Reliability refers to the consistency, stability and reliability of test results, and internal consistency is generally used to express the reliability of the test. The higher the reliability coefficient, the more consistent, stable and reliable the test results are.
System error has little influence on reliability, because system error always affects the measured value in the same way, so it will not cause inconsistency. On the contrary, random errors may lead to inconsistency, thus reducing reliability.
Reliability, that is, reliability, refers to the degree to which the results are consistent when the same object is repeatedly measured by the same method. On the other hand, reliability refers to the reliability of measurement data.
For example, the question 1 in the first part of the "Library Utilization and Satisfaction Questionnaire", if the same person is asked the same question every three days, if the respondent chooses A for the first answer, C for the second answer and D for the third answer, it shows that the reliability of the survey results is low, because the survey results are quite different.
If you choose the same answer three times or the answer with little difference, the reliability of the survey results is higher under the condition of excluding systematic errors.
Generally speaking, reliability is a necessary condition for validity, that is, validity must be based on reliability; But without effective measurement, even if its reliability is high, such measurement is meaningless.