parents and principals as partners in creating a culture of learning

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They are two ends of a continuum but at points in the middle it is difficult to
distinguish between them. Validity and reliability are especially important in
educational research because most of the measurements attempted in this area are
obtained directly. Researchers can never guarantee that an educational or
psychological measuring instrument measures precisely and dependably what it is
intended to measure (Van den Aardweg & Van den Aardweg, 1988: 198). It is
essential, therefore, to assess the validity and reliability of these instruments.
Researchers must therefore have a general knowledge as to what validity and
reliability are and how one goes about validating a research instrument and
establishing its reliability (Huysamen. 1989: 1-3).
(1) Validity of the questionnaire
Van Rensburg, Landman & Bodenstein (1994:560) define validity as the extent to
which a measuring instrument satisfies the purpose for which it was constructed.
It also refers to the extent to which it correlates with some criterion external to the
instrument itself. Validity is that quality of a data-gathering instrument or
procedure that enables it to determine what it was designed to determine. In
general terms validity refers to the degree to which an instrument succeeds in
measuring what it has set out to measure. Behr (1988: 122) regards validity as an
indispensable characteristic of measuring devices.
Van den Aardweg & Van den Aardweg (1988:237), Mulder (1989:215-217) and
Dane (1990:257-258) distinguish between three different types of validity:
* Content validity where content and cognitive processes are included can be
measured. Topics, skills and abilities should be prepared and items from
each category randomly drawn.