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Peer Review

Measures of Central Tendency & Outliers

by Robert Kelley


Overall Numeric Rating:

4.5 stars
Content Quality: 4.5 stars
Effectiveness: 4.5 stars
Ease of Use: 5 stars
Reviewed: Jan 28, 2013 by Psychology
Overview: This PowerPoint Presentation provides an overview of the statistical concepts mean, median and mode with a particular emphasis on the impact of outlier data on each of these indicators. It is useful for all levels of students who have already studied mean, median, and mode.
Type of Material: PowerPoint presentation (with notes)
Recommended Uses: This presentation would be useful in a basic statistics courses or any course considering the effects of outliers on a data set. It is designed as a supplement to accompany a more traditional lecture presentation of the material (although it has sufficient detail that one could likely read it and gain a basic understanding of the target topics).
Technical Requirements: Microsoft Office PowerPoint 2007
Identify Major Learning Goals: Learners who successfully master the information presented in this presentation will be able to: a) Define and determine the mean, median and mode of a data set; b) Understand the impact of outlier data on the representativeness of these statistical measures.
Target Student Population: Any major or discipline of any level interested in the effects of outliers would find this presentation useful. However, it would most appropriately be utilized with advanced high school students or undergraduate students in a statistics or research methods course.
Prerequisite Knowledge or Skills: A basic understanding of mathematical computations is required. In addition, a basic introduction to mean, median, and mode would be helpful to fully benefit from this presentation.

Evaluation and Observation

Content Quality

Rating: 4.5 stars
Strengths: • The PowerPoint presentation requires no real technical skill and provides clear examples regarding the effect of outliers. • The content is clear, easy to understand, and presented at a very basic level. The presentation includes examples to illustrate each point. • All material is correctly cited and references are provided. The citations help remind the students of the importance of citing their work.
Concerns: • The examples are not fully worked through mathematically. That could easily be added in the classroom. • As a stand-alone entity, this presentation may lack the level of detail to fully convey all information. But, this concern is strictly related to using the presentation without an accompanying lecture. With an accompanying lecture or context, the quality of the presented material is outstanding.

Potential Effectiveness as a Teaching Tool

Rating: 4.5 stars
Strengths: • Examples are critical when explaining the effect of outliers. These examples will assist the student in understanding the relevant concepts of outliers as well as the importance of considering how we present data with outliers. • The presentation effectively incorporates text and graphics to explain and illustrate each point. As a supplement to a lecture (with additional audio presentation), the potential effectiveness of this presentation is very high.
Concerns: • Based on classroom experience, some students will be confused by the math. • Used without an accompanying lecture presentation, the PowerPoint alone lacks detail and explanation to help learners fully understand the concepts. This resource really needs an accompanying audio to make it fully complete.

Ease of Use for Both Students and Faculty

Rating: 5 stars
Strengths: • While one could argue for making this more interactive, its simplicity is its strength. Anyone with access to PowerPoint can run this presentation. • As a standard PowerPoint presentation, it is very easy to view in either the notes view or the slideshow presentation mode. The presentation can be viewed with just the PowerPoint viewer or with the complete Microsoft Office program.
Concerns: None.

Other Issues and Comments: As a supplement to lecture (i.e., an interactive in-class presentation), this is an outstanding PowerPoint resource. In addition, it is also now available as a YouTube presentation with audio. The narrated YouTube video can be posted by either online (or on-site) instructors as a valuable class resource. The YouTube link follows: