ABSTRACT
An experiment is often designed in such a way that the researcher must collect values for a number of variables. Regardless of whether they vary in time (such as the NO2 concentration in air varying through the day) or in space (such as the increased sea salt deposition as you near the sea), these variables fall into three principal classes. These may be termed responses, causes and interference. Strictly, the latter two are little different from each other: interferences are simply causes that our experiment does not wish to consider. In the analysis stage of the experiment, we want to explore the relationship between the cause and response variables. An ideal starting point is the graph.
