MEASUREMENT and SCALING TECHNIQUES

MEASUREMENTProcess of assigning meaningful and relevant numbers or symbols to the characteristics of objects according to certain pre-specified rules.Level of measurement is a function of rules under which numbers are assignedOne-to-one correspondence between the numbers and the characteristics being measured.

MEASUREMENT SCALESFour Primary Scales of Measurement:NOMINAL SCALEORDINAL SCALEINTERVAL SCALERATIO SCALE

NOMINAL SCALENumbers serve only as labels or tags for identifying and classifying objects.Numerical symbols for nomenclature purpose only.Strict one-to-one correspondence.Numbers do not reflect the amount of characteristics possessed by the objects.Simplest and least powerful.

NOMINAL SCALEOnly permissible operation counting (frequency counts and percentages).Measure of Central Tendency- Mode.Measure of Dispersion- Nil.Measure of Relationship- Contingency Coefficient.Test of significance- Chi-square Test, Binomial Test.

ORDINAL SCALERanking or ordered scale of lowest order.Numbers are assigned to indicate the relative extent to which some characteristics is being possessed.Indicative of order (relative position) but not the magnitude of difference between two objects.Equivalent objects receive same rank.

ORDINAL SCALEPermissible operations- Counting and statistics based of centiles.Measure of Central Tendency- Median.Measure of Dispersion- Quartile Deviation.Measure of Relationship- Rank-Order Correlation.Test of significance- Non-Parametric Tests.

INTERVAL SCALENumbers are used to rate objects such that numerically equal distances on the scale represent equal distances in the characteristics being measured.Contains all information of an ordinal scale but also allows comparison of distances.Zero-point and the unit of measurement is arbitrary.Linear transformation is allowed.Not meaningful to take ratios because the zero-point is not fixed.

INTERVAL SCALEPermissible operations- Counting, ordering and measurement.Measure of Central Tendency- A. M.Measure of Dispersion- Range and Standard Deviation.Measure of Relationship- Product-Moment Correlation.Test of significance- Parametric Tests, Regression, Factor Analysis.

RATIO SCALEIt has the power of all the preceding scales as also the concept of absolute-zero.Allows identification/classification, ranking, comparing intervals/differences, also computation of meaningful ratios.Allows only proportionate transformation of the form y = bx.Most powerful, represents the actual amount of measurement.All statistical techniques can be applied.

SCALINGExtension of measurement.Involves creation of a continuum upon which measured objects are located.Scaling techniques help to measure abstract concepts more accurately.Scaling Techniques:Comparative ScalesNoncomparative Scales.

COMPARATIVE SCALESInvolves the direct comparison of the stimulus objects.May be interpreted in relative terms and have only Ordinal or Rank-Order properties.Non-metric scaling.Advantages: Small differences can be detected.Easily understood and applicable.Reduced halo/carryover effect.

COMPARATIVE SCALESDisadvantages:Ordinal nature of the data.Inability to generalize beyond stimulus objects scaled.Comparative Scaling Techniques:Paired Comparison ScalingRank Order ScalingConstant Sum ScalingQ-Sort Scaling.

COMPARATIVE SCALES: Paired Comparison ScalingRespondent is presented with two objects and asked to select one according to some criterion.Data obtained is ordinal.Most widely used comparative scaling technique.For n brands nC2 comparisons are requiredUseful when number of objects/brands are limited.Graded Paired Comparisons (MDS & AHP).

COMPARATIVE SCALES: RANK ORDER SCALINGThe second most popular technique.Respondents are presented with several objects simultaneously and asked to order/rank them according to some criterion.Commonly used to measure preferences for brands as well as attributes.Advantages - More closely resembles shopping environment, takes less time, only (n-1) scaling decisions, easily understandable.Disadvantage- Only Ordinal Data.

COMPARATIVE SCALES: CONSTANT SUM SCALINGRespondents are required to allocate a constant sum of units among a set of stimulus objects with respect to some criterion.Allocation of units reflects the importance attached to each attribute.Some times treated as metric but strictly speaking they are ordinal scale because of its comparative nature and lack of generalizability.Advantage- allows for fine discrimination.Disadvantages- process is cumbersome.

