Could a psychological test and assessment be invalid and still have reliability Why or why not?
ReliabilityRemember Kevin? He comes to you with a problem, and you choose an assessment to help you diagnose him. For example, let's say that you want to do an fMRI - a type of brain scan - to see if Kevin has a tumor. So you put Kevin in the MRI machine and the computer says that nope, Kevin doesn't have a tumor. But wait! Last week, Kevin had the same test done. That time, it showed that he does have a tumor. What's going on? Show In this case, the assessment (the fMRI) lacks reliability. Reliability is when an assessment consistently delivers the same results. Of course, usually fMRI machines have high reliability, but Kevin's case is an exception. Let's look at another example of reliability. Imagine that you have a bathroom scale. You get on it one morning and it says that you weigh 157 pounds. A minute later, you get on it and it says that you weigh 208 pounds. A third time, it tells you that you weigh 81 pounds. You're not changing your weight from minute to minute, so the scale is not reliable. If, however, you get on the scale three times in a row and each time the scale reads 150 pounds, it is reliable. Of course, there's usually some variance, so even if the scale reads 155, 157 and 156, you could say that it still has a high reliability. There are two major types of reliability that are important in psychological assessments: inter-rater reliability and test-retest reliability. Inter-rater reliability is when two people will come up with the same answer when using the same assessment. For example, let's say that you have a questionnaire that will help you diagnose Kevin. You ask him the questions and he answers. From his answers, you diagnose him with attention deficit disorder. But then Kevin goes down the street to another psychologist. That psychologist has the same questionnaire. She asks the same questions and gets the same responses from Kevin. But she diagnoses him with obsessive-compulsive disorder. In this example, the questionnaire has a low inter-rater reliability. If it had a high inter-rater reliability, each time a different psychologist used the questionnaire and got the same answers from Kevin, he or she would come up with the same diagnosis. The other type of reliability is test-retest reliability, which is when an assessment yields the same answer over and over. Remember your bathroom scale? If the readings on the scale are 157, 208 and 81 pounds, it has a low test-retest reliability because every time you get on the scale, the number is very different. On the other hand, if it reads 150 every time, it has a high test-retest reliability.
Can a test be reliable and yet not valid explain why or why not?How do they relate? A reliable measurement is not always valid: the results might be reproducible, but they're not necessarily correct. A valid measurement is generally reliable: if a test produces accurate results, they should be reproducible.
Why should a psychological test be valid and reliable?Reliability is important because it determines the value of a psychological test or study. If test results remain consistent when researchers conduct a study, its reliability ensures value to the field of psychology and other areas in which it has relevance, such as education or business.
Can an assessment be valid but not reliable?Validity will tell you how good a test is for a particular situation; reliability will tell you how trustworthy a score on that test will be. You cannot draw valid conclusions from a test score unless you are sure that the test is reliable. Even when a test is reliable, it may not be valid.
How can a test be reliable but not valid example?For a test to be reliable, it also needs to be valid. For example, if your scale is off by 5 lbs, it reads your weight every day with an excess of 5lbs. The scale is reliable because it consistently reports the same weight every day, but it is not valid because it adds 5lbs to your true weight.
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