CSC/ECE 517 Spring 2022 - E2212: Testing for hamer.rb

This page describes the changes made for the Spring 2022 OSS Project E2212: Testing for hamer.rb

About Expertiza

Expertiza is a multi-purpose web application built using Ruby on Rails for Students and Instructors. Instructors enrolled in Expertiza can create and customize classes, teams, assignments, quizzes, and many more. On the other hand, Students are also allowed to form teams, attempt quizzes, and complete assignments. Apart from that, Expertiza also allows students to provide peer reviews enabling them to work together to improve others' learning experiences. It is an open-source application and its Github repository is Expertiza.

Description

hamer.rb was the file that implemented one of the “reputation systems” that can be used to determine the reliability of peer reviewers. However, this file is no longer current, having been replaced by a web service in 2015. Therefore, we will be trying to describe and test this web service in the following sections.

Mentor

Ed Gehringer, efg@ncsu.edu

Team Members

• Joshua Lin (jlin36@ncsu.edu)
• Muhammet Mustafa Olmez (molmez@ncsu.edu)
• Soumyadeep Chatterjee (schatte5@ncsu.edu)

Reputation System

Online peer-review systems are now in common use in higher education. They free the instructor and course staff from having to provide personally all the feedbackthat students receive on their work. However, if we want to assure that all students receive competent feedback, or even use peer-assigned grades, we need a way tojudge which peer reviewers are most credible. The solution is to use a reputation system. The reputation system is meant to provide objective value to student assigned peer review scores. Students select from a list of tasks to be performed and then preparetheir work and submit it to a peer-review system. The work is then reviewed by other students who offer comments/graded feedback to help the submitters improvetheir work. During the peer review period it is important to determine which reviews are more accurate and show higher quality. Reputation is one way to achieve thisgoal; it is a quantization measurement to judge which peer reviewers are more reliable. Peer reviewers can use expertiza to score an author. If Expertiza shows aconfidence ratings for grades based upon the reviewers reputation then authors can more easily determine the legitimacy of the peer assigned score. In addition, theteaching staff can examine the quality of each peer review based on reputation values and, potentially, crowd-source a significant portion of the grading function.Currently the reputation system is implemented in Expertiza through web-service. The service does not work all the time although expertiza employees can sometimes run the system, we could not reach the service and values even though we tried it on our own local computer and vcl as well. Nevertheless, we have implement some test scenerios based on the algorithms used in the web service.

Algorithms

Reputation systems may take various factors into account: • Does a reviewer assign scores that are similar to scores assigned by the instructor (on work that they both grade)? • Does a reviewer assign scores that match those assigned by other reviewers? • Does the reviewer assign different scores to different work? • How competent has the reviewer been on other work done for the class?

There are two algorithms used, the Hamer-peer algorithm has the lowest maximum absolute bias and the Lauw-peer algorithm has the lowest overall bias.This indicates, from theinstructor’s perspective, if there are further assignments of this kind, expert grading may not be necessary. It is observed in the article (https://ieeexplore.ieee.org/abstract/document/7344292) that the overall bias is a little bit higher, but the max. absolute bias is very high (more than 20). This indicates that for future similar courses, the instructor can trust most students’ peer grading, but should be aware that the students may give inflated grades. Therefore spot-checking is necessary. However, overall bias is quite low, as the students gave grades at least 16 points lower than expert grades. This may because either more training is needed, or the review rubric is inadequate. The results also suggest that for future courses of this kind, the instructor cannot trust the students' grades; expert grades are still necessary. The main difference between the Hamer-peer and the Lauw-peer algorithm is that the Lauw-peer algorithm keeps track of the reviewer's leniency (“bias”), which can be either positive or negative. A positive leniency indicates the reviewer tends to give higher scores than average. Additionally, the range for Hamer’s algorithm is (0,∞) while for Lauw’s algorithm it is [0,1].

Test Plan

We followed the testing thought process recommended by Dr. Gehringer: In testing this service, we used an external program to send requests to a simulated service, and inspected the returned data. This decision was reached since our program of test was unfortunately not running, and could not be inspected in an ideal manner.

The test below sends real JSON to both peerlogic and mock. http://peerlogic.csc.ncsu.edu/reputation/calculations/reputation_algorithms

As we tested on the peerlogic and mock, current web-service is not correct, since the returned values do not match the expected values as can be seen in the picture. This is what we are supposed to reach in this project.
Proof of working:

Test Code Snippet:

require "net/http"
require "json"

INPUTS = {
    "submission9999": {
    "stu9999": 10,
    "stu9998": 10,
    "stu9997": 9,
    "stu9996": 5
    },
      "submission9998": {
    "stu9999": 3,
    "stu9998": 2,
    "stu9997": 4,
    "stu9996": 5
    },
      "submission9997": {
    "stu9999": 7,
    "stu9998": 4,
    "stu9997": 5,
    "stu9996": 5
    },
      "submission9996": {
    "stu9999": 6,
    "stu9998": 4,
    "stu9997": 5,
    "stu9996": 5
    }
}.to_json

EXPECTED = {
    "Hamer": {
    "9996": 0.6,
    "9997": 3.6,
    "9998": 1.1,
    "9999": 1.1
    }
}.to_json

describe "Expertiza" do
    it "should return the correct Hamer calculation" do
        uri = URI('http://peerlogic.csc.ncsu.edu/reputation/calculations/reputation_algorithms')
    
        response = Net::HTTP.post(uri, INPUTS, 'Content-Type' => 'application/json')
    
        expect(JSON.parse(response.body)["Hamer"]).to eq(JSON.parse(EXPECTED)["Hamer"])
    end
end

describe "Expertiza Web Service" do
    it "should return the correct Hamer calculation" do
        uri = URI('https://4dfaead4-a747-4be4-8683-3b10d1d2e0c0.mock.pstmn.io/reputation_web_service/default')
    
        response = Net::HTTP.post(uri, INPUTS, 'Content-Type' => 'application/json')
        expect(JSON.parse("#{response.body}}")["Hamer"]).to eq(JSON.parse(EXPECTED)["Hamer"])
    end
end

In addition, this plan enables us to test the current functionality by treating this system as a black box, and is able to provide conclusions on the accuracy of the implementation as a whole.

