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Table 1 Comparison of the underlying assumptions and properties of the CoDe 2.1 model and the LC model

From: Projecting delay and compression of mortality

Properties Model
LC CoDe 2.1
Mathematical form Models death rates and is linear Models death probabilities and is non-linear
Total number of parameters Two parameters for each age, one parameter for each year, minus two parameters for identification Six parameters to describe the age pattern plus four parameters for each year
Modeling of the age pattern More flexible to capture age-specific effects due to many age-dependent parameters Fixed mathematical form to describe the age pattern
Extrapolation to high ages Additional assumptions are required, such as additional parameters and a two-step approach Is part of the model. Death probabilities to higher ages are asymptotically equal to parameter g
Estimating modal age Limited, only integer values Possible
Modeling of the mortality trend One parameter explains the mortality trends across all ages For each age group, there is a parameter to explain the mortality trends
Ability to distinguish between compression and delay Cannot decompose Decomposes the two effects and projects them
Speed of mortality decline Death rates decrease exponentially for all ages Non-exponential decay for all age groups
Incorporation of exogenous variables and expert opinion Very limited Possible
Ability to use as diagnostic tool Not possible Possible