14.4 Calculate Probabilities from Survival/Hazard Tables

TreeAge Pro includes table functions that calculate event probabilities from survival and hazard tables.

• ProbHazardTable("tableName"; startCycleTime; cycleLength)

  • Calculates an event probability from a hazard table.

• ProbSurvTable("tableName"; startCycleTime; cycleLength)

  • Calculates an event probability from a survival table.

Note that we strongly recommend that the underlying tables use the lookup method "interpolate" to avoid odd probability and hazard calculations from flat portions of the table.

Both of these functions are demonstrated in the Healthcare Example Model TableFunctions-CDC-Markov.trex.

All strategies are simple 2-state Markov models tracking survival. However, the calculation of the pDie variables are different for each strategy so we can compare them. They differ in the following ways:

1. Strategy 1: Pull the hazard from the hazard table tHazard_KM_CDC for the midpoint of each cycle, then convert it to a probability.

2. Strategy 2: Use the ProbHazardTable function to calculate the probability directly from the hazard table.

3. Strategy 3: Use the ProbSurvTable function to calculate the probability directly from the survival table.

If you roll back the model, the results are nearly identical for the three strategies. The hazard-based strategies calculate the probability based on the hazard halfway through the cycle applied over the full cycle. The survival-based strategy results will differ slightly because this function calculates the probability based on survival 1 cycle into the future relative the survival in the current cycle.

TreeAge Pro also includes functions to calculate event probabilities from a Compound Curve.