Transcript WRDS - University of Windsor

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