Practical Strategies for Psychological Measurement, American Psychological Association (APA) Style, Writing a Research Report in American Psychological Association (APA) Style, From the “Replicability Crisis” to Open Science Practices. A person who is highly intelligent today will be highly intelligent next week. In simple terms, research reliability is the degree to which research method produces stable and consistent results. Test–retest is a concept that is routinely evaluated during the validation phase of many measurement tools. Take it with you wherever you go. Psychologists consider three types of consistency: over time (test-retest reliability), across items (internal consistency), and across different researchers (inter-rater reliability). If people’s 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. For example, they found only a weak correlation between people’s need for cognition and a measure of their cognitive style—the extent to which they tend to think analytically by breaking ideas into smaller parts or holistically in terms of “the big picture.” They also found no correlation between people’s need for cognition and measures of their test anxiety and their tendency to respond in socially desirable ways. The scores from Time 1 and Time 2 can then be correlated in order to evaluate the test for stability over time. Inter-rater reliability is the extent to which different observers are consistent in their judgments. Here, the same test is administered once, and the score is based upon average similarity of responses. Reliability refers to the consistency of the measurement. Reliability can vary with the many factors that affect how a person responds to the test, including their mood, interruptions, time of day, etc. Cacioppo, J. T., & Petty, R. E. (1982). It is also the case that many established measures in psychology work quite well despite lacking face validity. significant results must be more than a one-off finding and be inherently repeatable The text in this article is licensed under the Creative Commons-License Attribution 4.0 International (CC BY 4.0). Likewise, if as test is not reliable it is also not valid. Psychologists do not simply assume that their measures work. Consistency of people’s responses across the items on a multiple-item measure. Reliability shows how trustworthy is the score of the test. Before we can define reliability precisely we have to lay the groundwork. Criteria can also include other measures of the same construct. The assessment of reliability and validity is an ongoing process. Cronbach’s α would be the mean of the 252 split-half correlations. By this conceptual definition, a person has a positive attitude toward exercise to the extent that he or she thinks positive thoughts about exercising, feels good about exercising, and actually exercises. The reliability and validity of a measure is not established by any single study but by the pattern of results across multiple studies. Discussions of validity usually divide it into several distinct “types.” But a good way to interpret these types is that they are other kinds of evidence—in addition to reliability—that should be taken into account when judging the validity of a measure. Test-retest reliability It helps in measuring the consistency in research outcome if a similar test is repeated by using the same sample over a period of time. eval(ez_write_tag([[580,400],'explorable_com-box-4','ezslot_1',123,'0','0']));Even if a test-retest reliability process is applied with no sign of intervening factors, there will always be some degree of error. You don't need our permission to copy the article; just include a link/reference back to this page. Test-retest reliability involves re-running the study multiple times and checking the correlation between results. On the other hand, educational tests are often not suitable, because students will learn much more information over the intervening period and show better results in the second test. A second kind of reliability is internal consistency, which is the consistency of people’s responses across the items on a multiple-item measure. We have already considered one factor that they take into account—reliability. In this case, the observers’ ratings of how many acts of aggression a particular child committed while playing with the Bobo doll should have been highly positively correlated. However, this term covers at least two related but very different concepts: reliability and agreement. Define validity, including the different types and how they are assessed. This will jeopardise the test-retest reliability and so the analysis that must be handled with caution.eval(ez_write_tag([[300,250],'explorable_com-banner-1','ezslot_0',124,'0','0'])); To give an element of quantification to the test-retest reliability, statistical tests factor this into the analysis and generate a number between zero and one, with 1 being a perfect correlation between the test and the retest. However, this cannot remove confounding factors completely, and a researcher must anticipate and address these during the research design to maintain test-retest reliability.eval(ez_write_tag([[300,250],'explorable_com-large-leaderboard-2','ezslot_6',125,'0','0'])); To dampen down the chances of a few subjects skewing the results, for whatever reason, the test for correlation is much more accurate with large subject groups, drowning out the extremes and providing a more accurate result. When researchers measure a construct that they assume to be consistent across time, then the scores they obtain should also be consistent across time. So people’s scores on a new measure of self-esteem should not be very highly correlated with their moods. As an absurd example, imagine someone who believes that people’s index finger length reflects their self-esteem and therefore tries to measure self-esteem by holding a ruler up to people’s index fingers. It is a test which the researcher utilizes for measuring consistency in research results if the same examination is performed at … In reference to criterion validity, variables that one would expect to be correlated with the measure. People’s 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. Reliability and validity are two important concerns in research, and, both reliability and validity are the expected outcomes of research. 