Creating a Common Scale by Post-Hoc IRT Equating to Investigate the Effects of the New National Educational Policy in Japan

The new national educational policy was implemented at secondary schools in 2002 in Japan. The revised Course of Study for foreign language education corresponding to the national educational policy decreased the number of English lessons per week from four to three at the junior high school level, which resulted in a 25% decrease in English teaching hours over the year. Because there were no nationwide English tests to investigate the effects of this policy, this study used a prefecture-wide English test for high school students to examine the trends in English scores during the implementation of the new educational policy. Because the test was not developed with an equating design, which is common in Japan, the scores of the tests administered in different years were not comparable on a common scale. Therefore, post-hoc Item Response Theory (IRT) equating, which makes the scores of tests comparable after their administration, was conducted on the test forms that were administered from 2003 to 2008. The results showed an overall decline in the English ability measured by the test after the implementation of the new educational policy. A close examination of the data revealed that the scores of students with a lower proficiency in English showed a particularly larger drop during that period.