This paper presents the results of analyses of viewing and listening rates observed in 1974, 1976, and 1977 surveys of student use of Open University broadcasting in conjunction with data regarding transmission times and number of television or radio programs per course. In this analysis, nine different transmission time categories are identified, from very early weekday morning to late night transmission. Data are summarized for all courses included in the three broadcast surveys regarding: transmission time combinations for television broadcasting; number of TV programs in the course; expected and observed viewing rates for all students and for non-dropouts; residual viewing rates, i.e., difference between observed and expected rate, for all students and for non-dropouts. Analyses of these data led to the following main conclusions: (1) the allocation of transmission times, for first or second, or for single transmissions, can considerably affect the viewing/listening rates for the broadcasts; (2) TV viewing rates are to some extent affected by the number of programs in each course; no similar correlation has been observed between listening rate and number of programs for radio broadcasts; (3) most of the variation (80+%) among courses in viewing/listening rates must be attributed to factors other than transmission time variation. (VT)