SOCR EduMaterials Activities BoxPlot
Contents
SOCR Educational Materials - Activities - SOCR Box-and-Whisker Plot Activity
Summary
This activity describes the construction of the box-and-whisker plot in SOCR. The applets can be accessed at SOCR Charts by clicking on Miscellaneous.
Goals
The aims of this activity are to:
- show the importance of the box plot in explonatory data analysis (EDA)
- illustrate how to use the SOCR to construct a box plot
- present some peculliarities of a box plot
Background & Motivation
The boxplot (or box-and-whisker-plot), invented by John Tukey in 1977, is an efficient way for presenting data. In the box plot we can mark-off the five-number summay of a data set (minimum, 25th percentile, median, 75th percentile, maximum). The box contains the \( 50 % \) of the data. The upper edge of the box represents the 75th percentile, while the lower edge the 35th percentile. The median is represented by a line drawn in the middle of the box. If the median is not in the middle of the box then the data are skewed. The ends of the lines (called whiskers) represent the minimum and maximum values of the data set, unless there are outliers. The advantage of a box plot is that it provides grahically the location and the spread of the data set, it provides an idea about the skewness of the data set, and can provide a comparison between variables by constructiing a side-by-side box plots.
Exercises
- Exercise 1: Go to the SOCR Charts and click first on the Miscellaneous tab and then on "BoxAndWhiskerChartDemo1". . In the Demo1 boxplot we can see side-by-side box plots of two categories for each of three series. These demonstration data can be viewed by clicking on DATA. Clicking on MAPPING you can choose the variables. Clicking on SHOW ALL the applet will present the graph, the data, and the mapping environment. Let’s clear this data set (click on CLEAR) so that we can enter our own data. After you click on CLEAR click on DATA to enter the spreadsheet. The following data will be entered (don’t forget to separate the data by commas!):
| C1 | C2 | C3 |
| Series 1 | 1,2,3,4,5,6 | 2,4,6,8,10,12 |
| Series 2 | 3,4,5,6,7,8 | 6,8,10,12,14,16,18 |
| Series 3 | 5,6,7,8,9 | 10,16,18,20,22 |
- Exercise 2:
Applications
- SOCR Home page: http://www.socr.ucla.edu
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