In a study of the effectiveness of biological control of the exotic weed tansy ragwort, researchers manipulated the exposure to the ragwort flea beetle on 15 plots that had been planted with a high density of ragwort. Harvesting the plots the next season, they measured the average dry mass of ragwort remaining (grams/plant) and the flea beetle load (beetles/gram of ragwort dry mass) to see if the ragwort plants in plots with high flea beetle loads were smaller as a result of herbivory by the beetles.
A data frame with 15 observations on the following 2 variables.
flee beetle load (in beetles/gram of ragwort dry mass)
dry mass of ragwort weed
Ramsey, F.L. and Schafer, D.W. (2013). The Statistical Sleuth: A Course in Methods of Data Analysis (3rd ed), Cengage Learning.
McEvoy, P. and Cox, C. (1991). Successful Biological Control of Ragwort, Senecio jacobaea, by introducing insects in Oregon, Ecological Applications 1(4): 430–442.