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.

Notes for use of table functions above:

• 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.

• Be careful using ProbSurvTable on an incomplete survival table. Once the survival data runs out, ProbSurvTable will return a probability of 0.

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.