Some Approaches to Measuring Hypothetical Constructs (e.g. Attitudes) Following are approaches that have been used to measure psychological constructs: 1.Physiological Measures, e.g.: –Galvanic skin response (Galvanometer). –Pupil dilations (Pupilometer). –Eye Movement (Eye-tracking equipment). –Voice-pitch levels. 2.Observation of overt behavior. Subjects’ self-reports a)Choice b)Ranking c)Sorting d)Rating Attitude rating scales Selecting a measurement scale

Rating Scales Measurement scales that allow a respondent to register the degree (or amount) of a characteristic or attribute possessed by an object directly on the scale. Six main types of rating scales: 1.Category scale 2.Semantic differential scale 3.Stapel scale 4.Likert scale (Summated ratings scale) 5.Constant sum scale 6.Graphic scale

Category Scale A rating scale which the response options provided for a closed-ended question are labeled with specific verbal descriptions. Example: Please rate car model A on each of the following dimensions: PoorFairGoodV.goodExcellent a)Durability[ ][ ][ ][ ][ ] b)Fuel consumption [ ][ ][ ][ ][ ] Characteristics: Response options are still verbal descriptions. Response categories are usually ordered according to a particular descriptive or evaluative dimension. Therefore scale has ordinal properties. However, researchers often assume that it possesses interval properties => but this is only an assumption. ** One special version is the Simple category scale.

Simple Category Scale A category scale with only two response categories (or scale points) both of which are labeled. Example: Please rate brand A on each of the following dimensions: poor excellent a) Durability [ ][ ] b) Fuel consumption[ ][ ]

Semantic Differential Scale A rating scale in which bipolar adjectives are placed at both ends (or poles) of the scale, and response options are expressed as “semantic” space. Example: Please rate car model A on each of the following dimensions: Durable ---:-X-:---:---:---:---:--- Not durable Low fuel consumption ---:---:---:---:---:-X-:--- High fuel consumption Characteristics 1.The scale has properties of an interval scale. 2.Sometimes descriptive phrases are used instead of bipolar adjectives, especially when it is difficult to get adjectives that are exact opposites 3.It is often used to construct an image profile.

Stapel Scale A simplified version of the semantic differential scale in which a single adjective or descriptive phrase is used instead of bipolar adjectives. Characteristics 1.The scale measures both the direction and intensity of the attribute simultaneously. 2.It has properties similar to the semantic differential. Example:

Constant-Sum Scale A rating scale in which respondents divide a constant sum among different attributes of an object (usually to indicate the relative importance of each attribute). Assumed to have ratio level properties. Example: Divide 100 points among the following dimensions to indicate their level of importance to you when you purchase a car: Durability Fuel Consumption Total 100

Numerical Scale Any rating scale in which numbers rather than semantic space or verbal descriptions are used as response options. Examples: PoorExcellent Durability Durable Not durable

Graphic Ratings Scales Rating scales in which respondents rate an object on a graphic continuum, usually a straight line. Modified versions are the ladder scale and happy face scale. Characteristics 1.The straight line scale has ratio level properties. 2.The ladder and happy face scales have properties depending on the labeling option chosen – whether all response categories are labeled (ordinal properties) or only the scale end-points are labeled (interval properties).

The Likert Scale (Summated Ratings Scale) A multiple item rating scale in which the degree of an attribute possessed by an object is determined by asking respondents to agree or disagree with a series of positive and/or negative statements describing the object. Example:

Characteristics of the Likert Scale The following procedure is used to analyze data from Likert scales: 1.First, weights are assigned to the responses options, e.g. Totally agree=1, Agree=2, etc 2.Then negatively-worded statements are reverse-coded (or reverse scored). E.g. a score of 2 for a negatively-worded statement with a 5-point response options is equivalent to a score of 4 on an equivalent positive statement. 3.Next, scores are summed across statements to arrive at a total (or summated) score. 4.Each respondent’s score can then be compared with the mean score or the scores of other respondents to determine his level of attitude, loyalty, or other construct that is being measured Note that the response for each individual statement is expressed on a category scale.

Hard to attach a verbal explanation to response Visual impact, easy for poor readers Choose a visual picture8. Graphic scale-picture response No standard answersVisual impact, unlimited scale points Choose a point on a continuum 7. Graphic scale Endpoints are numerical, not verbal. Easier to construct than semantic differential Choose point on scale with 1 center adjective 6. Stapel scale Difficult for respondents with low education levels Scale approximates an interval measure Divide a construct sum among response alternatives 5. Constant sum scale Bipolar adjectives must be found, data may be ordinal, not interval Easy to construct, norms exist for comparison, e.g. profile analysis Choose points between bipolar adjectives on relative dimensions 4. Semantic differential and numerical scales Hard to judge what a single score means Easiest scale to constructEvaluate statements on a 5-point scale 3. Likert scale Ambiguous items, few categories, only gross distinction. Flexible, easy to respondIndicate a response category 2.Category scale 1. Simple attitude scaling DisadvantagesAdvantagesSubject must: Rating Scale Characteristics Different Types of Rating Scales

Issues In Selecting A Measurement Scale 1.Whether to use single or index measure. 2.Whether to use a ranking, sorting, choice, or rating scale. 3.Whether to use monadic or comparative scale. Monadic rating scale is one in which respondents evaluate an object in isolation Comparative scale s one in which the object is evaluated in relation to other objects Construction and labeling is different for monadic and comparative scales 4.Whether to use category labels or not. 5.If the decision is to use category labels, what labels to use.

Issues In Selecting A Measurement Scale 6.Number of response options (scale categories) to use, i.e whether to use 2, 3, 4, 5, etc response categories In general, the larger the number of categories the more sensitive the scale is; but also the more difficult it is for respondents to answer 7.Whether to use balanced or unbalanced scale. A balanced scale has an equal number of points to the left and right of a mid-point. An unbalanced scale has more response options on one side than the other 8.Whether the scale should force choice among the response categories, i.e should the scale contain a “neutral” or “don’t know” category.