This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening, Subject name: Social & Preventive Medicine
amount of previously unrecognised disease which is diagnosed by screening effor, is- 
Select and explain. 
A. Yield, B. Sensitivity, C. Specifivity, D. PPV
A: Yield
Answer: A: Yield 
Explanation: .<p>yield is the amount of previously unrecognised diseases that is diagnosed as a result of the screening effo .it depends upon many factors.like sensitivity and specificity of the tets in the detection programmes.for example by limiting a diabetes screening programme to persons over 40 years we can increase the yield of the screening test.high risk populations are usually selected for screening thus increasing the yield.</p><p>ref:park&;s textbook of preventive and social medicine,22 nd edition,pg no132</p>