difference between reliability and validity in research pdf

Difference between reliability and validity in research pdf

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Public Health Notes

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What is Validity?

Public Health Notes

By Dr. Saul McLeod , published The concept of validity was formulated by Kelly , p. For example a test of intelligence should measure intelligence and not something else such as memory. A distinction can be made between internal and external validity.

Internal validity refers to whether the effects observed in a study are due to the manipulation of the independent variable and not some other factor.

Internal validity can be improved by controlling extraneous variables, using standardized instructions, counter balancing, and eliminating demand characteristics and investigator effects. External validity refers to the extent to which the results of a study can be generalized to other settings ecological validity , other people population validity and over time historical validity.

External validity can be improved by setting experiments in a more natural setting and using random sampling to select participants. There there are two main categories of validity used to assess the validity of test i. Face validity is simply whether the test appears at face value to measure what it claims to. This is the least sophisticated measure of validity. Accordingly, tests wherein the purpose is unclear have low face validity Nevo, A direct measurement of face validity is obtained by asking people to rate the validity of a test as it appears to them.

This rater could use a likert scale to assess face validity. For example:. It is important to select suitable people to rate a test e. For example, individuals who actually take the test would be well placed to judge its face validity.

Also people who work with the test could offer their opinion e. Finally, the researcher could use members of the general public with an interest in the test e. The face validity of a test can be considered a robust construct only if a reasonable level of agreement exists among raters. It should be noted that the term face validity should be avoided when the rating is done by "expert" as content validity is more appropriate.

Having face validity does not mean that a test really measures what the researcher intends to measure, but only in the judgment of raters that it appears to do so. Consequently it is a crude and basic measure of validity. A test item such as ' I have recently thought of killing myself ' has obvious face validity as an item measuring suicidal cognitions, and may be useful when measuring symptoms of depression.

However, the implications of items on tests with clear face validity is that they are more vulnerable to social desirability bias. Individuals may manipulate their response to deny or hide problems, or exaggerate behaviors to present a positive images of themselves. It is possible for a test item to lack face validity but still have general validity and measure what it claims to measure. This is good because it reduces demand characteristics and makes it harder for respondents to manipulate their answers.

For example, the test item ' I believe in the second coming of Christ ' would lack face validity as a measure of depression as the purpose of the item is unclear.

Because most of the original normative sample of the MMPI were good Christians only a depression Christian would think Christ is not coming back. Thus, for this particular religious sample the item does have general validity, but not face validity.

Construct validity was invented by Cornball and Meehl This type of validity refers to the extent to which a test captures a specific theoretical construct or trait, and it overlaps with some of the other aspects of validity. Construct validity does not concern the simple, factual question of whether a test measures an attribute.

To test for construct validity it must be demonstrated that the phenomenon being measured actually exists. So, the construct validity of a test for intelligence, for example, is dependent on a model or theory of intelligence.

Construct validity entails demonstrating the power of such a construct to explain a network of research findings and to predict further relationships. The more evidence a researcher can demonstrate for a test's construct validity the better. However, there is no single method of determining the construct validity of a test.

Instead, different methods and approaches are combined to present the overall construct validity of a test. For example, factor analysis and correlational methods can be used. This is the degree to which a test corresponds to an external criterion that is known concurrently i. If the new test is validated by a comparison with a currently existing criterion, we have concurrent validity. Very often, a new IQ or personality test might be compared with an older but similar test known to have good validity already.

This is the degree to which a test accurately predicts a criterion that will occur in the future. For example, a prediction may be made on the basis of a new intelligence test, that high scorers at age 12 will be more likely to obtain university degrees several years later. If the prediction is born out then the test has predictive validity. Cronbach, L.

Psychological Bulletin , 52, Hathaway, S. Manual for the Minnesota Multiphasic Personality Inventory. New York: Psychological Corporation. Nevo, B. Face validity revisited. Journal of Educational Measurement , 22 4 , McLeod, S. What is validity? Simply Psychology. Toggle navigation.

Research Methods Validity What is Validity? What is Validity? Saul McLeod , published What is the meaning of validity in research? Back to top.

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Here you have all the major differences between Validity and Reliability and what it actually means:. External reliability etc. Face validity is when the tool appears to be measuring what it is supposed to measure with the content of test matching instructional objectives. Construct validity seeks the implications between a theoretical concept and a specific measuring device. It includes constructs like concepts, ideas, theories, etc. Content validity is qualitative measure where the actual content matches the measurement which is a logical method of measurement. Intra rater reliability is a measure in which the same assessment is completed by the same rater on two or more occasions.

Validity is the extent to which a concept , conclusion or measurement is well-founded and likely corresponds accurately to the real world. The validity of a measurement tool for example, a test in education is the degree to which the tool measures what it claims to measure. In psychometrics , validity has a particular application known as test validity : "the degree to which evidence and theory support the interpretations of test scores" "as entailed by proposed uses of tests". It is generally accepted that the concept of scientific validity addresses the nature of reality in terms of statistical measures and as such is an epistemological and philosophical issue as well as a question of measurement. The use of the term in logic is narrower, relating to the relationship between the premises and conclusion of an argument. In logic, validity refers to the property of an argument whereby if the premises are true then the truth of the conclusion follows by necessity. The conclusion of an argument is true if the argument is sound, which is to say if the argument is valid and its premises are true.

By Dr. Saul McLeod , published The concept of validity was formulated by Kelly , p. For example a test of intelligence should measure intelligence and not something else such as memory. A distinction can be made between internal and external validity. Internal validity refers to whether the effects observed in a study are due to the manipulation of the independent variable and not some other factor. Internal validity can be improved by controlling extraneous variables, using standardized instructions, counter balancing, and eliminating demand characteristics and investigator effects.

What is Validity?

The importance of measuring the accuracy and consistency of research instruments especially questionnaires known as validity and reliability, respectively, have been documented in several studies, but their measure is not commonly carried out among health and social science researchers in developing countries. This has been linked to the dearth of knowledge of these tests. This is a review article which comprehensively explores and describes the validity and reliability of a research instrument with special reference to questionnaire.

Reliability is the degree to which an assessment tool produces stable and consistent results. The obtained correlation coefficient would indicate the stability of the scores. Inter-rater reliability is especially useful when judgments can be considered relatively subjective. Thus, the use of this type of reliability would probably be more likely when evaluating artwork as opposed to math problems. Validity refers to how well a test measures what it is purported to measure.

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Understanding reliability vs validity

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5 comments

  • Preciosa C. 04.06.2021 at 20:08

    One of the following tests is reliable but not valid and the other is valid but not reliable.

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  • Pierre B. 08.06.2021 at 11:38

    John deere x485 service manual pdf earth wind and fire september piano sheet music pdf

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  • Ancelina R. 10.06.2021 at 14:22

    Reliability and validity are concepts used to evaluate the quality of research. They indicate how well a method, technique or test measures something. Reliability is about the consistency of a measure, and validity is about the accuracy of a measure.

    Reply
  • Ross C. 10.06.2021 at 14:36

    Again, measurement involves assigning scores to individuals so that they represent some characteristic of the individuals.

    Reply
  • Dirk L. 12.06.2021 at 22:31

    directly or indirectly to the study of similarities of various kinds of objects or events​. One of the two fundamental criteria of measurement, i.e., reliability and validity​. The basic difference between these two criteria is that they deal with different.

    Reply

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