Question

One of the most common screening tests for epithelial ovarian cancer involves the use of biomarkers. Biomarkers have been applied in the management of epithelial ovarian cancer in several different ways, including predicting primary disease at an early stage, distinguishing malignant from benign pelvic masses, monitoring responses to treatment, and estimating prognosis. A number of proteins present in either blood or urine have been identified as specific markers for epithelial ovarian cancer. Let’s say that you collected data from patients on two of these biomarkers (A and B):

Biomarker A	0.08	0.19	0.22	0.35	0.51	0.66	0.78	0.82	0.91	0.96
Biomarker B	2.02	2.16	2.39	2.47	2.17	2.67	2.90	2.41	2.13	3.66

Examine the correlation among the preoperative serum levels of the two biomarkers presumed to be useful for early detection of epithelial ovarian cancer.

Answer 1

X Values
∑ = 5.48
Mean = 0.548
∑(X - M_x)² = SS_x = 0.937

Y Values
∑ = 24.98
Mean = 2.498
∑(Y - M_y)² = SS_y = 2.147

X and Y Combined
N = 10
∑(X - M_x)(Y - M_y) = 0.832

R Calculation
r = ∑((X - M_y)(Y - M_x)) / √((SS_x)(SS_y))

r = 0.832 / √((0.937)(2.147)) = 0.5869