A common objection to comparative judgment (CJ) is that it is impractical and takes too much teacher time. A single comparison is quick, but a reliable scale needs many comparisons per essay. At matched reliability, CJ usually takes about the same teacher time as rubric marking, or more. This page describes what a CJ scale records and what it does not, and then reports the time and reliability evidence.

CJ produces a measurement scale: a statistical model of the pairwise decisions places every essay at an estimated position on one continuous scale, with a standard error for each position. The scale shows the order of the essays within and across grade bands and how far apart the essays lie. It is also the continuum on which a panel then locates grade boundaries, using graded reference essays, and measures how wide each band is and where each essay sits within its band. A raw absolute grade records which band an essay belongs to and leaves the essay's place inside the band and the size of the step to the next band unobserved.

For Study 1, this evidence supports a bounded design. A panel of teachers judges a set of candidate anchor essays through CJ. The resulting scale becomes material for mediated panel discussion, through which the teachers establish the anchor set, and the anchor set becomes a reusable reference for placing later essays.

Information in a Comparative Judgment Scale

From Pairwise Decisions to One Scale

In CJ, a judge reads two essays written to the same task and decides which one better demonstrates the intended quality. In an Austrian national EFL test, a subset of judges decided quickly without reading the scripts in detail, and the authors conclude that participants "could judge both fast and reliably" (Sickinger et al., 2025, p. 156).

The decisions are analysed with the Bradley–Terry model, which is the logistic form of Thurstone's law of comparative judgment and a form of the Rasch model. The model gives each essay a position so that the difference between two positions predicts how often the first essay is judged better than the second (Pollitt, 2012, p. 282; Heldsinger & Humphry, 2010, pp. 5–6). Each position comes with a standard error, which states how precisely the decisions available locate that essay; every further comparison of the essay adds information and shrinks the standard error (Pollitt, 2012, p. 283; Kinnear et al., 2025, p. 2). Scale separation reliability (SSR) is the share of the spread in positions that reflects real differences between essays rather than estimation error, and it is read like Cronbach's alpha (Wheadon et al., 2020, p. 53).

Order, Distance, and Grade-Band Boundaries

Compared with raw absolute grades, the scale also records the following.

An absolute grade places an essay in an ordered category. Essays in the same band share one grade, a raw grade leaves the size of the step between bands unobserved, and any averaging of grades or conversion to points fixes the steps by assumption. Scaling grades with a Rasch model estimates the steps as category thresholds on the logit scale (Barkaoui, 2008, pp. 32–33), but these thresholds are common to all essays and do not place each essay within its band. Where each band begins rests on the rater's internal standard: a rater who awards a grade compares the essay with imagined essays, which opens the way to differences in personal standard, in how finely the rater differentiates, and in how the rater interprets the scale (Pollitt, 2012, p. 293). Rater severity, central tendency, restriction of range, and halo effects are well documented in rating data (Eckes, 2017, pp. 444–445). In a pairwise decision, the judge applies one standard to both essays at once, so differences in severity and in spread cancel out of the decision (Pollitt, 2012, p. 287; Humphry & Heldsinger, 2019, p. 505). The source of error that remains is how judges conceive quality, which is a question of validity (Pollitt, 2012, p. 293).

Swedish national-test studies show the same pattern in practice. When three external raters and the students' teachers graded 100 English national-test texts, their rank orders correlated .86–.93, while only 8 of the 100 texts received the same grade from all four (Erickson, 2009, pp. 14–16). In a national re-marking, 57 percent of the re-marked scripts received a different grade from the re-marker than from the school's teacher (Skolinspektionen, 2021, pp. 4, 9). In Coertjens et al. (2017), the share of score variance attributable to raters was 21.9 percent for rubrics and 14.6 percent for CJ. In Sickinger et al. (2025), the teachers' judgments were more consistent under CJ than under analytic rating in every group except one teacher without experience of the marking scheme.

