Overview
A personality test aims to describe certain characteristics that usually stay with a person for life. The first used personaltiy test was the Woodworth Personal data sheet, which appeared in 1919. This test was used by the US Military to screen soldiers who might be susceptible to shell shock.

Types of Personality Tests
Psychologists and psychiatrists use personality tests to identify personality characterists or problems. A personality test can either be objective or projective. Objective personality tests are usually multiple choice and require the taker to select the most accurate answer.
An objective personality test uses the following steps:
  • Making decisions on nature, goal, target population, power.
  • Creating a bank of questions.
  • Estimating the validity of the questions, by means of statistical procedures and/or judgement of experts in the field.
  • Designing a format of application (a clear, easy-to-answer questionnaire, or an interview, etc.).
  • Detecting which questions are better in terms of discrimination, clarity, ease of response, upon application on a pilot sample.
  • Applying a revised questionnaire or interview to a sample.
  • Use appropriate statistical procedures to establish norms for the test.

Projective personality tests are more open tests that encourage the taker to respond freely. This is different from an objective test because responses are based on a universal standard rather than an individual's judgement.
An example of a projective personality test is the Inkblot Test.
Inkblot Test- There are ten official inkblots. Five inkblots are black ink on white paper. Two are black and red ink on white paper. Three are multicolored. After the individual has seen and responded to all the inkblots, the tester then gives them to him again one at a time to study. The patient is asked to note where he sees what he originally saw and what makes it look like that. The blot can also be rotated. As the patient is examining the inkblots, the psychologist writes down everything the patient says or does.

inkblot.jpg

Projective personality tests have lost populalrity as psychology has advanced. The main cause of this decline is because many psychologists no longer adhere to Freudian principles.

Validity of Personality Tests
A personality test is valid when the available evidence indicates that the test and its subscales measure the attribute it is intended to measure.
That is, if a test measures what it claims to, it is considered a valid test. If it doesn't, it is invalid.
A set of official standards for validity also exist. in a book called the Standards for Educational and Psychological Tests. The standards are produced by a joint committee of the APA, the AERA, and the NCME.

Assessing Validity of Personality Tests
When a person takes a personality test, they go through the mental process of picking an answer. Studies reveal that using think-aloud methods provide a way to measure a tests validity. The main point is whether or not these tests accurately predicts what it is supposed to. Convergant validity, discriminant validity, and criterion validity are the main concepts to examine.
Convergent validity -- The test should converge (correlate highly) with other tests of the same concept
Discriminant validity -- The test should not correlate with other measures of different concepts or constructs. For example, a test of extraversion should not correlate with a test of anxiety
Criterion validity -- Finally, test scores should be related to a criterion of importance

Works Cited

"Personality Test." Wikipedia. 16 Jan 2008. 20 Jan 2008 http://en.wikipedia.org/wiki/Personality_test.

Owen, Chris. "The Personality Test." Critical Essays on Scientology. 10 Feb 1997.
16 Jan 2008 http://www.xenu.net/archive/oca/oca.html#1

Mayer, John. "Personality Psychology." A Systems Approach.
19 Jan 2008 <http://www.thepersonalitysystem.org/index.htm>.