Interesting questions! Let's take a closer look through discussion and examples from the testing literature.
1. What personality description are personality tests based on?
Personality Tests: A selection procedure measure the personality characteristics of applicants that are related to future job performance. Personality tests typically measure one or more of five personality dimensions: extroversion, emotional stability, agreeableness, conscientiousness, and openness to experience (http://www.hr-guide.com/data/G311.htm).
The personality description is based on a personality theory or several theoretical constructs; so it depends. Every personality test is theoretically based on a specific personality theory or perhaps a combination of several theories. In the test manual, this information is usually discussed in some detail in the section explaining test construction e.g., theoretical underpinnings of the test. For example, the MIPS test is based on the theory of Carl Jung.
Other personality tests are the: Minnesota Multiphasic Personality Inventory, Allport-Vemon-Lindzey Study of Values, and Gough Adjective Check List.
2. What are the strengths and weaknesses you can see in a personal interview and observation type test?
The interview and observation fall under the umbrella of qualitative methods. Therefore both are subject to the criticisms posed for qualitative methods of testing.
For illustrative purposes, the strengths and weaknesses of the interview and observation refer to real-life ...
This solution examines the type of personality description that personality tests are based on. It also identifies the strengths and weaknesses of personal interviews and observation type tests. Supplemented with information on an observation instrument.