Gradually, investigation techniques have developed and diversified, being considered
independent method alongside with questionnaire, interview, opinion poll.
There are however a few unanimously recognized differences when analysed
comparatively:
- investigation, unlike interview, uses standardized techniques, this is why it is
occasionally called a standardized interview; - investigation is always based on a questionnaire, while the interview unfolds
on the basis of an interview guide or even without a previously prepared
instrument; - investigation (like the opinion poll) must have a representative sample, while
the interview is addressed to particular persons; - investigation is an extensive method, requiring the collection of relatively
simple information, while the interview is an intensive techniques used to get
deeper psychological insight; - results of the investigation, unlike those of an interview, usually require
statistical qualitative and quantitative processing; - investigation can unfold with oral and written techniques, direct or indirect,
while the interview is mainly oral; - within an investigation, the information is especially collected from groups of
subjects, while in an interview from individuals; - investigation requires neutral operators, while an interview is conducted by
professionals; - investigation and the opinion poll are generally quantitative methods, while
the interview is mainly qualitative.
By admitting the non-uniformity and non-existence of the same points of view in defining
investigation, John Wise (1988) in a study on method defines the investigation as “an
attempt to add and interpret facts on a social institution, group, or field... conducted to
establish existing conditions.”
In Webster’s Dictionary there is a definition of investigation as “an inspection, often
official, to provide accurate information, an inspection or critical study, usually about the
social implications of the object under study; the success of it consists in describing the
existing conditions and depends on the careful collection of data and their competent
interpretation.” (apud Gugiuman, 1978).
When an investigation is undertaken with a view to knowing a person, the investigation
takes place as a conversation, and when questionnaires are given to people they are semi-