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. For example, people might make a series of bets in a simulated game of roulette as a measure of their level of risk seeking. Inter-rater reliability can be used for interviews. In order for the results from a study to be considered valid, the measurement procedure must first be reliable. Validity is the extent to which the scores from a measure represent the variable they are intended to. The consistency of a measure on the same group of people at different times. Instruments such as IQ tests and surveys are prime candidates for test-retest methodology, because there is little chance of people experiencing a sudden jump in IQ or suddenly changing their opinions. ). Description: There are several levels of reliability testing like development testing and manufacturing testing. They indicate how well a method, technique or test measures something. This means you're free to copy, share and adapt any parts (or all) of the text in the article, as long as you give appropriate credit and provide a link/reference to this page. Reliability Testing Tutorial: What is, Methods, Tools, Example Again, measurement involves assigning scores to individuals so that they represent some characteristic of the individuals. To the extent that each participant does in fact have some level of social skills that can be detected by an attentive observer, different observers’ ratings should be highly correlated with each other. When the criterion is measured at the same time as the construct, criterion validity is referred to as concurrent validity; however, when the criterion is measured at some point in the future (after the construct has been measured), it is referred to as predictive validity (because scores on the measure have “predicted” a future outcome). When a measure has good test-retest reliability and internal consistency, researchers should be more confident that the scores represent what they are supposed to. Researchers repeat research again and again in different settings to compare the reliability of the research. The extent to which people’s scores on a measure are correlated with other variables that one would expect them to be correlated with. In evaluating a measurement method, psychologists consider two general dimensions: reliability and validity. Here researcher when observe the same behavior independently (to avoided bias) and compare their data. Perfection is impossible and most researchers accept a lower level, either 0.7, 0.8 or 0.9, depending upon the particular field of research. Instead, it is assessed by carefully checking the measurement method against the conceptual definition of the construct. For example, if a group of students takes a test, you would expect them to show very similar results if they take the same test a few months later. The 4 different types of reliability are: 1. People may have been asked about their favourite type of bread. Internal Consistency Reliability: In reliability analysis, internal consistency is used to measure the reliability of a summated scale where several items are summed to form a total score. When new measures positively correlate with existing measures of the same constructs. This is known as convergent validity. This measure of reliability in reliability analysis focuses on the internal consistency of the set of items forming the scale. Face validity is the extent to which a measurement method appears “on its face” to measure the construct of interest. Your clothes seem to be fitting more loosely, and several friends have asked if you have lost weight. The extent to which the scores from a measure represent the variable they are intended to. Like Explorable? 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. For example, self-esteem is a general attitude toward the self that is fairly stable over time. When the criterion is measured at the same time as the construct. If the results are consistent, the test is reliable. Test-retest reliability is the extent to which this is actually the case. This ensures reliability as it progresses. Split-half reliability is similar; half of the data are … One approach is to look at a split-half correlation. So a questionnaire that included these kinds of items would have good face validity. The project is credible. Method of assessing internal consistency through splitting the items into two sets and examining the relationship between them. What data could you collect to assess its reliability and criterion validity? Revised on June 26, 2020. However, in social sciences … For example, one would expect new measures of test anxiety or physical risk taking to be positively correlated with existing measures of the same constructs. Comment