Cited by 6Online Learning and AnalyticsStudent Assessment and FeedbackEducational Technology and Assessment

Better Peer Grading through Bayesian Inference

Open access
Zarkoob, Hedayat, D'Eon, Greg, Podina, Lena, Leyton-Brown, Kevin·2023·Proceedings of the AAAI Conference on Artificial Intelligence

Abstract

Peer grading systems aggregate noisy reports from multiple students to approximate a "true" grade as closely as possible. Most current systems either take the mean or median of reported grades; others aim to estimate students’ grading accuracy under a probabilistic model. This paper extends the state of the art in the latter approach in three key ways: (1) recognizing that students can behave strategically (e.g., reporting grades close to the class average without doing the work); (2) appropriately handling censored data that arises from discrete-valued grading rubrics; and (3) using mixed integer programming to improve the interpretability of the grades assigned to students. We demonstrate how to make Bayesian inference practical in this model and evaluate our approach on both synthetic and real-world data obtained by using our implemented system in four large classes. These extensive experiments show that grade aggregation using our model accurately estimates true grades, students' likelihood of submitting uninformative grades, and the variation in their inherent grading error; we also characterize our models' robustness.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper extends Bayesian peer-grading models by adding latent grader effort, treating discrete rubric reports as censored observations, and using mixed-integer programming to produce interpretable discrete final grades. Experiments on four large-class datasets and synthetic data show improved held-out likelihood, accurate grade/reliability recovery with enough data, and MIP grades that rarely differ from MAP estimates.

Key findings

  • A model combining effort and censoring had the highest held-out likelihood; ablations showed removing censoring always caused significant drops, while removing effort had significant effects in one class. Model changes altered final grades by an average of 0.05–0.15 points on a 5-point scale and very rarely exceeded a single point.
  • Replacing MAP grades with MIP output changed only 6.5% of grades across the four offerings, using defaults S = 0.09 and minimum non-zero weight T = 0.1.
  • On synthetic data, reliability estimates reached a Spearman correlation of 0.6 after one week and 0.9 after eight weeks; effort estimates were harder, rising from 0.3 to 0.7. True-grade MAE fell from 0.52 with one grader to 0.41 with four graders—below a TA with reliability 2 (MAE 0.48)—and reached below 0.2 with 32 graders.
  • Robustness tests found many hyperparameter misspecifications had small, statistically insignificant effects, but incorrect true-grade prior mean or standard deviation increased true-grade MAE from 0.44 to as high as 0.53; incorrect low-effort precision hurt effort estimates; and a bias prior standard deviation far below its true value hurt bias estimates.

Methods

  • The paper extends the PG1 graphical model with latent effort decisions, effort probabilities, censored discrete grade reports, and a MIP formulation for explainable weighted-average grades. Inference uses Gibbs sampling, with marginalization and discrete grid approximations for censored observations.
  • Real data came from four offerings of an undergraduate computer science course between September 2018 and December 2021: approximately 120 students, 11 weekly essays, four rubric components graded 0–5, 6,088–7,068 peer grades per dataset, 3–5 TAs who spot-checked 474–644 essays, and 60–84 gold-standard calibration submissions. Evaluation used 10-fold stratified cross-validation, held-out likelihood, and paired t-tests.
  • Synthetic experiments simulated 10 weeks, 120 students, four peer grades per submission, three TAs grading 25% of submissions, and TAs with mean reliability 2; results report means and 95% confidence intervals across 15 simulated datasets, using MAE and Spearman rank-order correlation.

Limitations

  • The paper states that the model has 9 hyperparameters, making tuning daunting for instructors, though it reports robustness to misspecifying reliability, bias, and effort priors. It also states that effort probabilities are difficult to estimate, converge more slowly than reliabilities, and are worsened by coarse rubrics where high-effort grades can match the class average.
  • The paper states that real-world datasets provide no ground-truth values for true grades or reliabilities, so real-data evaluation relies on held-out likelihood rather than parameter recovery. Synthetic experiments assume data generated from the best-fitting models and hyperparameters.
  • Evident from the text: validation is limited to four offerings of one undergraduate course and one grading rubric, and the MIP evaluation uses default constants rather than a broad sensitivity analysis over those constants.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1609/aaai.v37i5.25757

Cites

42 of 42 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

8 of 18 cited sources checked · 6 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    The first methods for aggregating peer grades and many more recent methods produce point estimates of each assignment's grade and each grader's quality.

