Campus Units

Statistics

Document Type

Article

Publication Version

Published Version

Publication Date

2005

Journal or Book Title

Ecology

Volume

86

Issue

7

First Page

1751

Last Page

1756

DOI

10.1890/04-1343

Abstract

The usual statistical tests of trend are inappropriate for demonstrating the absence of trend. This is because failure to reject the null hypothesis of no trend does not prove that null hypothesis. The appropriate statistical method is based on an equivalence test. The null hypothesis is that the trend is not zero, i.e., outside an a priori specified equivalence region defining trends that are considered to be negligible. This null hypothesis can be tested with two one-sided tests. A proposed equivalence region for trends in population size is a log-linear regression slope of (−0.0346, 0.0346). This corresponds to a half-life or doubling time of 20 years for population size. A less conservative region is (−0.0693, 0.0693), which corresponds to a halving or doubling time of 10 years. The approach is illustrated with data on four amphibian populations; one provides significant evidence of no trend.

Comments

This is an article from Ecology 86 (2005): 1751, doi:10.1890/04-1343. Posted with permission.

Copyright Owner

Ecological Society of America

Language

en

File Format

application/pdf

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