Psychological assessment is a systematic process of collecting, integrating, and interpreting information about an individual’s behaviour, personality, cognitive abilities, emotional functioning, and adjustment. In psychodiagnostics, accurate assessment depends on obtaining information from multiple data sources rather than relying on a single method. Different sources provide different perspectives and help the psychologist develop a comprehensive understanding of the person. One important source is clinical interview data. The interview provides direct information about the individual’s presenting problems, personal history, family relationships, education, occupation, social experiences, emotions, and coping patterns. Interviews may be structured, semi-structured, or unstructured. The psychologist can also observe the individual’s communication style, affect, attitude, and behaviour during the interview. The interview is therefore both a source of information and an opportunity for behavioural observation. Behavioural observation is another significant source of assessment data. Psychologists systematically observe behaviour in clinical, educational, occupational, or natural settings. Information may include patterns of interaction, emotional expression, attention, aggression, withdrawal, cooperation, or problem-solving behaviour. Naturalistic observation can reveal behaviours that may not appear during formal testing. Controlled observation may also be used when specific behaviours need to be examined under standardized conditions. Psychological tests constitute a major source of