Rubric Scaling

Rubric scores can also be placed on an interval scale. Many-facet Rasch measurement (MFRM) models each rubric score as a function of essay quality, task difficulty, and rater severity, and reports all three on a common logit scale (Sugita, 2012, p. 65; Barkaoui, 2008, p. 32). In Sugita's (2012, p. 69) study of ten raters, the most severe and the most lenient rater differed by 3.11 logits, or 0.86 of one grade on the rating scale, and MFRM measures adjust for such differences. Interval-level measures and severity adjustment are therefore available for rubric data once it is scaled. Compared with MFRM-scaled rubric scores, CJ differs in three respects:

Three matters remain outside the CJ scale. The scale has an arbitrary origin, so positions become grades only after boundaries are located with graded reference essays, as in the New Zealand studies (Marshall et al., 2020, pp. 55, 57–58). Judges still differ in what they value (Pollitt, 2012, p. 293; Lesterhuis et al., 2022, pp. 7–8). When teachers later assess new essays against calibrated exemplars, rater harshness returns as a source of variation: in Humphry and Heldsinger (2020, p. 8), variation in harshness was generally modest relative to the spread of performances, but some teachers gave average scores about 30 scale points below the other raters.

Limits of the Scale

Positions and distances are model estimates with standard errors, not observed quantities. They hold as far as the decisions fit the model, and the residuals of each decision can be summed per judge and per essay to find judges and essays that the model fits poorly (Pollitt, 2012, pp. 289–290). Under adaptive pairing, where each new pair is chosen from interim results, the reported SSR can be inflated (Verhavert et al., 2019, p. 543; Kinnear et al., 2025, p. 4).

The validity of the scale depends on whether judges attend to the intended construct. Among 64 assessors of argumentative texts, all assessor types based their decisions mainly on argumentation and organisation, and they differed in how often they considered language use, sources, and layout; the authors argue that combining several assessor types broadens the construct the scale represents (Lesterhuis et al., 2022, pp. 7–8). For 25 L2 English argumentative essays judged by three groups, 32 of 6,792 decision comments concerned construct-irrelevant features (Thwaites et al., 2025, accepted manuscript p. 8). The groups still differed in the breadth and depth of the qualities they commented on, and the trained raters' CJ scale reached an SSR of .86 and correlated ρ = .67 with an MFRM-scaled rubric scale of the same essays (Thwaites et al., 2025, accepted manuscript pp. 10–11). For L2 essays of this kind, a CJ scale and a scaled rubric scale order the essays in related but different ways, and the correlation alone does not show which order is more valid.

Time per Comparison Compared With Absolute Grading

Studies that timed both methods on the same or similar material report the following. A comparison involves two texts; the absolute-grading column refers to one text.

Study and material CJ, time per comparison Absolute grading, time per text
Coertjens et al. (2017): Dutch argumentative texts, upper-secondary, at most one A4 page about 2.6 min (1:17 per text in the first comparison) 7:08 (first rubric rating)
Benton & Gallacher (2018): GCSE English essays, about 500 words each 3.5 min (mean) about 7 min
Steedle & Ferrara (2016): US grade-11 state essays, trained teachers 62 s (median) 119 s (mean)
Marshall et al. (2020): New Zealand NCEA English reports, at least 350 words about 84 s (derived from 7 min judge time per script) about 7.2 min
Bouwer et al. (2024): Flemish primary descriptive texts about 64 s about 79 s (rating with benchmarks)
Sickinger et al. (2025): Austrian Year 8 national EFL test, A2 and B1 tasks 34 s and 51 s (medians) 240 s and 420 s (self-reported)
McMahon & Jones (2015): Irish chemistry test responses, students aged 14–15 33 s (mean) about 51 s
Pollitt (2012): English primary writing, ages 9–11, two pieces per script 195 s (mean of the faster half of judges; may include idle time) 15–20 min (reported as normal)

