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# Chapter 1 descriptive_stats_2_rev_2009

## on Jun 23, 2011

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## Chapter 1 descriptive_stats_2_rev_2009Presentation Transcript

• CHAPTER 2 DESCRIPTIVE STATISTICS
• L2 - Graphical display of Data
• At the end of the lesson, students should be able to:
• Construct and interpret pictorial and tabular display of data
Learning Objectives:
• Pictorial & Tabular Methods 1. Stem-and-Leaf Displays : How to construct a Stem-and-Leaf Display:
• 1. Each numerical data is divided into two parts:
• - The leading digit(s) becomes the stem,
• and the remaining digit(s) becomes the leaf
2. List the stem values in a vertical column. 3. Record the leaf for each observation beside its stem. 4. Write the units for stems and leaves on the display.
• Result of Math. Exam.
• of a 50-student class:
• 35 42 56 41 63
• 26 37 66 92 16
• 49 28 56 64 72
• 59 17 45 56 29
• 30 45 39 37 43
• 76 73 64 51 60
• 40 52 57 65 83
• 68 52 84 91 64
• 45 76 56 90 73
• 34 26 57 41 56
1 6 7 2 6 6 8 9 3 0 4 5 7 7 9 4 0 1 1 2 3 5 5 5 9 5 1 2 2 6 6 6 6 7 7 9 6 0 3 4 4 4 5 6 8 7 2 3 3 6 6 8 3 4 6 9 0 1 2
• Stem-and-Leaf Display
Stem & Leaf Display Stem: tens digit Leaf: ones digit
• 2. Histogram : A bar graph representing a frequency distribution of a quantitative variable.A histogram is made up of the following components. Histograms are used to summarize large data sets . Histogram: ages of 100 students Age Freq. Rel. Freq. 18 20 0.20 19 24 0.24 20 26 0.26 21 18 0.18 22 5 0.05 23 3 0.03 24 2 0.02 25 2 0.02 Sum 100 1.00 0.20 0.30 Rel. Freq.
• 3. Box plot :
• a graphical display that simultaneously describes several
• important features of a data set:
• center