The SAS output at the bottom of this page is based on data from the article “Evidence for and the Rate of Denitrification in the Arabian Sea” (Deep Sea Research, 1978: 431–435). The variables under study are x salinity level (%) and y nitrate level (mM/L).

a. What is the sample size n? [Hint: Look for degrees of freedom for SSE.]

b. Calculate a point estimate of expected nitrate level when salinity level is 35.5.

c. Does there appear to be a useful linear relationship between the two variables?

d. What is the value of the sample correlation coefficient?

e. Would you use the simple linear regression model to draw conclusions when the salinity level is 40?