good scale measurement

CRITERIA FOR GOOD MEASUREMENT

Goodness of measurement• Make sure the accuracy of the instrument.

For that:• Ensure not missing any dimension, element,

and question. Nothing irrelevant.• Assess the “goodness” of measuring

instrument.• Characteristics of a good measurement: Validity, Reliability, and Sensitivity –

accuracy of the measuring instrument.

The Goal of Measurement: Validity and Reliability

Validity

• 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

construct and its indicators.

Types of Validity

• 1. Content validity

• 2. Criterion-related validity

• 3. Construct validity

RELIABILITY• The degree to which measures are free from

random error and therefore yield consistent results

• 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 applied.

Note• 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 concept.

Old Rifle New Rifle New Rifle Sun glare

Low Reliability High Reliability Reliable but Not Valid

(Target A) (Target B) (Target C)

Reliability and Validity on Target

Sensitivity• 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

Practicality• Validity, reliability, and sensitivity

are the scientific requirements of a project.

• Operational requirements call for it to be practical in terms of economy, convenience, and interpretability.

Conclusion:

• 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.