Chapter Three - Variability

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Chapter Objectives

• Explain the concept of variablility
• Find the range of a distribution
• Distinuish among the following: the standard deviation of a population, the standard deviation of a sample used to describe the sample, and the standard deviation of a sample used to estimate the population standard deviation
• Calculate a standard deviation from grouped or ungrouped data and interpret its meaning
• Add standard deviation measures to a line graph
• Calculate the variance of a distribution
• Convert raw scores to z scores
• Use z scores to compare two scores in a distribution or a score in one distribuiton with a score ina second distribution

• The Range
• The Standard Deviation
• The Standard Deviation as a Descriptive Index of Variability
• s as an Example of o
• The Variance
• A Summary Section on Descriptive Statistics
• z Scores
• Transition Page