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MEASUREMENTAND

SCALING CONCEPTS

GROUP 7

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WHAT IS TO BE MEASURED???

The CONCEPT

which can beSales Performance, height, Rate of

Absenteeism or anything you want to measure

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HOW IT WILL BE MEASURED???

True Measurement of a concept requires aprocess of assigning precise scores or numbers

to the attributes of people or objects.

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CONCEPT

A generalized idea about a class of objects,attributes, occurrences, or processes.

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CONCEPT cont.. Concrete Concept: Age, Gender etc Abstract Concept: Loyalty, Job Involvement.

Abstract Concept Measurement generally involves anumber of measurements and scales.

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OPERATIONAL DEFINITIONIt gives meaning to a concept by specifying theactivities/operations necessary to measure it. Ex: Concept: Interest

Operational Definition: A certain increase in

pupil DilationOR

What people say they are interested in.

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An Example: Media SkepticismConceptual definition

Media skepticism - the degree to whichindividuals are skeptical toward the reality presented in the mass media. Media skepticism varies across individuals, from those who aremildly skeptical and accept most of what they

see and hear in the media to those whocompletely discount and disbelieve the facts, values, and portrayal of reality in the media.

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Media Skepticism

Operational DefinitionPlease tell me how true each statement is aboutthe media. Is it very true, not very true, or not atall true?1. The program was not very accurate in itsportrayal of the problem.

2. Most of the story was staged forentertainment purposes.3. The presentation was slanted and unfair.

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Rules of Measurement A Guide that tells someone what to do.

Simply put: Assign the numerals 1 to 7 toindividuals acc to how productive they are.If the individual is extremely productive assign a 7.

If the individual is an unproductive worker assign a1.

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SCALE Series of items arranged according to value, into which an item can be placed for the purpose of quantification

A continuous spectrum 4 types:

Nominal

Ordinal

Interval

Ratio

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NOMINAL SCALE The numbers or letters assigned to objects which

serve as labels for identification or classification.

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ORDINAL SCALE Scale which arranges objects or alternatives

according to their magnitude in an orderedrelationship.

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ORDINAL SCALE cont.. Ordinal measurements

describe order

But relative size ordegree of difference between the items

CANNOT be measured

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INTERVAL SCALE An order which not only indicates order, but

also measure order (or distance) in units of equal interval

The location of zero point is arbitrary. Ex: CPI,Sensex

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INTERVAL SCALE cont.. Ex: The Fahrenheit scale is aninterval scale.

Since each degree is equal butthere is no absolute zeropoint .

This means that although wecan add and subtract degrees(100 is 10 warmer than 90), we cannot multiply values orcreate ratios (100 is not twiceas warm as 50).

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RATIO SCALE Ratio Scales are the ones which have absolute

rather than relative quantities. Ratio scales have non-arbitrary zero value.

Ex: Money and Weight possess an absolute zeroon the scale where there is an absence of thegiven attribute.

Mass, length, time, plane angle, energy

and electric charge are examples of physicalmeasures that are ratio scales.

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Key Features

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Properties: A Comparison

NominalScale

Uniquely classifies Sammy Sosa # 21 Barry Bonds # 27

OrdinalScale

Uniquely classifiesPreserves order

1st , 2nd and 3 rd

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Properties: A Comparison

IntervalScale

Uniquely classifies Preserves order Equal intervals

Consumer Price Index (Base 100) Fahrenheit temperature

RatioScale

Uniquely classifies Preserves order Equal intervals Natural zero

Weight and distance

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To Summarize: Typical Examples

NominalScaleMale, Female,Race, Political

Party

(categoricaldata thatcannot beranked)

OrdinalScale

Degree of Satisfaction

at Restaurant(data that

can beranked)

IntervalScale

Temperature,Dates (data

that have anarbitrary zero)

Ratio ScaleHeight,

Weight, Age,Length (data

that has anabsolutezero)

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What We Can COMPUTE ??

Can Compute.. Nominal Ordinal Interval Ratio

Frequency Distribution. Yes Yes Yes Yes

Median and Percentiles. No Yes Yes Yes

Add or Subtract. No No Yes Yes

Mean, StandardDeviation, Standard Errorof The Mean.

No No Yes Yes

Ratio or Coefficient of Variation. No

No No Yes

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Index Measures

Attribute A single characteristic or fundamentalfeature of an object, person, situation orissue.

