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MERLOT II


    

Peer Review


Scatterplot and Correlation Coefficient

 

Ratings

Overall Rating:

4.75 stars
Content Quality: 4.75 stars
Effectiveness: 4.75 stars
Ease of Use: 5 stars
Reviewed: Nov 06, 2006 by Statistics Editorial Board
Overview: This series of nine Flash based applets gives the users the ability ot explore bivariate relationships through scatter plots, Pearson's correlation coeafficient and least squares regression. The applets cover a variety of topics that would be useful at a variety of educational levels. For example, basic correlation and scatterplots could be used at the K-12 and introductory statistics levels. Topics such as leverage or confidence bands could be used in more advanced regression courses. Several of the applets are provided with both black and white backgrounds that might be useful for vision impaired individuals.
Learning Goals: The collection has numerous learning goals, including: demonstration of the connection between scatterplots and the direction and magnitude of Pearsons correlation demonstrate the impact of outliers on correlation coefficients and regression lines illustrate the concept of leverage in relation to the least squares line.
Target Student Population: Students in introductory statistics or perhaps students in a regression analysis class.
Prerequisite Knowledge or Skills: Students should be familiar with the basic ideas of scatterplots, correlation and regression
Type of Material: Flash based applet
Recommended Uses: Class demonstration.
Technical Requirements: Flash player 6.0

Evaluation and Observation

Content Quality

Rating: 4.75 stars
Strengths: A powerful illustration of the connection between scatterplots, correlation and regression. The instructor has a wide variety of tools available for illustrating various concepts.
Concerns: Several of the applets provide statistical techniques that are rarely seen in current introductory statistics books, such as the SD line and the 90% contour ellipse. Explanations and definitions of these techniques are not given and the reviewers could not verify the accuracy of these. A user may want to reference "Statistics" by Freedman, Pisani adn Purves (W.W. Norton and Company, 3rd edition, 1998) for background on these terms.

Potential Effectiveness as a Teaching Tool

Rating: 4.75 stars
Strengths: This set of applets have excellent potential as a demonstration tool. The use of Flash rather than Java allows the user to resize the applet to fit the screen, making projection for a class much easier. The use of Flash also allows the user to zoom in on specific parts of the applet which is typically not available for Java based applets.
Concerns: This site does not provide any specific guidance for activities or demonstrations. This item would not be appropriate for assignment for out of class work without substantial instructor created materials. The instructor will also need to spend time carefully planning the in class use to best select the appropriate applet from this site.

Ease of Use for Both Students and Faculty

Rating: 5 stars
Strengths: The software is easy to use and very intuitive. Controls are large and obvious.
Concerns: There are few instructions or definitions of the items presented here. Although it is a minor point some controls take manual input but the some parts do not respond . For example the user could type a new number in the sample size window, which will change the number of points displayed but will not change the slider location.