The indicator is calculated from nationally representative household surveys with questions on current use of contraception. Surveys that commonly include this information are: Demographic and Health Surveys (DHS), Fertility and Family Surveys (FFS), Reproductive Health Surveys (RHS), Multiple Indicator Cluster Surveys (MICS) and other national surveys.Edan Transducer
On average, surveys are undertaken every three to five years.
World Contraceptive Use 2009 provides information on the source of each data point (usually denoted by an acronym). A description of each acronym is given in the worksheet labeled "Sources". Cephasonic Ultrasound ProbeFor surveys that are not part of an international survey programme, the full name is provided in the field "Survey name".
Contraceptive prevalence is useful for tracking progress towards the target of achieving universal access to reproductive health, especially when the indicator is considered in conjunction with other information about women's knowledge of family planning or accessibility and quality of family planning services. Information on contraceptive prevalence complements the indicator of unmet need for family planning. One of the most common differences relates to the range of contraceptive methods included and the existence or not of probe questions regarding the types of methods used. The lack of probe questions, asked to ensure that the respondent understands the meaning of the different contraceptive methods, can result in an underestimation of contraceptive prevalence.
The characteristics (age, sex, marital or union status) of the persons for whom contraceptive prevalence is measured (base population) can also affect the comparability of data on contraceptive prevalence. Illustrations of alternative base populations that are sometimes used are: sexually active women (irrespective of marital status), ever married women, or men and women who are married or in union.
The time frame used to assess contraceptive prevalence can also vary. Often it is left to the respondent to determine what is meant by "currently using" a method of contraception. Some surveys ask about use within the past month. Occasionally, when information on current use is not collected, data on use of contraceptive methods at last sexual intercourse or during the previous year are utilized. Notes are used to indicate any differences between the data presented in World Contraceptive Use 2009 and the standard definition of contraceptive prevalence given above.
Estimates for the world and its regions are weighted averages derived by weighting the indicators for each country, extrapolated as needed to 2007, by the estimated number of women who, in 2007, were aged 15 to 49 and married or in union. The estimates weights were derived from data on the proportion of women who were married or in union in each country as presented in World Marriage Data 20081and from estimates of the number of women by age group obtained from World Population Prospects: The 2008 Revision.2