--- title: "Banding" description: "Banding reports a score as a range rather than a point, on the reasoning that differences smaller than the measurement error are not real differences. Candidates whose scores fall inside the same band are treated as equivalent, and any ordering among them is decided on other evidence rather than on the score." canonical: https://www.assessall.com/guides/glossary/b/banding updated: 2026-09-28 source: AssessAll --- # Banding _Also known as: Score banding, Confidence banding._ Banding reports a score as a range rather than a point, on the reasoning that differences smaller than the measurement error are not real differences. Candidates whose scores fall inside the same band are treated as equivalent, and any ordering among them is decided on other evidence rather than on the score. ## The argument for it Every score carries error. If the standard error of measurement on a scale is four points, then a candidate on 71 and a candidate on 68 are not distinguishable by that instrument, and a shortlist built by sorting the column has manufactured a distinction the data cannot support. Banding makes that explicit. It also changes behaviour: a reader handed a band asks what else they know about the two people, whereas a reader handed 71 and 68 simply picks 71. ## The honest objection Banding does not remove the arbitrary line, it moves it. Two candidates either side of a band boundary may differ by one point and be treated as different, which is the same problem the bands were introduced to solve, now occurring less often. The defensible position is that fewer arbitrary lines are better than many, and that a band boundary is at least placed where the measurement error says it can be. What is not defensible is publishing bands and then quietly ranking within them. ## The rule you use inside a band is regulated, in the United States at least Banding hands the decision inside a band to some other rule, and which rule that is turns out to be a legal question as well as a measurement one. 42 U.S.C. §2000e-2(l), added by section 106 of the Civil Rights Act of 1991 and read at source on 16 September 2026, makes it an unlawful employment practice “to adjust the scores of, use different cutoff scores for, or otherwise alter the results of, employment related tests on the basis of race, color, religion, sex, or national origin”. A banding scheme whose within-band selection rule refers to one of those characteristics is therefore within the words of that provision, whatever the intent behind it. A scheme that decides inside a band on independent job-related evidence — a work sample, a structured interview, a reference on a specific behaviour — is not doing the thing the provision names. The distinction is the selection rule, not the band. This is United States federal law, it is not legal advice, and other jurisdictions regulate the question differently. The general point survives the jurisdiction: a band with no stated rule for deciding inside it is not a fairness measure, it is a place for an unexamined rule to live. ## How many people end up in one band, and the thing banding does not do The number nobody puts next to the word banding is how many candidates it declares equal. Campion and six co-authors — Outtz, Zedeck, Schmidt, Kehoe, Murphy and Guion — put it in print in Personnel Psychology in 2001, in a paper structured as ten questions with the authors disagreeing on the record. Read at source on 28 September 2026: with a test reliability of 0.80 and the two-SED band width Cascio and colleagues recommended in 1991, taking the top score as the one at the 99.9th percentile, the resulting 95% band contains 38% of the score range and about 25% of the job applicants. A quarter of everyone who applied, treated as having equal true scores. That is the correct consequence of the arithmetic above and it is also the reason the choice of within-band rule carries so much weight: the rule is not a tiebreaker applied to two people, it is the actual selection procedure for a quarter of the field. The second finding in the same paper is the one vendors leave out. Banding is frequently sold as a diversity measure. Frank Schmidt's answer in that paper is that banding without minority preferences — traditional or SED — typically does little to reduce adverse impact, and preferences inside the band are the part courts have struck down. Outtz and Zedeck, arguing the other side in the same document, agree the effect depends on being able to select within bands on factors that do not show group differences. Both sides therefore agree on the mechanism: the band itself changes nothing, and everything turns on the rule you put inside it. If a vendor offers banding as an adverse-impact remedy, that is the sentence to quote back. Ask what the within-band rule is, what evidence supports it as job-related, and what the band width is at their published reliability. --- Source: https://www.assessall.com/guides/glossary/b/banding