The present study investigated varieties of C-lest as measures of General Language prolictenry (GLP). C-test was first introduced into language testing as a modification of close procedure. The original C-test was developed by mutilating the second half of every other vord. beginning from word two in sentence two of a passage. Through various studies, C-test proved afl integrative and a highly reliable and valid measure of GLP. The present study was also aimed at further confirming those findings by investigating not only the original C-test hut other varietis of C-test. To this end ten C-test versions were developed, by applying different deletion techniques and deletion rates, and were administered among nearly 500 senior Eli. students, in the way that each form was given to almost 50 subjects. All the subjects had already taken a TOEFI. and a ctose test prior to the administration of the C-tests. The results of data analyses showed that C-test may measure different things one of which might he general language proficienry and as such, not all varieties of C-test measure this construct to the same extent.
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