Table 1.

WMH sample characteristics by World Bank income categories^a

					Sample size
Country by income category	Surveyb	Sample characteristicsc	Field dates	Age range	Part I	Part II	Part II aged 18–44	Response rated
Low and lower middle income countries
Colombia	NSMH	All urban areas of the country (approximately 73% of the total national population).	2003	18–65	4,426	2,381	1,731	87.7
Peru	EMSMP	Five urban areas of the country (approximately 38% of the total national population).	2004–5	18–65	3,930	1,801	1,287	90.2
Total					(8,356)	(4,182)	(3,018)	88.9
Upper-middle income countries
Brazil - São Paulo	São Paulo Megacity	São Paulo metropolitan area.	2005–8	18–93	5,037	2,942	1,824	81.3
Colombia – Medelline	MMHHS	Medellin metropolitan area	2011–12	19–65	3,261	1,673	970	97.2
Mexico	M-NCS	All urban areas of the country (approximately 75% of the total national population).	2001–2	18–65	5,782	2,362	1,736	76.6
Romania	RMHS	Nationally representative.	2005–6	18–96	2,357	2,357	940	70.9
Total					(16,437)	(9,334)	(5,470)	80.5
High-income countries
N. Ireland	NISHS	Nationally representative.	2005–8	18–97	4,340	1,986	907	68.4
Poland	EZOP	Nationally representative	2010–11	18–65	10,081	4,000	2,276	50.4
Spain - Murcia	PEGASUS- Murcia	Murcia region.	2010–12	18–96	2,621	1,459	631	67.4
United States	NCS-R	Nationally representative.	2001–3	18–99	9,282	5,692	3,197	70.9
Total					(26,324)	(13,137)	(7,011)	60.8
TOTAL N					(51,117)	(26,653)	(15,499)	69.9

^aThe World Bank (2012) Data. Accessed May 12, 2012 at: http://data.worldbank.org/country. Some of the WMH countries have moved into new income categories since the surveys were conducted. The income groupings above reflect the status of each country at the time of data collection. The current income category of each country is available at the preceding URL.

^bNSMH (The Colombian National Study of Mental Health); EMSMP (La Encuesta Mundial de Salud Mental en el Peru); MMHHS (Medellín Mental Health Household Study); M-NCS (The Mexico National Comorbidity Survey); RMHS (Romania Mental Health Survey); NISHS (Northern Ireland Study of Health and Stress); EZOP (Epidemiology of Mental Disorders and Access to Care Survey); PEGASUS-Murcia (Psychiatric Enquiry to General Population in Southeast Spain-Murcia);NCS-R (The US National Comorbidity Survey Replication).

^cMost 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. Several WMH surveys (Poland, Spain-Murcia) used country resident or universal health-care registries to select respondents without listing households. 4 of the 10 surveys are based on nationally representative samples.

^dThe 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 69.9%.

^eColombia moved from the “lower and lower-middle income” to the “upper-middle income” category between 2003 (when the Colombian National Study of Mental Health was conducted) and 2010 (when the Medellin Mental Health Household Study was conducted), hence Colombia’s appearance in both income categories. For more information, please see footnote a.