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Reliability & Validity

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❶This is also important for other researchers who may want to replicate the study.

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What is Reliability?
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By following a few basic principles, any experimental design will stand up to rigorous questioning and skepticism. The idea behind reliability is that any significant results must be more than a one-off finding and be inherently repeatable. Other researchers must be able to perform exactly the same experiment , under the same conditions and generate the same results. This will reinforce the findings and ensure that the wider scientific community will accept the hypothesis.

Without this replication of statistically significant results , the experiment and research have not fulfilled all of the requirements of testability. This prerequisite is essential to a hypothesis establishing itself as an accepted scientific truth.

For example, if you are performing a time critical experiment, you will be using some type of stopwatch. Generally, it is reasonable to assume that the instruments are reliable and will keep true and accurate time. However, diligent scientists take measurements many times, to minimize the chances of malfunction and maintain validity and reliability. At the other extreme, any experiment that uses human judgment is always going to come under question. Human judgment can vary wildly between observers , and the same individual may rate things differently depending upon time of day and current mood.

This means that such experiments are more difficult to repeat and are inherently less reliable. Reliability is a necessary ingredient for determining the overall validity of a scientific experiment and enhancing the strength of the results.

Debate between social and pure scientists, concerning reliability, is robust and ongoing. 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 the allocation of controls. Internal validity dictates how an experimental design is structured and encompasses all of the steps of the scientific research method. The following module discusses reliability and validity in qualitative research, with an emphasis on establishing credibility and transferability.

Qualitative research is based on subjective, interpretive and contextual data, making the findings are more likely to be scrutinized and questioned. Therefore, it is critical that researchers take steps to ensure the reliability and validity of their research findings.

The findings must be believable, consistent, applicable and credible if they are to be useful to readers and other researchers. Reliability refers to consistency with which the research will produce the same results if repeated. Validity refers to accuracy or correctness of the findings. The following video provides an excellent introductory overview to reliability and validity, including an explanation of terms and specific examples. Qualitative research has become increasingly popular in the past two decades.

Therefore, much time has been spent reviewing ways to judge the reliability and validity of qualitative research findings.

In order to withstand the scrutiny, researchers should spend time giving serious consideration to the following four aspects:. Qualitative Validity - The following overview compares validity in qualitative research with quantitative research validity.

Validity - This link provides an overview of the ways in which validity in analyzed in qualitative research and includes an explanation of common terminology.

Triangulation - Establishing Validity - Types of triangulation that are used to improve the validity of qualitative research are discussed in this link. Techniques for Establishing Validity - The following resource provides links to techniques for establishing credibility, transferability, dependability and confirmability in qualitative research.

Believe it or Not: This pin will expire , on Change. This pin never expires. 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. For example, we can measure strength of grip very reliably, but that does not make it a valid measure of intelligence or even of mechanical ability.

Reliability is a necessary, but not sufficient, condition for validity.


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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 .

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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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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. You are here: AllPsych > Research Methods > Chapter Test Validity and Reliability Test Validity and Reliability Whenever a test or other measuring device is used as part of the data collection process, the validity and reliability of that test is important.

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When we look at reliability and validity in this way, we see that, rather than being distinct, they actually form a continuum. On one end is the situation where the concepts and methods of measurement are the same (reliability) and on the other is the situation where concepts and methods of measurement are different (very discriminant validity). Reliability and Validity. In order for research data to be of value and of use The answer depends on the amount of research support for such a relationship. 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.