Introduction

We begin this Chapter by reviewing the meaning of tests and statistical significance and providing guidance on when to use one- and two-tailed tests in behavioral ecology. Confidence intervals are then discussed including their interpretation, why they provide more complete information than tests, and how to decide when to use them. We also discuss confidence intervals for the ratio of two random variables such as estimates of population size in two consecutive years. Sample size and power calculations are then reviewed emphasizing when and how they can be most useful in behavioral ecology. The rest of the Chapter discusses procedures for carrying out tests. We first discuss parametric methods for one and two samples including paired and partially paired data. A discussion is included of how large the sample size must be to use t-tests with data that are not distributed normally. The Chapter ends with some simple guidelines for carrying out multiple comparisons.

Statistical tests

Carrying out hypothesis tests to determine whether a parameter is different from a hypothesized value, or to determine whether two parameters are different from each other, is undoubtedly the most common statistical technique employed by behavioral ecologists. Understanding what these tests reveal is thus important, but is also surprisingly difficult. In this section we review some general principles briefly and identify a few subtleties that are easily overlooked in behavioral ecology. These principles are introduced in the context of testing hypotheses about a proportion.