Coertjens et al. (2017) summarize the first judgment of a text as 5.5 times faster through pairwise comparison than through a rubric. Comparison time follows reading time: Benton and Gallacher (2018) note that 3.5 minutes for a pair of 500-word essays is close to normal on-screen reading speed. For the 250–600-word English essays in Study 1, this reading rate gives an estimate of 1.75–4.2 minutes per comparison. The estimate transfers an L1 rate to L2 essays and has to be checked in a pilot with the participating teachers; the comparison application records how long each pair stays in view, so the pilot supplies these timings. For paragraphs of about 150 words written by learners of English, Şahin (2021) reports 4.17 minutes per comparison for instructors and expects full essays to take two to three times as long, which would give about 8.3–12.5 minutes per comparison.

Total Time for a Reliable Scale

The time advantage of a single comparison does not carry over to total cost, because each text must appear in many comparisons. Across 49 CJ assessments, a scale separation reliability of .70 required 10–14 comparisons per text and .90 required 26–37 (Verhavert et al., 2019).

When both methods are compared at equal reliability, CJ takes about the same time or more. In Coertjens et al. (2017), 10 comparisons per text reached a reliability of .69 in 10:36 minutes of judge time per text, while two rubric ratings reached .67 in 11:34. At higher levels the two methods also followed nearly the same time curve, and the authors conclude that both methods require almost the same time investment to reach equally stable rank orders. Steedle and Ferrara (2016) reached a reliability above .80 at about nine judgments per essay; the authors put this at 279 seconds per essay with the median comparison time, against 239 seconds for double rubric scoring at the mean rubric time, or 17 percent more time. The mean comparison time of 93.5 seconds gives about 421 seconds per essay, or roughly 76 percent more. Both figures hold only at a reliability of .80 (pp. 220–222). With all judgments, about 18 per essay, CJ reached .89 and .90 (p. 220), a level comparable to double rubric scoring, whose two scorers correlated .81 and .85 (p. 216; the authors note that such correlations tend to be inflated), or about .90 and .92 for two scores combined by the Spearman–Brown formula. At that level the same calculation gives 558 seconds per essay with the median comparison time (18 × 62.0 ÷ 2) and about 842 seconds with the mean (18 × 93.5 ÷ 2), or about 2.3 and 3.5 times the 239 seconds of double rubric scoring. The combined rubric reliabilities and these multiples are my calculations from the paper's numbers; the authors do not report them. Bouwer et al. (2024) warn that the total time needed for reliable CJ scores can exceed the time needed for reliable absolute ratings.

A study that compared CJ with single marking, not at equal reliability, found a larger gap. In McMahon and Jones (2015), five teachers made 1,550 judgments of 154 science test responses, about 20 per response, and reached a reliability of .87. The judging took about 14 hours, while marking every response once took about 3 hours; the authors note that the judging took more than twice as long as even double marking would have, about 6 hours.

At matched reliability, the extra time for CJ ranges from none to large, and the result is the scale described above: a position and distance for every essay on one continuum where band boundaries can then be located, with rater severity removed from each decision. The number of comparisons remains the main practical cost at scale, and recruiting enough judges can itself be difficult, time-consuming, and expensive (Kinnear et al., 2025, p. 4). In this project, a language model makes the same pairwise comparisons as a judge (an LLM-as-judge); the project's hypothesis is that this approach addresses the cost. In the Study 1 design, human comparisons are limited to the candidate anchor essays; they are not repeated for every new set of student essays.

Use in High-Stakes and Low-Stakes Assessment

CJ is not confined to research settings. It has been piloted in examination awarding and grade-boundary setting, evaluated on national and state test material, and used in moderation and school-level assessment of writing. The high-stakes uses reported here are pilots and evaluations; the school-level uses include operational assessment at scale.

