Appendix l: Statistical Methods

Appendix L

Statistical Methods

L.1 Introduction

This Appendix presents appropriate statistical methods for analyzing data

from confined disposal facility (CDF) pathway testing procedures. The

methodology is not intended to be exhaustive, nor is it intended to be a "cook-

book" approach to data analysis. Statistical analyses are routine only under ideal

experimental conditions. The methods presented here will usually be adequate

for the tests conducted under the conditions specified in this document. An

experienced applied statistician should be consulted whenever there are

questions.

The following are examples of departures from ideal experimental

conditions that may require additions to or modifications of the statistical

methods presented in this chapter:

Unequal numbers of experimental organisms assigned to each treatment

container, or loss of organisms during the experiment.

Unequal numbers of replications (e.g., containers or aquaria) of the

treatments.

Different conditions of salinity, pH, dissolved oxygen, temperature, etc.,

among exposure chambers.

Differences in placement conditions of the testing containers, or in the

organisms assigned to different treatments.

Contaminant concentration data reported as less than detection limit.

Treatment of nonideal data from dredged sediment evaluations is discussed

at length in Clarke and Brandon (1996).

Statistical analysis of CDF pathway testing data is needed primarily for two

types of biological testsBwater column toxicity and bioaccumulation. The

following statistical procedures will be covered:

Appendix L

Statistical Methods