One of the big issues in the MN GOP Chair race has been the impact of moving the MN primary date from August to June. There has been a great deal of debate on whether this move would help or hinder the incumbents and therefore impact future grassroots candidates.
It just so happens that 7 states moved their primaries up in the last election cycle. This provides a rather convenient way to evaluate the impact of an earlier primary. Here are the raw numbers from ballotpedia:
The net effect is an increase in the average win chance for incumbents of 5.2% and a decrease in challenger win chance of 24.0%. A Chi-Square analysis yields a 17.7% chance of this result being random. That is to say this evidence is not sufficient to conclude that an earlier primary favors incumbents at a standard level of significance of 5%, but it sure does look like it is trending in that direction.
There are obvious short-comings to this sort of analysis. I did this in about an hour for a quick evaluation. That said I do believe the aforementioned provides a strong indication of the potential negative impact toward earlier primaries on the grassroots of the MN GOP. I challenge earlier primary supporters to issue their own evidence as to the benefits an earlier primary could offer the MN GOP.