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Eating PCBs from Lake Ontario - Is There an Effect or Not?

A News Release Case


Eric Ribbens
Department of Biological Sciences
Western Illinois University


This case is based on an actual news release reporting on research about the effects of eating Lake Ontario fish contaminated with PCBs. Developed to teach students about statistical analysis and experimental design, the case has been used in a senior-level biostatistics course as well as part of a one-week survey of statistics for a biological methods course.  It could also be used in an ecology or environmental science course or as a component of a course examining how the media reports science.


  • Understand that statistical analysis is simply a tool to aid in the process of conducting research.
  • Evaluate the statistical presentation of research results.
  • Examine how the media reports scientific results.


Biostatistics; polychlorinated biphenyl; PCBs; experimental design; statistical analysis; news media; Lake Ontario; Great Lakes

Topical Areas

Scientific argumentation, Scientific method, Science and the media

Educational Level

Undergraduate lower division , Undergraduate upper division



Type / Methods




Subject Headings

Statistics  |   Epidemiology  |   Public Health  |   Ecology  |   Environmental Science  |   Journalism  |  

Date Posted


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Una Bray
Mathematics Department
Skidmore College
Saratoga Springs, NY 12866
This case was a big success in my course "Disease and the Environment." I was searching for a way to engage the students in talking about the choice of research population, formulation of research questions, data gathering and interpretation, presentation of research findings, and the reporting of scientific results in the popular press. All this was to prepare them for their own case studies. The class was also an unusually quiet one, given the subject matter, so I was also trying to liven things up a bit. This case was the perfect vehicle for all of the above.

I followed the questions and teaching notes very carefully. The students were given the case five days in advance of the discussion and they submitted their assigned critiques as scheduled. Then we turned to the question of who wrote the story. Things heated up very quickly and there was a great deal of discussion surrounding each of the suggested questions. I remained the silent recorder of comments most of the time. I found it very useful to list responses on the blackboard so that the class could see the twists and turns that ensued. We arrived at the predicted "wide range of answers to the question about validity" of conclusions. The class agreed that taking a statistics course, as one-third of the group had, would help in this type of analysis. Together they formulated a long list of questions involving confounding variables, researcher bias, and missing information. They agreed that they would like to see the original papers on which the news release was based.

The class lasted a very short 85 minutes. The students were engaged and active the entire time. I agree with the author that this case encourages independent thinking in students and reduces their fear of attacking statistical statements. The group work on this case was both liberating and empowering for the class as a whole.

This is a very well conceived and useful case study. My personal field test was a rousing success. I'll use it again the next time this course is offered and I plan to use it in my introductory statistics class and have passed it on to two colleagues who also teach statistics who are very excited about using a case like this.