Using a new technique, Hemoglobin 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, 10.5, 12.1. Accurate value of Hb was estimated by standard test to be 10.2. The new technique has:

Ans. is 'b' i.e., Low validity and low reliability o Reliability is synonymous with consistency of test, i.e. it should produce consistent results when repeated n number of times. o Validity refers to the degree in which our test or other measuring device is truly measuring what we intended it to measure, i.e. accuracy of the test. The validity often is associated by comparing a measurement method with the best possible method of measure that is available. For example, the validity of BP measurements obtained by a sphygmonanometer might be compared with those obtained by intra-aerial measurements. o A test may have: (1) High Reliability (consistent) and High validity (accurate) The test produces consistent results when repeated several times and values are close to the true values. In above graph and figure the test has produced consistent results whose values are around the true values. For example, a person of 70 kg steps on a scale 10 times gets reading 69, 69, 70, 71, 69, 69, 71, 70. So, the test is showing consistent results (69-71 kg) and the values are very close to the true values. (2) Low reliability and low validity The test produces inconsistent results and values are far from the true values. For example, a person of 200 pounds steps on a scale 10 times and gets reading of 15, 250, 95, 140, 80, 100, 130, 400, 50, 100. So, the tests results are inconsistent and the values are far away from the true value. The test produces consistent results but the values are far away from true value. For example, a person of 200 pounds steps on a scale 10 times and gets reading 150 pounds all ten times. So, the tests resulsts are consistent (150 pounds all ten times) but values are far away from true value. o From above discussion it is clear that reliability does not imply validity. A test may be reliable (consistent) but not valid (accurate). However, unreliable test (inconsistent) test cannot be valid. "Reliability is necessary but not sufficient for validity" Coming to the question o Test in question showing different values everytime it is repeated. So, the result is not reliable (inconsistent). o Unreliable test cannot be valid. o So, the test in question has low reliability and low validity.