S.D. Codified Laws § 12-1-36
The secretary of state shall verify the signatures received pursuant to § 12-1-35 by random sampling. The random sample of signatures to be verified shall be drawn so that each signature received by the secretary of state is given an equal opportunity to be included in the sample. The secretary of state shall calculate the number of valid signatures by multiplying the total number of signatures received by the percentage of successfully verified signatures from the random sample. The secretary of state shall promulgate rules, pursuant to chapter 1-26, establishing the methodology for conducting the random sample. The random sampling shall be an examination of the signatures received consisting of a number of signatures that is statistically correlative to not less than ninety-five percent level of confidence with a margin of error equal to not more than three and sixty-two one-hundredths percent.
SDCL 12-1-36