Table 1. WMH sample characteristics—developed and developing countries.
| Country | Surveya | Sample Characteristicsb | Field Dates | Age Range (y) | n (Part 1) | n (Part II) | n (Part II and Age≤44 yc) | Response Rated , e |
| I. Developed | ||||||||
| Belgium | ESEMeD | Stratified multistage clustered probability sample of individuals residing in households from the national register of Belgium residents. NR | 2001–2002 | 18+ | 2,419 | 1,043 | 486 | 50.6 |
| 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 | 2001–2002 | 18+ | 2,894 | 1,436 | 727 | 45.9 |
| Germany | ESEMeD | Stratified multistage clustered probability sample of individuals from community resident registries. NR | 2002–2003 | 18+ | 3,555 | 1,323 | 621 | 57.8 |
| Israel | NHS | Stratified multistage clustered area probability sample of individuals from a national resident register. NR | 2002–2004 | 21+ | 4,859 | — | — | 72.6 |
| Italy | ESEMeD | Stratified multistage clustered probability sample of individuals from municipality resident registries. NR | 2001–2002 | 18+ | 4,712 | 1,779 | 853 | 71.3 |
| Japan | WMHJ2002–2006 | Unclustered two-stage probability sample of individuals residing in households in ten metropolitan areas (Fukiage, Higashi-ichiki, Ichiki, Kushikino, Nagasaki, Okayama, Sano, Tamano, Tendo, and Tochigi) | 2002–2006 | 20+ | 3,416 | 1,305 | 425 | 59.2 |
| Netherlands | ESEMeD | Stratified multistage clustered probability sample of individuals residing in households that are listed in municipal postal registries. NR | 2002–2003 | 18+ | 2,372 | 1,094 | 516 | 56.4 |
| New Zealand | NZMHS | Stratified multistage clustered area probability sample of household residents. NR | 2004–2005 | 18+ | 12,790 | 7,312 | — | 73.3 |
| Spain | ESEMeD | Stratified multistage clustered area probability sample of household residents. NR | 2001–2002 | 18+ | 5,473 | 2,121 | 960 | 78.6 |
| United States | NCS-R | Stratified multistage clustered area probability sample of household residents. NR | 2002–2003 | 18+ | 9,281 | 5,691 | 3,196 | 70.9 |
| II. Developing | ||||||||
| Brazil | São Paulo Megacity | Stratified multistage clustered area probability sample of household residents in the São Paulo metropolitan area. | 2005–2007 | 18+ | 5,037 | 2,942 | — | 81.3 |
| Bulgaria | NSHS | Stratified multistage clustered area probability sample of household residents. NR | 2003–2007 | 18+ | 5,318 | 2,233 | 741 | 72.0 |
| 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 | 18–65 | 4,426 | 2,381 | 1,731 | 87.7 |
| India | WMHI | Stratified multistage clustered area probability sample of household residents in Pondicherry region. NR | 2003–2005 | 18+ | 2,992 | 1,373 | 825 | 98.6 |
| Lebanon | LEBANON | Stratified multistage clustered area probability sample of household residents. NR | 2002–2003 | 18+ | 2,857 | 1,031 | 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). | 2001–2002 | 18–65 | 5,782 | 2,362 | 1,736 | 76.6 |
| Nigeria | NSMHW | Stratified multistage clustered area probability sample of households in 21 of the 36 states in the country, representing 57% of the national population. The surveys were conducted in Yoruba, Igbo, Hausa, and Efik languages. | 2002–2003 | 18+ | 6,752 | 2,143 | 1,392 | 79.3 |
| PRC | B-WMH S-WMH | Stratified multistage clustered area probability sample of household residents in the Beijing and Shanghai metropolitan areas. | 2002–2003 | 18+ | 5,201 | 1,628 | 859 | 74.7 |
| PRC | Shenzhen | Stratified multistage clustered area probability sample of household residents and temporary residents in the Shenzhen area. | 2006–2007 | 18+ | 7,132 | 2,475 | 2,190 | 80.0 |
| Romania | RMHS | Stratified multistage clustered area probability sample of household residents. NR | 2005–2006 | 18+ | 2,357 | — | — | 70.9 |
| South Africa | SASH | Stratified multistage clustered area probability sample of household residents. NR | 2003–2004 | 18+ | 4,315 | — | — | 87.1 |
| Ukraine | CMDPSD | Stratified multistage clustered area probability sample of household residents. NR | 2002 | 18+ | 4,724 | 1,719 | 714 | 78.3 |
B-WMH, The Beijing World Mental Health Survey; CMDPSD, Comorbid Mental Disorders during Periods of Social Disruption; 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; NHS, Israel National Health Survey; NSHS, Bulgaria National Survey of Health and Stress; NSMH, The Colombian National Study of Mental Health; NSMHW, The Nigerian Survey of Mental Health and Wellbeing; NZMHS, New Zealand Mental Health Survey; RMHS, Romania Mental Health Survey; SASH, South Africa Stress and Health Study; S-WMH, The Shanghai World Mental Health Survey; WMHI, World Mental Health India; WMHJ2002–2006, World Mental Health Japan Survey.
Most WMH surveys are based on stratified multistage clustered area probability household samples in which samples of areas equivalent to counties or municipalities in the US were selected in the first stage followed by one or more subsequent stages of geographic sampling (e.g., 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. The Japanese sample is the only totally unclustered sample, with households randomly selected in each of the four sample areas and one random respondent selected in each sample household. 16 of the 22 surveys are based on nationally representative (NR) household samples, while two others are based on NR household samples in urbanized areas (Colombia, Mexico).
Brazil, Israel, New Zealand, Romania, and South Africa did not have an age restricted part II sample. All other countries, with the exception of India, Nigeria, the People's Republic of China, and Ukraine (which were age restricted to ≤39 y) were age restricted to ≤44 y.
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 of being vacant at the time of initial contact or because the residents were unable to speak the designated languages of the survey.
The weighted average response rate is 73%.