lecture 17 sec. 5.3.3 wed, feb 13, 2008 boxplots
TRANSCRIPT
Boxplots
Boxplot – A graphical display of a five-number summary. Draw and label a scale representing the variable. Draw a box over the scale with its left and right ends
at Q1 and Q3. Draw a vertical line through the box at the median. Draw a left tail (whisker) from the box to the minimum. Draw a right tail from the box to the maximum.
Boxplots and Shape
What would a boxplot for a uniform distribution look like?
What would a boxplot for a symmetric distribution look like?
What would a boxplot for a right-skewed distribution look like?
TI-83 – Boxplots
Press STAT PLOT.Select Plot1
Turn Plot 1 On. Select the Boxplot Type. Specify list L1.
Press ZOOM.Select ZoomStat (#9) and press ENTER.
TI-83 – Boxplots
Press TRACE.Use the arrow keys to see the values of the
minimum, Q1, the median, Q3, and the maximum.
Modified Boxplots
Q1 Q3
Draw the box part of the boxplot as usual. Compute STEP = 1.5 IQR. The inner fences are at Q1 – STEP and Q3 +
STEP.
Modified Boxplots
Q1 Q3
IQR
Draw the box part of the boxplot as usual. Compute STEP = 1.5 IQR. The inner fences are at Q1 – STEP and Q3 +
STEP.
Modified Boxplots
Q1 Q3
IQR 1.5 IQR1.5 IQR
Draw the box part of the boxplot as usual. Compute STEP = 1.5 IQR. The inner fences are at Q1 – STEP and Q3 +
STEP.
Modified Boxplots
Q1 Q3
IQR 1.5 IQR1.5 IQR
Lowerfence
Upperfence
Draw the box part of the boxplot as usual. Compute STEP = 1.5 IQR. The inner fences are at Q1 – STEP and Q3 +
STEP.
Modified Boxplots
Extend the whiskers from the box to the smallest and largest values that are within the inner fences.
Any values that are outside the inner fences should be drawn as individual dots. These dots represent outliers.
Case Study 8
2007 Small Arms Study (p. 47)Find the five-number summary of the data.Draw a modified boxplot.