A Bayesian Network Modeling Approach to Forecasting the 21st Century Worldwide Status of Polar Bears - Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications - page 252

Table B19. Node V1: Cub Production per Event

Cub Production per Event

Node F2: Factor
A—habitat
Threats

Fewer
Than Now

Same as
Now

More Than
Now

Improvement 0.0 0.3 0.7

No effect 0.0 1.0 0.0

Minor restriction 0.6 0.4 0.0

Major restriction 1.0 0.0 0.0

APPENDIX C: RESUlTS OF SENSITIVITy
ANAlySES OF ThE BAyESIAN NETWORk
POPUlATION STRESSOR MODEl

lected input or summary variables influence the calculated
values of a specified output variable. Tables C1 and C2
present results of 10 sensitivity tests on various summary
and output nodes in the model (see text for explanation of
calculations). Note that mutual information is also called
entropy reduction. All tests were conducted using the Baye-
sian network modeling software package Netica® (Norsys,
Inc.).

Tables C1 and C2 present the results of conducting a se-
ries of sensitivity analyses of the Bayesian network popu-
lation stressor model discussed in the text (also see Plate
3). Sensitivity analysis reveals the degree to which se-

Table C1. Sensitivity Group 1: Sensitivity of Overall Population Outcome
Node

Mutual Information Node Title
Test 1: Sensitivity of Node D1—Overall Population Outcome to All Input Nodes

B 0.12974 Foraging habitat Quantity Change

C 0.04876 foraging habitat absence change

M 0.04166 ecoregion

F 0.02590 alternate regions available

E 0.01607 intentional takes

N 0.01393 shelf distance change (km)

S1 0.01037 foraging habitat character

B1 0.00821 bear-human interactions

T 0.00506 parasites and disease

R4 0.00271 hydrocarbons/oil spill

R1 0.00254 oil and gas activity

J 0.00198 shipping

T2 0.00092 predation

T1 0.00073 contaminants

R3 0.00069 alternate prey availability

R2 0.00065 relative ringed seal availability

J1 0.00040 tourism

Test 2. Sensitivity of Node D1—Overall Population Outcome to Listing Factor Nodes

F2 0.66422 factor a: habitat threats

A1 0.05253 factor b: direct mortalities

A6 0.03150 factor e: other factors (natural or man-made)

A4 0.01039 factor c: disease, predation

Test 3: Sensitivity of Node D1—Overall Population Outcome to Intermediate Nodes a

l2 0.56624 vital rates

l 0.54067 juvenile survival

l1 0.54057 adult female survival

k 0.53353 adult body condition

V1 0.44705 cub production per event