Theories of Language Testing

Theories of Language Testing
Theories of Language Testing

Theories of Language Testing



The needs of assessing the outcome of learning have led to the development and elaboration of different test formats. Testing language has traditionally taken the form of testing knowledge about language, usually the testing of knowledge of vocabulary and grammar.

Language tests are formal instruments of assessment. They can be used either to measure proficiency without reference to a particular programme of learning or to measure the extent to which learners have achieved the goals of a specific course. The language tests that adult migrants are sometimes required to take in order to secure entry to their host country, permanent residence or citizenship, may fall into either of these categories.

Language tests are not necessarily the most appropriate form of assessment to use with adult migrants, especially when linked to financial or social sanctions, because they can undermine motivation to learn. In some circumstances, particularly when assessment is associated with a language course, it may be preferable to use an alternative instrument, for example a portfolio.




Classical Test Theory (CTT), also known as the true score theory, refers to the analysis of test results based on test scores. The statistics produced under CTT include measures of item difficulty, item discrimination, measurement error and test reliability. The term “Classical” is used in contrast to “Modern” test theory which usually refers to item response theory (IRT). The fact that CTT was developed before IRT does not mean that CTT is outdated or replaced by IRT.

Both CTT and IRT provide useful statistics to help us analyse test data. Generally, CTT and IRT provide complementary results. For many item analyses, CTT may be sufficient to provide the information we need. There are, however, theoretical differences between CTT and IRT, and many researchers prefer IRT because of enhanced measurement properties under IRT.

IRT also provides a framework that facilitates test equating, computer adaptive testing and test score interpretation. While this book devotes a large part to IRT, we stress that CTT is an important part of the methodologies for educational and psychological measurement. In particular, the exposition of the concept of reliability in CTT sets the basis for evaluating measuring instruments. A good understanding of CTT lays the foundations for measurement principles. There are other approaches to measurement such as generalizability theory and structural equation modeling.

  1. Generalizability theory

Generalizability theory (G theory), originally developed by Lee J. Cronbach and his associates, is a measurement theory that provides both a conceptual framework and a set of statistical procedures for a comprehensive analysis of test reliability. Building on and extending classical test theory (CTT) and analysis of variance (ANOVA), G theory provides a flexible approach to modeling measurement error for different measurement conditions and types of decisions made based on test results.

Reliability investigation in educational measurement, and consequently in language assessment, primarily focuses on estimating the consistencies and inconsistencies in test scores.

Therefore, we contend that generalizability (G) theory allows the design of psychometric approaches to testing English-language learners (ELLs) that are consistent with current thinking in linguistics. We used G theory to estimate the amount of measurement error due to code (language or dialect).


This sensitivity to language appears to take place at the level of dialect. Also, students from different speech communities within the same broad linguistic group may differ considerably in the number of items needed to obtain dependable measures of their academic achievement. Whether students are tested in English or

in their first language, dialect variation needs to be considered if language as a source of measurement error is to be effectively addressed.


  1. Item response theory (IRT)

Item response theory is a method of developing and scoring tests that attempts to have questions of different difficulty in such a way that the total test maximally differentiates people in terms of ability on the underlying trait.

Item response theory (IRT) models, in their many forms, are undoubtedly the most widely used models in large-scale operational assessment programs. They have grown from negligible usage prior to the 1980s to almost universal usage in large-scale assessment programs, not only in the United States, but in many other countries with active and up-to-date programs of research in the area of psychometrics and educational measurement.

Language test tasks and items are particularly susceptive to factors that make responses by test candidates ambiguous. Such factors include random error, guessing, compromised test security, and systematic bias. Test analysis technology has evolved since the 1970s to reduce the influence of such construct-irrelevant factors on test score interpretation.

Theories of Language Testing


Language testing is concerned with the measurement of language knowledge. Language knowledge is the trait and how we go about measuring it is the method.  

Language tests should be taken under conditions which are equally fair for all test-takers. This entails that test centres are suitably accredited for the administration of the tests and meet general quality requirements; test centre staff are professionally competent; a high level of security and confidentiality is maintained throughout the testing process; physical conditions in the test centre are appropriate (e.g. noise and temperature level, distance between candidates); and all necessary arrangements are made for test takers with special requirements. If not appropriately managed, each aspect of test administration has the potential to infringe the human rights of test-takers.


BACHMAN, L. F. (1990) Fundamental Considerations in Language Testing. Oxford: Oxford University Press.

BAKER, D. (1988) Language Testing: A Critical Surveyand Practical Guide. London: Edward Amold.

DAVIES, A. (1990) PrincipIes of Language Testing. Oxford: Blackwell

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