How the LEED AP exam is scored

Eighty multiple choice questions, a score range of 125–200, a passing score of 170. If you've taken or are considering taking the LEED Professional Accreditation exam to become a LEED AP, you're familiar with these numbers. And you might have wondered, how does it all add up? What does my score mean?

The official explanation from the Green Building Certification Institute (GBCI) and its LEED Candidate Handbook mentions a scaled score but does not explain how it is calculated. The information compiled here is from correspondence with Peter Templeton, a senior V.P. at the U.S. Green Building Council, and Beth Holst, recently hired at the GBCI as V.P. overseeing the LEED AP program. If I miss any details, I certainly hope they'll correct me.

First, there are what Holst calls "multiple forms" of the 80-question exam.

In other words, there are a finite number of question sets. Those question sets are not mixed and matched; questions are not randomly delivered from individual sets. How many sets are there? Neither Holst nor Templeton would tell me. Does that mean that there aren't very many? I don't know.

When the test was developed, each of the question sets was delivered to a number of guinea pigs. The results were compiled, and, to no one's surprise, some question sets were found to be harder than others. Rather than try to make all of the question sets equally hard, the USGBC used that experimental data to establish a coefficient, or multiplier, for each question set.

A raw score--the number of questions you get right--is multiplied by the coefficient for that question set to arrive at the scaled score. For more difficult question sets, a higher multiplier is used to convert a lower raw score to a higher scaled score, and vice versa.

This process of coming up with the "scaled score" could mathematically result in a score higher than 200 or lower than 125, but what typically occurs with scaled scores, and I assume is the case here, is that any score higher than 200 is called 200, and any score lower than 125 is called 125.

How was the passing score of 170 determined? Says Holst:

A representative group of LEED AP Professionals recommended to GBCI a standard of what a minimally competent professional needs to know about the tested content to obtain a passing score. The chosen passing score was selected by GBCI and was then converted to a scale score.

Key points:

• No partial credit, and all questions are worth the same amount.
• The same raw score on two different 80-question sets will result in different final scores via a scaling process based on the relative difficulty of the questions.
• Your score on the LEED AP exam is neither the number of questions you answered correctly nor the percentage of questions you answered correctly. But if you divide it by two and look at it with squinty eyes it might be kind of close to the latter.
• If you've taken a practice exam and want to know how you've done relative to the real exam, a passing score of 170 correlates roughly with a score of 85% on a practice exam, or 68 out of 80 questions correct. But this is only a rough guide. Don't let a practice exam score of 85% give you confidence. Let your confidence in the material give you confidence.

All of this leads me to wonder:

How many LEED AP exam authors does it take to screw in a lightbulb?

1.85 if it's hard to reach, but 0.90 if it's right on your desk.

More green building humor is here. The equations shirt (image above) is here.