4.2. Sensitivi ty Analysis
63
1: INFECTED
1:
1000.00 . ,- - - - -
. - - - -
2: INFECTED
._- -l-- --. , - - -3: INFECTED
- - -- - - ,...--- -- --'.'.._-----,
_. + - - -----'--- - - - - 1
1:
500.00 01-1.1- - - -1
1:
Weeks
FIGURE 4.9
if the length of temporary immunity is half as long or twice as long as modeled here? Experiment with STELLA's sensitivity analysis features to find answers to these que stions.
Additional options for sensitivity analysis enable you to vary initial conditions and parameter values such that they are defined rando mly or specified ad hoc. If you wish to let them vary from run to run along a normal
distribution with a known mean and standard deviation , choose the "Distribution " option instead of "Incremental" (Figure 4.10). If you spec ify "Seed"
as a positive int ege r, yo u e ns ure th e ability to replicat e a p articul ar random
Uariation Type:
o Incremental
@ Distribution
o Rd hoc
Mean:11
F======
S.D.: I
1======
Seed: IL....
_
FIGU RE 4 . 1 0