A. C. Nielsen Co. is expected to reveal plans in Los Angeles today to more accurately measure the size and makeup of audiences watching national network and cable-TV programming.
In a marked break with its past practices, the ratings company is expected to announce that it gradually will adopt a new ratings technology to measure the individual viewing of TV programs rather than aggregate household tune-in patterns.
As part of the new system, Nielsen plans eventually to increase the size of its national sample of electronically surveyed homes to 6,000 from the current 1,700.
The company said that the new system could cut in half its standard margin of error in national TV ratings.
Full implementation of the new ratings system is planned for September, 1988, said Nielsen spokesman Larry Frerk. Details of the new system are expected to be unveiled at a meeting of Nielsen's clients this morning at the Century Plaza Hotel in Century City.