    “The first methods for aggregating peer grades-and many others introduced more recently-produce point estimates of each assignment's grade and each grader's quality (Walsh 2014;Chakraborty, Jindal, and Nath 2018;Prajapati et al. 2020;de Alfaro and Shavlovsky 2014;Hamer, Ma, and Kwong 2005).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Walsh 2014 source
    • cites Chakraborty, Jindal, and Nath 2018
    • cites Prajapati et al. 2020 source
  • Premisecitation

    These parameters can be estimated from grading data through Bayesian inference, producing posterior distributions on each assignment's grade and each student's grading abilities.

    “Their core”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Piech et al. (2013) source
  • Premisecitation

    Piech et al. (2013) introduced the first system using graphical models to simultaneously determine distributions over both grades for student submission and accuracy assessments for each grader.

    “A seminal paper due to Piech et al. (2013) introduced the first such system, using graphical models to simultaneously determine distributions over both grades for student submission and accuracy assessments for each grader.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Piech et al. (2013) source

      Section 3.2 (p. 4) says the models infer a joint posterior distribution over submission scores and each grader’s bias and reliability, supporting the substance of the claim. But the paper does not claim to be the first such system; its Related Work section (p. 7) describes earlier Bayesian models for peer grading. The priority claim is therefore unsupported. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
  • Premisecitation

    Hartline et al. (2020) showed that the most robust 'low effort' strategy is to report the class average, because it minimizes the expected distance to an effortful report.

    “Hartline et al. (2020)showed that the most robust”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Hartline et al. (2020) source

      Section 6, “Application to Peer Grading” (page unavailable), says that when a peer does not read a submission, her optimal strategy is to report her prior belief—the class average mark for each criterion. It does not say this is the “most robust” strategy or explain its optimality as minimizing expected distance to an effortful report. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • Premisecitation

    Burrell and Schoenebeck (2021) found that rewards from out-of-the-box peer prediction mechanisms do not accurately reflect grader effort levels on realistic simulated data.

    “Further, Burrell and Schoenebeck (2021) found that rewards from out-of-the-box peer prediction mechanisms do not accurately reflect grader effort levels on realistic simulated data.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Burrell and Schoenebeck (2021) source
  • Classified as probably not a substantial claim. 25
  • May combine two claims. 19
  • The quote only partly states this claim. 2
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    The extensions can be added to the PG5 model of Mi and Yeung (2015), additionally modeling correlations between students' submission grades and reliabilities.

    “In Appendix B, we show how these extensions could be added to the PG5 model of Mi and Yeung (2015), additionally modeling correlations between students' submission grades and reliabilities.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Mi and Yeung (2015) source
  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The PG1 model assumes that each assignment has a latent true grade and each peer grader has a latent bias and reliability.

    “Their core”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Piech et al. (2013) source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Follow-up work extended these models to allow for more complex reliability-grade correlations (PG4 and PG5) and to more explicitly account for differences between a single grader's reported grades (PG6 and PG7).

    “Follow-up work by others further extended these models to allow for more complex reliability-grade correlations (the PG4 and PG5 models of Mi and Yeung 2015) and to more explicitly account for differences between a single grader's reported grades (the PG6 and PG7 models of Wang et al. 2019).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Mi and Yeung 2015 source
    • cites Wang et al. 2019
  • May combine two claims.

    Findingown data

    Reliability estimates had a correlation of 0.6 after one week of data and improved to 0.9 after 8 weeks.

    “Reliability estimates had an appreciable correlation of 0.6 after just one week of data, improving substantially to 0.9 after 8 weeks.”
    Quote in the paperSubstantial claim
  • The quote only partly states this claim.

    Findingown data

    The method for generating interpretable grades closely tracked MAP estimates, using real data from four offerings of a large class.

    “and that our method for generating interpretable grades closely tracked MAP estimates (Section 4)”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Adding additional peer graders on each submission substantially reduced true grade MAE, from 0.52 with a single grader to 0.41 with four, which is below the MAE of a TA.

    “These results indicate that adding additional peer graders on each submission substantially reduced true grade MAE, from 0.52 with a single grader to 0.41 with four-well below the MAE of a TA.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). The quote only partly states this claim.

    Findingnone given

    In Fall21 and Winter21, greater efforts were made to detect low-effort behavior.

    “we made greater efforts to detect low-effort behavior”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    The previous section showed that a model incorporating both efforts and censoring had the best performance on all four datasets, but its optimal hyperparameters varied.

