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Peer Review

Scatter, Correlation, & Regression Applet

by Philip Stark


Overall Rating:

3.25 stars
Content Quality: 3.25 stars
Effectiveness: 3 stars
Ease of Use: 3.25 starsstar
Reviewed: Oct 31, 2010 by Statistics Editorial Board
Overview: This resource provides tools for exploring scatterplots, regression, and correlation.
Learning Goals: To help students understand regression and correlation.
Target Student Population: Students in a first statistics course
Prerequisite Knowledge or Skills: None
Type of Material: web applet, tutorial, case study
Recommended Uses: Individual exploration, in-class discussion/activity
Technical Requirements: Any brower

Evaluation and Observation

Content Quality

Rating: 3.25 stars
Strengths: The applet is highly visual. Concepts are well demonstrated with four examples. Explains major concepts well in a dictionary. Contains self-explanatory buttons.
Concerns: I had trouble getting the applet to work properly. In fact, I was never able to select the Y vs X graph that I wanted to play with, nor could I consistently implement the option in which "users can select the correlation and sample size." The module demonstrates important components in Exploratory Data Analysis (EDA), but it needs more interpretation as a teaching tool. For example, how to make sense of the plots. These important explanations are missing even for the self-containing examples. This module needs a systematic organization of the contents. It shows only part of the EDA. These components might be important for some discipline, such as Biology, but not for others, such as Finance and Engineering.

Potential Effectiveness as a Teaching Tool

Rating: 3 stars
Strengths: Robustness, or lack thereof, can be explored and is made visually clear by adding points to a scatterplot and watching the regression line and the correlation change. This promotes student discovery. This module is easy to use and contain clear buttons. It is very efficient to create plots. It supports self-generated data, and it is easy to use in assignments.
Concerns: It would be more instructive to start with a blank scatterplot, rather than with one that someone else chose. Doing this should be easy, rather than merely being possible. It would be helpful to see the regression equation in addition to seeing r. One big concern for the module is it cannot serve as stand-alone teaching material. It is largely based on students' previous knowledge. It does not identify teaching goals, and statistical concepts, or explain the results in detail. On the other hand, only a limited number of plots are allowed which also limits what can be taught and shown.

Ease of Use for Both Students and Faculty

Rating: 3.25 stars
Strengths: Drop down menus are helpful, as is the interactive nature of the applet. It's very easy to use. It's easy to switch from mode to mode and it supports self-generated data. This tool shows relations efficiently and clearly.
Concerns: Being unable to chose the Y vs X graph that I wanted was very frustrating. This tool also needs more explanation about the results.

Other Issues and Comments: I like the inclusion of the Graph of Averages as an option. It would be nice if the vertical slices used to make this graph were (a) shown (on demand) and (b) adjustable by the user. I would also like to see the equation of the regression line.