Demographic and Health Surveys Methodology - Measure DHS

Statistics: Median Number of Months Since Preceding BirthDefinitionMedian number of months since the preceding birth for births in the five years preceding the survey.A. Coverage: All second- and higher-order births that occurred in the 0–59 months preceding theinterview.B. Median: Interpolated retrospective median.CalculationA. Covered births: Children both surviving and dead who have a difference between the date ofinterview and their birth date (both in CMC format) of 0–59 months, excluding first-bornchildren.B. Preceding birth interval: Difference between birth date of child and birth date of preceding child(in CMC format) grouped into categories. For children of multiple births, the birth date of thepreceding child is the number of months since the end of the preceding pregnancy that ended in alive birth.C. Median is calculated from single month percent distributions of durations of preceding birthintervals. Median is linearly interpolated between the duration month values by which 50 percentor more of the preceding intervals were closed by a birth.Handling of Missing ValuesNot applicable—Birth dates of children are imputed if missing; therefore birth dates do not have missingvalues.Notes and Considerations1. First-order-birth children (and their twins) are excluded from calculation.2. Births in the month of interview are included and births 60 or more months before theinterview are excluded.3. Since birth dates at both ends of the birth interval are in CMC, difference between them istaken as an exact difference. No adjustment is made to the interpolated median.Guide to DHS Statistics 37 Updated September 2006