Let:

r = race of individual

s = sex of individual

g = age at entry into life table

y = calendar year of entry into life table

x = interval of follow up

## Index for Expected Probabilities

Annual Interval | Race | Sex | Age | Age Date |
---|---|---|---|---|

1 | r | s | g | y |

2 | r | s | g+1 | y+1 |

3 | r | s | g+2 | y+2 |

... | ... | ... | ... | ... |

x | r | s | g+(x-1) | y+(x-1) |

For non-annual intervals, the expected survival table is expanded from years to months by taking the twelfth root of the yearly survival. For example, if the annual (January to December) expected survival for white males age 6 in 1970 is 0.99957, then 0.99996 would be the survival for each month of 1970.