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The Bar Graph or Bar Chart What is it? How to Draw it.

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Presentation on theme: "The Bar Graph or Bar Chart What is it? How to Draw it."— Presentation transcript:

1 The Bar Graph or Bar Chart What is it? How to Draw it

2 2 What is a Bar Graph? A bar graph is a graph that displays the frequency or numerical distribution of a categorical variable, showing values for each bar next to each other for easy comparison. Alternate Name: Bar Chart

3 3 Bar Graph Example In June 2005, the US Dept of Transportation reported the following data by observing 1700 motorcyclists nationwide at randomly selected roadway location: –Proper Helmet 731 –Insufficient Helmet 153 –No Helmet 816 Total1,700

4 4 Vertical Bar Graph Example

5 5 x-axis & y-axis Variables On a vertical bar graph, the y-axis variable is normally a quantitative variable. Is it discrete or continuous?  On a vertical bar graph, the x-axis variable is normally a categorical variable Categorical Variable 

6 6 Type of Variables on the Previous Motorcycle Bar Graph x-axis? Categorical Variable. Name the categories Proper, Insufficient, None y-axis Discrete Quantitative Variable What are the units? Helmets

7 7 Making a Bar Graph Look Better What would make this bar graph look better? If we ranked the numbers by either increasing or decreasing value, the appearance would be less jagged, making a Pareto Chart. What is a Pareto Chart? A bar graph in which the bars are ordered according to value, in either increasing or decreasing order. Why Pareto Charts? Graph is named for Vilfredo Pareto, an Italian mathematician & economist

8 8 Vertical Bar Graph as Pareto Chart

9 9 Education & Annual Income Survey

10 10

11 11 Retail Sales

12 12 Pareto Chart of Sales At Retail Outlets

13 13 Non Pareto Version of Sales

14 14 Bar Graphs: VERY FLEXIBLE FORMAT Advantage over Pie Charts Bar Graphs are easier to make & to read than pie charts. How are they similar to Pie Charts? Both pie charts & bar graphs can display the distribution of a categorical variable How are they different from Pie Charts? A bar graph can also compare any set of quantities measured in the same units.

15 15 Psychic Phenomena

16 16 Pareto Chart of Psychic Phenomena

17 17 In Class Survey: Do you believe in Supernatural Phenomena?

18 18 In Class Survey: Do you believe in Supernatural Phenomena?

19 19 In Class Survey Results from 2009: Do you believe in Supernatural Phenomena?

20 20 In Class Survey Results from Level Comparative Bar Graph

21 21 In Class Survey Results from 2009: Simple Bar Graph

22 22 In Class Survey Results from 2009: Pie Chart

23 23 Rainfall In Hawaii

24 24

25 25 Bar Graph Characteristics 1.Data can be quantitative or categorical 2.Bars can be vertical or horizontal 3.The x-axis represents the category displayed 4.The y-axis represents the quantitative values of the variable being displayed 5.Bars are of uniform width and uniformly spaced

26 26 Bar Graph Characteristics 6.A consistent measurement scale is used for each vertical bar 7.Height of bars represent the values of the variable displayed, the frequency of occurrence or percentage of occurrence 8.The graph is well-annotated with title, labels for each bar, vertical scale, horizontal categories, source

27 27 Changing Scale – The Squiggle What is a squiggle? At least a 2-angle line on a bar graph axis that abbreviates a scale. When do you use a squiggle? Use a squiggle on the changed axis whenever you change scale in a bar graph. Horizontal SquiggleVertical Squiggle or

28 28 Pie to Bar: Spending On NY Lottery

29 29 Spending On NY Lottery

30 30 Spending On NY Lottery

31 31

32 32 Turning a Pie Chart into a Bar Graph

33 33 Turning a Pie Chart into a Bar Graph

34 34 Turning a Pie Chart into a Bar Graph

35 35 Turning a Pie Chart into a Bar Graph

36 36 “Would The Bar Graph Make a Good Pie Chart?” Only when Bar Graphs represent parts of a whole, can it be made into a Pie Chart. If the answer is NO, you could write: –No, because these values are comparative data only. –No, because these values DO NOT represent parts of the whole. If the answer is YES, you could write: –Yes, because these values represent parts of the whole.

37 37 Bar Graph & Pie Chart Relationship Summary Every Pie Chart COULD be made into a Bar Graph BUT NOT all Bar Graphs CAN be made into Pie Charts Pie Chart  Bar Graph Bar Graph  Pie Chart

38 38 Turning a Pie Chart into a Bar Graph

39 39 Turning a Pie Chart into a Bar Graph

40 40 Turning a Pie Chart into a Bar Graph

41 41 Turning a Pie Chart into a Bar Graph

42 42 Turning a Pie Chart into a Bar Graph

43 43 Turning a Pie Chart into a Bar Graph

44 44 Turning a Pie Chart into a Bar Graph

45 45 Turning a Pie Chart into a Bar Graph

46 46 Deciding Which Graph is Better The Chicago Tribune polled 380 randomly selected Chicago residents from August 27 to 31, 2009 on the subject of the potential Chicago Olympics of The question asked was, “Do you favor or oppose Chicago hosting the 2016 Olympic games?” The results of the poll were: Supply the remainder of the data labels

47 47 Could the Pie Chart Become a Bar Graph? The answer is obviously yes, But the question remains, Which Graph looks better? Which Graph is better for display purposes? This is a matter of opinion Supply the remainder of the data labels

48 48 Examining a Bar Chart for Meaning What’s the question? What’s the title? What’s the population? What’s the sample? How many variables? What are they? What’s the conclusion? Good pie chart? Is this a Pareto chart?

49 49 Turning a Pie Chart into a Bar Graph

50 50 Turning a Pie Chart into a Bar Graph

51 51 Turning a Pie Chart into a Bar Graph

52 52 Turning a Pie Chart into a Bar Graph

53 53 Turning Pie Charts to Bar Graphs

54 54 Turning Pie Charts to Bar Graphs

55 55 Turning Pie Charts to Bar Graphs

56 56 Turning Pie Charts to Bar Graphs

57 57 Turning Pie Charts to Bar Graphs

58 58 Turning Pie Charts to Bar Graphs

59 59 Turning Pie Charts to Bar Graphs

60 60 Turning Pie Charts to Usual Bar Graphs

61 61 Turning Pie Charts to Pareto Bar Graphs

62 62 Steps in Bar Chart Construction 1.Use a straight edge on a piece of graph paper 2.Make a first-quadrant x-y axis, unless some of your data is negative 3.Examine the data and determine the maximum value of the quantitative data. Your y-scale must be at least this high

63 63 Steps in Bar Chart Construction 4.Choose an appropriate scale for the y- axis. 5.Mark scale ticks consistently & label them, until you reach a mark greater than the highest value of data. 6.Mark of the bar width of each piece of categorical data you will be using on the x-axis.

64 64 Steps in Bar Chart Construction 7.Make sure you place a space between each of the data bars. 8.Plot each data point by drawing a bar of the correct width & height for each. 9.Label the top of each bar with a value. 10.Label both x- and y-axes with a title 11.Title the graph 12.Label the source of the data.

65 65 What Comes After High School?

66 66

67 67 Pareto Chart of “Path After Graduation”

68 68 Kids Borrowing Money (Replace)

69 69

70 70 Mountains to Climb

71 71

72 72 Hints: Complete the Vocabulary Then do the front page Place your HW in the HW box Quiz #103 Bar Charts You need: Pencil, Eraser Calculator Graph Paper (for 2 graphs: one sheet okay) No bags on desk Clear all lists in Calculator


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