The question used to register people's assessment of the overall condition is (in Cantonese): "Hong Kong has already reunified with China for [so many days/years], do you think the overall condition now is better or worse?" The respondents should have used the condition shortly before the handover in 1997 as their benchmarks, and then compared the prevailing conditions with that benchmark. Obviously, memory lapses and comparison becomes less accurate as time rolls on. However, four years is only a short period, and respondents' assessment should be rather accurate.