Seventh, because the immune system is weak it cannot kill enough cancer cells and the cancer cells grow out of control. Thus, in summary, the root cause of cancer is microbes and parasites that are in the organs or colon (or bloodstream), which weakens the immune system. However, other things can cause cancer.
Test Reliability and Validity Defined Reliability. Test reliablility refers to the degree to which a test is consistent and stable in measuring what it is intended to measure. Most simply put, a test is reliable if it is consistent within itself and across time.
Reliability is the consistency or precision with which the test or assessment method measures what it claims to measure. 1  Any assessment method or test needs to be a consistent measure â this means if the test was used repeatedly on the same candidate it would produce similar results. Assessments or tests with lower reliability are of little practical use. Reliability is a very important concept and works in tandem with validity. A guiding principle for psychology is that a test can be reliable but not valid for a particular purpose, however, a test cannot be valid if it is unreliable.