Slope currently supports three kinds of decrement/lapse tables which can be used interchangeably in a Projection.
Standard – The standard decrement table contains decrement or lapse rates indexed by Age and Gender Only
Improving – The improving decrement table contains decrement/lapse rates indexed by Age and Gender, but also include an improvement factor indexed by Age and Gender. The improving decrement table includes a decrement start year property. When reading from this table, the calculation engine will automatically apply exponential improvement to the decrement or lapse rates using the improvement factors and the number of whole years that have elapsed since the improvement start year. The improved decrement rate is reflected as
[Improved qx] = [Base qx]*[1 - Improvement Rate]^[Whole years since improvement start year]
Note that since the improvement rates are explicitly provided by age/gender in the Improving Decrement Table structure, improved decrement tables do allow for base decrement rates at all ages, including ages with a base decrement assumption of 100%. In order to maintain a decrement rate of 100% at limiting ages, the user can simply specify 0% as the Improvement Rate for that row; otherwise they may set an improvement assumption greater than zero resulting in improved decrement less than 100% at those ages.
Select and Ultimate – The Select and Ultimate decrement table contains decrement or lapse rates indexed by Age, Gender, and Duration. The select period can be specified as any integral number of years. After the select period, the table contains a set of ultimate rates.