Chapter 1.1 Displaying Distributions with Graphs
statistics
 the science of learning from data
Chapter 1 descriptive statistics
Chapter 1.1 describe data set graphically
Chapter 1.2 describe data set numerically
cases
 objects described by set of data (individuals, companies, states…)
variable
 any characteristic of a case
distribution
 tells us what values a variable takes and how often it takes those values
categorical variable
 places a case into one of several groups or categories (gender, race,
ethnicity…)
quantitative variable
 takes numerical values for which arithmetic operations (adding,
averaging…) make sense (test scores, income…)
Bar Graphs
•use for categorical variables
•plot count or percent on vertical axis versus categories on horizontal axis
•can also plot mean or median against different categories
•include spaces between bars to distinguish between different categories
Histograms
•use for quantitative variables
•divide the data into classes of equal width and record count in each class
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 '08
 ABDUS,S.
 Standard Deviation, Mean

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