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Table 1 Interventions, Parameters, and Terms

From: The effect of different public health interventions on longevity, morbidity, and years of healthy life

Algebraic Descriptive Mnemonic Label
No Intervention No Change Status Quo
Change the Initial Conditions:   
Let π' be π + λ(1 - π) Move 100*λ% of the sick persons to healthy, at baseline only. One-Shot
Improve the Probabilities:   
P(S|H) * (1-α) At every age, lower the probability of a healthy person getting sick by a factor of (1-α), perhaps through such health promotion and disease prevention activities as smoking prevention programs or vaccinations HP/DP
P(D|H) * (1-α) At every age, lower the probability that a healthy person dies, perhaps by improving automobile, workplace, or gun safety. Safety
P(D|S) * (1-α) At every age, lower the probability that a sick person dies, perhaps by improving intensive care units. ICU
P(H|S) * (1+α) At every age, increase the probability that a sick person becomes healthy, possibly by improving treatment. Treatment
λ Proportion of sick persons moved instantaneously to the healthy state by the One-Shot intervention (usually set to 1.0)  
α Amount of improvement to a transition probability (usually set to 0.1)  
β Worth to society of an additional YSL divided by worth of an addition YHL (usually set to 0.5) Relative Worth
π Proportion who are healthy at baseline (usually set to 0.98 for birth cohort and 0.80 for retiree cohort)  
YHL Years of healthy life (years in excellent, very good, or good health) YHL
YSL Years of sick life (years in fair or poor health) YSL
YHL + β*YSL Worth-adjusted years of life Worth