utility of complex alternatives in multiplechoice items: the case of all of the above

This study investigated the utility of all of the above (aota) as a test option in multiplechoice items. it aimed at estimating item fit, item difficulty, item discrimination, and guess factor of such a choice. five reading passages of the key english test (ket, 2010) were adapted. the test was reconstructed in 2 parallel forms: test 1 did not include the abovementioned alternative, whereas test 2, administered 2 weeks later, included such an alternative. the 2 tests, 32 items each, were administered to 142 high school thirdgraders. results, analyzed through 3parameter logistic model, indicated that the multiplechoice questions, including the alternative all of the above, were easier. results also revealed that the option all of the above increased the guess factor. because guess factor is a source of measurement error, it may threaten test validity and reliability.