Setting Use Result
Examinations and national or state tests
England, examination awarding (Ofqual, 2019) Paired CJ piloted for maintaining grade standards across exam years At about ten judgments per script, estimated awarding workload similar to current practice (6–16 judge-days); roughly double at higher judgment counts
England, OCR examinations (Benton et al., 2022) CJ pilots for setting grade boundaries About 30 judge-hours per exercise; 13–139 hours across studies
Austria, Year 8 national EFL test (Sickinger et al., 2025) 27 teachers judged national-test scripts without prior CJ training Reliability .89–.92; correlation .77–.83 with expert analytic scores
United States, grade-11 state essays (Steedle & Ferrara, 2016) Trained teachers judged state-assessment essays in an evaluation of CJ as a scoring method Reliability .89 and .90; above .80 at about nine judgments per essay
New Zealand, NCEA English (Marshall et al., 2020) Teachers and moderators judged students' summative reports; grade boundaries were located afterward by grading six scripts near each boundary traditionally and finding their positions in the ranking Reliability .85; judge time about 7 min per script, similar to traditional marking
England, moderation of non-exam assessment (Vidal Rodeiro & Chambers, 2022) Six moderators compared candidate portfolios Reliability .76; correlation .85 with marks
School and classroom assessment
England, primary writing (Wheadon et al., 2020) Teachers in participating schools judged the writing of 55,599 pupils on the No More Marking platform Median 11–41 s per decision; 88–330 decisions per hour
Australia, primary writing (Heldsinger & Humphry, 2010) 20 raters, 17 of them classroom teachers, at one primary school judged 30 narrative scripts in about three hours Reliability .98; correlation .92 with independent marking against the state testing program's rubric
Australia, classroom essay assessment (Humphry & Heldsinger, 2019, 2020) Teachers first calibrate exemplars through pairwise comparison, then assess new essays against the calibrated exemplars Reliability .96 in the first, pairwise stage, with 23 teachers after 30 minutes of training
Research comparison
Flanders, primary writing (Bouwer et al., 2024) 14 undergraduate students rated primary-school texts by benchmark rating or by CJ, with or without CJ training Reliability .82 with training and .79 without, at 15 comparisons per text

The two-stage method of Humphry and Heldsinger (2019, 2020) and the statistics study of Marshall et al. (2020), in which six official boundary scripts were judged alongside the student scripts and fell in the correct order, are the closest precedents for Study 1: a scale produced through pairwise comparison becomes the reference against which later essays are placed.

Implications for Study 1

Study 1 examines how teachers collectively mediate essay quality into an anchor set. CJ gives this mediation a common starting point: one scale built from every teacher's relative judgments. On that scale the panel can see which candidate essays lie near the top, middle, and bottom of each grade band, where it places the boundaries between bands, whether the bands are of similar width, and which positions are too uncertain to decide on. The scale also shows where the panel's judgments converge and where they do not. Disagreement is expected: in van Daal et al. (2017), 18–22 percent of individual decisions went against the final rank order, while the scales still reached reliabilities of .74–.86. Judges found pairs harder when the two texts lay close on the final scale, and decisions that went against the final order felt hard however far apart the texts lay. The essays that fit the scale poorly, including discordant texts, are therefore likely to be where the panel discussion does most of its work. The discussion then settles which essays represent which grade levels and records the teachers' rationales. The resulting anchor set carries its scale positions with it, so later essays can be placed against calibrated reference points in the way the two-stage method describes.

The panel workload can be estimated in advance. For illustration, the table assumes 40 candidate anchor essays, a panel of six teachers, random pairing, and 1.75–4.2 minutes per comparison. Panel discussion time is not included. The comparison counts come from assessments with random pairing; the comparison application stops at a target reliability only with its non-adaptive pair selection, which spreads comparisons across the essays instead of targeting them from interim results.

