A. Introduction to Standard Deviation
Make sure students are prepared to answer questions at the end of this unit by having them take notes on the following sites that develop the concept of standard deviation.
Have students log on to the Internet and type in the following web address in their web browser. http://www.cs.rice.edu/~bchristo/lessons/sta ndev/ Students should work through all five parts to this self-directed tutorial.
The five sections are:
1. An Introduction
2. Why We Need It
3. Calculating It & Understanding It
4. Using It in the Real World
The creator of the above tutorial, Barb Christopher has also written two lessons about standard deviation that can be found at http://www.cs.rice.edu/~bchristo/lessons/Sta nDev1.html and http://www.cs.rice.edu/ ~bchristo/lessons/StanDev2.html that may be useful. In addition to this tutorial, the students should look at the following sites for additional information about standard deviation. If the above link isn't complete yet, start at http:// nilesonline.com/stats/stdev.html This section is from an online guide called Statistics Every Writer Should Knowand is very practical for student use because it gives a down-to-earth description of standard deviation. It is written for journalists but is easily transferrable to students.
B. The Math Behind Standard Deviation
Next onto how the standard deviation formula is useful.
Have students go to Math Central (U of R math web site) at http://mathcentral.uregina.ca/RR/ database/RR.09.95/weston2.html Here they will find "A Note on Standard Deviation" by Harley Weston. This is an excellent explanation of how the standard deviation formulas are obtained. Plus Harley describes the difference in the statistical standard deviations (n-1) and the population standard deviation (n). The curriculum guide points out that both are useful but for the B30 course, we are to use the standard deviation for a population.
For the more advanced students, another explanation for the standard deviation formula may be obtained from http://forum.swarthmore.edu/dr.math/proble ms/morris20.html The following two questions are posed to Dr. Math of Swarthmore University about standard deviation. Possible Questions: Explain why one needs standard deviation. Briefly explain to your partner how the standard deviation formula is found. Why are there two standard deviation formulas and when is it appropriate to use sample or population standard deviation formulas?
C. Calculating Standard Deviation
Now that the students understand the concept of standard deviation, they should begin calculating it. I will provide some sites with data that you can use to find standard deviation but leave the actual calculations up to you. You may want to do a few examples using tables and charts to find standard deviation by hand. When using the calculator, each student will need some time to become comfortable with how their calculator changes modes and calculates the different statistical calculations. If you have TI-82 calculator, the LIST option is very handy for entering data, sorting it and finding the many variance statistics all at once.
Wanting a link to more sites on statistics? Try the following.
US Based Stats but well organized. http://nilesonline.com/data/links.shtml
Canadiana Resource Page http://www.cs.cmu.edu/Unofficial/Canadiana/
Stats Can http://WWW.StatCan.CA/start.html
TI 82 Calculator Self Tutorial: http://www-cm.math.uiuc.edu/MathLink/ algebra-module/ALG.index.html
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