Lecture 1.2 - Characteristics of distributions

Characteristics of distributions

Distribution of common quantities

Many phenomena in nature have a relatively easily guessed distribution characteristics

• What is the distribution of length of rivers in the U.S.?
• What is the distribution of width of flower sepals?
• What is the distribution of life expectancy across countries in 2007?

Features to guess:

• Shape
• Center
• Spread

Graphs of common quantities

Length of rivers in the U.S.

Flower sepal width

Life expetancy in 2007

Height activity

What do you expect the shape, center, and spread of class height to be? Why? Write down with your partner your guesses.

Height distribution

Closing thoughts

• Many distributions can be guessed in advanced based on the data generating process
• You should have at least a guess as to what the distribution is before starting your exploratory data analysis
• Think carefully about what your variable is actually measuring
• Characteristics of distributions are summaries of the data, almost always obscure features of the data
• Don’t mislead your readers!!