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To Construct a Boxplot
Example: Use the below data to construct a Boxplot of the three-year rates of return of small-capitalization growth mutual funds.
Three-Year Rate of Return of Mutual Funds
|
27.4 |
16.7 |
10.8 |
24.1 |
35.9 |
|
12.7 |
28.5 |
22.2 |
18.4 |
17.4 |
|
22.6 |
29.6 |
11.6 |
45.9 |
16.6 |
|
32.1 |
47.7 |
10.9 |
18.4 |
23.3 |
|
18.2 |
32.0 |
25.5 |
23.7 |
38.1 |
|
23.7 |
14.7 |
12.8 |
31.1 |
21.9 |
|
18.4 |
21.3 |
27.0 |
19.6 |
15.8 |
|
14.7 |
37.0 |
19.2 |
18.5 |
29.1 |
Press STAT and select 1: Edit. Clear L1 and then enter the data from table above into L1.
Press
STAT highlight CALC to display the Calc Menu. Select 1:1-Var Stats, and press 2nd
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ENTER.
Scroll down to the 2nd screen to obtain the five values: MinX, Q1,
med, Q3, and maxX.
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Press 2nd
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.
Select 1: Plot 1 and press ENTER. Turn On Plot 1. Move to the Type options.
Using the right arrow (you can not use the down arrow to drop to the second
line), scroll through the Type options and choose the first box plot which is
the first entry in row 2 of the TYPE options. Press ENTER. Move to the Xlist and
type in L1. Press ENTER and move to Freq. Set Freq to 1. If Freq is set on L2,
press CLEAR, and press ALPHA to return the cursor to a flashing solid rectangle
and type in 1. Press ZOOM and 9 to select ZoomStat. The boxplot will appear on
your screen.
.doc_files/image008.jpg)
If you press TRACE and use the left and right arrow keys, you can display the following information: the smallest data point in which is 10:8; Q1 (17.05); the median (22.05); Q3 (28.8); the largest data point in the dataset, which falls inside the upper fence which is 45.9 and the largest data point in the dataset, which 47.7. This largest value is also an outlier because it lies outside the upper fence. Notice that this value is donated by a small box at the extreme right side of the diagram. (Note: The boxplot does not display the lower and upper fences.)
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