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Comparative Scaling Some Key Concepts • Measurement – Assigning numbers or other symbols to characteristics of objects being measured, according to predetermined rules. • Concept (or Construct) – A generalized idea about a class of objects, attributes, occurrences, or processes. • Relatively concrete constructs – Age, gender, number of children, education, income • Relatively abstract constructs – Brand loyalty, personality, channel power, satisfaction Some Key Concepts • Scaling – The generation of a continuum upon which measured objects are located. • Scale – A quantifying measure – a combination of items that is progressively arranged according to value or magnitude. – Purpose is to quantitatively represent an item’s, person’s, or event’s place in the scaling continuum. Primary Scales of Measurement Primary Scales Nominal Scale Ratio Scale Ordinal Scale Interval Scale Primary Scales of Measurement • Nominal – A scale in which the numbers or letters assigned to objects serve as labels for identification or classification. • Ordinal – A scale that arranges objects or alternatives according to their magnitude in an ordered relationship. Primary Scales of Measurement • Interval – A scale that both arranges objects according to their magnitudes and – Distinguishes the ordered arrangement in units of equal intervals – I.e., indicate order and measure order (or distance) in units of equal intervals Primary Scales of Measurement • Ratio –A scale that has absolute rather than relative quantities and an absolute zero where a given attribute is absent. –Money & weight are good examples of attributes that possess absolute zeros and interval properties. Primary Scales of Measurement Scale Nominal Numbers Assigned 1 31 88 to Drivers/Cars Ordinal Rank Order Third Second First of race finishers Place Place Place Interval Championship Points earned 170 175 185 Ratio Time to Finish, behind winner 5.1 2.3 0.0 Classifying Scaling Techniques • Comparative Scales –Involve the direct comparison of two or more objects • Noncomparative Scales –Objects or stimuli are scaled independently of each other. Classifying Scaling Techniques Scaling Techniques Comparative Noncomparative Scales Scales Continuous Itemized Paired Constant Rating Scales Rating Scales Comparison Sum Rank Order Likert Stapel Semantic Differential Paired Comparison Scaling • Respondent is presented with two objects at a time • Then asked to select one object in the pair according to some criterion • Data obtained are ordinal in nature – Arranged or ranked in order of magnitude • Easy to do if only a few items are compared. • If number of comparisons is too large, respondents may become fatigued and no longer carefully discriminate among them. Paired Comparison Scaling: Example For each pair of professors, please indicate the professor from whom you prefer to take classes with a 1. Cunningham Day Parker Thomas Cunningham 0 0 0 Day 1 1 0 Parker 1 0 0 Thomas 1 1 1 0 # of times 3 1 2 0 preferred Rank Order Scaling • Respondents are presented with several objects simultaneously • Then asked to order or rank them according to some criterion. • Data obtained are ordinal in nature – Arranged or ranked in order of magnitude • Commonly used to measure preferences among brands and brand attributes Rank Order Scaling Please rank the instructors listed below in order of preference. For the instructor you prefer the most, assign a “1”, assign a “2” to the instructor you prefer the 2nd most, assign a “3” to the instructor that you prefer 3rd most, and assign a “4” to the instructor that you prefer the least. Instructor Ranking Cunningham 1 Day 3 Parker 2 Thomas 4 Constant Sum Scaling • Respondents are asked to allocate a constant sum of units among a set of stimulus objects with respect to some criterion • Units allocated represent the importance attached to the objects. • Data obtained are interval in nature • Allows for fine discrimination among alternatives Constant Sum Scaling Listed below are 4 marketing professors, as well as 3 aspects that students typically find important. For each aspect, please assign a number that reflects how well you believe each instructor performs on the aspect. Higher numbers represent higher scores. The total of all the instructors’ scores on an aspect should equal 100. Instructor Availability Fairness Easy Tests Cunningham 30 35 25 Day 30 25 25 Parker 25 25 25 Thomas 15 15 25 Sum Total 100 100 100 Non-Comparative Scaling Classifying Noncomparative