The indicator is computed as the ratio of the number of people using improved sanitation facilities, to the total population, expressed as a percentage. The same method applies to the rural and urban estimates.

Coverage estimates are based on data from nationally representative household surveys and national censuses, which in some cases are adjusted to improve comparability among data over time. Survey and census data for urban and rural areas are then plotted on a time scale from 1980 to present. A linear trend line, based on the least-squares method, is drawn through these data points to estimate urban and rural coverage for the baseline year 1990 and for the year of most recent estimate. A linear regression line is drawn only if at least two survey data points are available, and they are spaced five or more years apart. The linear regression line maybe extrapolated up to two years after, or before, the latest or earliest survey data point. Outside of these time limits, the extrapolated regression line is flat for up to four years, as necessary. If the extrapolated regression line would reach 100% coverage or beyond, or 0%, a flat line is drawn from the year prior to the year where coverage would reach 100% (or 0%).

Total coverage estimates are computed from the urban and rural coverage estimates using the latest population estimates and distribution of urban and rural population provided by the United Nations Population Division http://www.un.org/esa/population/unpop.htm

More information on this methodology is available at http://www.childinfo.org and http://www.wssinfo.org.

Project Countries

Zambia

Comparisons

Country Indicators

Differences

Why is there a difference?

International

Country