What Makes a Good Personality Test?

There are many different sorts of personality tests, word list choices (which is most like me or least like me), statement list choices, rate this statement as to how much it reflects who you are, picture tests asking you to interpret what you are seeing, lickert scale response tests, ipsative tests and a host of others.  How do you know which one is the best to use for hiring or developmental purposes?

I think the first question to ask yourself is “what am I trying to accomplish?”  Is it an issue of finding out if the person might work well in a team made of other diverse individuals?  Is it an issue of finding out if the individual matches the criteria for success you have identified in your environment?  Is it an issue of understanding what you will need to do to develop the individual after you hire him/her and will you invest the funds?  Or is it an issue of getting the test to make your selection for you?

The first three questions are fine uses of personality tests.  The last one is not appropriate.  Any assessment you use should be for the purpose of gathering valid and reliable information to help you or the individual better understand the true capabilities, motivators, potentials or personal styles that the person possesses.  And to ensure that the results you get are valid and reliable, make sure that your assessment meets this criteria:

1. Does it measure what it purports to measure?  Another way to ask this question is “Is the assessment valid?”  We can get into a long discussion around validity.  Face validity, content validity, context validity…all important.  Is it the right instrument to use in your particular situation?  Does it measure job-specific requirements, motivators and behavioral traits?
2. Does it measure what it purports to measure consistently?  Another way to ask this question is “Is the assessment reliable?”  Does it consistently produce the same scores for a person through test-retest review in a population?
3. Is it a tool that is more appropriate for use in team building?  Styles inventories (Myers Briggs, DISC, color grouping inventories) are excellent tools for team building, but assigning a particular quadrant of preferred style is not an ideal way to select staff.  Myers Briggs’ validation literature states that the tool is not appropriate for selection purposes.
4. Is the tool fakable?  Is it easy for the person to skew the results through answering a particular way or by choosing answers likely for a particular type of person?  One of the problems encountered with lickert scale type tests (ones where the respondent is asked to rate a statement on a scale of 1 to 5) tend to have this issue.  This is the reason that additional items are often used to determine the levels of fakability.  Ipsative tests (forced rank type items, where the individual is presented with a number of statements and asked them to order them) overcome the issue of fakability.  Depending upon how the scoring routine works, the frequently made argument that ipsative tests cause scores to be high in one area, while automatically causing another area to be low, can be overcome.
5. Does the instrument show good predictive capability?  Can to results predict, consistently and accurately, whether the individual will be a success greater than 75% of the time?  We offer an ipsative assessment that has shown to predict success at better than 97% of the time in some situations.

Personality tests are very useful tools, providing you integrate the use of the instrument within a process and let the tool offer objective information to support your selection process, assist you with developmental planning, or to increase team effectiveness by enabling people to understand how others might be the same or different from themselves.