Inclusion of mobile telephone numbers into an ongoing population health survey in New South Wales, Australia, using an overlapping dual-frame design: impact on the time series

Table 6 Summary of the factors used to predict if the design change was likely to impact on the time series

Health indicators	50% or more different for non-landline frame	Association between phone usage and indicator	Sig diff 2011 and 2012 (dual- frame)	Sig diff 2011 and 2012 (landline frame)	Change in significance between sampling designs	Change in direction between sampling designs
Five or more drinks of alcohol in a day	√	√
More than two alcoholic drinks in a day				√	√
Recommended fruit intake			√	√
Recommended vegetable intake		√	√	√
Current smoking	√	√	√		√	√
Adequate physical activity
Positive self-reported health status			√		√
Current asthma
Ever diagnosed with diabetes
Overweight or obese		√	√		√	√

ISSN: 1756-0500