How to tell the president the facts

Haiganoush K. PreislerPacific Southwest Research StationUSDA Forest Service, Albany, CA

6 August, 2003JSM – San Francisco

• Whenever possible say it with pictures/figures.

• Complicated concepts may be conveyed using figures.

Generalized Additive Models

• Often data non Gaussian (e.g., logistic)

• Multiple regression with partial effects

• Relationships approximated by sum of non linear non parametric curves.

• Output is graphical

elevation

lo(elevation)

0 1000 2000 3000

0.0

0.2

0.4

0.6

0.8

sday

lo(sday)

100 150 200 250

-1.2

-0.8

-0.4

0.0

sc

lo(sc)

0 50 100 150

-0.5

0.5

1.5

2.5

er

lo(er)

0 20 40 60 80

-1

0

1

2

3

4

Effects of observed variables on probability of fire spread

elevation

lo(elevation)

0 1000 2000 3000

-2

0

2

4

sday

lo(sday)

100 150 200 250

-4

-3

-2

-1

0

1

2

sc

lo(sc)

0 50 100 150

0

2

4

6

er

lo(er)

0 20 40 60 80

0

2

4

6

Effects of observed variables on probability of fire spread

Color map based on fire danger class

Color map based on probability

-2

012

Estimated Ozone levels, September 21, 1999

Very highHighAverageLowVery low

Conclusion

• Different situations require different solutions

• Whenever possible say it with a ‘picture bite’