Determining Minimum Test Length for Reliable Assessment Using Generalizability Theory: Evidence from an Economics Multiple-Choice Test
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| Title: | Determining Minimum Test Length for Reliable Assessment Using Generalizability Theory: Evidence from an Economics Multiple-Choice Test |
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| Language: | English |
| Authors: | Ossai Elizabeth Ngozika |
| Source: | African Educational Research Journal. 2026 14(1):128-133. |
| Availability: | Net Journals. 25 Akintola Road, Sapele, Delta State, 331107, Nigeria. e-mail: service@netjournals.org; Web site: https://www.netjournals.org/aer_index.html |
| Peer Reviewed: | Y |
| Page Count: | 6 |
| Publication Date: | 2026 |
| Document Type: | Journal Articles Reports - Research |
| Education Level: | Secondary Education |
| Descriptors: | Test Length, Test Reliability, Generalizability Theory, Economics Education, Multiple Choice Tests, Secondary School Students, Foreign Countries, Scores, Test Construction, Student Evaluation, Accuracy |
| Geographic Terms: | Nigeria |
| ISSN: | 2354-2160 |
| 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. |
| Abstractor: | As Provided |
| Entry Date: | 2026 |
| Accession Number: | EJ1502531 |
| Database: | ERIC |
| 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. |
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| ISSN: | 2354-2160 |
