Changing AP score cutoffs now that the guessing penalty is gone

In early June, the College Board released the news that, starting next year, the raw score for an AP multiple choice section will be the total number of correct questions, without a "guessing penalty."  You first heard it here, on the Jacobs Physics blog.

One of my major recommendations to AP physics teachers is to make ALL classroom tests in AP format.  This means use authentic AP questions, give the appropriate amount of time for each (one minute per point free response, 7 multiple choice every 9 minutes)... and use a scale converter to translate each student's grade into an approximate AP score.

In past Physics B exams, it's taken roughly 65% of the available points to get a 5, 50% to get a 4, and 35% or so to get a 3.  That exact conversion fluxuates year-to-year depending on the difficulty of that year's exam, but this was a good rule of thumb.  Problem is, now that the subtraction of 1/4 point for each wrong multiple choice question is gone, raw scores will be higher.  How will these numbers change?

The calculation is not quite as simple as it initially might look.  Scores of the weaker students will improve more than those of stronger students, because weaker students will miss more questions and thus fail to be penalized for "guessing" more often.  And free response scores will not go up, only multiple choice.  This all points to adding a bit to each score cutoff, with more being added to the lower cutoffs.

This year, I'm going to use these cutoffs in my class.  I'll see if they work... and I'll appreciate feedback, as well:

5  68%

4  55%

3  41%

2  30%

We'll only know more through experience, and when another released exam comes out.

GCJ