Chapter 1: Exploring Data

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Chapter 1 Exploring Data

• Section 1 Displaying Data with Graphs

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Variables

• Individuals
• Variables
• Categorical and quantitative

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Pie Chart
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Bar Graph
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Graph Types
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Dotplot
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Dotplot with outliers removed
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HistogramsThe following are ages in months of 15
AP Stat students

• 195
• 204
• 204
• 192
• 192
• 193
• 209

• 194
• 199
• 204
• 204
• 192
• 214
• 222
• 209

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Histogram (zoom 9)

• See your neighbors

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Histogram (Xmin at 189)
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Things to look for

• Center
• Shape
• Spread
• Outliers
• Cautions Pancake and skyscraper effect

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Stemplots

• A stem consists of all but the rightmost digit.
  The leaf is the final digit.
• 1. Write the stems vertically, from smallest to
  largest. Draw a vertical
• line to separate the stems from the leaves.
• 2. Go through the data and write each leaf next
  to the appropriate stem.
• 3. Re-write the data, rearranging the leaves from
  smallest to largest.
• 4. You should indicate the units for the stems
  and leaves
• somewhere in the display.

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Stemplots

• A stemplot is a sideways histogram. BUT, a
  stemplot contains the actual data.
• Sometimes it may be necessary to round data or
  split stems.
• For ngt100, use a histogram.
• A back to back stemplot contains stems with
  leaves on both sides. This is useful to separate
  the data into two classes (boys and girls,...).
  Smaller leaves should be close to the stem.

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Time Plots

• Place the time on the x axis. Time is the
  explanatory variable.
• Place the observations on the y axis. The
  observations represent the response variable.