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Reliability (statistics)

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❶For instance, let's say you had observations that were being rated by two raters. Scales which measured weight differently each time would be of little use.

Test-Retest Reliability

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Assessing Reliability
What is Reliability?

Scales which measured weight differently each time would be of little use. The same analogy could be applied to a tape measure which measures inches differently each time it was used. It would not be considered reliable.

If findings from research are replicated consistently they are reliable. A correlation coefficient can be used to assess the degree of reliability. If a test is reliable it should show a high positive correlation. Of course, it is unlikely the exact same results will be obtained each time as participants and situations vary, but a strong positive correlation between the results of the same test indicates reliability.

Internal reliability assesses the consistency of results across items within a test. External reliability refers to the extent to which a measure varies from one use to another. The split-half method assesses the internal consistency of a test, such as psychometric tests and questionnaires.

There, it measures the extent to which all parts of the test contribute equally to what is being measured. This is done by comparing the results of one half of a test with the results from the other half.

A test can be split in half in several ways, e. If the two halves of the test provide similar results this would suggest that the test has internal reliability. The reliability of a test could be improved through using this method. For example any items on separate halves of a test which have a low correlation e.

The split-half method is a quick and easy way to establish reliability. 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.

Even if your results are great, sloppy and inconsistent design will compromise your integrity in the eyes of the scientific community. Internal validity and reliability are at the core of any experimental design. External validity is the process of examining the results and questioning whether there are any other possible causal relationships.

Control groups and randomization will lessen external validity problems but no method can be completely successful. This is why the statistical proofs of a hypothesis called significant , not absolute truth. Any scientific research design only puts forward a possible cause for the studied effect. There is always the chance that another unknown factor contributed to the results and findings. This extraneous causal relationship may become more apparent, as techniques are refined and honed.

If you have constructed your experiment to contain validity and reliability then the scientific community is more likely to accept your findings. Eliminating other potential causal relationships, by using controls and duplicate samples, is the best way to ensure that your results stand up to rigorous questioning. Check out our quiz-page with tests about:. Martyn Shuttleworth Oct 20, Retrieved Sep 11, from Explorable. The text in this article is licensed under the Creative Commons-License Attribution 4.

Criterion-Related Validity is used to predict future or current performance - it correlates test results with another criterion of interest. If a physics program designed a measure to assess cumulative student learning throughout the major. The new measure could be correlated with a standardized measure of ability in this discipline, such as an ETS field test or the GRE subject test.

The higher the correlation between the established measure and new measure, the more faith stakeholders can have in the new assessment tool. If the measure can provide information that students are lacking knowledge in a certain area, for instance the Civil Rights Movement, then that assessment tool is providing meaningful information that can be used to improve the course or program requirements. Sampling Validity similar to content validity ensures that the measure covers the broad range of areas within the concept under study.

Not everything can be covered, so items need to be sampled from all of the domains. When designing an assessment of learning in the theatre department, it would not be sufficient to only cover issues related to acting.

Other areas of theatre such as lighting, sound, functions of stage managers should all be included. The assessment should reflect the content area in its entirety. National Council on Measurement in Education. Standards for educational and psychological testing.

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Reliability refers to whether or not you get the same answer by using an instrument to measure something more than once. In simple terms, research reliability is the degree to which research method produces stable and consistent results. A specific measure is considered to be reliable if its.

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Reliability has to do with the quality of measurement. In its everyday sense, reliability is the "consistency" or "repeatability" of your measures. Before we can define reliability precisely we have to .

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Internal validity dictates how an experimental design is structured and encompasses all of the steps of the scientific research method. Even if your results are great, sloppy and inconsistent design will compromise your integrity in the eyes of the scientific community. Internal validity and reliability are at the core of any experimental design. Research Methods › Reliability. What is Reliability? Saul McLeod, published The term reliability in psychological research refers to the consistency of a research study or measuring test. For example, if a person weighs themselves during the course of a day they would expect to see a similar reading. Scales which measured weight Author: Saul Mcleod.

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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. Inter-method reliability assesses the degree to which test scores are consistent when there is a variation in the methods or instruments used. This allows inter-rater reliability to be ruled out. This allows inter-rater reliability to be ruled out.