Some of the material in my lecture is not in the book and won't be on the homework. Here is an additional homework problem to ensure that you understand it:
A radiologist reading an image and searching for skin cancer learns that the patient has a family history of skin cancer. How do you think this will affect her interpretation of a lesion which may or may not be skin cancer? Describe how this knowledge could increase or decrease her sensivity and selectivity and why. Show these changes in an R.O.C. graph.See also the Wikipedia pages on Sensitivity and Specificity and Receiver Operating Characteristic (R.O.C.) Function.