Wharton%20Research%20Data%20Services

1
Wharton Research Data Services

• Using WRDS to access CRSP and Computstat data

2
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)

3
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

4
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

5
PC SAS-Connect
6
Important Identifiers CRSP

• Primary identifiers
• Permno Permanent security identifier
• Permco Permanent company identifier
• Other identifiers
• CUSIP Identifier assigned to a company by
  Standard and Poors. 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

7
CUSIP and NCUSIP
DATE NCUSIP CUSIP PERMNO
28/12/2005 763212345 112233445 65432
29/12/2005 763212345 112233445 65432
30/12/2005 112233445 112233445 65432
8
CUSIP and NCUSIP
After an update
DATE NCUSIP CUSIP PERMNO
10/9/1991 763212345 112233445 65432
11/9/1991 763212345 112233445 65432
12/9/1991 112233445 112233445 65432
DATE NCUSIP CUSIP PERMNO
28/12/2005 763212345 555555666 65432
29/12/2005 763212345 555555666 65432
30/12/2005 112233445 555555666 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.
9
CUSIP and NCUSIP

• CUSIP nows CUSIP
• NCUSIP thens 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

10
Important Identifiers Compustat

• Primary identifier
• GVKey Permanent company identifier, equivalent
  of CRSPs 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