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Knowledgebase : Psychometrics Knowledge
     
Psychometric tests should have been validated by a test publisher prior to being published. However, the test user should also pay due diligence and ensure that the test cannot be accused of having unjustifiable adverse impact for one group of people o...
Yes. Research shows that online psychometric tests are generally as valid as hard-copy tests. This is of course only true when comparing reputable tests developed by experts in psychometrics and assessment. What about non-proctored tests (i.e., those the ...
This statistic is useful when we are trying to assess the amount of coverage (prediction) of job performance that is afforded by a test score or composite of scores. Most trained users of psychometric assessments will be familiar with the correlation c...
The following table shows corresponding percentile scores for a range of Z scores. PsyAsia's Psychometric Training Course attendees will recall that to calculate a Z score from a raw score one uses the following formula: Z SCORE = Raw Score minus ...
Occupational tests may be classified in numerous different ways.  The use of each term provides a language by which test administrators are able to understand what the test measures, how it measures, what scores are compared against and conditions under w...
A common problem in psychometrics research is the fact that a correlation coefficient is indicative of the relationship between two variables plus measurement error. As a correction for measurement error, Nunnally (1978) provided an equation that resul...
The first thing to remember is that if you are using a purely ipsative personality test then you should not be comparing test results between candidates. Ipsative tests are self-referencing - they are comprised of force-choice items. They are useful in...
Some test publishers do publish ipsative (forced choice) tests for use in selection. However, caution is required here. If your test is purely ipsative, then you should not use it in selection. See the references below for reasons why. The main reaso...
As noted in the _Standard Error of Measurement_ knowledgebase article [1], a respondent's score on any test or scale is not their true score, rather their true score + error. Therefore, if we want to compare two respondents who have taken the same test...
No method of assessment is 100% reliable - this applies to psychometrics just as it applies to interviews or reference checks and so forth. Psychometrics as a science is more likely however to apply statistical correction techniques to account for such...
With the demand and need for psychological tests increasing in various different cultures and countries, there has been much greater awareness regarding some of the issues that are associated with the development or adaptation of tests to be used in co...
Personality assessment can be divided into two categories, type and trait based personality assessments. Across both types of personality assessments, it is assumed that personality remains stable over time, involves a genetic basis and influences individ...
Firstly, ensure that you understand the theoretical rationale upon which the test was developed.  It should be based upon sound scientific theory!  Keep this in mind, in addition to your own reason for using the test (staff selection, departmental develop...
A derived dimension is similar to a scale on a personality test. However, a scale is a direct measure of a particular construct, such as openness to experience or extraversion. In contrast, a derived dimension is "derived" statistically using a formula...
A _norm group_ is a reference group that is used to compare your respondent's scores on a test or scale against similar others. This gives the score meaning. For example, a score of 20/30 (known as the _raw score_) means nothing on it's own. We need to...
The percentile score is the value below which x% of values fall. That is, if your respondent scores in the 60th percentile, the data is indicating that 60% of similar others (assuming you are using the correct norm table) would score less than your ...
A psychometric test is a measure of a psychological construct (such as personality or aptitude) that has been constructed according to psychometric principles.  In addition, the test should be administered, scored and interpreted in a standardised manner....
Most psychological societies (e.g., British Psychological Society) and academics (e.g., Devellis, 1991) suggest that an acceptable level of reliability for psychometric tests is:Ability/Aptitude Tests: .80 Personality Tests: .70Acceptable and unacceptable...
There is not a figure for acceptable validity of a psychometric test.  When scrutinizing test manuals, the qualified user is recommended to assess whether or not validity studies have been conducted and whether they are criterion or construct validity stu...
Reliability refers to consistency of measurement.If you measure the length of your office wall on two occasions and get two different measurements, you know that something is not right!  Maybe you changed your viewing angle of the tape measure between the...
Validity means "Is the test fit for purpose?"Some different types of validity:Face Validity (low-level of importance overall)Asks: "Do the questions appear to measure what the test purports to measure?"Important for: Respondent buy-inH...
There have been a number of comments from clients and the general public regarding the length of psychometric assessments and queries about the reasons why psychometric assessments are so long. It needs to be kept in mind that for psychometric assessments...
One of the first things clients will want to know when choosing who to work with when ordering psychometric tests is “why should I choose xyz company”?As the field of psychometrics continues to grow, overseas publishers are working hard to make inroads in...
Choosing the right psychometric testHuman resource professionals are unlikely to need any convincing that the use of psychometric tests as an aid to employee selection and development is probably at an all time high.  The increase in the use of aptitude a...