The missing tail and other considerations for the use of fire history models
Document Type: Journal Article
Author(s): Mark A. Finney
Publication Year: 1995

Cataloging Information

  • age class distinctions
Record Maintained By:
Record Last Modified: December 13, 2016
FRAMES Record Number: 3842


This paper reviews methods used for testing the fit of the cumulative form of a negative exponential distribution to the cumulative distribution of forest age-classes. It is shown that existing methods can lead to a greater chance of falsely rejecting the fit of the negative exponential model and inferring that fire frequencies have changed through time. This results when the old-age tail of a negative exponential distribution is mathematically assumed to be present at the end of the age-class distribution. In reality, the tail is censored from sample distributions of forest age-classes. Censoring alters the shape of a cumulative age-class distribution from the straight line expected for a semi-log graph of the cumulative negative exponential model. A solution to this problem is proposed that restricts the tests-of-fit to the portion of the negative exponential distribution that overlaps with the data to be tested. The cumulative age-class distribution can then be compared directly with the cumulative of a truncated negative exponential distribution. Considerations for interpreting a poor fit are then discussed.

Online Link(s):
Finney, Mark A. 1995. The missing tail and other considerations for the use of fire history models. International Journal of Wildland Fire 5(4):197-202.