We all make decisions as individuals, as family or departmental units, as communities and as nations. How do the choices that individuals make affect outcomes on a community, national or global level? Does it matter if many individuals make poor choices? How does the nature of the communication between individuals affect the collective outcome? This talk will explore these questions using examples from nest-site selection and foraging in honeybees. Mathematical models at various scales will be used to elucidate links between behaviour at different scales. http://www.maths.usyd.edu.au/u/AppliedSeminar ------------------------------------------------------------------------