Chapter 7: Statistics Application
137
Med-Box Plot (MedBox)
This type of graph is often called a “Box and Whisker” graph. It lets you see
how a large number of data items are grouped within specific ranges. The lines
from minX to Q
1
, and from Q
3
to maxX are called “whiskers”. If [Show Outliers]
box is checked on the Set StatGraphs dialog box (page 136), “outlier” square
symbols are shown instead of “whisker” lines where a data value is relatively
large or small compared to the other data values.
minX Q1
Med
Q3
maxX
Normal Distribution Curve (NDist)
The normal distribution curve is graphed using the following normal distribution
function.
y
=
1
2
π σ
e
–
2
σ
2
(
x
–
x
)
2
Histogram Bar Graph (Histogram), Broken Line Graph (Broken)
A histogram shows the frequency (frequency distribution) of each data class as
a rectangular bar. Classes are on the horizontal axis, while frequency is on the
vertical axis.
In the broken line graph, lines connect the pointers that fall at the center of
each histogram bar.
The Set Interval dialog box appears before the graph is drawn. You can use
this dialog box to change the start value (HStart) and step value (HStep) of the
histogram, if you want.
Graphing Paired-Variable Statistical Data
You can produce any of the graphs described below using paired-variable data. The text in the parentheses of
the graph names below shows text that appears in the Type menu of the Set StatGraphs dialog box (page 136).
k
Plot graphs
Draws graphs by plotting paired-variable points with
x
data on the horizontal axis and
y
data on the vertical
axis.
Scatter plot (Scatter)
xy
line graph (
xy
Line)