    “The previous section showed that a model incorporating both efforts and censoring had the best performance on all four datasets, but its optimal hyperparameters varied.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The TAs were diligent and responsible.
    • Rests on an assumption: The gold-standard calibration submissions' grades were painstakingly agreed upon by the whole course staff.
  • May combine two claims.

    Findingreasoning

    In simulations, changing the number of students in the class had surprisingly little impact on the inference problem's difficulty, because each grader continued to grade 40 submissions and each submission continued to receive 4 grades.

    “However, this change had surprisingly little impact on the inference problem's difficulty, because as the class size varies, each grader continued to grade a total of 40 submissions, and each submission continued to receive 4 grades.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based). May combine two claims.

    Findingnone given

    In our experience, students find such grades confusing and unfair; they instead expect to receive final grades that interpolate their received grades, such as averages weighted by each grader's perceived trustworthiness.

    “In our experience, students find such grades confusing and unfair; they instead expect to receive final grades that interpolate their received grades, such as averages weighted by each grader's perceived trustworthiness.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    All model changes made small but meaningful changes to final grades, averaging between 0.05 and 0.15 points on a 5-point scale, and very rarely exceeding a single point change.

    “All model changes made small but meaningful changes to the final grades, averaging between 0.05 and 0.15 points on our 5-point scale, and very rarely ever exceeding a single point change.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    A hypothetical TA with a reliability of 2 achieves a mean absolute error of 0.48.

    “a hypothetical TA with a reliability of 2 (who achieves a mean absolute error of 0.48)”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    With only a single grader, the MIP output was equal to the mean of the Gibbs samples, which is much less accurate than the MAP.

    “With only a single grader, the MIP output was equal to the mean of the Gibbs samples, which is much less accurate than the MAP.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Effort estimates had a correlation of 0.3 after one week of data and improved to 0.7 in later weeks.

    “Effort estimates followed a similar trend, but were much more difficult to estimate: one week of data produced a much poorer correlation of 0.3, with later weeks improving to 0.7.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Using 4,000 Gibbs samples caused average error of 1%, 3%, and 1% on estimates of true grades, reliabilities, and effort compared to 10,000 samples, and had a small impact on results.

    “comparing to runs with 10,000 Gibbs samples, our protocol of gathering 4,000 samples caused an average error of 1%, 3%, and 1% on our estimates of true grades, reliabilities, and effort, respectively, and therefore had a small impact on our results.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Accuracy and RMSE gave qualitatively similar conclusions to MAE.

    “We also computed accuracy (the fraction of true grade MAP estimates equal to the rounded true grade) and RMSE, finding qualitatively similar conclusions with these measures.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    When low-effort behavior is successfully disincentivized, detecting it will have less impact on model performance.

    “of course, when such behavior is successfully disincentivized, detecting it will have less impact on model performance.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    The study collected 4 runs of 1,100 Gibbs samples, discarding the first 100 burnin samples from each run and concatenating the remainder, taking about 8 CPU hours.

    “Each time we fit our model to a dataset, we collected 4 runs of 1,100 Gibbs samples, discarding the first 100 burnin samples from each run and concatenating the remainder; this took about 8 CPU hours.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The study used paired t-tests to compare held-out likelihoods of models on the same dataset.

    “We use paired t-tests to make statistical comparisons between held-out likelihoods of several models on the same dataset.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Piech et al. also introduced PG2 and PG3 models that respectively permit graders' biases to change over time and students' grading reliability to be correlated with their own assignments' grades.

    “Piech et al. also introduced PG2 and PG3 models that respectively permit graders' biases to change over time and students' grading reliability to be correlated with their own assignments' grades.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Piech et al.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisereasoning

    Work in this area is mostly centered around the idea of peer prediction, developing mechanisms that incentivize graders to grade carefully by rewarding them based on comparing their peer grades to others'.

    “Work in this area is mostly centered around the idea of peer prediction, developing mechanisms that incentivize graders to grade carefully by rewarding them based on comparing their peer grades to others'.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    An extensive line of work in mechanism design focuses on incentivizing high quality reporting in peer grading and other crowdsourcing environments.

