Table 1:  environmental and demographic factors with their definitions and data sources
Factor	Definition	Data source
Percentage of households practicing open defecation	Number of households practicing open defecation divided by the total number of households, expressed as a percentage. For the purpose of this study open defecation includes the following modes of human waste disposal from the 2009 census: bush, bucket, and other.	2009 Kenya Population and Housing Census
Percentage of households using an improved water source	Number of households with access to an improved water source divided by the total number of households, expressed as a percentage. Improved water sources include the following categories from the 2009 census: protected spring, protected well, borehole, piped into dwelling, piped, rain water collection; does not include pond, dam, lake, stream/river, unprotected spring, unprotected well, jabia^+, water vendor, or other.	2009 Kenya Population and Housing Census, 10% micro-data set
Poverty headcount ratio	Percentage of persons living below the poverty line, calculated as the number of persons living below the poverty line divided by the total population.	2005/2006 Kenya Integrated Household Budget Survey data as presented in “Exploring Kenya’s Inequality” report, 2013
Percentage of population with at least some secondary education	Number of people with at least some secondary or higher level education divided by the total population, expressed as a percentage. From the 2009 census the following categories of highest level of education reached were included: secondary, tertiary, university, and youth polytechnic. The following categories were not included: never attended, pre-primary, primary, basic literacy, and madrassa.	2009 Kenya Population and Housing Census
Percentage of population living in urban areas	Population living in urban centers (settlements with population estimated at 2,000 or higher during the 2009 census) divided by total population, expressed as a percentage.	2009 Kenya Population and Housing Census
Population density	Number of people per unit area. In the 2009 census, population density is expressed as number of people per square kilometer.	2009 Kenya Population and Housing Census
Number of health facilities per 100,000 population	Number of healthcare facilities in a district divided by district population and expressed per 100,000 people. Healthcare facilities include public, non-governmental, faith-based, and private facilities. Data were derived from the Ministry of Health’s Master Facility List. The following categories of facilities were not included: HIV counseling and testing center, nursing home, regional blood transfusion center, training institution, dental clinic, laboratory, radiology unit, health project, and facilities labeled as “not operational” or “pending opening.”	Ministry of Health Master Facility List, http://www.ehealth.or.ke accessed 23 Oct 2013
^+“jabia” is a term used in Kenya to describe a traditional rainwater storage system