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Learn about the different shapes of distributions and how to identify and interpret them. Explore symmetric, skewed, and uniform distributions, and understand the concepts of mean, median, and mode.
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Distributions: The nature or shape of the data within its range.
Essentials:Distribution Shapes(Lots of them , but we will focus on three main types.) • Be able to explain what constitutes a distribution. • Be able to identify Left, Right and Normal distributions (and a Uniform distribution). • Be able to determine if a distribution is normally distributed or skewed through use of a formula or computer software and, be able to interpret the results of this process.
Distributions can occur in a number of shapes including: Symmetric – a distribution is symmetric if the left half of the distribution is roughly a mirror image of its right half. Skewed – a distribution is skewed if it is not symmetric and if it extends more to one side than the other Uniform - Each value occurs in approximately the same amount.
The Shape of Distributions • Symmetric Distribution • A vertical line can be drawn through the middle of a graph of the distribution and the resulting halves are approximately mirror images. Larson/Farber 4th ed.
The Shape of Distributions • Skewed Left Distribution (negatively skewed) • The “tail” of the graph elongates more to the left. • The mean is to the left of the median. • Skewed Right Distribution (positively skewed) • The “tail” of the graph elongates more to the right. • The mean is to the right of the median. Larson/Farber 4th ed.
The Shape of Distributions • Uniform Distribution (rectangular) • All entries or classes in the distribution have equal or approximately equal frequencies. • Symmetric. Larson/Farber 4th ed.
Symmetry Mode = Mean = Median SYMMETRIC Mean Mean Mode Mode Median Median SKEWED LEFT (negatively) SKEWED RIGHT (positively) • Symmetry – a distribution is symmetric if the left half of the distribution is roughly a mirror image of its right half. • Skewness – a distribution is skewed if it is not symmetric and if it extends more to one side than the other