on its face and content validity. There are two distinct criteria by which researchers evaluate their measures: reliability and validity. Practice: Ask several friends to complete the Rosenberg Self-Esteem Scale. In general, a test-retest correlation of +.80 or greater is considered to indicate good reliability. There has to be more to it, however, because a measure can be extremely reliable but have no validity whatsoever. Search over 500 articles on psychology, science, and experiments. As an informal example, imagine that you have been dieting for a month. But other constructs are not assumed to be stable over time. The need for cognition. On the other hand, reliability claims that you will get the same results on repeated tests. But if it were found that people scored equally well on the exam regardless of their test anxiety scores, then this would cast doubt on the validity of the measure. Reliability is about the consistency of a measure, and validity is about the accuracy of a measure. But how do researchers make this judgment? This means that any good measure of intelligence should produce roughly the same scores for this individual next week as it does today. Pearson’s r for these data is +.95. For example, if you were interested in measuring university students’ social skills, you could make video recordings of them as they interacted with another student whom they are meeting for the first time. Then assess its internal consistency by making a scatterplot to show the split-half correlation (even- vs. odd-numbered items). If your method has reliability, the results will be valid. Theories are developed from the research inferences when it proves to be highly reliable. Validity means you are measuring what you claimed to measure. Instead, they collect data to demonstrate that they work. In this method, the researcher performs a similar test over some time. There are three main concerns in reliability testing: equivalence, stability over … It is most commonly used when the questionnaire is developed using multiple likert scale statements and therefore to determine if … The very nature of mood, for example, is that it changes. Face validity is at best a very weak kind of evidence that a measurement method is measuring what it is supposed to. Reliability and validity are concepts used to evaluate the quality of research. On the Rosenberg Self-Esteem Scale, people who agree that they are a person of worth should tend to agree that that they have a number of good qualities. What construct do you think it was intended to measure? In the years since it was created, the Need for Cognition Scale has been used in literally hundreds of studies and has been shown to be correlated with a wide variety of other variables, including the effectiveness of an advertisement, interest in politics, and juror decisions (Petty, Briñol, Loersch, & McCaslin, 2009)[2]. Test-retest reliability on separate days assesses the stability of a measurement procedure (i.e., reliability as stability). Both these concepts imply how well a technique, method or test measures some aspect of the research. Reliability testing as the name suggests allows the testing of the consistency of the software program. This project has received funding from the, You are free to copy, share and adapt any text in the article, as long as you give, Select from one of the other courses available, https://explorable.com/test-retest-reliability, Creative Commons-License Attribution 4.0 International (CC BY 4.0), European Union's Horizon 2020 research and innovation programme. The shorter the time gap, the highe… Validity is a judgment based on various types of evidence. Describe the kinds of evidence that would be relevant to assessing the reliability and validity of a particular measure. Thus, test-retest reliability will be compromised and other methods, such as split testing, are better. For example, if a researcher conceptually defines test anxiety as involving both sympathetic nervous system activation (leading to nervous feelings) and negative thoughts, then his measure of test anxiety should include items about both nervous feelings and negative thoughts. The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) measures many personality characteristics and disorders by having people decide whether each of over 567 different statements applies to them—where many of the statements do not have any obvious relationship to the construct that they measure. ETS RM–18-01 There are a range of industry standards that should be adhered to to ensure that qualitative research will provide reliable results. This approach assumes that there is no substantial change in the construct being measured between the two occasions. It is not the same as mood, which is how good or bad one happens to be feeling right now. Samuel A. Livingston. There is a strong chance that subjects will remember some of the questions from the previous test and perform better. Assessing convergent validity requires collecting data using the measure. Test validity is requisite to test reliability. Retrieved Jan 01, 2021 from Explorable.com: https://explorable.com/test-retest-reliability. The finger-length method of measuring self-esteem, on the other hand, seems to have nothing to do with self-esteem and therefore has poor face validity. For example, intelligence is generally thought to be consistent across time. If, on the other hand, the test and retest are taken at the beginning and at the end of the semester, it can be assumed that the intervening