This in turn leads to people receiving inappropriate understanding and a lack of better advice and treatment to better protect their interests. These tests are used to screen out possible blood donors, but more expensive and more precise tests are used in medical practice, to determine whether a person is actually infected with these diseases.įalse negatives in medical testing provide false, incorrect reassurance to both patients and physicians that patients are free of disease which is actually present.

For example, the simplest tests for HIV and hepatitis in blood have a significant rate of false positives.

In some cases, there are two or more (often many) tests that could be used, one of which is simpler and less expensive, but less accurate, than the other.

The higher this threshold, the more false negatives and the fewer false positives.įalse negatives are a significant issue in medical testing. Usually there is a threshold of how close a match to a given sample must be achieved before the algorithm reports a match. When developing detection algorithms or tests, a balance must be chosen between risks of false negatives and false positives. Increasing the sensitivity of the test lowers the probability of Type II errors, but raises the probability of Type I errors (false positives that reject the null hypothesis when it is true). In statistical hypothesis testing, this fraction is given the symbol β, and is defined as the power of the test. It is equal to 1 minus the sensitivity of the test. The false negative rate is the proportion of positive instances that were erroneously reported as negative.

Type ii error