Reliability can be referred as the ability to be dependent on or relied on, for the honesty, achievement or accuracy. It is the quality of being trustworthy and dependable. In the field of education, it is the ability to conduct an experiment or a test that gives the same results consistently whenever it is repeated. In engineering, it can be understood as the measureable time of work before the occurrence of any failure.
Reliable is something on which we can count or bank on, for an instance when we talk about a machine being reliable, we can say about the car being reliable. We also talk about the news we hear, whether it is from the reliable source or it might be fake. In both the previous cases, the word reliable simply means trustworthy or dependable. In research, the word reliable is considered as consistent or occurring repeatedly.
Following are the types of reliability:-
1. Test Retest Reliability- This type of reliability estimate is used to assess the consistency of results from one time to another.
2. Internal Consistency Reliability- This is used to gauge the consistency of outcome across the items that are within a test.
3. Parallel Forms Reliability- This is used to gauge the consistency of the outcome of the two evaluations constructed in a similar way from the same content domain.
4. Inter Rater or Inter Observer Reliability- This type is used to estimate the level to which different observers/raters give consistent results of the same phenomenon.
When we talk about a dependable measure, we consider the one which is both valid and reliable.