14. Creating, Editing and Referencing Tables

TreeAge Pro can store indexed tables of numeric values that represent parameters in your model. Tables are frequently used to store data that changes over time.

Here are some basic facts about tables:

• Tables store a 2-dimensional grid of data which can be referenced within a model.

• Every table has an index column and one or more value columns.

• Each row’s index value must be unique, but indexes are not required to be consecutive integers.

• Tables are referenced by providing an index value in a table lookup, and a value is returned.

  • You should also provide a value column in table lookups if there are multiple value columns.

• Tables can linearly interpolate between rows and columns when there is no direct match in the table.

• Only numeric values (no variables or formulas) can be entered in a table.

• In Markov models, tables are often used to represent probabilities that vary over time (or other dimensions). You can use the index column to represent the time, and the values column to represent the changing probability. More details can be found in the section: Building and Analysing Cost Effectiveness Models.

• Distributions can be fitted to survival tables to extrapolate disease progression beyond the end time of the table.

• A table can represent a parameter’s empirical probability distribution to sample from during Monte Carlo simulation. You can refer to the section Sampling from tables for details on sampling from tables and other distribution types.

• Table Values can be loaded into a table in a variety of ways, including: paste tab-delimited text; edit via the Excel add-in; manually enter index-value combinations. These will be described in the sections which follow.

Tables are typically created and stored with models in *.trex files. It is also possible to store tables in a global table file, but this is not recommended.