To calculate a <b>linear correlation coefficient</b>, you can use the menus or the
command line.
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For the dataset, "cadiz", there are 2 variables of interest, "Cost"
and "Volume".
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To calculate the linear correlation coefficient, you can go to the
Command Line in Splus:
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> cor(cadiz$Cost,cadiz$Volume)
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Another way is to go to "Statistics", "Data Summaries",
"Correlations".  Control-Click on the variables of interest.  Splus
will produce a "correlation matrix".  You should understand how to
read this, and compare it to the command line output.