Scatter plot of the proportion of children with wheezing in the last 12 months (weighed by the inverse of the variance) against selected socioeconomic indicators by age group, (11 studies in children aged 6–7; and 16 studies in children aged 13–14 years). Y axis: proportion of children with wheezing in the last 12 months. X axis, a – mortality rate for external causes per 10,000; b – sanitation (percent of houses with poor sanitation); c – infant mortality at birth (per 1,000); d – GINI coefficient for wealth inequality; e – illiteracy rate (percent); f – infant mortality in the survey year (per 1,000). Straight line: predicted values in bivariable linear regression.
da Cunha et al. BMC Public Health 2007 7:205 doi:10.1186/1471-2458-7-205