**Measures of Central Tendency and Outliers

Share with your students why the presence of an outlier affects which measure of central tendency to report. Feel free to modify this Powerpoint presentation to fit the needs of your students. Included at the end are additional online resources to further engage your students in their learning about the mean, median, and mode. The presentation is covered by a Creative Commons Attribution-Share Alike 3.0 License.
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Author Name: 
Robert Kelley
Technical Requirements: 
Microsoft PowerPoint, Internet Browser, Java (to view applet)
Content Quality Concerns: 
It is not clear if the data included in the presentation is real data or made up data. It might be nice to include real data sets from real studies in order engage students more (e.g., perhaps a reference to Gould's article "The Median is not the Message").
Content Quality Strengths: 
The presentation is well organized. It attempts to illustrate different measures of center with simple data sets and real-life scenarios that students will likely be able to relate to rather easily (eating out, income, etc.). The presentation is short and succinct. Big ideas are summarized at the end and students are encouraged to think about the appropriate use of different measures of center in different contexts.
Ease of Use Concerns: 
It is not particularly interactive now--just a presentation. It would have been nicer to have the videos/applets embedded directly into the slides for easier viewing. Including more animations and more color in the slides might engage students more. However, this might also distract from the content.
Ease of Use Strengths: 
This presentation is very easy to use or to alter. The instructions are clear. The graphics are good. The video/applet references at the end of it are good. This presentation could be easily embedded into many different types of courses, and it is easy to follow and not terribly overwhelming in terms of the amount of information included on each slide.
Potential Effectiveness Concerns: 
It's unclear how this presentation might promote student discovery, or how students might actively engage with this content if presented in the classroom. It would be nice if another example was included which allowed for class participation and reinforcement. However, this would likely be up to the instructor and how he or she decides to use the presentation. I could see an instructor sharing certain parts of the presentation with the class and questioning them along the way (e.g., asking them to predict how the mean and median would change if unusual values or outliers are included or omitted from a data set).
Potential Effectiveness Strengths: 
This is a simple and straightforward presentation with decent graphics and clear explanations. It shows a nice comparison between the three measures of center. This could easily be incorporated into a lecture. It is general enough so that any instructor might use it--or parts of it--with some modification. For example, there is not reference to any particular statistical software package that students might use, so an instructor can tailor things to the technology he or she uses in his or her classroom. The presentation not only includes information about how to calculate different measures of center, but it attempts to help students visualize how these measures compare to one another, and to reason about which measures would be most appropriate in different situations. It seems that it would be easy to write assignments that go along with this presentation or that assess student understanding of the ideas discussed in the presentation. The slides includes some notes with more details about things that could be brought to students' attention in the classroom.
Content Quality Rating: 
Ease of Use Rating: 
Potential Effectiveness Rating: 
Source Code Available: 
Source Code Available
Intended User Role: 
Learner, Teacher
Resource Type: 
Free for All, Free for Nonprofits

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