MOI UNIVERSITY SCHOOL OF BUSINESS AND ECONOMICS CONCEPT MEASUREMENT, SCALING, VALIDITY AND RELIABILITY BY MUGAMBI G.K. M’NCHEBERE EMBA NAIROBI RESEARCH METHODS

MEASUREMENT Before measurement process can be initiated, concepts (constructs) relevant to the problem must be identified. A concept is generalized idea about a class of objects, attributes, occurrences or processes. Concepts e.g. loyalty, power, performance etc are difficult to measure and should therefore be operationalized. Operational definition gives meaning to a concept by specifying the activities or operations necessary in order to measure it. In research measurement process, scale values are assigned and can be manipulated according to certain mathematical rules.

SCALING Scale- Series of items that are arranged progressively according to value or magnitude into which an item can be placed according to its quantification. There are four types of scales. 1.Nominal Scale- simplest type of scale. -letters or numbers assigned to objects serve as labels for identification or classification. 2.Ordinal Scale- arranges objects or alternatives according to their magnitude. -ranks in order. 3. Interval Scale- not only arranges objects or alternatives according to their magnitudes but also distinguishes order arrangements in units of equal intervals.

SCALING (cont..) Ordinal Scale cont.. -the location of zero point is arbitrary implying inconclusiveness. - used in research to measure attitudes. -the researcher can compare average differences in attributes but cannot determine the actual strength of attributes. 4. Ratio Scale- has absolute rather than relative quantities and possessing an absolute zero, where there is absence of a given attribute.

DESCRIPTIVE STATISTICS FOR TYPES OF SCALES Type of scale Numerical operation Descriptive statistics 1.Nominal Counting Freq, %ge, mode 2.Ordinal Rank ordering Median, range, %ntile 3.Interval Interval operations mean, δ, δ 2 4.Ratio quantity operation Geo mean, CV

MEASURES OF VALIDITY Soundness of inferences based on scores. The assurance that a construct measures what it is supposed to measure. Four main categories of validity, content, construct, criterion, external. 1. Content validity- extent to which the measuring instrument provides adequate coverage of investigative questions guiding the study. - ensured by double checking the questionnaire to ensure it captures the main areas of the study. - Piloting with experts. 2. Construct validity- has four dimensions. a)Face validity- belief that an instrument seems to correspond to common sense without empirical evidence. - ensured by constructing questionnaires based on previous studies.

MEASURES OF VALIDITY (cont…) b) Convergent validity- extent to which items that are indicators of a specific construct share a high proportion of variance in common. - ensured through factor analysis indicators like factor loadings higher than 0.32 with a composite reliability of α>0.5 and a total variance explained of 50%. c) Discriminant validity- extent to which a construct is truly distinct from other constructs. - ensured through orthogonal varimax in factor rotation analysis. d) Nomological validity- tests whether the correlations among constructs in measurement theory make sense. - ensured by in depth review of correlations among constructs.

MEASURES OF VALIDITY (cont…) 3. Criterion related validity- reflects the success of measures for prediction and estimation. - ensured through hypothesis testing. 4. External validity- extent to which findings of a particular study can be reflected to other settings. -ensured through hypothesis testing and confirmatory factor analysis.

RELIABILITY ANALYSIS Reliability concerns the degree to which the scores are free from random errors. Measures the degree to which responses are consistent across the items in a single measure. Ensured by 4 steps: 1.Adopting items tested for reliability by other researchers. 2.Revision of questionnaires after pre-testing. 3.Exploratory factor analysis to exclude redundant items. 4.Cronbach alpha coefficient- 0.5 and above.