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What is Reliability?

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❶Thus, we are trying to discriminate between two concepts and we would consider this discriminant validity. Consider that a test developer wants to maximize the validity of a unit test for 7th grade mathematics.

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Split-half method
What is Reliability?
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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 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.

Define and reliability and validity in qualitative research. Discuss the importance of establishing validity. List strategies used by researchers to improve reliability and validity. In order to withstand the scrutiny, researchers should spend time giving serious consideration to the following four aspects: Credibility - Often called internal validity, refers to the believability and trustworthiness of the findings. This depends more on the richness of the data gathered than on the quantity of data.

The participants of the study are the only ones that decide if the results actually reflect the phenomena being studied and therefore, it is important that participants feel the findings are credible and accurate.

Triangulation is a commonly used method for verifying accuracy that involves cross-checking information from multiple perspectives. The link in Resources Links on the left describes different types of triangulation methods.

Transferability - Often called external validity, refers to the degree that the findings of the research can be transferred to other contexts by the readers. This means that the results are generalizable and can be applied to other similar settings, populations, situations and so forth.

Researchers should thoroughly describe the context of the research to assist the reader in being able to generalize the findings and apply them appropriately. Dependability - Otherwise known as reliability, refers to the consistency with which the results could be repeated and result in similar findings. The dependability of the findings also lends legitimacy to the research method. Because the nature of qualitative research often results in an ever changing research setting and changing contexts, it is important that researcher document all aspects of any changes or unexpected occurrences to further explain the findings.

This is also important for other researchers who may want to replicate the study. Confirmability - A measure of the objectivity used in evaluating the results, describes how well the research findings are supported by the actual data collected when examined by other researchers. Your measure is both reliable and valid I bet you never thought of Robin Hood in those terms before. Another way we can think about the relationship between reliability and validity is shown in the figure below.

Here, we set up a 2x2 table. The columns of the table indicate whether you are trying to measure the same or different concepts. The rows show whether you are using the same or different methods of measurement. Imagine that we have two concepts we would like to measure, student verbal and math ability. Furthermore, imagine that we can measure each of these in two ways. Second, we can ask the student's classroom teacher to give us a rating of the student's ability based on their own classroom observation.

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.

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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.

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Construct validity is the term given to a test that measures a construct accurately and there are different types of construct validity that we should be concerned with. Three of these, concurrent validity, content validity, and predictive validity are discussed below. Concurrent Validity. 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).

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Define reliability, including the different types and how they are assessed. Define validity, including the different types and how they are assessed. Describe the kinds of evidence that would be relevant to assessing the reliability and validity of a particular measure. 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.