This type of assessment varies from case to case and from one assessor to another and is open to subjective interpretations. Which of the following kind of assessment of an individual is being referred to here?

Informal

Our assessment of an individual may be informal or formal. Formal assessment is objective, standardised, and organised. On the other hand, informal assessment varies from case to case and from one assessor to another and, therefore, is open to subjective interpretations. Psychologists are trained in making formal assessment of psychological attributes.