Calibration - VTS
Client: Cancer Council Victoria
Calibration adjusts for under- or over-represented groups in the sample, relative to the population, to account for differences between people who elect to participate in nonprobability online panels and the rest of the target population. For example, in 2018 the Cancer Council Victoria changed its tracking survey of smoking behaviour from a dual-frame RDD CATI survey to a nonprobability based online panel. The Social Research Centre used calibration methodology to adjust results from the nonprobability panel with the help of the Victorian Smoking and Health Survey which is a general population probability survey. As a result of calibration, the average absolute error was reduced by approximately 50% compared to the standard approach to weighting of nonprobability surveys.