Table 1. Response rates.

	Australia	Canada	Denmark	Norway	Sweden	UK
Total number of households with connected telephone numbers approached	35 730	46 672	5369	8921	7411	80 210
Number of households of unknown eligibilitya	20 719	34 828	899	1922	1901	55 979
Number of households of known eligibility	15 011	11 844	4470	6999	5510	24 231
Number of households in which the individual declined to take part either during or after assessment of eligibility	433	1195	2337	4726	3345	3468
Number of ineligible householdsa	10 119	8571	12	24	19	13 234
Number of eligible householdsa	4892	3273	4458	6975	5491	10 997
Proportion of households eligible among those assessed for eligibility (%)	32.6	27.6	99.7	99.7	99.7	45.4
Completed interviews	4002	2064	2000	2009	2039	6965
Minimum response rate (%)b	15.9	5.4	31.5	23.2	28.0	10.5
Estimated response rate (%)c	47.4	38.8	31.6	23.0	27.5	40.0

^aA household was eligible if one or more people aged ⩾50 years lived in the household.

^bThe minimum response rate represents the response rate assuming all households that we could not assess for eligibility were eligible, in other words the lowest possible response rate. It is calculated as the number of complete interviews divided by the number of interviews plus the number of incomplete interviews among eligible people (refusals and break-offs plus non-contacts) plus the number of all households of unknown eligibility (equivalent to the American Association for Public Opinion Research response rate formula 1).

^cThe estimated response rate respresents the response rate after adjusting the size of the denominator for the likely proportion of housholds that were eligible. It is calculated by assuming that the proportion eligible among households of unknown eligibility is the same as the proportion of those tested for eligibility who were eligible (equivalent to American Association for Public Opinion Research response rate formula 3).