Diameter of bacteria cleared by antibiotic
Use this diagram to explain that the response, Y, has a distribution at each x-value and that the conditional distributions of Y given x can be displayed as histograms.
Drag the centre of the diagram towards the top left to rotate it and show the conditional histograms.
By rotating the diagram, you can also discuss linearity and constant variance in the data.
(Note that the crosses have been jittered a little to separate them in the scatterplot — the x-values in each of the six groups are identical.)
An experiment was conducted to assess how well an antibiotic, polymyxin B, killed the bacterium, Brucella bronchiseptica. Petri dishes containing the bacterium (grown in agar) were used and different doses of the antibiotic were added. The diameter of the area cleared around the addition point were recorded. Each of 6 different doses of antibiotic was used 10 times.