Power and Sample Size Estimation Techniques for Fisheries Management: Assessment and a New Computational Tool

Abstract

Formulae for sample size calculations in the literature are often predicated on unrealistic assumptions (e.g., equal variances) or on unrealistic or undesirable designs (e.g., two independent samples of the same size). In addition, sample size and power calculations usually involve repeated use of a given formula that the researcher works through varying inputs (significance level (α), power choices, design choices, etc.), making the process of considering sample size and power issues unpleasantly tedious and error prone. I survey those formulae in the fisheries literature and describe deficiencies. I then discuss sample size formulae that correct these deficiencies and describe a freely available Excel tool that enables the calculations.