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Reliability & Validity

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❶Internal validity and reliability are at the core of any experimental design. Some qualitative researchers reject the concept of validity due to the constructivist viewpoint that reality is unique to the individual, and cannot be generalized.

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What is Reliability?
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The first cell on the upper left shows the comparison of the verbal written test score with the verbal written test score. But how can we compare the same measure with itself? We could do this by estimating the reliability of the written test through a test-retest correlation, parallel forms, or an internal consistency measure See Types of Reliability.

What we are estimating in this cell is the reliability of the measure. The cell on the lower left shows a comparison of the verbal written measure with the verbal teacher observation rating. Because we are trying to measure the same concept, we are looking at convergent validity See Measurement Validity Types. The cell on the upper right shows the comparison of the verbal written exam with the math written exam.

Here, we are comparing two different concepts verbal versus math and so we would expect the relationship to be lower tha n a comparison of the same concept with itself e. Thus, we are trying to discriminate between two concepts and we would consider this discriminant validity. Finally, we have the cell on the lower right. Here, we are comparing the verbal written exam with the math teacher observation rating. Like the cell on the upper right, we are also trying to compare two different concepts verbal versus math and so this is a discriminant validity estimate.

But here, we are also trying to compare two different methods of measurement written exam versus teacher observation rating. So, we'll call this very discriminant to indicate that we would expect the relationship in this cell to be even lower than in the one above it. Latest content Current issue Archive Authors About. Log in via Institution. Issues of validity and reliability in qualitative research. Are the terms reliability and validity relevant to ensuring credibility in qualitative research?

View inline View popup. What strategies can qualitative researchers adopt to ensure the credibility of the study findings? Evid Based Nurs ; Validity, trustworthiness and rigour: J Adv Nurs ; Rigor or rigor mortis: Adv Nurs Sci ; Long T , Johnson M. Rigour, reliability and validity in qualitative research.

Clin Eff Nurs ; 4: Verification strategies for establishing reliability validity in qualitative research. Int J Qual Res ; 1: In order to have external validity, the claim that spaced study studying in several sessions ahead of time is better than cramming for exams should apply to more than one subject e. It should also apply to people beyond the sample in the study.

Different methods vary with regard to these two aspects of validity. Experiments, because they tend to be structured and controlled, are often high on internal validity. However, their strength with regard to structure and control, may result in low external validity. The results may be so limited as to prevent generalizing to other situations. In contrast, observational research may have high external validity generalizability because it has taken place in the real world.

However, the presence of so many uncontrolled variables may lead to low internal validity in that we can't be sure which variables are affecting the observed behaviors. Relationship between reliability and validity. If data are valid, they must be reliable. If people receive very different scores on a test every time they take it, the test is not likely to predict anything. However, if a test is reliable, that does not mean that it is valid.

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Issues of research reliability and validity need to be addressed in methodology chapter in a concise manner. Reliability refers to the extent to which the same answers can be obtained using the same instruments more than one time. In simple terms, if your research is associated with high levels of.

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Research validity in surveys relates to the extent at which the survey measures right elements that need to be measured. In simple terms, validity refers to how well an instrument as measures what it is intended to measure.

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Validity encompasses the entire experimental concept and establishes whether the results obtained meet all of the requirements of the scientific research method. For example, there must have been randomization of the sample groups and appropriate care and diligence shown in . Different methods vary with regard to these two aspects of validity. Experiments, because they tend to be structured and controlled, are often high on internal validity. In contrast, observational research may have high external validity (generalizability) because it has taken place in the real world. Relationship between reliability.

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Reliability is consistency across time (test-retest reliability), across items (internal consistency), and across researchers (interrater reliability). Validity is the extent to which the scores actually represent the variable they are intended to. Reliability and validity, jointly called the “psychometric properties” of measurement scales, are the yardsticks against which the adequacy and accuracy of our measurement procedures are evaluated in scientific research.