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Televisions, Physicians, and Life Expectancy

This article describes a dataset on life expectancies, densities of people per television set, and densities of people per physician in various countries of the world. The example addresses correlation versus causation and data transformations. Key Word: Prediction.
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Date Of Record Creation 2005-07-26 15:26:00
Date Last Modified 2006-06-20 16:59:00
Date Of Record Release 2005-07-26 15:26:00
Alternate Title One Sample Nonparametric Survival
Source Journal of Statistics Education
Email Address
Date Issued 1998
Resource Type
Typical Learning Time 4 lessons
Author Name Allan J. Rossman
Author Organization Dickinson College
General Comments Dead Link
Technical Requirements Adobe Acrobat Reader
Comments Broken link
Content Quality (Concerns) * The concept that this applet is designed to teach, though important, is simple and fairly easy to grasp, which limits its impact. * On the technical side, the applet provides a "click and drag" method for dynamically changing the bin width, which is convenient and intuitive, but lacks precision. It would be helpful if, in addition, the user could see, and to be able to input, numerical values of bin width. * The use of the applet with one's own data seems to require entering all its numerical values directly within one's HTML file. This can be cumbersome for large datasets, as well as for plotting multiple variables from a single dataset.
Content Quality (Strengths) Very clearly demonstrates that choice of bin width can dramatically alter the appearance of a histogram, possibly affecting our perception of key features such as number of modes and type of skew. The particular dataset used in the demo (eruption times of Old Faithful) appears to have only one mode when the bin width is large, but clearly has two modes for smaller bin widths. It is also nice that one can create weblinks to the applet to plot one's own data. The overall strength is that this applet is simple, clear and does a good job of demonstrating what it intends to.
Ease of Use (Concerns) If possible, it would be a key enhancement if the coding framework is extended to allow users to specify a datafile when linking to the applet. If the browser is not java enabled, there may be some issues downloading java on lab computers, which often have draconian security settings.
Ease of Use (Strengths) Very easy and intuitive to use the applet with the default dataset (eruption times of Old Faithful) that it comes with. Should be accessible to users with a broad range of technical backgrounds and hardware/software platforms. Moderately easy to link to the applet with one's own datasets.
Potential Effectiveness (Concerns) There should be additional datasets (and associated histograms) and follow-up questions to get students to investigate other issues that emerge when adjusting bin widths. It would be helpful if the applet showed numerical value of bin widths as part of the demo.
Potential Effectiveness (Strengths) Should be very effective for teaching the importance of choosing appropriate scale and bin widths when plotting and interpreting a histogram. Should enhance a classroom discussion on this topic. It should also readily fit into an introductory statistics curriculum, regardless of specific textbook. Students learn on their own that the bimodal nature of the dataset is hidden, and for small bin widths the plot reduces to a spike at each data point.
Source Code Available 1
Material Type
Statistical Topic
Application Area
Cost involved with use
Intended User Role
Math Level

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