A universal timer system with selectable time base and clock output is operable in several modes, including a plurality of timers interconnected in a sequentially mutually exclusive operation mode. In this mode, a succession of n number of events is counted using n number of timer units. The initial event is counted and timed on unit no. 1, the second on unit no. 2, etc., each unit operating to the mutual exclusion of all others. A group of three displays for each unit provides unique statistical information about each event which is useful to the time study engineer or statistician in computing values such as the number of observations necessary for a specific level of confidence, so that a real time determination of the required duration of study may be made.