Scaling Techniques Noncomparative Rating Scales Continuous Itemized Rating Scales Rating Scales Semantic Stapel Likert Differential Continuous Rating Scale Example Very Very X Poor Good 0 10 20 30 40 50 60 70 80 90 100 Method of Summated Ratings: The Likert Scale • Extremely popular means for measuring attitudes. • Respondents indicate their own attitudes by checking how strongly they agree/disagree with statements. • Response alternatives: – “strongly agree”, “agree”, “uncertain”, “disagree”, and “strongly disagree”. • Generally use either a 5- or 7-point scale Semantic Differential Scales • A series of numbered (usually seven-point) bipolar rating scales. • Bipolar adjectives (for example, “good” and “bad”), anchor both ends (or poles) of the scale. • A weight is assigned to each position on the rating scale. – Traditionally, scores are 7, 6, 5, 4, 3, 2, 1, or +3, +2, +1, 0, -1, -2, -3. Semantic Differential Scales for Measuring Attitudes Toward Tennis Exciting ___ : ___ : ___ : ___ : ___ : ___ : ___ : Calm Interesting ___ : ___ : ___ : ___ : ___ : ___ : ___ : Dull Simple___ : ___ : ___ : ___ : ___ : ___ : ___ Complex Passive ___ : ___ : ___ : ___ : ___ : ___ : ___ Active Stapel Scales • Modern versions of the Stapel scale place a single adjective as a substitute for the semantic differential when it is difficult to create pairs of bipolar adjectives. • The advantage and disadvantages of a Stapel scale, as well as the results, are very similar to those for a semantic differential. • However, the Stapel scale tends to be easier to conduct and administer. A Stapel Scale for Measuring a Store’s Image Department Store Name +3 +2 +1 Wide Selection -1 -2 -3 Graphic Rating Scales n A graphic rating scale presents respondents with a graphic continuum. Graphic Rating Scale Stressing Pictorial Visual Communications 3 2 1 Very Very Good Poor Balanced and Unbalanced Scales Balanced Scale Unbalanced Scale Surfing the Internet is Surfing the Internet is ____ Extremely Good ____ Extremely Good ____ Very Good ____ Very Good ____ Good ____ Good ____ Bad ____ Somewhat Good ____ Very Bad ____ Bad ____ Extremely Bad ____ Very Bad Scale Evaluation Scale Evaluation Validity Reliability Content Test-Retest Internal Criterion Consistency Alternative Forms Construct Convergent Validity Discriminant Validity Nomological Validity Reliability • Extent to which a scale produces consistent results • Test-retest Reliability – Respondents are administered scales at 2 different times under nearly equivalent conditions • Alternative-form Reliability – 2 equivalent forms of a scale are constructed, then tested with the same respondents at 2 different times Reliability • Internal Consistency Reliability – The consistency with which each item represents the construct of interest – Used to assess the reliability of a summated scale – Split-half Reliability • Items constituting the scale divided into 2 halves, and resulting half scores are correlated – Coefficient alpha (most common test of reliability) • Average of all possible split-half coefficients resulting from different splittings of the scale items Validity • Extent to which true differences among the objects are reflected on the characteristic being measured • Content Validity – A.k.a., face validity – Subjective, but systematic evaluation of the representativeness of the content of a scale for the measuring task at hand • Criterion Validity – Examines whether measurement scale performs as expected in relation to other variables selected as meaningful criteria – I.e., predicted and actual behavior should be similar Construct Validity • Addresses the question of what construct or characteristic the scale is actually measuring • Convergent Validity – Extent to which scale correlates positively with other measures of the same construct • Discriminant Validity – Extent to which a measure does not correlate with other constructs from which it is supposed to differ • Nomological Validity – Extent to which scale correlates in theoretically predicted ways with measures of different but related constructs Relationship Between Reliability and Validity • A scale can be reliable, but not valid • In order for a scale to valid, it must also be reliable. • In other words, –Reliability is a necessary but insufficient condition for Validity. Reliability and Validity on Target Old Rifle New Rifle New Rifle Sunglare Low Reliability High Reliability Reliable but Not Valid (Target A) (Target B) (Target C)
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