Data Analysis Examples

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Data Analysis Examples

• Lecture Notes
• January 15, 2009
• R. Sinn

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Data Analysis Questions

• What are Central Tendencies of data?
• Mean, Median, Histogram (tallest bars)
• What is the Shape of the data? Is it Skewed?
• Histogram, Box-Plot, Mean vs. Median
• What is the Spread / Dispersion of the data?
• Standard Deviation, Range, Box-Plot
• Are there Outliers?
• Z-Scores, Box-Plot

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Example 1

• The Survey of Study Habits and Attitudes (SSHA)
  was given to 18 female college freshmen. Higher
  scores indicate a more interested and motivated
  student.
• Analyze the data graphically, and give a basic
  data table

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Example 2

• A survey compared the average amount college
  females studied (minutes in last 2 days) to the
  amount their males peers studied. The data is
  given below.

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Example 3

• The following test scores were earned on a
  calculus test in Dr. Sinns class first semester.

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Example 3 Data Analysis

• Numeric Summary of Data
• Mean 75.3
• Median 76.5
• Standard Deviation 14.3
• Analysis questions we should be asking
• Is the data set normally distributed
  (bell-shaped)?
• Are there any outliers? Is it skewed?
• Yes, normal but skewed left due to outliers
• Yes, normal but skewed right due to outliers
• No outliers, approximately normal

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Relative Frequency Histogram
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Why Calculate Descriptives Draw Histograms?

• We want to know
• Is the data set normally distributed
  (bell-shaped)?
• Inspect Histogram
• If mean median, it is symmetric
• Are there any outliers?
• Box Plot (Z-scores)
• Is it a skewed bell curve?
• Left mean lt median
• Right mean gt median

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Example 4

• How hot is Death Valley? The following ground
  temperatures (o F) were taken in the vicinity of
  Furnace Creek from May to November

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Questions

• Find the mean, median and mode.
• What is the best description of central tendency
  for the data?
• Find the upper and lower quartiles for the data
  and discuss the dispersion of the data.
• Are there any outliers in the data set?
• Z-Score method?
• Box-plot method?

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Data Analysis Questions

• What are Central Tendencies of data?
• Mean, Median, Histogram (tallest bars)
• What is the Shape of the data? Is it Skewed?
• Histogram, Box-Plot, Mean vs. Median
• What is the Spread / Dispersion of the data?
• Standard Deviation, Range, Box-Plot
• Are there Outliers?
• Z-Scores, Box-Plot