Is there a strong correlation between the number of miles driven by a salesperson and sales volume achieved? Data were gathered from nine salespeople who worked territories of similar size and potential. Determine the correlation coefficient for these data. Assume the data are ordinal in level of measurement.
Sales .... Miles per Month
$150,000 ... 1,500
210,000 .. 2,100
285,000 .. 3,200
301,000 .. 2,400
335,000 .. 2,200
390,000 .. 2,500
400,000 .. 3,300
425,000 .. 3,100
440,000 .. 3,600