Electronic group measurement systems to this point were not portable. Technological advances in microcomputer development made possible the first portable system in the early 80's, introduced by PEAC Research in Toronto. This allowed flexibility in testing locations and for the first time, researchers were not restricted to wired theaters and permanent rooms. The PEAC system stored participant reactions in a data buffer located in the hand held units. Later, collected data would be down loaded into a central processing unit for analysis.
Today there are several respondent input devices available for gauging continuous audience response.
Some input units combine the keypad function with the dial or slider. There are advantages and disadvantages to each type of input device, but dial based systems tend to be the most commonly used for testing continuous material like audio and video. Professor G. David Hughes, at the University of North Carolina, introduced one of the first dial systems, which used a 0 to 7 scale. Most of the dial or slider based systems currently use a 0 to 10 or 0 to 100 scale and can record even minor variations in reaction. Responses can be displayed as a line graph for the group as a whole, with additional lines representing particular subgroups or segments defined by answers to earlier categorical questions.