    “In response to this issue, an extensive line of work in the mechanism design literature focuses on incentivizing high quality reporting in peer grading and other crowdsourcing environments (Prelec 2004;Jurca andFaltings 2009, 2005;Faltings, Li, and Jurca 2012;Witkowski and Parkes 2012;Witkowski et al. 2013;Radanovic andFaltings 2013, 2014;Riley 2014;Kamble et al. 2015;Kong, Ligett, and Schoenebeck”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Prelec 2004 source
    • cites Jurca andFaltings 2009, 2005

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Faltings, Li, and Jurca 2012 source
  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    The specification of low-effort behavior is important both for boosting model performance and for disincentivizing bad behavior.

    “The second is the specification of low-effort behavior, which is important both for boosting model performance and for disincentivizing bad behavior”
    Quote in the paperSubstantial claim
    • Rests on an assumption: If the model is good at identifying low effort behavior, students will exhibit this behavior less often.
  • Classified as probably not a substantial claim.

    Study design and conductcitation

    The study evaluated models based on held-out likelihood.

    “Instead, we evaluated our models based on their ability to predict held out data: specifically, their held-out likelihood (Vehtari, Gelman, and Gabry 2016).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Vehtari, Gelman, and Gabry 2016

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    A key advantage of a Bayesian approach to reasoning about peer grades is that it yields distributional posterior beliefs about each quantity of interest rather than point estimates.

    “A key advantage of a Bayesian approach to reasoning about peer grades is that it yields distributional posterior beliefs about each quantity of interest rather than point estimates.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationnone given

    Performing naive Gibbs sampling on the latent peer grade variables would lead to extremely sample-inefficient inference: the posterior distribution has multiple modes where the true grade nearly matches one latent peer grade, and Gibbs sampling rarely moves between these modes.

    “Performing naive Gibbs sampling on the latent peer grade variables would lead to extremely sample-inefficient inference: the posterior distribution has multiple modes where the true grade nearly matches one latent peer grade, and Gibbs sampling rarely moves between these modes.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    Most current peer grading systems either take the mean or median of reported grades; others aim to estimate students' grading accuracy under a probabilistic model.

    “Most current systems either take the mean or median of reported grades; others aim to estimate students' grading accuracy under a probabilistic model.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationcitation

    The MAP approach leaves students with little insight about how their peer grades influenced the calculation; this can lead to reduced trust in the system and more appeals.

    “While this approach is statistically sensible, it leaves students with little insight about how their peer grades influenced the calculation; this can lead to reduced trust in the system (Kizilcec 2016) and more appeals.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Kizilcec 2016 source
  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    The study evaluated reliability and effort estimates with the Spearman rank-order correlation coefficient.

    “Accordingly, we evaluated our reliability and effort estimates with the Spearman rank-order correlation coefficient, measuring how similarly students were ranked by the estimates and true values.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Mapping the mean of the Gibbs samples to the nearest rubric element can lead to rounding errors.

    “One might map the mean of the Gibbs samples to the nearest rubric element, but this can lead to rounding errors.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    Explicitly modeling low-effort behavior can reduce students' incentives for such behavior and help avoid assigning high reliabilities to low-effort students.

    “We can reduce students' incentives for such low-effort behavior by explicitly modeling it, helping us to avoid assigning high reliabilities to low-effort students.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: Each time a grader grades a submission, they make a binary decision about whether to make an effort.
    • The authors state this as an assumption: If a grader does not make an effort, they choose a random grade from a fixed low-effort distribution Dℓ.
    • The authors state this as an assumption: Effort decisions are independent of the content of the submission.
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    These mechanisms typically rely on restrictive modeling assumptions, making them inapplicable to most practical peer grading systems.

    “While our model of low-effort grading is inspired by work in this area, these mechanisms typically rely on restrictive modeling assumptions, making them inapplicable to most practical peer grading systems.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationnone given

    Regardless of the choice of Dl, Gibbs sampling remains straightforward: both efforts and effort probabilities yield closed-form updates, and all other parameter updates simply exclude grades that a given sample calls low effort.

    “Regardless of our choice of D ℓ , Gibbs sampling remains straightforward: both efforts and effort probabilities yield closed-form updates, and all other parameter updates simply exclude grades that a given sample calls low effort.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    The 10-fold stratified cross-validation ensured that no two peer grades on the same submission were in the same group.

    “We first split the dataset into 10 groups of n/10 peer grades, ensuring that no two peer grades on the same submission were in the same group.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Even if the mapping from real-valued grades to the course's rubric produces accurate grades, students must be able to understand it in order to trust the system.

