<prompt> Lead time is defind is -Time between diagnosis and treatmentTime between point where the diagnosis is made by screening test to usual diagnosisTime between disease onset and outcomeTime between usual time of diagnosis and outcome  <response>: Lead time is the advantage gained by screening. It is the period between diagnosis by early detection and diagnosis by other means Detection programmes should concentrate on those condition where the time lag between the diseases onset and its final critical point is sufficiently long to be suitable for population screening Ref: 25th edition, Parks Textbook of Preventive and Social Medicine, Page no. 148 