Chapter 2 Presenting Data in Tables and Charts Business Statistics A First Course Fifth Edition Business Statistics A First Course 5e 2009 Prentice Hall Inc Learning Objectives In this chapter you learn nTo develop tables and charts for categorical data nTo develop tables and charts for numerical data nThe principles of properly presenting graphs Business Statistics A First Course 5e 2009 Prentice Hall Inc Categorical Data Are Summarized By Tables Graphs Categorical Data Graphing Data Pie Charts Pareto Chart Bar Charts Tabulating Data Summary Table Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Categorical Data Summary Table A summary table indicates the frequency amount or percentage of items in a set of categories so that you can see differences between categories Banking Preference Percent ATM16 Automated or live telephone2 Drive through service at branch17 In person at branch41 Internet24 Business Statistics A First Course 5e 2009 Prentice Hall Inc Bar and Pie Charts nBar charts and Pie charts are often used for categorical data nLength of bar or size of pie slice shows the frequency or percentage for each category Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Categorical Data Bar Chart In a bar chart a bar shows each category the length of which represents the amount frequency or percentage of values falling into a category Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Categorical Data Pie Chart The pie chart is a circle broken up into slices that represent categories The size of each slice of the pie varies according to the percentage in each category Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Categorical Data Pareto Chart nUsed to portray categorical data nominal scale nA vertical bar chart where categories are shown in descending order of frequency nA cumulative polygon is shown in the same graph nUsed to separate the vital few from the trivial many Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Categorical Data Pareto Chart Business Statistics A First Course 5e 2009 Prentice Hall Inc Tables and Charts for Numerical Data Numerical Data Ordered Array Stem and Leaf Display HistogramPolygonOgive Frequency Distributions and Cumulative Distributions Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Numerical Data Ordered Array An ordered array is a sequence of data in rank order from the smallest value to the largest value Shows range minimum value to maximum value May help identify outliers unusual observations Age of Surveyed College Students Day Students 161717181818 191920202122 222527323842 Night Students 181819192021 232832334145 Business Statistics A First Course 5e 2009 Prentice Hall Inc Stem and Leaf Display nA simple way to see how the data are distributed and where concentrations of data exist METHOD Separate the sorted data series into leading digits the stems and the trailing digits the leaves Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Numerical Data Stem and Leaf Display A stem and leaf display organizes data into groups called stems so that the values within each group the leaves branch out to the right on each row StemLeaf 167788899 20012257 328 42 Age of College Students Day Students Night Students StemLeaf 18899 20138 323 415 Age of Surveyed College Students Day Students 161717181818 191920202122 222527323842 Night Students 181819192021 232832334145 Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Numerical Data Frequency Distribution The frequency distribution is a summary table in which the data are arranged into numerically ordered classes You must give attention to selecting the appropriate number of class groupings for the table determining a suitable width of a class grouping and establishing the boundaries of each class grouping to avoid overlapping The number of classes depends on the number of values in the data With a larger number of values typically there are more classes In general a frequency distribution should have at least 5 but no more than 15 classes To determine the width of a class interval you divide the range Highest value Lowest value of the data by the number of class groupings desired Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Numerical Data Frequency Distribution Example Example A manufacturer of insulation randomly selects 20 winter days and records the daily high temperature 24 35 17 21 24 37 26 46 58 30 32 13 12 38 41 43 44 27 53 27 Business Statistics A First Course 5e 2009 Prentice Hall Inc Organizing Numerical Data Frequency Distribution Example 1 Sort raw data in ascending order 12 13 17 21 24 24 26 27 27 30 32 35 37 38 41 43 44 46 53 58 2 Find range 58 12 46 3 Select number of classes 5 usually between 5 and 15 4 Compute class interval width 10 46 5 then round up 5 Determine class boundaries limits 1 Class 1 10 to less tha