Using a new technique, Hb was estimated in a blood sample. The test was repeated for 10 times. The repos were: 9.5, 9.2, 9.4, 9.6, 9.7, 9.9, 10.2, 10.3, 10.5 and 12.1. Accurate value of Hb was estimated by standard tests to be 10.2. The new technique has:

In the given question, Mean of 10 Hb values = Sum (9.5, 9.2, 9.4, 9.6, 9.7, 9.9, 10.2, 10.3, 10.5 and 12.1)/10 = 100/10 = 10 Validity means getting the right results, whether positive or negative and reliability means getting the same result every time, irrespective of whether it is right or wrong. Since the results obtained by test are different than the actual value of Hb, it is not valid or accurate. Also, since every time we are getting different values , the test is not reliable.