Sample Size Calculations for Vegetation Studies

Abstract

A nonsignificant result may be obtained in a study despite that there is an ecologically important and strong effect and difference. This lack of significance may be due to a small sample size and low statistical power of the test. Therefore an adequate sample size is required for accurately estimating and comparing vegetation characteristics and obtaining an acceptable power for the test. This paper presents sample size equations and explains, with examples, how to use the equations for estimating vegetation quantitative characteristics, proportion tests, comparing between two independent samples and two paired samples, correlation analysis, simple and multiple linear regression and logistic regression, chi-square test using contingency tables and analysis of variance (ANOVA).