Determining minimum test length for reliable assessment using generalizability theory - Evidence from an economics multiple-choice test

Oct 15, 2026

Uploaded by Patrick

This study investigated the reliability of a multiple-choice Economics test for senior secondary school students using Generalizability Theory, aiming to identify the minimum test length for dependable assessment. A stratified random sample of 350 SS2 students was selected from 3,869 students in government schools in Nsukka Education Zone, Enugu State, Nigeria. The 50-item test was administered twice, and variance components for students, items, occasions, and interactions were analyzed with EduG software to determine acceptable reliability targets.

LanguageEnglish

CategoryExam

FormatPDF

Pages6

Reading Time15 min

AccessFree to download

Introduction

Assessment and reliability in Economics

Classical Test Theory limitations

Generalizability Theory as a reliability framework

African Educational Research Journal Vol. 14(1), pp. 128-133, February 2026 ISSN: 2354-2160 Full Length Research Paper Determining minimum test length for reliable assessment using generalizability theory: Evidence from an economics multiple-choice test Ossai Elizabeth Ngozika Department of Science Education, University of Nigeria, Nsukka. Accepted 24 February, 2026 | ABSTRACT
This study investigated the reliability of a multiple-choice Economics test for senior secondary school students using Generalizability Theory, with the goal of determining the minimum test length required for dependable assessment. A stratified random sample of 350 SS2 students was drawn from 3,869 students in government secondary schools in Nsukka Education Zone, Enugu State, Nigeria. The Economics Multiple Choice Test, consisting of 50 items, was administered twice to capture occasion-related variance. Data were analyzed using EduG software version 6. 1e. The Generalizability study estimated variance components for students, items, occasions, and their interactions, while the Decision study simulated changes in test length to identify the minimum number of items needed for acceptable reliability. Results indicated that student item interactions and residual error were the major sources of score variability, whereas item and occasion effects were minimal. Relative reliability reached acceptable levels with 51 items, but absolute reliability required 52 items. The study demonstrates that carefully designed test length is critical for reliable assessment and recommends using Generalizability Theory to guide test development, ensuring accurate and trustworthy evaluation of student performance.
Keywords: Generalizability theory, test reliability, multiple-choice test, economics education, test length. | | --- | | Email: [elizabethngozika@gmail.com](elizabethngozika@gmail.com). | INTRODUCTION Assessment is a fundamental component of education, providing essential information about learners’performance and the effectiveness of instructional practices (Nworgu, 2015) . In senior secondary school Economics education, accurate assessment is particularly important because the subject emphasizes critical thinking, economic reasoning, and decisionmaking skills (Ezigbo, 2014) . Economics has been defined as the study of scarcity and the allocation of limited resources to meet human needs (American Economic Association, 2016) . As a discipline, it equips learners with analytical tools to evaluate economic policies, interpret data, and participate in national development. Effective teaching and learning in Economics, therefore, must be supported by valid and reliable assessment instruments that accurately capture students’ knowledge and skills. Assessment in education is commonly carried out using structured tools such as tests, which measure learners’ achievement in specific domains (Nworgu, 2015) . A test is defined as a set of items designed to elicit responses that reflect the extent to which an individual possesses a particular trait or knowledge domain. Among the types of tests used in the cognitive domain are essay tests, which allow openended responses (Nwagu, 2015), and objective tests, such as multiple-choice tests, in which examinees select Ossai 129 the correct answer from a set of options (Ifeakor, 2011) . Multiple-choice tests, in particular, are widely used in Economics education because they efficiently assess abroad range of content and cognitive skills. Despite the use of structured assessments, students’ performance in Economics in the West African Senior School Certificate Examination (WASSCE) has been consistently low in recent years. WAEC Chief Examiners’ Reports (2023– 2025) indicate that students frequently struggle to apply economic concepts, interpret data, and analyze relationships among economic variables. In 2025, performance on objective questions declined sharply due to changes in examination design and anti

FAQs

What was the main goal of the study?

To determine the minimum number of items needed for reliable assessment of Economics using Generalizability Theory.

How was the Economics multiple-choice test administered?

The 50-item test was administered twice to capture occasion-related variance.

Which variance sources contributed most to score variability?

Student-by-item interactions and residual error were the major sources of variability, while item and occasion effects were minimal.

Oct 15, 2026

Uploaded by Patrick