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Beginning with a set of n paired values of Xa and Xb, this page will perform the necessary rank- ordering along with all other steps appropriate to the Wilcoxon test. As the page opens, you will be prompted to enter the number of paired values of Xa and Xb.
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Date Of Record Creation 2004-07-23 21:33:00
Date Last Modified 2004-07-28 14:20:00
Date Of Record Release 2004-07-20 13:43:00
Alternate Title Chebychev's Law
Email Address
Date Issued 1999
Resource Type
Typical Learning Time Various
Author Name Richard Lowry
Author Organization Vassar College
General Comments Originally a module for an online class.--Dead Link
Technical Requirements Adobe Acrobat Reader
Comments Broken Link. BMJ reorganized websites. Can't find article on new system. BMJ Journals is now at and specifically the Journal of Epidemiology and Community Health (JECH) is now at
Content Quality (Concerns) Only a small weakness: All the information was not on the first screen without scrolling, so I was temporarily confused about how to get the results out. Just a little sentence saying, scroll down for results, or something similar, would be helpful to the first time user. After that, it was great! It might be helpful if the area shaded into the curve was available in picture form for the z to P calculator. And it is unclear if "one-tailed for -z" is meaning that the alternative hypothesis is "". In which case the probabilities should add to 1, instead of being the same. If this is not the case, I think it should be specified. In the "Convert to standard scores" tab, procedure steps, the "When all" bullet point is not in the same format as the others, and the word "all" is repeated unnecessarily. On the simple graph maker, 5 columns are allowed, but only 4 colors. It might be helpful to add another color. In the Distributions tab, there seems to be an extra bracket after "Frequency Data". For Logistic Regression, there are 3 input boxes at the bottom of the page that seem to be out of place. For t-Test for independent and correlated samples, the results are the same no matter which selection (independent or correlated) is chosen. Output for .95 and .99 Confidence intervals for the estimated mean of a population is a text output in a new window rather than specified outputs in the same window which has been the norm for most of the site. Two-Factor ANOVA with Repeated Measure on Both Factors, the Procedure, does not have bold bulleted headlines like other Procedure steps. For ANCOVA, also the procedure steps are not as clearly labeled as in previous pages.
Content Quality (Strengths) The material is presented clearly, the values I put in were calculated correctly, and the results were clearly labeled. Once one knows the format, it was easy to see the values, and the labels told what the value was. Several different results were given, for the different types of test intervals, so it would be very useful. The site looks professional, with minimal typographical errors, has a consistent theme, and link/pictures/help are all clearly labeled.
Ease of Use (Concerns) It is not always evident what areas the user should not input data. There are some pages that have yellow output boxes indicating the computer will use those spaces, whereas other pages, the output boxes are white and show no indication that the user should not place data in such boxes. Some boxes also have dashed lines rather than a yellow highlight, so slightly more consistency might be beneficial. Also, again, the results need to be scrolled down to. A simple indication that this was needed would help the first-time user.
Ease of Use (Strengths) It is easy to use, and after I found the results, was great! It's not too cluttered, but the figures one would use are readily available when clicking, so they don't clutter up the screen, but are accessible. The site is very visually appealing, with large consistency and clarity throughout. Instructions are given to make it clear what user input is needed and what output will be given. Help menus are available for further explanations of concepts and computations behind the scenes.
Potential Effectiveness (Concerns) It is debatable whether opportunities for student learning are lost when calculations are simply given to students according to the user input; however, students do need to know how to use such tools effectively to achieve the answers they are looking for. It may be helpful to be more explicit as to what computations are used to derive the output given in many of the situations. Formulas may not necessarily be used by the students, but it may be helpful to see what formulas are used.
Potential Effectiveness (Strengths) This is a tool, not a set of learning modules, so this is not evident here as much. I did find the presentation of the different test conditions at once to be helpful to students. The material develops and explains in great detail a multitude of statistical concepts and allows users to input data freely and easily. The toolkit could be easily implemented into a course, and since it presents the results after the conditions are entered, it could be easily used by students. Using this tool, the students won't get lost in the process of looking up values in the table, etc., which can happen easily otherwise.
Source Code Available 1
Material Type
Statistical Topic
Application Area
Cost involved with use
Intended User Role
Math Level

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