Difference Between Validity and Reliability with Proper Definition and Brief Explanation

The main difference between validity and reliability is that validity is the extent to which a test measures and what it purports to measure, while reliability refers to the consistency of the test results.

Tests or investigations of any kind are measured according to their validity and reliability. Generally, these two measures are used in psychological tests and research materials. Outside the field of research, however, these two words are used interchangeably.

Key areas covered

1. What is validity? 
     – Definition, characteristics, types
2. What is reliability
     – Definition, characteristics, types
3. What is the relationship between validity and reliability?
     – Scheme of common characteristics
4. What is the difference between validity and reliability?
     – Comparison of key differences

What is validity?

Validity is the extent to which a test measures what it claims to measure. In other words, it means the precision of a test. Therefore, it is a scientific test or research that actually measures what it sets out to measure, or how well it reflects the reality it claims to represent.

Kelly (1927) who declared that a test is valid if it measures what it claims to measure, formulated the concept of validity. Therefore, validity refers to the credibility or credibility of the research. Let’s say, for example, that your test aims to measure a community’s attitudes toward a social practice in the area. So if the test measures the community’s attitude levels towards the particular social practice, without measuring anything else like the impact of the social practice on the social community, then we can say that the test is valid or the validity of the proof is achieved. Therefore, validity is an indication of how strong your research or proof is.

There are two types of validity:

  • Internal validity: the instruments or procedures used in the research study measured what they were supposed to measure
  • External validity: whether the results can be generalized beyond the immediate study

Both types of validity are relevant to assessing the validity of a research study or procedure.

What is reliability

Reliability refers to the degree to which the result of a measurement, calculation, or specification can be depended on for accuracy or the consistency of test results. Therefore, we can say that a test is reliable if the test results it produces are consistent without changing every time.

So, in short, reliability is the parameter that we can use to measure the stability or consistency of the test from its results. So if we take the same example we took before, if the test result is the same, even when we do it again, using the same test subjects, we can say that the test is reliable or that reliability is reached.

Similarly, if the results of a research study are consistently replicated, then the results or the finding of the test are reliable. In addition, a correlation coefficient can be used to assess the degree of reliability. Therefore, the theory is that if a test is reliable, it should show a high positive correlation.

There are two types of reliability that we use when evaluating reliability in a test. Are

  • Internal reliability: the extent to which a measure is consistent within itself.
  • External reliability: the extent to which a measure varies from one use to another

Relationship between validity and reliability

  • Validity and reliability are interrelated aspects of the research. In other words, if the research or a test is valid, then the data is reliable. However, if a test is reliable, that does not mean that it is valid.

Difference between validity and reliability

Definition

Validity refers to the extent to which a test measures and what it purports to measure. Reliability, on the other hand, refers to the consistency of test results.

Measurement

While validity measures whether the extent to which the test can be measured is achieved, reliability measures whether the test gives consistent results in its result.

The types

There are two types of validity like internal validity and external validity, while reliability has two types like internal and external reliability.

conclusion

Validity and reliability are parameters of research and tests. Therefore, for the research to be useful, these two aspects should be there. The difference between validity and reliability is that validity refers to the extent to which a test measures and what it purports to measure, while reliability refers to the consistency of the test results. However, when research or evidence is valid, then the data is reliable. However, if a test is reliable, that does  not mean that the test is valid.

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