lessons will have improved the ability of the students. Inter-rater reliability would also have been measured in Bandura’s Bobo doll study. Pearson’s r for these data is +.88. Test-retest reliability evaluates reliability across time. If at this point your bathroom scale indicated that you had lost 10 pounds, this would make sense and you would continue to use the scale. We know that if we measure the same thing twice that the correlation between the two observations will depend in part by how much time elapses between the two measurement occasions. Researchers John Cacioppo and Richard Petty did this when they created their self-report Need for Cognition Scale to measure how much people value and engage in thinking (Cacioppo & Petty, 1982)[1]. Like face validity, content validity is not usually assessed quantitatively. In M. R. Leary & R. H. Hoyle (Eds. Research Methods in Psychology by Paul C. Price, Rajiv Jhangiani, & I-Chant A. Chiang is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted. Even in surveys, it is quite conceivable that there may be a big change in opinion. Check out our quiz-page with tests about: Martyn Shuttleworth (Apr 7, 2009). So, how can qualitative research be conducted with reliability? For example, people’s scores on a new measure of test anxiety should be negatively correlated with their performance on an important school exam. Or consider that attitudes are usually defined as involving thoughts, feelings, and actions toward something. Note that this is not how α is actually computed, but it is a correct way of interpreting the meaning of this statistic. In the intervening period, if a bread company mounts a long and expansive advertising campaign, this is likely to influence opinion in favour of that brand. The test-retest method assesses the external consistency of a test. The extent to which scores on a measure are not correlated with measures of variables that are conceptually distinct. But how do researchers know that the scores actually represent the characteristic, especially when it is a construct like intelligence, self-esteem, depression, or working memory capacity? This involves splitting the items into two sets, such as the first and second halves of the items or the even- and odd-numbered items. The relevant evidence includes the measure’s reliability, whether it covers the construct of interest, and whether the scores it produces are correlated with other variables they are expected to be correlated with and not correlated with variables that are conceptually distinct. A statistic in which α is the mean of all possible split-half correlations for a set of items. A criterion can be any variable that one has reason to think should be correlated with the construct being measured, and there will usually be many of them. If it were found that people’s scores were in fact negatively correlated with their exam performance, then this would be a piece of evidence that these scores really represent people’s test anxiety. Note, it can also be called inter-observer reliability when referring to observational research. Reliability is the ability of a measure applied twice upon the same respondents to produce the same ranking on both occasions. But if it indicated that you had gained 10 pounds, you would rightly conclude that it was broken and either fix it or get rid of it. 3.3 RELIABILITY A test is seen as being reliable when it can be used by a number of different researchers under stable conditions, with consistent results and the results not varying. In its everyday sense, reliability is the “consistency” or “repeatability” of your measures. This is as true for behavioural and physiological measures as for self-report measures. Research Reliability Reliability refers to whether or not you get the same answer by using an instrument to measure something more than once. You can utilize test-retest reliability when you think that result will remain constant. (2009). Reliability refers to the consistency of a measure. Reliability reflects consistency and replicability over time. Reliability and validity are two important concepts in statistics. You can use it freely (with some kind of link), and we're also okay with people reprinting in publications like books, blogs, newsletters, course-material, papers, wikipedia and presentations (with clear attribution).eval(ez_write_tag([[728,90],'explorable_com-large-mobile-banner-1','ezslot_7',133,'0','0'])); Don't have time for it all now? For these reasons, students facing retakes of exams can expect to face different questions and a slightly tougher standard of marking to compensate. This is an extremely important point. Validity is the extent to which the scores actually represent the variable they are intended to. Again, a value of +.80 or greater is generally taken to indicate good internal consistency. In this case, it is not the participants’ literal answers to these questions that are of interest, but rather whether the pattern of the participants’ responses to a series of questions matches those of individuals who tend to suppress their aggression. In experiments, the question of reliability can be overcome by repeating the experiments again and again. Test-retest. A split-half correlation of +.80 or greater is generally considered good internal consistency. Different types of Reliability. In a similar way, math tests can be helpful in testing the mathematical skills and knowledge of students. For example, in a ten-statement questionnaire to measure confidence, each response can be seen