Measurement “If you can’t measure it, you can’t manage it.” Bob Donath, Consultant

Measurement Selecting measurable phenomena Developing a set of mapping rules Applying the mapping rule to each phenomenon

Measurement

What is Measured? Object-things that is experienced and also those that are not very concrete Properties – Characteristics of the object

Levels of Measurement Ordinal interval Ratio Nominal Classification Order Classification Order Classification Distance Natural Origin Order Classification Distance

Sources of Error in Measurement Respondent InstrumentMeasurer Situation

Characteristics of a Good Measurement Criteria Validity Practicality Reliability

Validity The ability of a scale to measure what was intended to be measured. Reliability The degree to which measures are free from random error and therefore yield consistent results. Practicality Relates to the economic factors, convenience and interpretability Characteristics of a Good Measurement

Validity and Reliability

Reliability and Validity on Target Old Rifle New Rifle New Rifle Sun glare Low ReliabilityHigh Reliability High Reliability Low Validity Validity ? Low Validity (Target A)(Target B)(Target C)

The Goal Of Measurement Validity

Validity Content Criterion Related Construct ConcurrentPredictiveDiscriminantConvergentFace

Content Validity

Criterion related Validity

Quality of Criterion Relevant (Proper measure) Sales performance measured using the total sales in a year Free from bias (Equal opportunity) Must be adjusted according to area, competition and potential Reliable (Stable or Reproducible) Monthly sales versus yearly sales Available (Ease of collection) Cost Difficulty in securing the data

Construct Validity

Reliability StabilityEquivalence Internal Consistency Parallel Form Inter raterInter-item Split Half Test-retest

Reliability (Stability)

Problems in Test-retest Time-delays between measurement leads to situational factor changes Insufficient time between measurements permit the respondents to remember previous answers Respondent’s discernment of a disguised purpose may introduce bias – opinion related to the purpose but not assessed Topic sensitivity occurs when the respondent seeks to learn more about the topic before retest Introduction of other variables – unrelated to the research

Reliability (Equivalence)

Reliability (Internal Consistency)

Improving Reliability Minimize external sources of variation Standardize the condition under which measurement occurs Use only trained and experienced investigators and motivated persons Broaden the sample of measurement questions Taken into consideration only extreme responses then eliminate questions that do not discriminate

Practicality EconomyInterpretabilityConvenience