Permco: Permanent company identifier • Other identifiers – CUSIP: Identifier assigned to a company by Standard and Poor’s. CUSIPs can change over time in cases of mergers and other reorganizations – NCUSIP: old CUSIPS are tracked in the NCUSIP variable – Ticker: least reliable because it can change within the same company and old ones can be reused

CUSIP and NCUSIP Merger or reorganization DATE NCUSIP PERMNO 28/12/2005 763212345 112233445 65432 29/12/2005 763212345 112233445 65432 30/12/2005 112233445 65432

CUSIP and NCUSIP After an update… Merger or reorganization DATE NCUSIP PERMNO 28/12/2005 10/9/1991 763212345 555555666 112233445 65432 29/12/2005 11/9/1991 763212345 555555666 112233445 65432 30/12/2005 12/9/1991 112233445 555555666 112233445 65432 30/1/2006 555555666 65432 On every update, CUSIPS are retroactively changed to reflect the CUSIP current as of the update. NCUSIP reflects the CUSIP current as of the date of the data record.

CUSIP and NCUSIP • CUSIP: now’s CUSIP • NCUSIP: then’s CUSIP • If you have a current CUSIP for a company and want to retrieve all available data for that company, use the CRSP CUSIP variable to retrieve data • If you have historical data and you only know what the CUSIP of a company was in 1994, use the NCUSIP variable to retrieve data from 1994 and find out the current CUSIP

Important Identifiers: Compustat • Primary identifier – GVKey: Permanent company identifier, equivalent of CRSP’s Permco • Other identifiers – CUSIP: COMPUSTAT has no equivalent to the NCUSIP variable; the CUSIP is always the CUSIP that was current as of the last update – CIK Number: U. S. SEC identifier – EIN: Employer Identification Number – Ticker