Evidence Strongly Favors Animal-Friendly Alternatives to Dissection
By Jonathan Balcombe, Ph.D.
February 14, 2005
Editor, NABT Publications Department
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I recently read a paper titled “Scalpel or Mouse?: A Statistical Comparison of Real & Virtual Frog Dissections,” published in the August 2004 issue of your journal.1 The authors compared the performance of AP biology students who did a traditional frog dissection with those using a computer program (Biolab Frog Dissection), and reported a statistically significantly superior performance for the traditional dissection.
I found a number of deficiencies in this report:
- Why were the sample sizes so unnecessarily skewed toward the dissecting students? Only 33 of the 74 students in the study were tested using both the dissection and the computer program; the remaining 41 students (including 21 who had not dissected) were only tested on the dissection.
- It is not clear whether just the dissecting group were given the “dissection worksheets” or whether the computer-using group also got them. Obviously, the former scenario would present an unfair handicap for the computer-using students, especially for those who were tested only on the dissection.
- It is not clear to what degree the grading system was subjective or objective, nor is there any indication that grading was performed blind (evaluator not knowing which group a given student belonged to). When subjective methods are used to score outcomes, it is important that evaluators not know to which treatment group any given subject belongs. This eliminates the potential for evaluator bias to influence the scoring.
- Table 1 provides t-scores, but no p-values. Nor does it give any indication of which data are statistically significant—an asterisk (*) is the conventional symbol. This hampers interpretation of the data.
The authors barely scrape the surface of a substantial literature comparing dissection with alternatives. Only the work of two researchers (including Mabel Kinzie, whom the authors mistook to be a male) is cited. I have provided succinct summaries of prior studies elsewhere.2,3 Of twenty-two studies comparing the performance of students using animal-consumptive methods (e.g., dissections) with those using animal-friendly alternatives, twelve found equivalence, nine found better outcomes for the animal-friendly method(s), and only one documented better outcomes for the dissecting group. Concise summaries of these studies are available online.4
On balance, the empirical evidence strongly favors using well-chosen, animal-friendly alternatives, and not harming animals in the name of biology education.
Jonathan Balcombe, Ph.D.
Physicians Committee for Responsible Medicine
5100 Wisconsin Avenue, NW, Suite 400
Washington, DC 20016
1. Cross T.R. & Cross, V.E. (2004). Scalpel or Mouse?: A Statistical Comparison of Real & Virtual Frog Dissections. The American Biology Teacher, 66(6), 408-411.
2. Balcombe J.P. (2000). The Use of Animals in Higher Education: Problems, Alternatives, and Recommendations. Washington, D.C.: Humane Society Press
3. Balcombe J.P. (2001). Dissection: The scientific case for alternatives. Journal of Applied Animal Welfare Science 4(2), 117-126.
Posted February, 2005