HOW TO CALCULATE SENSITIVITY & SPECIFICITY Still struggling to understand sensitivity & specificity? It often helps to draw a 2x2 table and to start calculating it! Sensitivity: The amount of people with a positive index test amongst the people who have the disease Specificity: The amount of people with a negative index test amongst the people who do NOT have the disease. The problem with sensitivity and specificity is that they tell us how often a test is positive in patients who we already kno