measurement and scaling -- noncomparative scaling techniques

chapter 9

In noncomparative scaling, each object is scaled independently of the other objects in the stimulus set. the resulting data is generally assumed to be interval or ratio scale. noncomparative rating scales can be either continuous or itemized. The itemized rating scales are further classified as Likert, semantic differential, or Stapel scales. When using noncomparative itemized rating scales, the researcher must decide on the number of scale categories, balanced verses unbalanced scales, odd or even number of categories, forced versus non-forced scales, nature and degree of verbal description, and a physical form or configuration.

Multi-item scales consist of a number of rating scale items. The scale should be evaluated in terms of reliability and validity. Reliability refers to the extent to which a scale produces consistent results if repeated measurements are made. Approaches to assessing reliability include test -- retest, alternative forms, and internal consistency. Validity, or accuracy of measurement, may be assessed by evaluating content validity, criterion validity, and construct validity.

The choice of particular scaling techniques in a given situation should be based on theoretical and practical considerations. As a general rule, the scaling technique used should be the one that will yield the highest level of information feasible. Also, multiple measures should be obtained.

An international marketing research, special attention should be debated to determining equivalent verbal descriptors in different languages and cultures. The researcher has a responsibility to both the client and the respondents to insure the applicability and usefulness of the scales. The Internet and computers are useful for developing and testing continuous and itemized rating scales, particularly multi-item scales.

Non-comparative scale -- 1 of two types of scaling techniques in which each stimulus object is scaled independently of the other objects in the stimulus set
continuous rating scale -- also referred to as graphic rating scale, this measurement scale has the respondents rate the objects by placing a market the appropriate position on a line that runs from one extreme of the criterion variable to the other
itemized rating scale -- a measurement scale having numbers and/or brief descriptions associated with each category. The categories are ordered in terms of scale position
Likert scale -- a measurement scale of five response categories ranging from strongly disagree to strongly agree, which requires the respondents to indicate a degree of agreement or disagreement with each of a series of statements related to the stimulus objects
semantic differential -- a seven-point rating scale with endpoint associated with bipolar labels that have semantic meaning
Stapel scale -- a scale for measuring attitudes that consists of a single objective in the middle of an even numbered range of values, from negative five to positive five, without a neutral point (zero)
balanced scale -- a scale with an equal number of favorable and unfavorable categories
forced rating scales -- a reading scale that forces the respondents to express an opinion because "no opinion" or "no knowledge" option is not provided
measurement error -- the variation in the information sought by the researcher and the information generated by the measurement process employed
true score model -- a mathematical model that provides a framework for understanding the accuracy of measurement
systematic error -- systematic error affects the measurement in a constant way and represents stable factors that affect the observed score in some way each time the measurement is made
random error -- measurement error that arises from random changes or differences and respondents were measurement situations
reliability -- the extent to which a scale produces constant results if repeated measurements are made on the characteristic
test-retest reliability -- an approach for assessing reliability in which respondents are administered identical sets of scale items at two different times under a nearly equivalent conditions as possible
alternative forms reliability -- an approach for assessing reliability that requires to equivalent forms of the scale to be constructed and then the same respondents are measured at two different times
internal consistency reliability -- an approach for assessing the internal consistency of the set of items when several items are summated in order to form a total score for the scale
split- half reliability -- a form of internal consistency reliability and which the items constituting the scale are divided into two halves and the resulting half scores are correlated
coefficient alpha -- it's a measure of internal consistency reliability that is the average of all possible split half coefficients resulting from different splitting of the scale items
validity -- the extent to which differences and observe scale scores reflect true differences among objects on the characteristic being measured, rather than systematic or random errors
content validity -- a type of validity, sometimes called face validity, that consists of a subjective but systematic evaluation of the representativeness of the content of a scale for the measuring task at hand
criterion validity -- a type of validity that examines whether the measurement scale performs as expected in relation to other variables selected as meaningful criteria
construct validity -- a type of validity that addresses the question of what construct or characteristic the scale is measuring. An attempt is made to answer theoretical questions of why a scale works and what deductions can be made concerning the theory underlying the scale
convergent validity -- a measure of construct validity that measures the extent to which the scale correlates positively with other measures are the same construct
discriminant validity -- a type of construct validity that accesses the extent to which a measure does not correlate with other constructs from which it is supposed to differ
nomological validity -- a type of validity that assesses the relationship between theoretical constructs. It seeks to confirm significant correlations between constructs as predicted by theory
generalizability -- the degree to which a study based on a sample of applies to a universe of generalization