Ma. Finney, THE MISSING TAIL AND OTHER CONSIDERATIONS FOR THE USE OF FIRE HISTORYMODELS, International journal of wildland fire, 5(4), 1995, pp. 197-202
This paper reviews methods used for testing the fit of the cumulative
form of a negative exponential distribution to the cumulative distribu
tion of forest age-classes. It is shown that existing methods can lead
to a greater chance of falsely rejecting the fit of the negative expo
nential model and inferring that fire frequencies have changed through
time. This results when the old-age tail of a negative exponential di
stribution is mathematically assumed to be present at the end of the a
ge-class distribution. In reality, the tail is censored from sample di
stributions of forest age-classes. Censoring alters the shape of a cum
ulative age-class distribution from the straight line expected for a s
emi-log graph of the cumulative negative exponential model. A solution
to this problem is proposed that restricts the tests-of-fit to the po
rtion of the negative exponential distribution that overlaps with the
data to be tested. The cumulative age-class distribution can then be c
ompared directly with the cumulative of a truncated negative exponenti
al distribution. Considerations for interpreting a poor fit are then d
iscussed.