Dichotomous Items

True  or False   and Yes or No  items  are generally unsatisfactory , as there is a 50%  possibility of getting  any item right by chance alone. In order  to learn anything  about a student`s  ability, it is necessary  to have a large  number of such items in order  to discount  the effects of chance.  The item writer reduces  trhe possibility of correct guessing  by including a third category such as " not given"  or " does not say" . This  can be useful  in a reading  comprehension text , but in a listening comprehension, especially  where the text  is only played once, it can be demanding and can lead to student`s confusion