1 Chapter Four understand the use and the importance of graphical presentation; recognise the features of varies graphical presentations; and organise and present the collected data in the most effectively way. Graphical Presentation Goal When you completed this chapter, you will be able to:

2 Graphical Presentation Problem Area Collecting the data Deriving the statistics Communicating the results 

3 Graphics can be used as an effective method of visual communication Graphical Presentation

4 Summary Table

5 Scatter Diagram zThe pattern of the scatter of the points provides insights into the existence and nature of the relationship between the two variables. the independent variable X and dependent variable Y

6 Scatter Diagram(2) Possible relationships between two variables:

7 Scatter Diagram (3) Possible relationships between two variables:

8 Scatter Diagram (4) Possible relationships between two variables:

9 Line Chart zLine chart use lines between data points to depict the magnitudes of data for two variables or for one variable over time. zThe height of the line allows the user to compare magnitude easily.

10 It reflects the moving total, moving average with the seasonal variations taken out - it is the trend line. Line Chart (2)

11 Bar Chart zBar chart is used to depict the magnitude of data for different qualitative categories or over time. Several points to note : 1.Bar chart consists of vertical or horizontal bars. 2.all bars should be in same width, but the width of each bar has no special meaning. 3.spaces between bars are suggested to range from one- half the width of a bar to the width of a bar.

12 4.scales and guidelines are useful aids in reading a chart and should be included. 5.the axes of the chart should be labelled. 6.any “keys” to interpreting the chart may be included within the body of the chart or below the body of the chart. 7.the title of the chart appears either below or above the body. 8.footnotes and source notes, when appropriate, are given following the title of the chart. Bar Chart (2)

13 Bar Chart (3) Note : Bad debts are excluded Source : ABC Co.

14 Grouped Bar Chart zGrouped bar chart is used to depict the magnitudes of two or more grouped data items for different qualitative categories or over time.

15 Multiple Bars zMultiple Bars: A number of single bar charts superimposed on top of each other. zThe purpose of this chart is to contrast more than one sequence of data values.

16 Multiple Bars (2)

17 Multiple Bars (3)

18 Component Bar Charts zMultiple bars laid directly on top of each other. zDifferent shading is used to distinguish one set of bars from another.

19 Combination Charts zWe may use lines and bars to depict the magnitudes of two or more data values for different categories or for different times.

20 Pie Charts zPie Chart is used effectively to depict the proportion or percentages of a total quantity by colour or shading zUsually five or fewer categories zShading for the key or makes more interesting

21 Exploded Pies zAn exploded pie has one or more segments slightly removed. zAn exploded pie gives dramatic effect.

22 Three-dimensional Pies zUsing three- dimensions in an exploded pie makes the picture much more eye-catching.

23 Comparative Pies zcompare relative proportions at two different times

24 Pictorial Charts

25 Pictorial Charts (2)  Pictorial symbols are used to depict data to gain attention z Difficult to interpret and also misused at times with the 2-d or 3-d symbols.

26 General Features of Data 1. Relative sizes of data The following statements concern the relative sizes of data, zWomen have a greater life expectancy then men. zMen generally taller then women. zThere is less black and white TV sets than colours. The most effective way to illustrate measurements of relative size is to use Bar Charts.

27 General Features of Data (2) 2. Proportional sizes The most effective way to illustrate proportional sizes of data is to use Pie Charts.

28 3. Change in data over time zBetween 1961 and 1981, the relative price index of domestic gas fell steadily whereas that of domestic electricity remained the same. zConsumer spending on personal telephones has steadily risen over the past twenty years. The most effective way to illustrate changes in data over time is to use Line Charts. General Features of Data (3)

29 4.Pictorial Charts can be designed to both convey the necessary message and to catch eye of the casual reader. 5.The use of words is important for summarising a table or picture, e.g. heading and title, and for conclusion. General Features of Data (4)

30 z Using ‘chart junk’ z No relative basis In comparing data Batches z Compressing the Vertical axis z No zero point on the Vertical axis Errors in Presenting Data

31 ‘Chart Junk’ Good Presentation 1960: $ : $ : $ : $3.80 Minimum Wage $ Bad Presentation

32 No Relative Basis Good Presentation A’s received by students. Bad Presentation 0  FRSOJRSR Freq.  10%  30% FRSOJRSR % FR = Freshmen, SO = Sophomore, JR = Junior, SR = Senior

33 Compressing Vertical Axis Good Presentation Quarterly Sales Bad Presentation Q1Q2Q3 Q4 $ Q1Q2 Q3 Q4 $

34 No Zero Point on Vertical Axis Good Presentation Monthly Sales Bad Presentation J F MAMJ $ JFMAMJ $ Graphing the first six months of sales. 36

35 No Zero Point on Vertical Axis Good Presentation Monthly Sales Bad Presentation JFM A MJ $ JFMAMJ $ Graphing the first six months of sales.