The techniques by which we can study an individual's personality by observing his/her style of life, behaviour, manner, thoughts and feelings is called-

Case history refers to all the relevant information or material gathered about an individual, family, group, etc., and arranged so as to serve as an organized record and have analytic value for a social worker, student, or the like: used especially in social work, sociology, psychiatry, and medicine.

According to the Merriam-Webster Dictionary, the formal definition of case histories is records (or files) containing relevant information pertaining to clients’ environments and history of services. This information is useful in many different fields for the purposes of illustration and case analysis.

In any case, some of the most common types of information often included in case histories are as follows:

• Basic Statistical Data (Client’s name, age, sex, address, phone number, occupation, marital status, and client ID number)
• Client’s History of Services
• Investigations pertaining to Client’s Case
• Investigation Outcomes
• Past and Present Treatments and/or Counseling Sessions
• History of Illnesses
• History of Complaints and Their Resolutions
• History of Referrals

Therefore, The techniques by which we can study an individual's personality by observing his/her style of life, behavior, manner, thoughts, and feelings is called- Case History.