Goodness of measurement
• Make sure the accuracy of the instrument.
• Ensure not missing any dimension, element,
and question. Nothing irrelevant.
• Assess the “goodness” of measuring
• Characteristics of a good measurement:
Validity, Reliability, and Sensitivity –
accuracy of the measuring instrument.
The Goal of Measurement:
Validity and Reliability
• The ability of an instrument to measure
what is intended to be measured.
• Validity of the indicator Is it a true
measure? Are we tapping the concept?
• Abstract ideas (construct) but concrete
observations. Degree of fit between a
• The degree to which measures are free from
random error and therefore yield consistent
• Stability and consistency with which the
instrument measures the concept and helps
to assess the goodness of a measure.
• Maintains stability over time in the
measurement of a concept.
• Two important dimensions of reliability: (a)
stability and (b) consistency
a. Stability of Measures
• Ability of the measure to remain the
same over time.
• It attests to the “goodness” of
measure because the measure of the
concept is stable, no matter when it is
• Reliability is necessary but not
sufficient condition of to test of
goodness of a measure.
• A measure could be highly stable and
consistent, but may not be valid.
• Validity ensures the ability of the
instrument to measure the intended
Reliability and Validity on Target
Low Reliability High Reliability Reliable but
• Instrument’s ability to accurately measure
variability in responses.
• A dichotomous response category, such as
“agree or disagree” does not allow the
recording of subtle attitude changes.
• A sensitive measure, with numerous items
on the scale, may be needed. For example:
• Increase items. Increase response
categories. (Strongly agree, agree, neutral,
disagree, strongly disagree). It will
increases a scale’s sensitivity
• Validity, reliability, and sensitivity
are the scientific requirements of a
• Operational requirements call for it
to be practical in terms of
economy, convenience, and
• It is important for marketers to measure
attitude scales and marketers try to
understand these scales and influence
them to gain an advantage in the market.