Saturday, 13 July 2013

Comparative scaling techniques, Non - comparative scaling techniques

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)

Comparative scaling techniques

 Pairwise comparison scale – a respondent is presented with two items at a time and asked to select one (example : Do you prefer Pepsi or Coke?). This is an ordinal level technique when a measurement model is not applied. Krus and Kennedy (1977) elaborated the paired comparison scaling within their domain-referenced model. The Bradley–Terry–Luce (BTL) model (Bradley and Terry, 1952; Luce, 1959) can be applied in order to derive measurements provided the data derived from paired comparisons possess an appropriate structure. Thurstone's Law of comparative judgment can also be applied in such contexts.
  • Rasch model scaling – respondents interact with items and comparisons are inferred between items from the responses to obtain scale values. Respondents are subsequently also scaled based on their responses to items given the item scale values. The Rasch model has a close relation to the BTL model.
  • Rank-ordering – a respondent is presented with several items simultaneously and asked to rank them (example : Rate the following advertisements from 1 to 10.). This is an ordinal level technique.
  • Bogardus social distance scale – measures the degree to which a person is willing to associate with a class or type of people. It asks how willing the respondent is to make various associations. The results are reduced to a single score on a scale. There are also non-comparative versions of this scale.
  • Q-Sort – Up to 140 items are sorted into groups based a rank-order procedure.
  • Guttman scale – This is a procedure to determine whether a set of items can be rank-ordered on a unidimensional scale. It utilizes the intensity structure among several indicators of a given variable. Statements are listed in order of importance. The rating is scaled by summing all responses until the first negative response in the list. The Guttman scale is related to Rasch measurement; specifically, Rasch models bring the Guttman approach within a probabilistic framework.
  • Constant sum scale – a respondent is given a constant sum of money, script, credits, or points and asked to allocate these to various items (example : If you had 100 Yen to spend on food products, how much would you spend on product A, on product B, on product C, etc.). This is an ordinal level technique.
  • Magnitude estimation scale – In a psychophysics procedure invented by S. S. Stevens people simply assign numbers to the dimension of judgment. The geometric mean of those numbers usually produces a power law with a characteristic exponent. In cross-modality matching instead of assigning numbers, people manipulate another dimension, such as loudness or brightness to match the items. Typically the exponent of the psychometric function can be predicted from the magnitude estimation exponents of each dimension



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