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Definition of Reliability

Reliability in research

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This article is a part of the guide:
Assessing Reliability

Degree of stability exhibited when a measurement is repeated under identical conditions. References in periodicals archive? Since that time, our group has changed its name to the Manufacturing Reliability Specialist Group. The next step for manufacturing reliability: The need for storage solutions to increase in performance while maintaining high levels of reliability will continue to be important because of the expected continued growth in the number of servers being deployed and the increasing number of people accessing the Internet for personal and eBusiness use.

Increasing of operational reliability of technical system. The sample reliability language consists of four parts: Building a reliable product: Army reliability improvement initiatives. Of the numerous causes of poor reliability , most are never recognized but contribute to poor performance of the reliability dimensions of uptime, dependability and FRY. Radically improving output capability: Reliability has turned this view around by providing a strategic lever to optimize return on assets.

Questing for the reliability "silver bullet". Serial Attached SCSI has emerged to deliver higher levels of reliability than previous generations of SCSI for mission-critical transactional applications that must be online around-the-clock with no data loss. But while squabbling goes on over who should write the new rules, Kean believes that overall, competition will dramatically improve reliability. The ability to safely complete a mission is directly related to the reliability of the critical safety items.

Users and managers of this infrastructure are concerned with reliability and service. Good experimental design will allow for plenty of replicate samples by the researchers. But other researchers should also be able to perform exactly the same experiment, with similar equipment, under similar conditions, and achieve exactly the same results. If they cannot, then the design is externally unreliable. A good example of a failure to apply the definition of reliability correctly is provided by the cold fusion case of Fleischmann and Pons announced to the world that they had managed to generate heat at normal temperatures, instead of the huge and expensive tori used in most research into nuclear fusion.

This announcement shook the world, but researchers in many other institutions failed to replicate the experiment. The reason some tests do this is to increase their internal reliability. Internal reliability is about the consistency across separate items within a measure.

A test is internally consistent if each item contributes equally to the overall construct being measured. If you are a physicist or a chemist, repeat experiments should give exactly or almost exactly the same results, time after time.

The behavior of phosphorous atoms, DNA molecules or natural forces like gravity are very unlikely to change. Ecologists and social scientists, on the other hand, understand that achieving identical results on repeat experiments is practically impossible. Complex systems, human behavior and biological organisms are subject to far more random error and variation. While any experimental design must attempt to eliminate confounding variables and natural variations, there will always be some disparities in these disciplines.

Reliability and validity are often confused; the terms describe two inter-related but completely different concepts. This difference is best described with an example:. A researcher devises a new test that measures IQ more quickly than the standard IQ test:. Reliability is an essential component of validity but, on its own, is not a sufficient measure of validity.

A test can be reliable but not valid, whereas a test cannot be valid yet unreliable. A test that is extremely unreliable is essentially not valid either. A bathroom scale that measures your weight one day as kg and the next day as 2 kg is not unreliable, it merely is not measuring what it is meant to. There are several methods to assess the reliability of instruments. In the social sciences and psychology, testing internal reliability is essentially a matter of comparing the instrument with itself.

How could you determine whether each item on an inventory is contributing to the final score equally? One technique is the split-half method which cuts the test into two pieces and compares those pieces with each other.

The test can be split in a few ways: Split-half methods can only be done on tests measuring one construct — for example an extroversion subscale on a personality test. The internal consistency test compares two different versions of the same instrument, to ensure that there is a correlation and that they ultimately measure the same thing.

For example, imagine that an examining board wants to test that its new mathematics exam is reliable, and selects a group of test students. For each section of the exam, such as calculus, geometry, algebra and trigonometry, they actually ask two questions, designed to measure the aptitude of the student in that particular area. If there is a high internal consistency, i.

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.

However it can only be effective with large questionnaires in which all questions measure the same construct. This means it would not be appropriate for tests which measure different constructs. For example, the Minnesota Multiphasic Personality Inventory has sub scales measuring differently behaviors such depression, schizophrenia, social introversion.

Therefore the split-half method was not be an appropriate method to assess reliability for this personality test. The test-retest method assesses the external consistency of a test.

Examples of appropriate tests include questionnaires and psychometric tests. It measures the stability of a test over time. A typical assessment would involve giving participants the same test on two separate occasions.

Split-half method

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Reliability is something that every scientist, especially in social sciences and biology, must be aware of. In science, the definition is the same, but needs a much narrower and unequivocal definition. Another way of looking at this is as maximizing the inherent repeatability or consistency in an experiment.

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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 Saul Mcleod.

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Reliability and Validity. In order for research data to be of value and of use, they must be both reliable and valid.. Reliability. 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 lay the groundwork.

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Definition of reliability. 1: the quality or state of being reliable. 2: the extent to which an experiment, test, or measuring procedure yields the same results on repeated trials. Reliability, like validity, is a way of assessing the quality of the measurement procedure used to collect data in a dissertation. In order for the results from a study to be considered valid, the measurement procedure must first be reliable.