An Explanation for Differences between Stop-Watch and Mechanical Timing of Races

Abstract

To ascertain the reasons for the differences between stop-watch and mechanical timing of races, each of the 11 timers participating in the study underwent two tests. In the first test, the delayed reaction of the timer to the firing of the starter's gun was measured. The second test was designed to determine how nearly simultaneously the timer stops his watch with the crossing of the finish line by a runner. The most important results were that: (1) the reaction lag in the timer's starting his stop-watch averages about 0.2 sec. and (2) the timer stops his watch on the average when the runner still has about 13.5 cm. to go before breasting the tape. It is noteworthy that this result was obtained under a test situation in which the timer had no reason to hope that the runner would make “good” time. In the hope or anticipation of a record, the likelihood is that the timer's watch would be stopped distinctly sooner. (3) The tests clearly demonstrate that the reason for the differences between stop-watch and mechanical timing is the delayed reaction of the timer in starting his watch at the start of a race, a loss not cancelled out at the finish. The difference in the timing results by the two methods tends rather to increase at the finish.