Generalisoitavuusteoria

Generalisoitavuusteoria, often translated as Generalizability Theory, is a statistical framework developed by Lee Cronbach and his colleagues in the 1960s. It is used to analyze the reliability of measurements, particularly in educational and psychological testing. Unlike traditional classical test theory which often focuses on a single estimate of reliability (like Cronbach's alpha), generalizability theory allows for the examination of various sources of error or variability that can affect a test score.

The core idea is to partition the total variance of a test score into different components. These components can include variance due to the person being measured, variance due to the items or tasks within the test, variance due to the conditions under which the test is administered, and even interactions between these factors. By quantifying these different sources of error, generalizability theory provides a more nuanced understanding of how reliable a measurement truly is across different facets of the testing situation.

This approach is particularly useful when a measurement procedure involves multiple facets that could influence the score. For example, if a student's performance is assessed by multiple raters, or across multiple test items, or in different testing sessions, generalizability theory can help determine how much of the observed score variation is due to the student's actual ability and how much is due to the raters, items, or sessions. The ultimate goal is to estimate the dependability of scores under specific conditions and to identify which sources of variation are most problematic, allowing for improvements in measurement design.