COMPARATIVE SCALES: Q-SORT SCALINGRank order procedure to sort objects (into piles) based on similarity with respect to some criterion.To discriminate among relatively large number of objects (60-140) quickly.Number of objects to be placed in each pile is pre-specified, resulting in a roughly normal distribution of objects over the whole set.

NON-COMPARATIVE SCALESMonadic (one object at a time) or Metric Scales.Each stimulus object is scaled independently of others in the stimulus set.Interval or Ratio Scaled, can be generalized.Non-Comparative Scales:Continuous Rating Scales.Itemized Rating Scales:Likert ScalesSemantic Differential Scales.Stapel Scales.

NON-COMPARATIVE SCALES:CONTINUOUS RATING SCALEGraphic rating scale.Respondent has to rate the objects by placing a mark at the appropriate position on a line running from one extreme of the criterion to the other.Forms: horizontal/vertical, scale points, in form of numbers/brief descriptions.Scores are treated as Interval Data.Easy to construct, freedom to choose.Scoring is cumbersome and unreliable.Computer assistance has increased the popularity (perception analyzer).

NON-COMPARATIVE SCALES:ITEMIZED RATING SCALESScale having numbers and/or brief description for each category.Categories are ordered in terms of scale position.Interval Data.Most widely used.Types:Likert ScaleSemantic Differential ScaleStapel Scale

NON-COMPARATIVE SCALES:ITEMIZED RATING SCALESLIKERT SACLE:Scale with 5 response categories ranging from strongly disagree to strongly agree.Numerical Score: 1 to 5 or -2 to +2.Analysis on item-to-item basis (profile analysis) or total (summated) score.Consistent scoring procedure for summated approach.Easy to construct and administer, easily understandable.

NON-COMPARATIVE SCALES:ITEMIZED RATING SCALESSEMANTIC DIFFERENTIAL SCALE:7-point rating scale with endpoints associated with bipolar labels that have semantic meaning.Mixing of positive and negative adjectives/phrases to control response-inertia.Numerical Score: 1 to 7 or -3 to +3.Data analysis by Profile Analysis, using mean/median followed by statistical analysis.Very versatile: comparing brands, products, image, develop advertising & promotional strategies, NPD.

NON-COMPARATIVE SCALES:ITEMIZED RATING SCALESSTAPEL SCALE:Unipolar rating scale with 10 categories (even) numbered from -5 to +5 without a neutral point.Single adjective in the middle.Attitude measurement.Analysis is same.Not very popular - confusing and difficult to apply.

NON-COMPARATIVE ITEMIZED RATING SCALE DECISIONSNumber of Scale CategoriesBalanced vs Unbalanced ScalesOdd or Even Number of CategoriesForced vs Non-forced ScalesNature & Degree of Verbal DescriptionPhysical Form or Configuration

MULTIITEM SCALE EVALUAIONA multi-item scale should be evaluated for accuracy and applicability.Assessment of Reliability, Validity and Generalizability.

MEASUREMENT ACCURACYMeasurement Error: Variation in the information sought (by the researcher) and information generated (by the measurement process).True Score Model:XO = XT + XS + XRSystematic Error (XS) affect the measurement in a constant way (stable factor) but Random Error (XR) is not constant.

RELIABILITYExtent to which a scale produces consistent results if repeated measurements are made.Random Error produces inconsistency, leading to lower reliability.Assessed by determining the proportion of systematic variation in a scale, i.e. by determining the association between scores obtained by different administration of scale.

RELIABILITYMethods of Assessing Reliability

Test-Retest Reliability: Identical sets of scale items at two different times and correlated.Alternative-Forms Reliability: Two equivalent forms of scale at two different times and correlated.Internal Consistency Reliability: To assess internal consistency of set of several items (summated scale).Split-Half Reliability: Items are divided into 2 halves and the resulting half scores are correlated.Coefficient alpha (Cronbachs alpha): Average of all possible split-half coefficients resulting from different ways of splitting.

VALIDITYThe ability to scale or measuring instrument to measure what is intended to measure (No measurement error).Content Validity: Face validity.Subjective & systematic evaluation of the representativeness of the content of a scale (measure what is intended to measure).Criterion Validity:Ability to correlate with other measures of the same construct.Construct Validity:Empirical evidences generated by a measure is consistent with the theoretical logic about the concept.