Advanced LSAT

LSAT Scores and the "LSAT Curve" Explained

Part of the reason LSAT scores are weighed so heavily in law school admissions is that they provides a qualitative basis for comparison among law school applicants. GPAs vary widely across schools and majors, but the LSAT is "curved" or equated, so that law schools can meaningfully compare prospective students by their particular LSAT scores.

But how is this achieved? How does LSAC (the creators of the LSAT) make it so that a law school can compare an applicant who took the June 2008 test and achieved an LSAT score of 158 against another who took the December 2011 test and achieved an LSAT score of 162?

Many people think the answer is the "LSAT curve", by which they probably the way in which raw LSAT scores are turned into scaled LSAT scores. In actuality, there's a bit more to the process, which LSAC refers to, not as a curve, but as "equating".

LSAT scores are not "curved" but normalized in the following ways:

1. The experimental section (pre-test)
2. The LSAT score conversion chart (equating)
3. The LSAT percentile table

LSAT Scores and the Experimental Section

All students who take the LSAT take an experimental section, typically given in one of the first three sections of the test. The experimental section is not part of your LSAT score, but it serves an important function in the LSAT curve, or equating, process. LSAC carefully analyzes these questions and assesses their difficulty. That way, when LSAC assembles future tests, they have an accurate gauge of the number of questions test takers can miss to obtain particular LSAT scores.

Here's what LSAC has to say about the experimental section, which they refer to as "pretest sections".

Questions that meet the strenuous LSAC review criteria are assembled into pretest sections. Pretest sections are administered to a sample of test takers from the LSAT test-taking population. Results from the pretest provide test development staff with statistical information about each question, and with information about possibly ambiguous or misleading information in the question or in one or more of the answer choices. If problems are identified, either the question is discarded or it is revised and pretested again. All questions that pass the quality standards of a pretest administration are placed in the LSAT test question item bank. New test sections are assembled by selecting questions from this LSAT item bank. Each fully assembled test section is administered on one or more separate occasions for the purpose of pre-equating the new form. Pre-equating is a statistical method used to adjust for minor fluctuations in the difficulty of different test forms so that a test taker is neither advantaged nor disadvantaged by the particular form that is given. Following each pre-equating administration, the statistical information about each question is reviewed to assure that the data support that the question is of appropriate difficulty, discriminates higher ability test takers from lower ability test takers, is unambiguous, and has a single best answer. When the test is given at a regular LSAT administration, but before final scoring is completed, statistical analysis is conducted one last time. Each question is evaluated using the same criteria that were applied following the pretesting and pre-equating administrations. If a problem is found, the question is eliminated from the test before final scoring and reporting are accomplished.

From LSAC's "Policies and Procedures Governing Challenges to Law School Admission Test Questions."
www.lsac.org/JD/pdfs/Policies-web.pdf

LSAT Scores, the Score Conversion Chart, and the LSAT "Curve"

Once a student has taken the LSAT, he or she will receive a raw LSAT score and a scaled LSAT score. The raw score is the number of questions answered correctly on the test. Test takers then use the conversion chart to arrive at their LSAT score, which is the number from 120 to 180 that law schools will see on your law school application.

Here's what LSAC has to say about the score conversion chart in a process that students typically refer to as the "LSAT curve" but that LSAC refers to as "equating."

Testing organizations typically disclose test forms after they have been administered to large test-taker populations. Therefore, several test forms must be developed annually to be as similar as possible to one another in terms of statistical and content attributes. Although a great deal of effort is placed on assembling comparable tests, forms will tend to vary somewhat in terms of their statistical characteristics. Hence, scores must be transformed in order to enable direct comparisons across forms. The process by which scores are adjusted so as to make them comparable to each other is referred to as equating.

From LSAC's "Assessing the Effect of Multidimensionality on LSAT Equating for Subgroups of Test Takers."
www.lsac.org/lsacresources/Research/SR/SR-95-01.asp

The LSAT Percentile Table and the LSAT "Curve"

The LSAT percentile table is calculated by using test data from three previous years of test takers. This is why, when taking the LSAT, you're not competing against the other students in the room for your LSAT scores (a common misconception along with the LSAT "curve"), but rather against students who took the test in the previous three years. This is a large enough test group that it smoothes out any oddities of testing populations and LSAT scores that might occur in one test administration.

The percentile score indicates where various LSAT scores are relative to other exam takers. For example, a student with an LSAT score of 152, which for a particular exam might be the 50th percentile, scored better than 50% of people, not on that particular test, but over the last three years. Law schools look closely at the percentile LSAT scores because these indicate LSAT scores relative to other applicants – allowing them to compare different students across different exams with reasonable accuracy.

Conclusion about LSAT Scores, and the LSAT "Curve"

It's important to note that both the pretesting data and the percentile data are set before students ever take the test and receive their LSAT scores. Because LSAC cannot anticipate every fluctuation in a particular test, it is the conversion chart for LSAT scores that changes from test to test. This is the mechanism by which LSAC can fine tune their data from pre-testing and fit it to the particular test taking population on a particular day. It is also this particular mechanism that students typically refer to as the "LSAT curve", which is understandable, because it's the thing that you can best understand as that which determines LSAT scores at the end of the day.

In conclusion, the best way for people to better their LSAT scores is not to worry about a better or worse LSAT "curve", but to realize that LSAC does a great job of normalizing LSAT scores. So to obtain higher LSAT scores, students should study hard for this difficult test and let the scoring be taken care of by LSAC.

Oh, and if you're taking the LSAT and you want to sound really smart, use the word "equating" rather than "curve."