10 ILCS 5/28-11
The Board shall design a standard and scientific random sampling method for the verification of petition signatures for statewide advisory referenda and shall conduct a public test to prove the validity of its sampling method. Notice of the time and place for such test shall be given at least 10 days before the date on which such test is to be conducted and in the manner prescribed for notice of regular Board meetings. Signatures on petitions for constitutional amendments initiated pursuant to Article XIV, Section 3 of the Illinois Constitution need not be segregated by election jurisdiction. The Board shall design an alternative signature verification method for referenda initiated pursuant to Article XIV, Section 3 of the Illinois Constitution.
Within 14 business days following the last day for the filing of the original petition as prescribed in Section 28-9, the Board shall apply its proven random sampling method to the petition sheets in each election jurisdiction section for the purpose of selecting and identifying the petition signatures to be included in the sample signature verification for the respective jurisdictions and shall prepare and transmit to each proper election authority a list by page and line number of the signatures from its election jurisdiction selected for verification.
For each election jurisdiction, the sample verification shall include an examination of either (a) 10% of the signatures if 5,010 or more signatures are involved; or (b) 500 signatures if more than 500 but less than 5,010 signatures are involved; or (c) all signatures if 500 or less signatures are involved.
Each election authority with whom jurisdictional copies of petition sheets were filed shall use the proven random sampling method designed and furnished by the Board for the verification of signatures shown on the list supplied by the Board and in accordance with the following criteria for determination of petition signature validity:
1. Determine if the person who signed the petition is a registered voter in that election jurisdiction or was a registered voter therein on the date the petition was signed;
2. Determine if the signature of the person who signed the petition reasonably compares with the signature shown on that person's registration record card.
Within 14 business days following receipt from the Board of the list of signatures for verification, each election authority shall transmit a properly dated certificate to the Board which shall indicate; (a) the page and line number of petition signatures examined, (b) the validity or invalidity of such signatures, and (c) the reasons for invalidity, based on the criteria heretofore prescribed. The Board shall prepare and adopt a standard form of certificate for use by the election authorities which shall be transmitted with the list of signatures for verification.
Upon written request of the election authority that, due to the volume of signatures in the sample for its jurisdiction, additional time is needed to properly perform the signature verification, the Board may grant the election authority additional days to complete the verification and transmit the certificate of results. These certificates of random sample verification results shall be available for public inspection within 24 hours after receipt by the State Board of Elections.
10 ILCS 5/28-11