A study examined whether type of ownership affected editorial endorsement patterns and the impact of endorsements on voters. The endorsements of 51 California daily newspapers were tabulated for 25 statewide candidate races and 158 ballot propositions during elections of 1970, 1972, 1974, 1976, 1978, and 1980. Each endorsement was judged to represent either a liberal or a conservative stand on the candidate or issue at stake. To determine the impact of endorsement editorials, the election results in the circulation areas of newspapers and in the areas of group-owned and independently owned papers were compared with statewide averages for various propositions and candidate races. Results indicated that (1) endorsements by independently owned papers had more apparent impact than those of group-owned papers, (2) group-owned papers tended to take more liberal stands than independent papers, and (3) papers sold during the period under study tended to take more liberal stands after they changed hands. (HOD)