QUESTIONNAIRES ,
vestigators who go to the sources for their facts. Such information
 is apt to be reliable but expensive. It is indispensible,
 however, in hiring some types of employees, such
as Pullman porters, where integrity and dependability are
most essential.
If the subjects of the investigation are employees, these
same sources of information may be used.
When the questionnaire is distributed to subordinates by
an executive who requires it to be filled out, he must explain
its purpose in a way which will insure a willingness to cooperate
 helpfully. The best way is for the investigator
himself, wherever possible, to present the questionnaire in
person, insuring an understanding of the instructions and a
willingness to give with the utmost frankness the information
 desired.
Questionnaires regarding employees may be devised for
completion by supervisors or fellow-workmen.
Information about employees may also be obtained from
company records and tabulated on specially constructed
questionnaires.
Much questionnaire information is best secured, not
through asking the worker or supervisor to fill out a blank,
but through the expensive but more reliable method of the
personal interview. People who neglect or refuse to fill in a
printed form or answer a letter are often glad to give the
desired facts to some one who comes to them in person.
Charters (30) has developed the techniques involved in this
procedure. They include a careful preliminary training of
the interviewers, as well as a standardization of the questions
 to be asked.
It must not be forgotten that a scientific method of selection
 bases itself on information whose predictive value has
been statistically determined. This information about the
applicant is obtained by tests, rating scales, and questionnaires
 at the time of employment.
The personal interview also has as its main purpose to

I53