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Charts and Graphs

Charts and Graphs. Chapter 2 MSIS 111 Prof. Nick Dedeke. Objectives. Understanding data presentation Discrete versus continuous data Differentiate between grouped and ungrouped data Construct frequency distributions Construct histogram, frequency polygon and other charts .

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Charts and Graphs

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  1. Charts and Graphs Chapter 2 MSIS 111 Prof. Nick Dedeke

  2. Objectives • Understanding data presentation • Discrete versus continuous data Differentiate between grouped and ungrouped data • Construct frequency distributions • Construct histogram, frequency polygon and other charts

  3. Types of Variables • Discrete variables have parameters that are whole numbers only, e.g. 3 cars, 5 cars, 6 cars , 7 cars, 9 cars, 11 cars • Continuous variables have parameters that allow both whole numbers and decimal numbers, e.g. $ 1.2, $ 1.4, $ 4.2

  4. Exercise: Using Frequency Distribution for Discrete Data • What is the average of these dimension data (all observations number of houses)?1,1,1,1,1,1,1,12,2,2,2,2,2,2,24,4,5,5,6,6,8,89,9,9, 10,10,10,10,10,1011,11,11

  5. Data Presentation • One of the characteristics of good statistics is the fact that everyone uses the same approach to organize data. • The approaches used are called tools of descriptive statistics

  6. Problem: Frequency Distribution for Continuous Data • What is the average of these continuous data (all observations in inches)?1.6,1.5,1.2,1.4,1.6,1.2,1.6,1.62.1,2.7,2.3,2.5,2.8,2.9,2.8,2.94.2,4.6,5.2,5.4,6.1,6.5,,7.6,8.3,8.69.6,9.1,9.6,10.0,10.5,10.6,10.8,10.3,10.4,11.8,11.8,11.8, 12.3,12.4,12.5

  7. Exercise: Frequency Distribution for Continuous Data • Range = Largest – Smallest number = 12.5 – 1.2 = 11.3Set number of classes to use to group data = 6 classesClass width = 11.3/6 = 1.88 or 2Class width of 2 means that one builds classes where the difference between the highest and lowest number in each class is 2

  8. Class Width $650 $750 $700 Lowercutpoint Uppercutpoint Midpoint

  9. Exercise: Frequency Distribution for Grouped Data

  10. Types of Charts:Pie Charts

  11. Types of Charts: Oglive

  12. Types of Charts: Histograms

  13. Graph: Box-plots IQR • Vertical line in box represents median • Left end of box depicts the 25th percentile (1st quartile) • Right end of box depicts the 75th percentile (2nd quartile) • Horizontal line from each end of box are drawn to the most extreme data points (only those no farther than 1.5 Inter quartile range (IQR)) 1Q 2Q 3Q 4Q 75th percentile 25th percentile 50th percentile

  14. Graph: Box-plots vs. Histograms 1Q 2Q 3Q 4Q • Vertical line in box represents median • Left end of box depicts the 25th percentile (1st quartile) • Right end of box depicts the 75th percentile (2nd quartile) • Horizontal line from each end of box are drawn to the most extreme data points ( no farther than 1.5 Inter quartile range (IQR) 25thpercentile 75th percentile 50th percentile Frequency 1Q 2Q 3Q 4Q X Median

  15. Simulations • Box plots vs. histograms • Hints • Match extreme values • Match the length of the inter quartile range or the middle 50% of the data to histogram • Use the pattern of the data to visualize the position of the median • Median moves forward • Median moves backwards

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