Chapter 5: Understanding and Comparing Distributions

What two things should we never do with outliers?

1. Silently leave an outlier in place and proceed as if nothing were unusual. 2. Drop an outlier from the analysis without comment just because its unusual.

List the six major components of a box plot.

1. horizontal line at median 2. horizontal line at Q3 3. horizontal line at Q1 4. upper fence/whisker 5. lower fence/whisker 6. outliers 7. far outliers

Primarily, what are logs used for in statistics?

-to make data behave better

How are outliers displayed within a box plot?

-using a circle

How are far outliers displayed within a box polt?

-using an asterisk

When does a boxplot reveal skewness?

-when the median of the box is not centered between the quartiles -when the whiskers of a boxplot are not the same length

How do you calculate the lower fence that should be displayed within a box plot?

Lower Fence = Q1 - 1.5*IQR

How do you calculate the upper fence that should be displayed within a box plot?

Upper Fence = Q3 + 1.5*IQR

What is a timeplot?

-a graph that displays values against time

What is an outlier?

-any point more than 1.5 IQR and less than 3.0 IQR from either end of the box in a boxplot

What is a far outlier?

-any point more than 3.0 IQR from either end of the box in a boxplot

What are boxplots particularly good at?

-pointing out outliers

What can variables that are skewed to the right often benefit from?

-re-expression by square roots, logs, or reciprocals

What is the heigh of a box within a boxplot equal to?

-the IQR