as a one-statement sub-test. reliability of the measuring instrument (Questionnaire). The similarity in responses to each of the ten statements is used to assess reliability. For example, Figure 5.3 shows the split-half correlation between several university students’ scores on the even-numbered items and their scores on the odd-numbered items of the Rosenberg Self-Esteem Scale. Reliability is consistency across time (test-retest reliability), across items (internal consistency), and across researchers (interrater reliability). Not only do you want your measurements to be accurate (i.e., valid), you want to get the same answer every time you use an instrument to measure a variable. Instead, they conduct research to show that they work. This measure would be internally consistent to the extent that individual participants’ bets were consistently high or low across trials. Types of Reliability Test-retest reliability is a measure of reliability obtained by administering the same test twice over a period of time to a group of individuals. Then a score is computed for each set of items, and the relationship between the two sets of scores is examined. All these low correlations provide evidence that the measure is reflecting a conceptually distinct construct. If the collected data shows the same results after being tested using various methods and sample groups, this indicates that the information is reliable. Then you could have two or more observers watch the videos and rate each student’s level of social skills. Cronbach Alpha is a reliability test conducted within SPSS in order to measure the internal consistency i.e. This refers to the degree to which different raters give consistent estimates of the same behavior. tive study is reliability, or the accuracy of an instrument. So, why do we care? If they cannot show that they work, they stop using them. Criterion validity is the extent to which people’s scores on a measure are correlated with other variables (known as criteria) that one would expect them to be correlated with. If their research does not demonstrate that a measure works, they stop using it. That instrument could be a scale, test, diagnostic tool – obviously, reliability applies to a wide range of devices and situations. Reliability; Reliability. Conceptually, α is the mean of all possible split-half correlations for a set of items. Some subjects might just have had a bad day the first time around or they may not have taken the test seriously. The amount of time allowed between measures is critical. For example, if a group of students takes a test, you would expect them to show very similar results if they take the same test a few months later. tests, items, or raters) which measure the same thing. Content validity is the extent to which a measure “covers” the construct of interest. In social sciences, the researcher uses logic to achieve more reliable results. So to have good content validity, a measure of people’s attitudes toward exercise would have to reflect all three of these aspects. Although face validity can be assessed quantitatively—for example, by having a large sample of people rate a measure in terms of whether it appears to measure what it is intended to—it is usually assessed informally. There are several ways to measure reliability. Reliability can be referred to as consistency in test scores. In the research, reliability is the degree to which the results of the research are consistent and repeatable. The extent to which a measurement method appears to measure the construct of interest. When they created the Need for Cognition Scale, Cacioppo and Petty also provided evidence of discriminant validity by showing that people’s scores were not correlated with certain other variables. No problem, save it as a course and come back to it later. Discriminant validity, on the other hand, is the extent to which scores on a measure are not correlated with measures of variables that are conceptually distinct. The fact that one person’s index finger is a centimetre longer than another’s would indicate nothing about which one had higher self-esteem. Reliability in research Reliability, like validity, is a way of assessing the quality of the measurement procedure used to collect data in a dissertation. The extent to which a measure “covers” the construct of interest. Again, measurement involves assigning scores to individuals so that they represent some characteristic of the individuals. Test-Retest Reliability. If the data is similar then it is reliable. The test-retest reliability method is one of the simplest ways of testing the stability and reliability of an instrument over time. Like test-retest reliability, internal consistency can only be assessed by collecting and analyzing data. The answer is that they conduct research using the measure to confirm that the scores make sense based on their understanding of the construct being measured. For example, if a group of students take a geography test just before the end of semester and one when they return to school at the beginning of the next, the tests should produce broadly the same results. These are used to evaluate the research quality. For example , a thermometer is a reliable tool that helps in measuring the accurate temperature of the body. 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. Many behavioural measures involve significant judgment on the part of an observer or a rater. Reliability has to do with the quality of measurement. 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