Barker, S. B., Best, A. M., Fredrickson, M., & Hunter, G. (2000). Constraints in assessing the impact of animals in education. Anthrozoos, 13(2), 74-79

The primary purpose of this article was to delineate constraints researchers may encounter in assessing the impact of animals in education, even when using rigorous research designs. A case study is used as a framework for this discussion and consists of a project conducted in a pre-school setting, using a cross-over design to control for most threats to internal and external validity. The project is presented first, with a brief description of the goals and methodology of the project followed by a summary of the outcomes. A discussion follows of the variables and unanticipated, intervening events occurring during the course of the project. Finally, suggestions are provided for addressing these types of constraints in future outcome studies of the impact of animals in education