Exam Tomorrow

1
Aim Review for Exam

• Exam Tomorrow

2
Properties of Standard deviation

• SD measures the spread about the mean and should
  be used only when the mean is chosen as the
  measure of center.
• The larger the standard deviation, the more
  disperse, or spread out, the distribution is.

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Summary of the Properties of the Theoretical
Normal Distribution

• Normal Distribution is a continuous, symmetric,
  bell shaped distribution of a variable.
• The mean, median and mode are equal and located
  at the center of the distribution.
• Curve never touches the x-axis but gets
  increasingly closer.

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Population variance and Standard deviation

• Population Variance/Standard Deviation
• - measures the variability of data in a
  population
• VARIANCE STANDARD DEVIATION

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Sample Variance and Standard Deviation

• Sample Variance/Standard Deviation
• - measures the variability of data in a sample
• - Usually based on a small and manageable sample
  size
• VARIANCE STANDARD DEVIATION

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Different Distributions
Bimodal Distribution
J-Curve
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Group Frequency Distribution

• Procedure
• Find class limits
• Find range of data
• Find the width (range divided by number of
  classes) ? always an odd number
• Find class boundaries (one decimal place more)
• Add 0.5 to upper class limit
• Subtract 0.5 to lower class limit
• Fill in tally, frequency and cumulative frequency

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Example
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Finding the Class Midpoint

• Class Midpoint
• obtained by adding the lower and upper boundaries
  and dividing by 2
• OR
• adding the lower and upper limits and dividing by
  2.

Lower boundary Upper boundary
2
Lower limit Upper limit 2
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Finding Outliers

• Find the first quartile and third quartiles
• Find the IQR (third quartile first quartile)
• Multiply IQR by 1.5
• Find Boundaries
• First Quartile Step 3
• Third Quartile Step 3
• Any data below Step 4-1 or above Step 4-2 are
  outliers

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Aim Review for Exam

• Exam Tomorrow

12
Review Sheet Question 1
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Review Sheet Question 2

• Find the range, variance and standard deviation
  of the following data. Assume that the data
  represents a sample of the population.
• 32, 36, 46, 20, 32, 18, 16, 34, 26, 27, 26

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Review Sheet Question 3

• Check the data for outliers 14, 18, 27, 26, 19,
  13, 5, 25

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Review Sheet Question 4

• A dietitian is interested in comparing the sodium
  content of real cheese with the sodium content of
  a cheese substitute. The data for two random
  samples are shown. Compare the distributions,
  using boxplots.
• Real Cheese
• 310, 420, 45, 40, 220, 240, 180,
  90
• Cheese Substitutes
• 270, 180, 250, 290, 130, 260, 340 310

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Review Question 5

• a. What is incorrect about the construction of
  the frequency distribution below?
• b. Find the midpoint of the first class below
  using the midpoint formula
• Class Frequency
• 27-32 1
• 33-38 0
• 39-44 6
• 45-49 4
• 50-55 2