Dr. Serhat Eren GRAPHICAL DISPLAYS OF DATA Graphical Displays for Qualitative Data There are two methods that you can use to display qualitative data, a bar chart and a pie chart. A bar chart represents the frequency or relative frequency from the table in the form of a rectangle or bar.
Dr. Serhat Eren Creating a Bar Chart for Qualitative Data In a bar chart, one of the axes is used to represent the categories from the frequency table and the other axis is used to represent the frequency or relative frequency for the categories. –Step 1: Draw a pair of axes, x and y. –Step 2: At evenly spaced intervals on the x axis put tick marks and label them with the categories from the frequency table. 3.3 GRAPHICAL DISPLAYS OF DATA
Dr. Serhat Eren 3 Step 3: Scale the y axis so that the category with the highest frequency or relative frequency can be graphed. Choose the scale so that you can distinguish different frequencies or relative frequencies from each other. Step 4: At each category on the x axis, draw a rectangle (bar) whose height is equal to the frequency or relative frequency for the category. The bases of the rectangles must be the same width and the bars should not touch each other. 3.3 GRAPHICAL DISPLAYS OF DATA
Dr. Serhat Eren 4 Step 5: Label the axes and give the graph an appropriate title. 3.3 GRAPHICAL DISPLAYS OF DATA
Dr. Serhat Eren 5
6
Pareto Analysis An important application of bar charts in the area of management is in Pareto analysis. Very often, managers are faced with numerous situations and problems that are not of equal importance. 3.3 GRAPHICAL DISPLAYS OF DATA
Dr. Serhat Eren 8 This principle, known as the principle of "the vital few and the trivial many" or the "80-20 rule," was named the Pareto principle in the 1940s by J. M. Juran, one of the major contributors in the field of Total Quality Management (TQM). A Pareto diagram is a bar chart in which the categories are plotted in order of decreasing relative frequency. 3.3 GRAPHICAL DISPLAYS OF DATA
Dr. Serhat Eren 9
10
Dr. Serhat Eren 11