Difference Between Validity and Reliability

Main difference

The difference between the terms “validity” and “reliability” is that validity is the measure of what is at hand that is right or wrong. While reliability is a simpler approach, it has nothing to do with the accuracy of the result, but what matters is the conclusion drawn by the result.

Validity versus reliability

The terms validity and reliability are used in different contexts, but when it comes to statistics, they have a different meaning. Both terms are not related to each other because in statistics if something is valid, it is not necessary that it be reliable. Similarly, if a result is reliable, it need not be valid. For example, if a weight machine is set to give a maximum weight of one hundred kilograms when something over one hundred kilograms is placed on it, it will still display one hundred kilograms because it cannot read more. This result would be reliable but not valid. Reliability is oriented towards consistency while; validity is more about the correctness of the results.

Comparison chart

Validity reliability
Validity refers to the accuracy of the results in hand. Reliability refers to the consistency of the results.
A valid result is not necessarily reliable. Similarly, a result that is reliable is not necessarily valid.
Ease of determining
Validity is difficult to measure as it refers to the accuracy of the result. Reliability is easier to determine because the only thing that matters here is the result of the result.
Conclusion, internal validity, external validity, construct validity Reliability is calculated by testing and internal consistency only.

What is validity?

In statistics, validity is determined as the measure of the precision of the results. Count the accuracy of the results. It is not possible for a human to give 100% accurate results as there are always lies and errors, be it human error or instrumentation error. The four types of validity include; Conclusion validity, the validity of the conclusion is basically the extent to which the conclusion based on the relationship of variables is reasonable or correct on the basis of the data provided. While the second type of validity is the internal validity that determines that the results obtained are only under the manipulation of independent variables. No other factor should be involved in the final results. While the third type of validity known as External Validity, which means the extent to which a result could be generalized or, in other words, it is the measure of how much a result is applicable to the other researchers or data. The fourth type known as construct validity could be defined as the degree to which a test could measure what it claims. Apart from these, validity also has many other types i.e. validity evidence, along with content validity, criterion validity, etc.

What is reliability?

Reliability refers to the consistency of the result. Let’s start with an example, if a survey is carried out and it gives the same result for a number of students in the school each year, the test would be reliable because it follows the same procedure that only twenty students can be in a class and in ten classes there must be two hundred people. The test is reliable but not valid. Since a general statement cannot be applied to all classes, since there might be fewer admissions, students might have dropped out, etc., it is only the result that matters for reliability. If a test result is consistent, it will be counted as a reliable result. But if the result doesn’t stay consistent, we can say that or claim that the result is unreliable.

Key differences

  1. Reliability refers to the consistency of the result, while resultant validity measures the accuracy of the result.
  2. A valid result may or may not be reliable or while the reliable result may or may not be valid.
  3. If a result repeatedly gives the same answer, it is said to be reliable, while if the result is correct or exact, it is said to be valid.
  4. There are no such types of reliability, all it includes is testing and internal consistency, while validity has various types depending on the degree of precision, accuracy, and general generalizability of the results.
  5. Reliability is easier to calculate as it refers only to consistent results, but validity is difficult to measure as it requires a certain degree of precision. As a result of being called exact.

Final Thought

Validity and reliability think that both terms sound like synonyms, but they are actually different due to the degree of accuracy and correctness (validity) and consistency of the results (reliability). A result could possibly be reliable but not valid and vice versa.

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