A new BARB Audience Measurement Service for the UK was introduced in August 1991 using larger more dispersed samples. Among its most important innovations has been disproportionate demographic sampling in favour of certain key target audience sub-groups in all but two of its 14 regional panels. This paper summarises the nature and degree of the disproportionate sampling employed. Due primarily to the regionality of terrestrial commercial television, the BARB Audience Measurement Service is based on geographically disproportionately sampled regional panels. Now that demographic disproportionate sampling is also employed within them, rim weighting procedures are used at both the regional and national level. This paper summarises the actual and effective sample sizes achieved. The Replication Study published by Arbitron in 1977 demonstrated that for a television audience measurement panel the averaging of separate estimates increases the efficiency of the result In 1980 a corresponding study of the UK measurement service was commissioned by JICTAR from AGB, and its findings endorsed those of the Arbitron study. The authors have conducted a repetition of the 1980 JICTAR study on the new BARB panel using the data for February 1992 in order to evaluate the gains and losses in efficiency due to disproportionate sampling and the possible increases in efficiency due to larger more dispersed samples, people-meter measurement, and a more fragmented market. The results show that there has been an increase in the efficiency gains as a result of averaging, which more than compensate for the small loss in efficiency from weighting. Such gains in efficiency tend to be greater for small audience categories and lower ratings.