Visualize summary statistics with box plot
boxplot(
creates a box plot of the data in
x
)x
. If x
is a vector,
boxplot
plots one box. If x
is a
matrix, boxplot
plots one box for each column of
x
.
On each box, the central mark indicates the median, and the bottom and top edges of the box indicate the 25th and 75th percentiles, respectively. The whiskers extend to the most extreme data points not considered outliers, and the outliers are plotted individually using the '+'
symbol.
boxplot(
creates
a box plot using the axes specified by the axes graphic object ax
,___)ax
,
using any of the previous syntaxes.
boxplot(___,
creates
a box plot with additional options specified by one or more Name,Value
)Name,Value
pair
arguments. For example, you can specify the box style or order.
boxplot
creates a visual representation
of the data, but does not return numeric values. To calculate the
relevant summary statistics for the sample data, use the following
functions:
min
—
Find the minimum value in the sample data.
max
—
Find the maximum value in the sample data.
median
—
Find the median value in the sample data.
quantile
— Find the
quantile values in the sample data. For example, to compute the 25th and
75th percentiles of x
, specify
quantile(x,[0.25 0.75])
. For more information on
how the percentiles are computed, see Algorithms.
iqr
— Find the
interquartile range in the sample data.
grpstats
—
Calculate summary statistics for the sample data, organized by group.
You can see data values and group names using the data
cursor in the figure window. The cursor shows the original values of
any points affected by the datalim
parameter. You can label
the group to which an outlier belongs using the gname
function.
To modify graphics properties of a box plot component,
use findobj
with the Tag
property
to find the component's handle. Tag
values for
box plot components depend on parameter settings, and are listed in
the following table.
Parameter Settings | Tag Values |
---|---|
All settings |
|
When 'PlotStyle' is 'traditional' |
|
When 'PlotStyle' is 'compact' |
|
When 'Notch' is 'marker' |
|
You can also create a BoxChart
object by using the boxchart
function. Although boxchart
does not include all the functionality
of boxplot
, it has some advantages. Unlike
boxplot
, the boxchart
function:
Allows for categorical rulers along the group axis
Provides the option of a legend
Works well with the hold on
command
Has an improved visual design that helps you see notches more easily
To control the appearance and behavior of the object, change the BoxChart Properties.
[1] McGill, R., J. W. Tukey, and W. A. Larsen. “Variations of Boxplots.” The American Statistician. Vol. 32, No. 1, 1978, pp. 12–16.
[2] Velleman, P.F., and D.C. Hoaglin. Applications, Basics, and Computing of Exploratory Data Analysis. Pacific Grove, CA: Duxbury Press, 1981.
[3] Nelson, L. S. “Evaluating Overlapping Confidence Intervals.” Journal of Quality Technology. Vol. 21, 1989, pp. 140–141.
[4] Langford, E. “Quartiles in Elementary Statistics”, Journal of Statistics Education. Vol. 14, No. 3, 2006.
anova1
| grpstats
| kruskalwallis
| max
| median
| min
| multcompare
| quantile