10.5 Optional: Reading scatterplots
(Answers are available in Sect. A.10)
Researchers in New Zealand were interested in:
…the behaviour of heather (Calluna vulgaris) in Tongariro National Park…: the potential for herbicidal control; likely changes in secondary vegetation if biological control is effective; some aspects of its demography; and, finally, whether heather acts to facilitate or impede rates of native shrub invasion of red tussock grassland.
— Rogers (1996)
The graph in Fig. 10.8 comes from this study examining heather in the central North Island of New Zealand.
- Identify a possible research question being answered by the graph.
- Critique the graph
- Compute the value of \(r\), and interpret.
- For a stem age of 20 years,
what does the regression model predict as the mean stem diameter?
- Interpret the meaning of the slope and intercept in the regression equation. Comment on these interpretations.
Rogers, G. M. 1996. “Control, Demography, and Post-Control Response of Heather in the Central North Island: Part 2.” 29. New Zealand Department of Conservation.