Target reliability Comparisons per essay Comparisons in total Panel hours Hours per teacher
.70 10–14 200–280 5.8–19.6 1.0–3.3
.80 about 17 340 9.9–23.8 1.7–4.0
.90 26–37 520–740 15.2–51.8 2.5–8.6

At the slower rate suggested by Şahin (2021), the .80 level would require 47–71 panel hours, or 8–12 hours per teacher. For comparison, double absolute grading of the same 40 essays at about 7 minutes per essay takes about 9 hours, and in Coertjens et al. (2017) two ratings per text reached a reliability of .67. The time cost of the CJ stage is therefore of the same order as careful double grading of the candidate essays, and it is paid once, when the anchor set is established. The double grading would yield two grades per essay; the CJ stage yields positions and distances on one scale, on which the panel then locates band boundaries that it can discuss and reuse.

Limits

References

Barkaoui, K. (2008). Effects of scoring method and rater experience on ESL essay rating processes and outcomes [Doctoral dissertation, University of Toronto].

Benton, T., & Gallacher, T. (2018). Is comparative judgement just a quick form of multiple marking? Research Matters, 26, 22–28. https://www.cambridgeassessment.org.uk/Images/514987-is-comparative-judgement-just-a-quick-form-of-multiple-marking-.pdf

Benton, T., Gill, T., Hughes, S., & Leech, T. (2022). A summary of OCR's pilots of the use of comparative judgement in setting grade boundaries. Research Matters, 33. https://doi.org/10.17863/CAM.100424

Bouwer, R., Lesterhuis, M., De Smedt, F., Van Keer, H., & De Maeyer, S. (2024). Comparative approaches to the assessment of writing: Reliability and validity of benchmark rating and comparative judgement. Journal of Writing Research, 15(3), 497–518. https://doi.org/10.17239/jowr-2024.15.03.03

Coertjens, L., Lesterhuis, M., Verhavert, S., Van Gasse, R., & De Maeyer, S. (2017). Teksten beoordelen met criterialijsten of via paarsgewijze vergelijking: Een afweging van betrouwbaarheid en tijdsinvestering. Pedagogische Studiën, 94(4), 283–303. https://hdl.handle.net/2078.1/192419

Eckes, T. (2017). Rater effects: Advances in item response modeling of human ratings – Part I. Psychological Test and Assessment Modeling, 59(4), 443–452.

Erickson, G. (2009). Nationella prov i engelska – en studie av bedömarsamstämmighet. Göteborgs universitet. https://gupea.ub.gu.se/bitstream/handle/2077/21781/gupea_2077_21781_1.pdf

Heldsinger, S., & Humphry, S. (2010). Using the method of pairwise comparison to obtain reliable teacher assessments. The Australian Educational Researcher, 37(2), 1–19. https://doi.org/10.1007/BF03216919

Heldsinger, S. A., & Humphry, S. M. (2013). Using calibrated exemplars in the teacher-assessment of writing: An empirical study. Educational Research, 55(3), 219–235. https://doi.org/10.1080/00131881.2013.825159

Humphry, S. M., & Heldsinger, S. (2019). A two-stage method for classroom assessments of essay writing. Journal of Educational Measurement, 56(4), 505–520. https://doi.org/10.1111/jedm.12223

Humphry, S. M., & Heldsinger, S. (2020). A two-stage method for obtaining reliable teacher assessments of writing. Frontiers in Education, 5, 6. https://doi.org/10.3389/feduc.2020.00006

Kinnear, G., Jones, I., & Davies, B. (2025). Comparative judgement as a research tool: A meta-analysis of application and reliability. Behavior Research Methods, 57(8), Article 222. https://doi.org/10.3758/s13428-025-02744-w

Lesterhuis, M., Bouwer, R., van Daal, T., Donche, V., & De Maeyer, S. (2022). Validity of comparative judgment scores: How assessors evaluate aspects of text quality when comparing argumentative texts. Frontiers in Education, 7, 823895. https://doi.org/10.3389/feduc.2022.823895