Therefore, in the section below, we have provided code that showcases this plan in action. The values returned by the algorithm are to be inspected both by code and by hand.

Simulation Code Segment to Test Web Service

import math

# Parameters: reviews list
# reviews list - a list of each reviewer's grades for each assignment
# Example:
# reviews = [[5,4,4,3,2],[5,3,4,4,2],[4,3,4,3,2]]
# Corresponding reviewer and grade for each assignment table
# Essay          Reviewer1 Reviewer2 Reviewer3
# Assignment1    5         5          4
# Assignment2    4         3          3
# Assignment3    4         4          4
# Assignment4    3         4          3
# Assignment5    2         2          2

# Reivewer's grades given to each assignment 2D array
# Each index of reviews is a reviewer. Each index in reviews[i] is a review grade
reviews = [[5,4,4,3,2],[5,3,4,4,2],[4,3,4,3,2]]

# Number of reviewers
numReviewers = len(reviews)
# Number of assignments
numAssig = len(reviews[0])
# Initial empty grades for each assignment array
grades = []
# Initial empty delta R array
deltaR = []
# Weight prime
weightPrime = []
# Reviewer's reputation weight
weight= []

# Calculating Average Weighted Grades per Reviewer
for numAssigIndex in range(numAssig):
    assignmentGradeAverage = 0
    for numReviewerIndex in range(numReviewers):
        assignmentGradeAverage += reviews[numReviewerIndex][numAssigIndex]
    grades.append(assignmentGradeAverage/numReviewers)
print("Average Grades:")
print(grades)

# Calculating delta R
for numReviewerIndex in range(numReviewers):
    reviewerDeltaR = 0
    assignmentAverageGradeIndex = 0
    for reviewGrade in reviews[numReviewerIndex]:
        reviewerDeltaR += ((reviewGrade - grades[assignmentAverageGradeIndex]) ** 2)
        assignmentAverageGradeIndex += 1
    reviewerDeltaR /= numAssig
    deltaR.append(reviewerDeltaR)
print("deltaR:")
print(deltaR)

# Calculating weight prime
averageDeltaR = 0
for reviewerDeltaR in deltaR:
    averageDeltaR += reviewerDeltaR
averageDeltaR /= numReviewers
print("averageDeltaR:")
print(averageDeltaR)

# Calculating weight prime
for reviewerDeltaR in deltaR:
    weightPrime.append(averageDeltaR/reviewerDeltaR)
print("weightPrime:")
print(weightPrime)
    
# Calculating reputation weight
for reviewerWeightPrime in weightPrime:
    if reviewerWeightPrime <= 2:
        weight.append(reviewerWeightPrime)
    else:
        weight.append(2 + math.log(reviewerWeightPrime - 1))
print("reputation per reviewer:")
i = 1
for reviewerWeight in weight:
    print("Reputation of Reviewer ", i)
    print(round(reviewerWeight,1))
    i += 1

Output

Reputation of Reviewer  1
1.0
Reputation of Reviewer  2
1.0
Reputation of Reviewer  3
1.0

Scenarios

1) Reviewer gives all max scores
2) Reviewer gives all min scores
3) Reviewer completes no review
alternative scenario - reviewer gives max scores even if no inputs

Conclusion

We as a team figured out the algorithms and applications and write some test scenarious. However, we did not have chance to work on web service since it does not work due to module errors. What we had is undefined method strip on Reputation Web Service Controller. Although sometimes it works on expertiza team side, we were not able to see the web service working. We created some test scenarios and write a python code for simulate the algorithm.
In the code segment written to simulate the hamer.rb algorithm as described in "A Method of Automatic Grade Calibration in Peer Assessment" by John Hamer Kenneth T.K. Ma Hugh H.F. Kwong (https://crpit.scem.westernsydney.edu.au/confpapers/CRPITV42Hamer.pdf), we take a list of reviewers and their grades for each assignment reviewed to compute the associated reputation weight. Since the algorithm described in the paper does not specify an original weight for first time reviewers, we coded it so the first time reviewers had an original weight of 1. In addition, this code does not have reviewer weights added in for reviewers who already have reputation weights but will be added in soon. Also, we followed the algorithm they mentioned in the paper to the dot, but even then the output values they wrote as the example did not match what we computed by hand and by code. In this situation, either we missed something completely or the algorithm has been changed. As we tested on the peerlogic and mock, current web-service is not correct, since the returned values do not match the expected values as can be seen in the picture. This can be what we are supposed to reach in this project.

GitHub Links

Link to Expertiza repository: here

Link to the forked repository: here

References

1. Expertiza on GitHub (https://github.com/expertiza/expertiza)
2. The live Expertiza website (http://expertiza.ncsu.edu/)
3. Pluggable reputation systems for peer review: A web-service approach (https://doi.org/10.1109/FIE.2015.7344292)