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STS489 Danielle J.R. et al.
                  2. Methodology
                    Study Area and Data
                     This  study  uses  data  collected  in  the Demographic  and  Health  Surveys
                  (DHS)  and  Malaria  Indicator  Surveys  (MIS)  carried  out  in  Kenya,  Malawi,
                  Tanzania and Uganda between 2015 and 2017, namely the 2015 Kenya Malaria
                  Indicator  Survey  (KMIS2015),  the  2017  Malawi  Malaria  Indicator  Survey
                  (MMIS2017), the 2015-2016 Tanzania Demographic and Health Survey and
                  Malaria Indicator Survey (TDHS2015) and the 2016 Uganda Demographic and
                  Health Survey (UDHS2016). These four countries are situated on the east of
                  sub-Saharan Africa  and together form one contiguous region. The surveys
                  were nationally represented and utilised a stratified two-stage cluster design.
                  Three questionnaires, the household, women and men questionnaires, were
                  carried out in the selected households. These questionnaires were designed
                  to  collect  information  regarding  the  characteristics  of  the  household  and
                  eligible women and men. All children under the age of five years old in the
                  selected households were tested for malaria and anaemia, with the consent of
                  a parent or guardian.
                    Outcome Variable
                     In all the surveys, a child’s haemoglobin concentration was measured by
                  finger- or heel-prick blood specimens using a portable HemoCue analyser. For
                  this study, a binary response variable was used, indicating whether the child
                  was anaemic if their altitude adjusted Hb level was less than 11 g/dL, or not
                  anaemic if their altitude adjusted Hb level was greater than or equal to 11
                  g/dL.
                    Explanatory Variables
                  The explanatory variables considered in this study comprised of a number of
                  demographic, socioeconomic and environmental factors. These potential risk
                  factors are shown in Figure 1. Such factors included the gender and age of the
                  child, number of members in the household (size of the household), mother’s
                  highest education level, the child’s malaria Rapid Diagnostic Test (RDT) result,
                  type of place of residence: rural or urban; cluster altitude, household wealth
                  index,  type  of  toilet  facility,  and  the  age  and  gender  of  the  head  of  the
                  household. In addition, certain geospatial covariates were also considered. As
                  no information regarding intestinal parasites was collected in the surveys used
                  in this study, certain geospatial covariates were used as a proxy. Specifically,
                  the cluster level average day land surface temperature (LST) and the cluster
                  level average Enhanced Vegetation Index (EVI) for 2015.
                     Furthermore,  the  spatial  variation  of  childhood  anaemia  across  the
                  administrative levels of the countries was investigated. The administrative levels
                  of each of the countries were chosen based on the levels for which public health
                  decisions  are  made.  Accordingly,  administrative  level  1  (called  “counties”  or
                  “districts”) for Kenya, which consisted of all 47 counties; administrative level 2

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