Time limits on tests often prevent some examinees from finishing all of the items on the test; the extent of this effect has been called the "speededness" of the test. Traditional speededness indices focus on the number of unreached items. Other examinees in the same situation rapidly fill in answers in the hope of getting some of the items right by chance. Those examinees who do not have unanswered items are not included in traditional measures of speededness. To obtain an accurate measure of speededness, however, those who guess rapidly also need to be included in the estimate of speededness. They will have very fast response times, and the responses will be at or near chance levels of accuracy. Therefore, item response times, in conjunction with accuracy rates, can be used to identify these examinees and provide a more rigorous measure of speededness than has previously been available. Analyses based on item response time distributions in the analytical section of the Graduate Record Examinations (GRE) General Test for over 17,000 examinees indicate that many examinees do guess rapidly on items and that the test is more speeded than traditional measures of speededness indicate. Six tables and seven figures present analyses results. (Contains eight references.) (Author)