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                                                                    EXHIBIT 31.1

                                 CERTIFICATION

I, Jack Noonan, certify that:

     1. I have reviewed the Annual Report on Form 10-K of SPSS Inc., as amended
by this Amendment No. 1 to Annual Report on Form 10-K (the "10-K/A");

     2. Based on my knowledge, the annual report, as amended by this 10-K/A,
does not contain any untrue statement of a material fact or omit to state a
material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading with respect
to the period covered by the annual report, as amended by this 10-K/A;

     3. Based on my knowledge, the financial statements, and other financial
information included in the annual report, as amended by this 10-K/A, fairly
present in all material respects the financial condition, results of operations
and cash flows of the registrant as of, and for, the periods presented in the
annual report, as amended by this 10-K/A;

     4. The registrant's other certifying officer(s) and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial
reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the
registrant and have:

          (a) Designed such disclosure controls and procedures, or caused such
     disclosure controls and procedures to be designed under our supervision, to
     ensure that material information relating to the registrant, including its
     consolidated subsidiaries, is made known to us by others within those
     entities, particularly during the period in which the annual report, as
     amended by this 10-K/A, is being prepared;

          (b) Designed such internal control over financial reporting, or caused
     such internal control over financial reporting to be designed under our
     supervision, to provide reasonable assurance regarding the reliability of
     financial reporting and the preparation of financial statements for
     external purpose in accordance with generally accepted accounting
     principles;

          (c) Evaluated the effectiveness of the registrant's disclosure
     controls and procedures and presented in the annual report, as amended by
     this 10-K/A, our conclusions about the effectiveness of the disclosure
     controls and procedures, as of the end of the period covered by the annual
     report, as amended by this 10-K/A, based on such evaluation; and

          (d) Disclosed in the annual report, as amended by this 10-K/A, any
     change in the registrant's internal control over financial reporting that
     occurred during the registrant's most recent fiscal quarter (the
     registrant's fourth fiscal quarter in the case of an annual report) that
     has materially affected, or is reasonably likely to materially affect, the
     registrant's internal control over financial reporting; and

     5. The registrant's other certifying officer(s) and I have disclosed, based
on our most recent evaluation of internal control over financial reporting, to
the registrant's auditors and the audit committee of the registrant's board of
directors (or persons performing the equivalent functions):

          (a) All significant deficiencies and material weaknesses in the design
     or operation of internal control over financial reporting which are
     reasonably likely to adversely affect the registrant's ability to record,
     process, summarize and report financial information; and

          (b) Any fraud, whether or not material, that involves management or
     other employees who have a significant role in the registrant's internal
     control over financial reporting.

                                          By:        /s/ JACK NOONAN
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                                                        Jack Noonan
                                               President and Chief Executive
                                                           Officer

Date: April 22, 2005