Stephen Pettigrew and Mayya Komisarchik for the Monkey Cage:

Presumably, the commission will use the names and birthdays in these lists to identify potential duplicate registration records between states. That’s the method used by the Interstate Crosscheck Program pioneered by Kansas Secretary of State Kris Kobach, a co-chair of the commission, which helps states identify voters who have moved to a new state by flagging potential duplicate registration records. In 2012, Crosscheck identified more than 1.4 million potential duplicate registrations.

Recent academic work, however, found that for every 200 registrations flagged using Crosscheck’s methodology, at least 199 were false matches in which the middle names or Social Security numbers did not line up. That’s one-half of one percent.

And the advisory commission will have considerably less information than is made available to Crosscheck. Twenty-two states have refused to comply with the commission’s request. Seventeen other states, such as Colorado, have said that they will provide only the publicly available voter information and omit confidential information like Social Security numbers or month and day of birth. Even more challenging for the commission will be states that only indicate the ages of voters in 10- or 20-year bins.