Index or Composite MeasureMulti-item instrument constructed tomeasure a single concept with severalattributes.

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Three Criteria For Good Measurement

Criteria

Reliability Validity Sensitivity

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RELIABILITY Degree to which measures are free from error and

therefore yield consistent results

Low reliability can be due toimperfections in measuringprocess that effect indifferent ways eachmeasurement.

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Dimensions of Reliability

Reliability

InternalConsistency

Split-half method

Equivalent-form method

Repeatability

Test-Retestmethod

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Two main dimensions are:REPEATABILITY Used to assess the consistency of a measure from

one time to another.

Measure of Stability.

INTERNAL CONSISTENCY Used to assess the consistency of results across

items within a test. Measure of Homogeneity.

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Test-Retest Method It is administering of same scale or measure to

the same respondents at two separate points intime under same conditions to test for stability.

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Problems in Test-Retest Reliability

PREMEASURE The first measure may sensitize respondents to their participation inresearch project and thus effect results of secondmeasure.

TIME PERIOD BETWEEN MEASUREMENTS -The shorter the time gap, the higher thecorrelation and the longer the time gap, thelower the correlation.

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Split Half Method

Is used to measure the degree of internalconsistency by checking one half of the results of a set of scaled items against the other half.

Used generally when measure contains a largenumber of items.

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Equivalent/Parallel Form Method Method of measuring correlation between

alternative instruments, designed to be asequivalent as possible and administered to thesame group of subjects.

There can be problem if low correspondence between two instruments

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Measurement needs to have not only

reliability but also VALIDITY.

The purpose of measurement is tomeasure what we intend to measure

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VALIDITY Ability of a scale or measuring instrument to

measure what is intended to measure.

Validity

Face validity Criterion Validity

Concurrent Validity

Predictive Validity

Construct Validity

Convergent Validity

Discriminant Validity

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Face / Content Validity Professional agreement that a scale logically

appears to accurately measure, what its isintended to measure.

Ex: What is your age?, What is your name?

In research its never sufficient to rely on face judgments alone and more quantifiable methodsof validity are necessary.

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Criterion Validity

Ability of some measure to correlate with othermeasure of the same construct

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Concurrent Validity new measure taken at

same time as criterion measure and is valid.

Predictive Validity new measure predicts afuture event or correlates with criterion measure

administered at a later time.

Criterion Validity (contd)

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Construct ValidityIs the extent to which a measure fits into thetheoretical scheme and research already established on the attribute or construct beingmeasured.

Convergent Validity - is the degree to which anew measure is similar to (converges on) othermeasure that it theoretically should also be similarto.Discriminant Validity is ability of measure tohave low correlation with measures of dissimilarconcepts

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Example

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QUESTION

Can survey be

Valid but not reliable ? Reliable but not valid ?

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Is instruments ability to accurately measure variability in stimuli or responses.

It can be increased by adding more questions.

Index measures are more sensitive than singleitem scales.

SENSITIVITY

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SUMMARY Four types of measuring scales:

Nominal Scales Ordinal Scales Interval Scales Ratio Scales

Index (composite) Measures Several attributes

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SUMMARY Contd.

Measurement Criteria for MeasuringInstruments:

Reliability: Provide consistent results

Validity: Measure what we intend to measure

Sensitivity: Measure variability

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A Small Quiz:

Type of scale used:

Fahrenheit Scale

Coding for Males and Females

Percentile Ranking

Kelvin Scale

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Quiz Contd.. Consider the centigrade scale for measuring

temperature. Which of the following measurementproperties is satisfied by the centigrade scale?

I. Magnitude.II. Equal intervals.III. Absolute zero.

(A) I only (B) II only (C) III only (D) I and II(E) II and III

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A researcher developed a measure of shyness and is now asking whether this measure does in fact measure a person'strue state of shyness. This is a question of:

a.) Sensitivity b.) Construct validity c.) Reliability.

Scores on a final exam are related to student grade pointaverage, the amount of time spent studying for the exam, andclass attendance. What type of validity is demonstrated in this

case?a.) Convergent validity b.) Discriminant validity c.) Criterion validity.

Quiz Contd..

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Which of the following statements accurately portrays the relationship of reliability to validity?

a.) Inferences must be valid before the scores can bereliable.

b.) Scores must be reliable before inferences can be valid.

c.) The more valid the inference is, the higher thereliability of the score must be.

d.) Score reliability is not related to inference validity.

Quiz Contd..

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