Determining confidence: sex and statistics

I n this article we demonstrate the use of a primary research paper as an assessment tool, helping to determine how well students understand a biological concept and their ability to interpret statistics. The article by Willingham (p 309–313) investigates the effects of temperature in conjunction with endocrine disrupting chemicals (EDCs) on sex determination in turtles. We have designed instruction and assessments on the subject of sex determination, a topic that is conceptually uncomplicated for most students, and statistical analyses which present them with some challenges. We have made the assumption that students have learned about mechanisms of sex determination among animal taxa, know how to develop and test hypotheses, and have a basic understanding of natural selection and fitness. Student goals • Apply understanding of sex determination to the consequences of altered sex ratios in animal populations. • Demonstrate understanding of statistical testing and skills in interpreting data used in a research paper. Instructor goals • Use primary literature as a source of information about biological topics and as an assessment tool. • Implement an active learning strategy to help students understand the concept of statistical testing and significance. Begin the class with a question for students to discuss in their groups: " In some coastal areas, well-meaning individuals dig up eggs laid by sea turtles on beaches and re-bury them further inland where the eggs are better protected. What impact(s) do you think this has on the sexual development of these turtles? " After selected groups report out, the instructor summarizes the discussion, adding information about sex determination and EDCs. The topic of EDCs is of interest to students, as the mechanisms and ubiquity of the effects are easily understood and are of personal relevance. Although controversy exists regarding the links between endocrine disruptors and negative impacts on human health, it is evident that these compounds are present on a global scale, with high levels occurring in the blood or body fats of humans and wildlife. This introduction leads to an exploration of the use of statistics in these types of studies. Explore – statistics and data Two objectives guide students' exploration of statistics: (1) connect data interpretation and confidence level with statistical testing, and (2) connect statistical analyses of data with support or rejection of hypotheses. The instructor polls the class, using computer-based personal response systems, " clickers " (Brewer 2004), or hand-held cards to provide real-time …