Business Statistics For Dummies, 2nd Edition

Chapter 2

Pictures Tell the Story: Graphical Representations of Data

IN THIS CHAPTER

Describing the properties of data with a frequency distribution

Illustrating frequency distributions with histograms

Tracking trends with line graphs, pie charts, and scatter plots

Much of statistical analysis is based on numerical techniques, such as confidence intervals, hypothesis testing, regression analysis, and so on. In many cases, these techniques are based on assumptions about the data being used. One way to determine whether the data conform to these assumptions is to analyze a graph of the data, as a graph can provide many insights into the properties of a data set. For example, a graph may be used to show

• How frequently a value occurs in a data set.
• The average value of the elements in a data set.
• Whether the elements in a data set are increasing or decreasing over time.
• Whether the elements in two different data sets are related to each other.

Graphs are particularly useful for non-numerical data, such as colors, flavors, brand names, and more, where numerical measures are difficult or impossible to compute. In this chapter, I explain how to organize data in a convenient form so ...