Understandings of margin of error

The goal of this study was to develop a theoretical framework for understandings of margin of error and to explore eight high school mathematics teachers’ understandings of margin of error as they engage in a two-week professional development seminar. Conceptual analysis of the concept of margin of error highlighted that understanding margin of error entails 1) an imagery of repeated sampling, 2) knowing that margin of error has nothing to do with the particular sample statistics. It is, rather, about the sampling method, and 3) understanding the concept of confidence level and how it relates to margin of error. Analysis of teachers’ interpretations of margin of error suggested that while teachers made significant progress in developing a scheme of repeated sampling, the idea of margin of error as a characteristic of sampling method, and the idea of confidence level were particularly hard for teachers to understand.