This study used data from March 2014 (when alcohol questions were first asked) until August 2021 from adults aged 18+. From March 2014 to February 2020, data were collected through face-to-face computer-assisted interviews. No data were collected in March 2020 because of the COVID-19 related social distancing restrictions, and from April 2020 onwards, data were collected via telephone using the same sampling and weighting approach (diagnostic analyses indicate good comparability between collection modalities21).
