California Code, Elections Code - ELEC § 8084

If the number of signatures affixed to an in-lieu filing fee petition filed pursuant to Section 8106 is 100 or more, the county elections official may use a random sampling technique for verification of the signatures.  If a random sampling technique is used, and the number of signatures on a petition is 100 or more but less than 2,000, the random sampling shall include an examination of 100 signatures.  If the number of signatures on a petition is 2,000 or more, the random sampling shall include an examination of 5 percent of the signatures.  Upon completion of the verification of signatures in the sample, the percentage of signatures which are valid shall be applied and projected to the total number of signatures submitted.