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Ch 9 Measurement and Scaling
Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Summary slide Measurement and scaling Scales of measurement
nominal scales ordinal scales interval scales ratio scales Attitude scales Comparative and non-comparative scales Reliability Tests Validity Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Measurement and scaling
We measure a variable against a scale e.g. We measure our height in meters Measurement Task of assigning numbers to characteristics of objects being investigated Variable A characteristic of an object that can be measured is called a variable e.g. age, level of education Scaling A criteria in which a characteristic is measured against e.g. age in years Text Ch 3, p. 155, Table 5.2 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley Ch
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Scales of measurement Four types of measurement Nominal Ordinal
Interval Ratio Text Ch 9, p. 313 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley Ch
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Nominal scale A scale in which the numbers used are only labels
Each number represents a particular object or response, but the numbers have no value apart from that: e.g. drivers licence, student ID, telephone number, credit card number Text Ch 9, p. 313 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley Ch
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Analysis of nominal scales
Count the number of times something occurs: e.g. males, age categories, preferences Calculate percentages based on responses: e.g. male 40 per cent, female 60 per cent; own a car 30 per cent List answers in order of the frequency they occur in the survey: most frequent value Text Ch 9, p. 315 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Ordinal scale A scale in which numbers have an ordered relationship and are assigned to objects to show how much of a characteristic they possess The location of an object on an ordinal scale is called its rank, e.g.: Hotel A – 1 Highest price Hotel B – 2 Second-highest price Hotel C – 3 Third-highest price however, there is no indication of the difference in value between the first and second the first could be five times dearer than the second, and the second choice twice as dear as the third Text Ch 9, p. 315 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Analysis of ordinal scales
Ordinal scales allow us to establish the rankings of various characteristics, but: it does not give us the difference in the amount of the characteristic (e.g. hotel price) between the different selections Text Ch 9, p. 316 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Interval scales Interval scales allow us to measure the difference between any two objects of a characteristic The distance or interval between any two adjacent points on an interval scale is equal and represents an equal value of the characteristic being measured There is no zero point on an interval scale e.g. temperature scale 30oC is 5oC hotter than 25oC 25oC is 5oC hotter than 20oC 20oC 25oC 30oC 35oC Text Ch 9, p. 318 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Analysis of interval scales
Interval scales allow us to measure the order of two objects and also the distance between those objects: Product A - 60 purchases Product B - 20 purchases Product C - 10 purchases The first product is purchased three times as often as the second, which is purchased twice as much as the third product A common analysis of interval scales is the average or ‘arithmetic mean’ Text Ch 9, p. 319 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Ratio scales A ratio scale is like an interval scale in that there are equal distances between values, but there is also a zero point: e.g. the cost of a hotel room could range from $0 to $750 Hotel A – $750/night Highest price Hotel B – $150/night Second-highest price Hotel C – $75/night Third-highest price the first hotel is five times more expensive than the second, and the second is twice as expensive as the third Text Ch 9, p. 320 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Analysis of ratio scales
There is a variety of ways of analysing data obtained from a ratio scale, including the average or mean, which can be used as a measure of central tendency Harmonic and geometric means can also be calculated Text Ch 9, p. 321 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Characteristics of scales
Example Nominal Numbers to identify and classify Medicare number Student number Ordinal Numbers indicate relative position of an object Quality ranking Hotel pricing Interval Difference between objects Zero point not fixed—arbitrary Temperature scale Ratio Zero point is fixed—no characteristic Ratio of values can be calculated Length, weight, expenditure Text Ch 9, p. 315 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Alternative analysis methods
Importance of scales Scale Basic operation Central tendency Alternative analysis methods Nominal p. 313 Puts objects into classes Mode Percentage frequency chi-square Ordinal p. 315 Indicates Rankings Median Multi-dimensional (non-metric) Interval p. 318 Determines differences in equal parts Arithmetic mean Variance Standard deviation Correlation Discriminant analysis Ratio p. 320 Determines differences in equal parts and has a zero Harmonic and geometric mean All of the above Text Ch 9, p. 322, Table 9.3 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Why use attitude scales
