Common issues in reliability include measurement errors like trait errors and method errors. The correlation between the scores from the two testing occasions is usually between 0. In a series of studies, they showed that peoples scores were positively correlated with their scores on a standardized academic achievement test, and that their scores were negatively correlated with their scores on a measure of dogmatism (which represents a tendency toward obedience). For example, they may be required to describe a trial of a robbery or a road accident someone has seen. You have probably assumed that a good test must be both reliable and valid (and you would be right about that). WebReliability refers to the consistency of a measure. Reliability in psychology is the extent to which a particular scale or measurement produces consistent scores or results across multiple uses. Validity, on the other hand, refers to whether a measurement procedure is actually measuring what it is supposed to measure. Someone might tell you that a certain quiz will show you how much social intelligence you have. Again, there is no need to bother with the math; we can think of Cronbach's Coefficient Alpha as the average of all the split-half reliabilities we could compute by all possible ways of dividing the items into two groups. I would like to end with some practical points about how you can apply the information I've presented here to your interaction with psychological measures. Split-Half Reliability: Definition + Examples Reliabilityrefers to the consistency of a measure. Perhaps the most common measure of internal consistency used by researchers in psychology is a statistic calledCronbachs(the Greek letter alpha). It is possible to draw tentative conclusions about the relation between psychological variables when the tests show reliabilities below .70. Inter-raterreliabilityis the extent to which different observers are consistent in their judgments. Test-retestreliabilityis the extent to which this is actually the case. Your understanding of reliability and validity from reading this blog post may help you to recognize when this happens and to use caution before accepting results based on overstated claims. How do we assess and improve reliability in Psychology research? Administer each half to the same individual. Essentially synonymous with the older term Einstellung, mental set is the Again, high test-retest correlations make sense when the construct being measured is assumed to be consistent over time, which is the case for intelligence, self-esteem, and the Big Five personality dimensions. If your measure assesses multiple constructs, split-half reliability will be and. WebReliability is not a constant property of a test and is better thought of as different types of reliability for different populations at different levels of the construct being measured. But how can we know the reliability of any measurement procedure? In simple words, psychometric properties reveal information about a tests adequacy, relevance, and usefulness (or its validity). In 2014, College Board president David Coleman expressed his awareness of these problems, recognizing that college success is more accurately predicted by high school grades than by SAT scores. It also suggests methods to enhance the tests and minimize errors. Reliability indicates measurement precision, reflected in producing similar measurements on multiple occasions. And that was probably true if we took the measurements one right after the other. Biases in terms of selection, deterioration of the mean, history, progression, mechanization, testing, social interaction, and attenuation are threats to validity. Validity indicates the correctness of a measure in research. Your clothes seem to be fitting more loosely, and several friends have asked if you have lost weight. 2. everyday uses vs. technical definition. A reliable steel tape measure would show different lengths for the board over these time periods, giving the impression that the tape measure is less reliable than it really is. If it does not, the quiz is unreliable (at least for you) and is basically useless to you. Describe the kinds of evidence that would be relevant to assessing the reliability and validity of a particular measure. We have two tape measures, one made out of cloth fabric, and one made of steel. A second kind of reliability isinternalconsistency, which is the consistency of peoples responses across the items on a multiple-item measure. The basic process of conducting psychology research involves asking a question, designing a study, collecting data, analyzing results, reaching conclusions, and sharing the findings. Reliability Reliability is the presence of a stable and constant outcome after repeated measurement and validity is used to describe the indication that a test or tool of measurement is true and accurate. Still, over time, the psychological research community has tended to rally around preferred measures. WebIn this vein, there are many different types of validity and ways of thinking about it. If findings or results remain the same or similar over multiple attempts, a researcher often considers it reliable. Is Memory Reliable? | The Classic Journal - UGA It is hard to settle on a unit of intelligence or personality when we are not in agreement about the definition of intelligence or personality. Internal Validity. In fact, it has been suggested that the SATs predictive validity may be overestimated by as much as 150% (Rothstein, 2004). If the new measure of self-esteem were highly correlated with a measure of mood, it could be argued that the new measure is not really measuring self-esteem; it is measuring mood instead. If that agreement is high enough we can then take the average judgment of all judges as our most reliable, accurate estimate of the person's personality. Reliability & Validity - Simply Psychology Reliability Applying What You've Learned about Reliability to the Real World. The extent to which a measure covers the construct of interest. Let's look at this question first with an example of physical measurement. In our example, the cloth measuring tape produced a number of readings that were either greater than or less than the actual length of the board. A good friend might overestimate a person's conscientiousness, while a critical supervisor might underestimate it. In carpentry, it is good sense to measure a piece of wood multiple times before cutting it to avoid cutting a board too short and wasting wood. When they created the Need for Cognition Scale, Cacioppo and Petty also provided evidence of discriminant validity by showing that peoples scores were not correlated with certain other variables. Reliability People generally accept that they will be able to recount events they have experienced accurately, so much so that historically many people have been convicted of crimes primarily on eyewitness testimony. For self-judgments, we have only one self, so it is impossible to average information from multiple judges. A measurement is said to be reliable or consistent if the measurement can produce similar results if used again in similar circumstances. If you want to measure a lot of different traits with one questionnaire, the questionnaire might have to be 200 or 300 or 400 items long. In fact, combining their single-item tests into multi-item measures yields reliability estimates in the .70s or .80s (Epstein and O'Brien, 1985). A peer-reviewed journal article is read by several other scientists (generally anonymously) with expertise in the subject matter. This means that any good measure of intelligence should produce roughly the same scores for this individual next week as it does today. Peoples scores on this measure should be correlated with their participation in extreme activities such as snowboarding and rock climbing, the number of speeding tickets they have received, and even the number of broken bones they have had over the years. Internal Consistency Reliability Any feedback scheme attempting to use more than three categories (e.g., very low, moderately low, average, moderately high, very high) is likely to provide inconsistent results because you are trying to make decisions that are more fine-grained than the reliability of the questionnaire supports. But optimal reliability demands a balance between using multiple measurements and limiting the length of measures to keep respondents engaged. As an absurd example, imagine someone who believes that peoples index finger length reflects their self-esteem and therefore tries to measure self-esteem by holding a ruler up to peoples index fingers. Personality is essentially our relational stylehow we view and interact with ourselves, the world, and others. If peoples responses to the different items are not correlated with each other, then it would no longer make sense to claim that they are all measuring the same underlying construct. ), The seventeenth yearbook of the National Society for Study of Education. Measurement Reliability Explained in Simple Language This occurs because random selection, random assignment, and a design that limits the effects of both experimenter bias and participant expectancy should create groups that are similar in composition and treatment. If you could not borrow the platinum-iridium bar to measure the wood or have a way of timing the fraction of a second it would take light to travel from one end of the piece of wood to the other, you wouldn't really know whether your steel tape's 98 measurements of 36" are right on the mark. The difference in indicators of validity refers to the deviation between the measurement and its real value. Clearly, a measure that produces highly inconsistent scores over time cannot be a very good measure of a construct that is supposed to be consistent. 3. To know it thoroughly involves knowing its quantity as well as its quality." Criteria can also include other measures of the same construct.
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