The Importance of Reporting Statistical Power: The Forest Decline and Acidic Deposition Example

The author uses papers which reported little evidence of the effect of acid deposition on forest ecosystems to point out the problems of statistical reporting practices in ecology. He suggests that often we are not given the information necessary to judge the strength of the evidence in these reports; i.e., their data analyses or experiments may have had power too low to warrant being used as evidence. Low power could result from sample sizes too small or data sets too variable to have a high chance of finding a statistically significant effect of acid deposition. Risk assessments relevant to natural resource management should be based on concepts of probability of type II error, power and detectable effect size.