Recent developments in seasonally adjusting vital statistics.

Birth rates, marriage rates, and death rates computed on a monthly basis have exhibited relatively stable seasonal patterns over a period of years. Elimination of these seasonal fluctuations facilitates the description and interpretation of month-to-month changes in the underlying trend of the rates. Several methods have recently been developed, using an electronic computer, to identify and remove the seasonal component from time series of monthly data. The methods are basically adaptations of a standard technique-the ratio-to-moving average method-for seasonally adjusting time series.The application of seasonal adjustment programs by electronic computer to vital statistics yields useful information about their seasonal component and provides a means to estimate the trend of current as well as retrospective data. Seasonally adjusted birth, marriage, and death rates for recent years are shown.Continuing research should yield better approximations of the trend for birth and marriages and improved methods for isolating the epidemic component of mortality time series.