QUALITY ISSUES IN TELEPHONE SURVEYS: COVERAGE, NON-RESPONSE and QUOTA SAMPLING

The quality of a telephone survey is affected by several factors: telephone coverage, non-response, the methods used to select households and persons, and the quality of responses obtained from respondents. Data are provided which show that a large proportion of Australian households have telephone connections. However, telephone coverage is not uniform and some subgroups of the population have much lower connection rates. This paper reviews evidence of the effect of non-response and the effectiveness of repeated call backs, and reports the results of a new study. The use of quota sampling to select respondents from randomly selected households is also examined. The results suggest that telephone surveys under-represent older persons and the unemployed, and over-represent middle-aged persons. It is shown that while call backs can increase the response rate, the effect on the composition of the sample and resulting estimates is minimal. The main effects are due to refusals and variation in coverage rates.