Figure 4.

Association between polio eradication campaign intensity and diphtheria-tetanus-pertussis vaccine coverage (data are from the Institute for Health Metrics and Evaluation, IHME; left side) and on attended birth coverage (right side). Thick lines indicate different levels of initial coverage (first quartile, median, and third quartile). Dotted lines represent 95% confidence intervals. Partial effects for both dependent variables were very similar for an alternate measure of campaign intensity, percentage of population targeted (not shown). The very wide confidence intervals in the right panel for higher initial values of coverage (dot-dash and solid lines) indicate a lack of observations at high levels of campaign intensity for countries. This selection bias complicates interpretation of this analysis.