The World Health Statisticsseries is WHO's annual compilation of health-related data for its 193 Member States, and includes a summary of the progress made towards achieving the health-related Millennium Development Goals (MDGs) and associated targets.

As with previous versions, World Health Statistics 2011has been compiled using publications and databases produced and maintained by the technical programs and regional offices of WHO. Indicators have been included on the basis of their relevance to global public health, the availability and quality of the data, and the reliability and comparability of the resulting estimates. Taken together, these indicators provide a comprehensive summary of the current status of national health and health systems in key areas. Every effort has been made to ensure the optimal use of reported country data--adjusted where necessary to deal with missing values, to correct for known biases and to maximize comparability. In addition, statistical techniques and modelling have been used to fill data gaps.

WHO presents World Health Statistics 2011as an integral part of its ongoing efforts to provide enhanced access to high-quality data on core measures of population health and national health systems. Unless otherwise stated, all estimates have been cleared following consultation with Member States and are published here as official WHO figures.