Marshall, N., Shaw, K., Hunter, J., & Jones, I. (2020). Assessment by comparative judgement: An application to secondary statistics and English in New Zealand. New Zealand Journal of Educational Studies, 55(1), 49–71. https://doi.org/10.1007/s40841-020-00163-3

McGrane, J., Humphry, S., & Heldsinger, S. (2018). Applying a Thurstonian, two-stage method in the standardized assessment of writing. Applied Measurement in Education, 31(4), 297–311. https://doi.org/10.1080/08957347.2018.1495216

McMahon, S., & Jones, I. (2015). A comparative judgement approach to teacher assessment. Assessment in Education: Principles, Policy & Practice, 22(3), 368–389. https://doi.org/10.1080/0969594X.2014.978839

Ofqual. (2019). Improving awarding: 2018/2019 pilots (Ofqual/19/6575). Office of Qualifications and Examinations Regulation. https://assets.publishing.service.gov.uk/media/5df2419340f0b6094e25ac37/Improving_awarding_-_FINAL196575.pdf

Pollitt, A. (2012). The method of adaptive comparative judgement. Assessment in Education: Principles, Policy & Practice, 19(3), 281–300. https://doi.org/10.1080/0969594X.2012.665354

Şahin, M. G. (2021). Feasibility of using comparative judgement and student judges to assess writing performance of English language learners. Journal of Pedagogical Research, 5(4), 140–154. https://doi.org/10.33902/JPR.2021474154

Sickinger, R., Brunfaut, T., & Pill, J. (2025). Comparative judgement for evaluating young learners' EFL writing performances: Reliability and teacher perceptions of holistic and dimension-based judgements. Language Testing, 42(2), 137–166. https://doi.org/10.1177/02655322241288847

Skolinspektionen. (2021). Ombedömning av nationella prov 2019. Skolinspektionen. https://www.skolinspektionen.se/globalassets/publikationssok/granskningsrapporter/omrattning/2021/ombedomning-av-nationella-prov-2019.pdf

Steedle, J. T., & Ferrara, S. (2016). Evaluating comparative judgment as an approach to essay scoring. Applied Measurement in Education, 29(3), 211–223. https://doi.org/10.1080/08957347.2016.1171769

Sugita, Y. (2012). Effects of rater training on raters' severity, consistency, and biased interactions in a task-based writing assessment. JLTA Journal, 15, 61–80. https://doi.org/10.20622/jltajournal.15.0_61

Thwaites, P., Jadoulle, P., & Paquot, M. (2025). Comparative judgment in L2 writing assessment: Reliability and validity across crowdsourced, community-driven, and trained rater groups of judges. Assessing Writing, 65, 100937. https://doi.org/10.1016/j.asw.2025.100937

van Daal, T., Lesterhuis, M., Coertjens, L., van de Kamp, M.-T., Donche, V., & De Maeyer, S. (2017). The complexity of assessing student work using comparative judgment: The moderating role of decision accuracy. Frontiers in Education, 2, 44. https://doi.org/10.3389/feduc.2017.00044

Verhavert, S., Bouwer, R., Donche, V., & De Maeyer, S. (2019). A meta-analysis on the reliability of comparative judgement. Assessment in Education: Principles, Policy & Practice, 26(5), 541–562. https://doi.org/10.1080/0969594X.2019.1602027

Vidal Rodeiro, C. L., & Chambers, L. (2022). Moderation of non-exam assessments: Is comparative judgement a practical alternative? Research Matters, 33, 100–119. https://doi.org/10.17863/CAM.100428

Wheadon, C., Barmby, P., Christodoulou, D., & Henderson, B. (2020). A comparative judgement approach to the large-scale assessment of primary writing in England. Assessment in Education: Principles, Policy & Practice, 27(1), 46–64. https://doi.org/10.1080/0969594X.2019.1700212