ABSTRACT
This chapter introduces some of the basic techniques that environmental and agricultural scientists use to describe and summarize important characteristics of a set of data. It discusses the use of descriptive statistics in summarizing data. The chapter explains the use of frequency distribution, frequency polygon, and histograms for efficient presentation of data. It is concerned with the descriptive measures of central tendency and dispersion. The chapter discusses the four major measures of variability or dispersion: the range, the average deviation, the variance, and the standard deviation. It illustrates the methods of determining or computing each of these measures. Environmental and agricultural scientists and managers alike collect data for decision-making purposes. Data can also be presented graphically using a relative frequency histogram. Agricultural and environmental scientists and managers alike often talk about averages in the context of average weight gain, average retail food price, average income of farm workers, average milk production per day, etc.
