| Country | Survey name* | Design overview† | Field dates | Sample size‡ | Response rate§ | ||
| (n1) | (n2) | ||||||
| Belgium | ESEMeD | Stratified multistage clustered probability sample of individuals residing in households from the national register of Belgium residents. NR | 2001–2 | (15) | (486) | 50.6 | |
| Colombia | NSMH | Stratified multistage clustered area probability sample of household residents in all urban areas of the country (approximately 73% of the total national population) | 2003 | (22) | (1731) | 87.7 | |
| France | ESEMeD | Stratified multistage clustered sample of working telephone numbers merged with a reverse directory (for listed numbers). Initial recruitment was by telephone, with supplemental in-person recruitment in households with listed numbers. NR | 2001–2 | (39) | (727) | 45.9 | |
| Germany | ESEMeD | Stratified multistage clustered probability sample of individuals from community resident registries. NR | 2002–3 | (19) | (621) | 57.8 | |
| Italy | ESEMeD | Stratified multistage clustered probability sample of individuals from municipality resident registries. NR | 2001–2 | (32) | (853) | 71.3 | |
| Lebanon | LEBANON | Stratified multistage clustered area probability sample of household residents. NR | 2002–3 | (5) | (595) | 70.0 | |
| Mexico | M-NCS | Stratified multistage clustered area probability sample of household residents in all urban areas of the country (approximately 75% of the total national population) | 2001–2 | (27) | (1736) | 76.6 | |
| Netherlands | ESEMeD | Stratified multistage clustered probability sample of individuals residing in households that are listed in municipal postal registries. NR | 2002–3 | (22) | (516) | 56.4 | |
| Spain | ESEMeD | Stratified multistage clustered area probability sample of household residents. NR | 2001–2 | (16) | (960) | 78.6 | |
| USA | NCS-R | Stratified multistage clustered area probability sample of household residents. NR | 2002–3 | (139) | (3197) | 70.9 | |
*ESEMeD, The European Study of the Epidemiology of Mental Disorders; LEBANON, Lebanese Evaluation of the Burden of Ailments and Needs of the Nation; M-NCS, The Mexico National Comorbidity Survey; NCS-R, The US National Comorbidity Survey Replication; NR, nationally representative; NSMH, The Colombian National Study of Mental Health.
†Most WMH surveys are based on stratified multistage clustered area probability household samples in which samples of areas equivalent to counties in the UK were selected in the first stage followed by one or more subsequent stages of geographic sampling (eg, towns within counties, blocks within towns, households within blocks) to arrive at a sample of households, in each of which a listing of household members was created and one or two people were selected from this listing to be interviewed. No substitution was allowed when the originally sampled household resident could not be interviewed. These household samples were selected from census area data in all countries other than France (where telephone directories were used to select households) and the Netherlands (where postal registries were used to select households). Several WMH surveys (Belgium, Germany, Italy) used municipal resident registries to select respondents without listing households. Eight of the 10 WMH surveys considered here are based on nationally representative (NR) household samples, while the two others are based on nationally representative household samples in urbanised areas (Colombia, Mexico).
‡ADHD was assessed only among respondents the age range 18–44 in the part II sample of each survey. Our focus is on the subsample of these respondents who were employed at the time of interview. The respondents within this subsample who were classified as meeting criteria for DSM-IV adult ADHD are reported in the column labelled n1, while the total subsample of employed part II respondents in the age range 18–44 are reported in the column labelled n2.
§The response rate is calculated as the ratio of the number of households in which an interview was completed to the number of households originally sampled, excluding from the denominator households known not to be eligible either because they were vacant at the time of initial contact or because the residents were unable to speak the designated languages of the survey.