The tītī (Sooty Shearwater or Mutton bird) has one of the longest migration routes in the world. They breed in the Southern Islands of New Zealand. The chicks are harvested and sustainability of the population is an important issue. This study investigates possible adverse effects of attaching transmitters to these birds.
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TasksThe data analysed and described in the video are in a file Titi Data.xls and Titi-TeachersCopy.xls has advice for teachers working on this data set.
- A file Task 1.pdf describes an exercise which compares the proportions of times there was burrow attendance resulting from birds which have and do not have transmitters attached. The confidence intervals described in the video are the normal confidence intervals for the differences between the proportions. You could discuss the problems of dealing with proportions from small samples.
- You can also draw the scatter diagrams for the Attended Proportions against Days and fit the regression lines for the Transmitter and Non-Transmitter groups. One of these shows a downward trend.
- You could also consider the bootstrap confidence interval for proportion differences. Use bootstrapper.xls to carry out the analysis. The data in the two samples will be a set of values 0 or 1 depending on the sample proportions.