    “Even if this mapping produces accurate grades, students must be able to understand it in order to trust the system (Kizilcec 2016).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kizilcec 2016 source
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    The extensions could be applied to any of the PG* models in the literature.

    “but they could be applied to any of the PG* models in the literature”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    At their best, methods that produce point estimates maximize the likelihood of the data given a model.

    “At their best, methods that produce point estimates maximize the likelihood of the data given a model, e.g., by assigning each grader a”
    Quote in the paperNot a substantial claim
37 of 37
  • The paper relies on this without support.

    For peer grading systems to be both useful to instructors and acceptable to students, they must produce grades sufficiently similar to those an instructor would have given.

    “In order for peer grading systems to be both useful to instructors and acceptable to students, they must produce grades that are sufficiently similar to those that an instructor would have given.”
  • The paper relies on this without support.

    Individual peer graders are biased (consistently give generous or harsh grades).

    “This is a challenging task because individual peer graders will be biased (consistently give generous or harsh grades); noisy (the same grader could grade an assignment differently on different days); and potentially strategic (some students will enter insincere peer grades unrelated to a submission's quality if they can get away with it).”
  • The paper relies on this without support.

    Individual peer graders are noisy (the same grader could grade an assignment differently on different days).

    “This is a challenging task because individual peer graders will be biased (consistently give generous or harsh grades); noisy (the same grader could grade an assignment differently on different days); and potentially strategic (some students will enter insincere peer grades unrelated to a submission's quality if they can get away with it).”
  • The paper relies on this without support.

    Students can behave strategically (e.g., reporting grades close to the class average without doing the work, or entering insincere peer grades unrelated to a submission's quality if they can get away with it).

    “This is a challenging task because individual peer graders will be biased (consistently give generous or harsh grades); noisy (the same grader could grade an assignment differently on different days); and potentially strategic (some students will enter insincere peer grades unrelated to a submission's quality if they can get away with it).”
    “recognizing that students can behave strategically (e.g., reporting grades close to the class average without doing the work)”
  • The paper relies on this without support.

    Students can subvert systems that assess grading quality by comparing individual grades to each other if they coordinate on all reporting the same grade.

    “For example, students can subvert systems that assess grading quality by comparing individual grades to each other if they coordinate on all reporting the same grade.”
  • The paper relies on this without support.

    The statistical literature allows both students and the peer grading system itself to assign real-valued grades, whereas real instructors tend to use coarse-valued rubrics, particularly when eliciting grades from students.

    “Furthermore, the statistical literature allows both students and the peer grading system itself to assign real-valued grades, whereas real instructors tend to use coarse-valued rubrics, particularly when eliciting grades from students.”
  • The paper relies on this without support.

    Censored data arises from discrete-valued grading rubrics.

    “appropriately handling censored data that arises from discretevalued grading rubrics”
  • The paper relies on this without support.

    Mixed integer programming improves the interpretability of the grades assigned to students.

    “using mixed integer programming to improve the interpretability of the grades assigned to students”
  • The paper relies on this without support.

    In order for a statistical model to be able to accurately recover true grades from peer reports, students must invest the effort required to grade as well as they can.

    “In order for a statistical model to be able to accurately recover true grades from peer reports, students must invest the effort required to grade as well as they can.”
  • The paper relies on this without support.

    It is not easy to determine whether a student has done a good job of peer grading when there are no instructor or TA grades to which their evaluation can be compared.

    “However, it is not easy to determine whether a student has done a good job of peer grading when there are no instructor or TA grades to which their evaluation can be compared.”
  • The authors state this as an assumption.

    Each time a grader grades a submission, they make a binary decision about whether to make an effort.

    “Each time a grader v grades a submission u, we assume they make a binary decision about whether to make an effort z v u on the submission.”
  • The authors state this as an assumption.

    If a grader does not make an effort, they choose a random grade from a fixed low-effort distribution Dℓ.

    “otherwise, they choose a random grade from a fixed”
  • The authors state this as an assumption.

    If a grader makes an effort, they produce a noisy grade as usual.

    “If they choose to make an effort, they produce a noisy grade as usual”
  • The authors state this as an assumption.

    Effort decisions are independent of the content of the submission.

    “For simplicity, we model these effort decisions as being independent of the content of the submission.”
  • The authors state this as an assumption.

    Each submission is graded on C components with possible grades of {0, 1, ..., M} for each.

