Gheissari et al. (2010) investigated the carotid intima-media thickness in children with end-stage renal disease on dialysis. As part of that study, they performed partial correlations.

Look at the following text:

After adjusting for age, partial correlation analysis showed significant correlation between carotid and bulb intima-media thickness (IMT-C)

and n-PTH level (r = 0.85, p = 0.04) and serum alkaline phosphatase (r = 0.86, p = 0.02). p. 30 Which answer is not correct? (Answers are at the end of the book.)

a) The correlation between IMTC and serum alkaline phosphatase is significant, once age is partialled out

b) The correlation between n-PTH level and serum alkaline phosphatase is significant, once age is controlled for

c) The correlation between carotid and bulb intima-media thickness (IMT-C) and n-PTH level (r =

0.85, p = 0.04) and serum alkaline phosphatase (r = 0.86, p = 0.02) would not be statistically significant if age had not been partialled out