Surveys often measure people’s opinions or attitudes about something Easier for people to choose from a scale More information is learnt when people answer with a scale rather than a yes or no Easier for people to answer than an open-ended question Easier to enter data Easier to analyse Less post-coding required Text Ch 9, p. 323 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Comparative and non-comparative scales
Respondents are asked to compare two objects directly: paired comparison rank order constant sum Q-sort Non-comparative Respondents are asked to give their opinion first for one object, then another: continuous itemised Text Ch 9, p. 322–3 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Comparative and non-comparative scales
Text Ch 9, p. 323 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Comparative—paired comparison
A technique in which a respondent is presented with two objects at a time and asked to select one object according to some criterion, e.g.: Coke vs. Pepsi Nike vs. Adidas Text Ch 9, p. 324 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Comparative—rank order
A comparative scaling technique in which respondents are presented with several objects simultaneously and asked to rank them according to some criterion e.g. rank the toothpaste in order of preference Product Rank Colgate 3 Macleans 1 AIM 2 Text Ch 9, p. 326 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Comparative—constant sum
Divide a given number (e.g. 100 points) among two or more attributes. e.g. divide 100 points between options in terms of their importance: Your sportswear is: Comfortable 35 Durable 25 Made in Australia Freedom of movement 5 Text Ch 9, p. 328 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Comparative—Q-sort A comparative scaling technique that uses a rank order procedure to sort objects based on similarity with respect to some criterion Generally for a large number of objects or attributes e.g. sort objects in order against a scale Essential Very Important Quite Important Not very Important Not at all Important Text Ch 9, p. 329 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Non-comparative options
Continuous: continuous rating or graphic scale preference is marked on a continuous line Itemised: respondents are asked to select one of several specified positions scales generally have five or seven options itemised scales allow the researcher to find out how strong the respondent’s attitude is to some issue Very good Very bad Text Ch 9, p. 331–2 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Types of non-comparative scale
Likert Semantic differential Stapel Text Ch 9, p. 335 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Itemised—Likert scale
A five-point scale in which the respondent specifies a level of agreement or disagreement with statements that express an attitude toward the concept under study, e.g.: Strongly disagree Disagree Neutral Agree Strongly agree Myer sells high- class products I like to shop at Myers Text Ch 9, p. 335 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Itemised—semantic differential
A seven-point scale bounded by bipolar adjectives: Cold -|- -|- -|- -|- -|- -|- -|- Hot Modern -|- -|- -|- -|- -|- -|- -|- Old fashioned Text Ch 9, p. 343–4 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Itemised—Stapel scale
Range of values with only one adjective +5 -|- +4 -|- +3 -|- +2 -|- +1 -|- Good value -|- -1 -| -2 -|- -3 -|- -4 -|- -5 -|- Text Ch 9, p. 351 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Analysing itemised scales
Itemised scales are ordinal scales; however, most researchers treat the scales as interval scales The researcher can calculate the mean score for each option Compare mean scores for different subsamples, e.g. by gender, age, education, location etc. Text Ch 9, p. 339 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Issues with rating scales
How many options should be given? Generally five or seven Should there be a neutral point? Balanced or unbalanced? Balanced Strongly disagree Disagree Neutral Agree Strongly agree Unbalanced Not important Slightly important Important Very important Extremely important Text Ch 9, p. 333 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Reliability Degree to which measurement is free from error
Two types of error: random and systematic Causes of error: the scale administration of the scale understanding of respondents Tests for reliability test-retest split-half consistency equivalent form Text Ch 9, p. 352 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Tests Test-retest: Split-half consistency: Equivalent form:
same scale used on same respondents under the same conditions Split-half consistency: statements measuring a topic are divided into halves and placed in different parts of the survey Equivalent form: using two statements (one positive and one negative) to test the respondent’s attitude Text Ch 9, p. 353 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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Validity Measuring what is intended to be measured
Reliability of measurement: consistency and accuracy Validity includes reliability Text Ch 9, p. 354 Copyright 2005 McGraw-Hill Australia Pty Ltd PowerPoint Slides t/a Marketing Research 2e by John Boyce Slides prepared by Mark Riley
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