Exploration and description

River variables

We begin by investigating overall correlations among the various variables in CS14Data1. Stats Summary Statistics Correlations .... produces the following table of correlations

There are high correlations between the number of Biomphalaria snails (NBiom) and water flow velocity (-0.749) and between NBiom and pH (0.614). Water flow velocity and pH are in turn highly correlated (-0.899) indicating a strong association between them.

We now need to look at plots of the individual points to see the patterns of association between pairs of variables. We can do this by Graphs Create Graph... 2D Scatter Plot and by selecting NBiom for the Y-variable and one of the other variables in turn for the X-variable. (We have selected the asterisk symbol in red to make the plots more visible.)