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                                                                    EXHIBIT 99.2

                                  SUPPLEMENT A
                                TO THE SPSS INC.
            CHARTER OF THE AUDIT COMMITTEE OF THE BOARD OF DIRECTORS

1.  PURPOSE.

     The Sarbanes-Oxley Act of 2002 (the "Act") requires the Audit Committee
(the "Committee") of the Board of Directors (the "Board") of SPSS Inc. (the
"Company") to pre-approve any non-audit related services performed by the
Company's independent auditor. The Committee must evaluate these non-audit
related services to ensure that such services would not impair the auditor's
independence from the Company. This Supplement A to the SPSS Inc. Charter of the
Audit Committee of the Board of Directors (the "Committee Charter") sets forth
the procedures and conditions pursuant to which the Committee may pre-approve
non-audit related services proposed to be performed by the Company's independent
auditor (the "Pre-Approval Policy").

     Section 4(f) of the Committee Charter specifically grants to the Committee
the authority to delegate pre-approval authority to one or more designated
members of the Committee, provided that such decisions are presented to the full
Committee for ratification at its next scheduled meeting. This Pre-Approval
Policy supplements the Committee Charter and is consistent with the terms
thereof. The Company's independent auditor has reviewed the policies set forth
in this Pre-Approval Policy and have agreed to satisfy the provisions hereof
applicable to the Company's independent auditor.

2.  PRE-APPROVAL CONDITIONS

     In determining whether to pre-approve certain non-audit related services,
the Committee will consider multiple factors taken as a whole, including without
limitation, the following:

          (a) whether proposed services have been specifically prohibited by the
     Securities and Exchange Commission (the "SEC");

          (b) whether the Company's independent auditor is best positioned to
     provide the most effective and efficient service; and

          (c) whether an appropriate ratio exists between the total amount of
     fees for audit services, audit-related services, tax services and other
     services which are non-audit related services.

3. PRE-APPROVAL PROCEDURE

     Requests for the Company's independent auditor to perform non-audit related
services shall be made pursuant to the following procedure:

          (a) Company Request

          (i) The Company shall submit a written request (the "Company Request")
     to its independent auditor, which request shall include the following:

             (A) a detailed description of the type and scope of the non-audit
        related service that the Company desires its independent auditor to
        perform (the "Requested Non-Audit Related Services"); and

             (B) a written explanation as to why the Company believes that the
        Company's independent auditor is best positioned to provide the most
        effective and efficient service.

          (ii) The Company Request shall be sent via electronic mail, facsimile
     or United States mail to the Company's independent auditor with a copy to
     the Committee chairman.
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          (b) Auditor Response

          (i) Upon the receipt of the Company Request, the Company's independent
     auditor shall calculate the fees that would be charged by the independent
     auditor in providing the Requested Non-Audit Related Services.

          (ii) The Company's independent auditor shall provide the following to
     the Committee's chairman via electronic mail, facsimile or United States
     mail:

             (A) a written description of the Requested Non-Audit Related
        Services;

             (B) a written description of the fees that would be charged by the
        independent auditor in providing the Requested Non-Audit Related
        Services, which description shall include (A) the amount of such fees
        denominated in the applicable local currency and (B) the amount of such
        fees denominated in United States dollars (the "Dollar Denominated
        Fee");

             (C) a written request for Committee approval of the Requested
        Non-Audit Related Services in the amount of (A) the Dollar Denominated
        Fee plus (B) ten percent (10%) of the Dollar Denominated Fee rounded to
        the nearest $1,000. If the amount of the Dollar Denominated Fee exceeds
        $10,000, the request required by this Section 3(b)(ii)(C) shall be in
        the form of a formal engagement letter.

          (c) Committee Decision.

          (i) The Committee chairman shall review the materials provided
     pursuant to Section 3(b)(ii) above.

          (ii) If the Committee chairman determines that the Requested Non-Audit
     Related Services are appropriate, the Committee chairman is authorized to
     and shall approve the Requested Non-Audit Related Services. The Committee
     chairman shall provide written notice of such approval to the Company's
     independent auditor and the Company via electronic mail, facsimile or
     United States mail. Notwithstanding the foregoing, if the written request
     for Committee approval required by Section 3(c)(ii) above requires a formal
     engagement letter, the Committee chairman shall evidence approval of the
     Requested Non-Audit Related Services by executing the engagement letter and
     returning an executed copy to the Company's independent auditor via
     facsimile or United States mail.

          (iii) The Committee chairman shall collect all materials relating to
     Requested Non-Audit Related Services, including without limitation, the
     Committee chairman's authorization of such Requested Non-Audit Related
     Services and shall present a copy of all such material to the full
     Committee for ratification at the next scheduled Committee meeting.

          (iv) All written correspondence relating to Requested Non-Audit
     Related Services shall be included in the official records of the
     Committee.

4.  PROHIBITED SERVICES

     Notwithstanding the procedure set forth in Section 3 above, neither the
Committee chairman nor the full Committee shall have the authority to approve
non-audit related services that have been specifically prohibited by the SEC.
The non-audit related services that have been specifically prohibited by the SEC
are:

          (a) Bookkeeping and other services related to the accounting records
     or financial statements of SPSS;

          (b) Financial information systems design and implementation;

          (c) Appraisal or valuation services, fairness opinions or
     contribution-in-kind reports;

          (d) Actuarial services;

          (e) Internal audit outsourcing services;

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          (f) Management functions;

          (g) Human resources;

          (h) Broker-dealer, investment adviser or investment banking services;

          (i) Legal services;

          (j) Expert services unrelated to the audit.

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