    “we assume that each submission is graded on C components C = {1, 2, . . ., C}, with possible grades of {0, 1, . . ., M } for each.”
  • The paper relies on this without support.

    Some low-effort students may adopt other, idiosyncratic strategies such as assigning everything a low or high grade.

    “Some low-effort students may adopt other, idiosyncratic strategies such as assigning everything a low or high grade.”
  • The paper relies on this without support.

    In practice, submissions are usually graded on coarse, discrete rubrics such as five-point scales, and virtually no class allows graders arbitrary decimal precision.

    “In practice, submissions are usually graded on coarse, discrete rubrics such as five-point scales (and virtually no class allows graders arbitrary decimal precision).”
  • The paper relies on this without support.

    Students expect to receive discrete grades rather than probability distributions.

    “However, students still expect to receive discrete grades rather than probability distributions.”
  • The paper relies on this without support.

    Students tend to fixate on low-quality peer reviews and strongly prefer for such graders to receive zero weights rather than small positive weights.

    “However, students also tend to fixate on low-quality peer reviews and strongly prefer for such graders to receive zero weights rather than small positive weights.”
  • The paper relies on this without support.

    The TAs were diligent and responsible.

    “Our TAs were diligent and responsible”
  • The paper relies on this without support.

    The gold-standard calibration submissions' grades were painstakingly agreed upon by the whole course staff.

    “these grades were painstakingly agreed upon by the whole course staff”
  • The paper relies on this without support.

    Giving accurate grades (for submissions or students' grading abilities) is a primary focus of peer grading systems.

    “Of course, giving accurate grades (either for submissions or students' grading abilities) is a primary focus of peer grading systems.”
  • The paper relies on this without support.

    Rewarding good grading only requires students to be ranked in the correct order.

    “rewarding good grading only requires students to be ranked in the correct order”
  • The paper relies on this without support.

    If the model is good at identifying low effort behavior, students will exhibit this behavior less often.

    “if the model is good at identifying low effort behavior, students will exhibit this behavior less often.”
  • The authors state this as an assumption.

    Low-effort graders in the model choose grades that are as difficult as possible to distinguish from effortful graders.

    “our low-effort graders choose grades that are as difficult as possible to distinguish from effortful graders.”
  • The paper relies on this without support.

    Coarse rubrics cause many high-effort grades to match the class average exactly.

    “The problem is exacerbated by coarse rubrics, which cause many high-effort grades to match the class average exactly.”
26 of 26

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Single-grader MIP output cannot generally equal the Gibbs-sample mean

    Minor

    With one peer grade, the MIP's weighted average must equal that reported grade. It cannot generally equal the mean of the Gibbs samples; the two could match only by coincidence.

  • Beta prior mean is misstated

    Minor

    The model defines the effort probability prior as Beta(α e, β e), whose mean is α e /(α e + β e), not α e /β e as stated in the hyperparameter discussion.

2 of 2

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Authors
Zarkoob, H., D'Eon, G., Podina, L., & Leyton-Brown, K.
Affiliations
University of British Columbia (CA)
Venue
Proceedings of the AAAI Conference on Artificial Intelligence
Published
2023-06-26
Volume
37
Issue
5
Pages
6137-6144
ISSN
  • 2159-5399 (ISSN-L)
  • 2374-3468
OpenAlex
W4382239954
Cited by
6
References
32
Citations by year
2026: 1 · 2025: 1 · 2024: 2 · 2023: 2
FWCI
1.81
Type
conference paper
Language
en
Open access
Locations
  • Proceedings of the AAAI Conference on Artificial Intelligence (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • AAAI Publications (The Association for the Advancement of Artificial Intelligence (AAAI)) (submittedVersion)
  • arXiv (Cornell University)
Funders
  • Canadian Institute for Advanced Research
  • Compute Canada
  • Alberta Machine Intelligence Institute
  • University of British Columbia
  • Defense Advanced Research Projects Agency (FA8750, FA8750-19-2-0222)
  • Simons Institute for the Theory of Computing, University of California Berkeley
  • Natural Sciences and Engineering Research Council of Canada
Topics
  • Physical Sciences › Computer Science › Computer Science Applications › Online Learning and Analytics
  • Social Sciences › Education › Student Assessment and Feedback
  • Physical Sciences › Computer Science › Information Systems › Educational Technology and Assessment
Keywords
peer grading, Bayesian inference, strategic reporting, censored data, rubrics, mixed integer programming, large classes, robustness

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-29.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-29.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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