Next: Annex: Variance of Sullivan Up: From a complete life Previous: The last interval

### The abridged life table

Often, the prevalence ratios of disability (for example) by single years of age show considerable fluctuations due to sampling variations. Thus, it is preferred to use average prevalence ratios for a five or ten years age interval for Sullivan method. It implies to estimate the total years of life lived in such age intervals. There are two possibilities:

1. The use of a classical abridged life table. An abridged life table contains columns similar to those of the complete life table; the only difference is the length of the intervals. The length of a typical interval in the abridged life table is , which is greater than one year. Formulae from 9 to  13 can be extended in that case.
2. The use of an abridged life table with values of derived from the life table (i.e. ) and values of calculated by summing values of for single years of age x from the unabridged life table. In the example above (see 1.3), were calculated with the following formulae:

Because the second method is generally more accurate, it is highly recommended to use it if possible.

Eric Hauet
Fri Apr 25 22:40:35 DFT 1997