Citations:incall


 * 1981, Benjamin D. Singer, Social functions of the telephone, R & E Pub, page 17:
 * Further studies may be made of three categories of outcallers, low, typical, and high, in order to assess, e.g., the socioeconomic characteristics of each group, as well as utilty, trip substitution, sociation and other functions performed for each usage group. A measure of association between outcalls and incalls will also be of interest.