Taste test of samples of cheese
Use this diagram to explain how the plotting symbol can represent a third numerical variable in a scatterplot. Use the pop-up menu to select different representations for lactic acid.
In this example, abrasion loss is the response variable. What combinations of tensile strength and hardness correspond to high abrasion loss?
From the main scatter of crosses, the taste rating is higher for cheese samples with higher hydrogen sulphide content. Taking into account the size of the circles, there is also evidence of a higher taste rating for samples with more lactic acid. (Consider the cheese samples with hydrogen sulphide content of between 3 and 5.)
Mention that it is often hard to interpret this kind of diagram.
In an attempt to understand differences in the perceived taste of cheddar cheese, several samples were analysed chemically and were also subjectively rated for taste by a panel of trained tasters. This data set contains the taste rating and the amount of two chemicals of importance to taste, hydrogen sulphide and lactic acid.