Mearurement Measurement Scales
-
Upload
shah-vicky -
Category
Documents
-
view
221 -
download
0
Transcript of Mearurement Measurement Scales
-
7/29/2019 Mearurement Measurement Scales
1/32
Measurement and
Measurement/Attitudescales
-
7/29/2019 Mearurement Measurement Scales
2/32
Measurement and Scaling
Measurement means assigning numbers orother symbols to characteristics of objects
according to certain pre-specified rules.
One-to-one correspondence between the numbersand the characteristics being measured.
The rules for assigning numbers should be
standardized and applied uniformly.
Rules must not change over objects or time.
-
7/29/2019 Mearurement Measurement Scales
3/32
Measurement and Scaling
Scaling involves creating a continuum uponwhich measured objects are located.
Consider an attitude scale from 1 to 100. Eachrespondent is assigned a number from 1 to 100, with 1 =
Extremely Unfavorable, and 100 = Extremely Favorable.
Measurement is the actual assignment of a number from
1 to 100 to each respondent. Scaling is the process ofplacing the respondents on a continuum with respect to
their attitude toward department stores.
-
7/29/2019 Mearurement Measurement Scales
4/32
Primary Scales of Measurement
7 38
Scale
Nominal NumbersAssignedto Runners
Ordinal Rank Orderof Winners
Interval PerformanceRating on a0 to 10 Scale
Ratio Time to
Finish, inSeconds
Thirdplace
Secondplace
Firstplace
Finish
Finish
8.2 9.1 9.6
15.2 14.1 13.4
-
7/29/2019 Mearurement Measurement Scales
5/32
DEFINITION OF ATTITUDE
A learned predisposition to respond in a
consistently favourable or unfavourableway to some aspect of the individuals
environment
-
7/29/2019 Mearurement Measurement Scales
6/32
COMPONENTS OF AN ATTITUDE
An attitude is an underlying construct
As an operational variable, it is an
evaluated belief that predisposes the
holder to behave in one way or another.
Three components
a belief component
the affective component
the behavioural component
-
7/29/2019 Mearurement Measurement Scales
7/32
THREE COMPONENTS
Three components a belief component I believe that.
the affective component emotional-evaluative component
the behavioural component what theperson does on the basis of the two
previous components
-
7/29/2019 Mearurement Measurement Scales
8/32
Attitude Measurement
Most widely used approach to attitude measurement isthe application of standardized attitude questionnaires orscales
An attitude scale usually consists of sets of statementsor words relating to an attitude item.
Individual items in an attitude scale are usually not of
interest in themselves; the interest is normally located inthe total score or mean of sets of items grouped on thebasis of factor analysis or Cronbach alpha reliability,i.e.we know all the items are measuring the same thing
-
7/29/2019 Mearurement Measurement Scales
9/32
ATTITUDE SCALES
An attitude scale usually uses sets of
statements or words relating to an attitude
item.
They are usually concerned with
measuring the degree of positive or
negative feeling (evaluation), that is
degree of favourability, towards theperson, object or event.
The best-known rating scale techniques
are described below.
-
7/29/2019 Mearurement Measurement Scales
10/32
TYPES OF ATTITUDE SCALE
Differential Scales (Thurstone Type)
The Likert Scale
The Semantic Differential (Osgood)
Kelly's Repertory Grid Technique
-
7/29/2019 Mearurement Measurement Scales
11/32
DIFFERENTIAL SCALES (THURSTONETYPE)
Initial selection of a large number of evaluative-tinged
statements about a particular object or topic
Judges assess the degree to which each statement
expresses a positive or negative attitude towards the object A calculation is made of the median score for each item
using scale values
Scale values indicate the degree to which it represents a
favourable or unfavourable attitude
Selection of items made on basis of covering scale value
range with items on which there is small range of judgement
variation
-
7/29/2019 Mearurement Measurement Scales
12/32
DIFFERENTIAL SCALES (THURSTONETYPE)
Scale Value Statement0.5 I believe Savemor provides the best value of any
supermarket chain in the country
2.4 I believe Savemor has the consumers needs atheart
5.2 I believe Savemor is as good as any other supermarket.8.7 I believe Savemor sacrifices quality for cheapness.10.3 I believe Savemor should be boycotted because of its policy
towards unionization.
-
7/29/2019 Mearurement Measurement Scales
13/32
THE LIKERT SCALE
Subjects are asked to what extent they agree or disagree with eachstatement
Items are placed in the scale at random and may be positive ornegative towards the topic
* Reverse scoring on this item - all items marked favourably towardstrade unions should be scored in the same direction.
Items worded in a reverse direction are placed at random to stoppeople filling in the scale carelessly by going down in one column.
SA A ? D SD1* Trade unions hold back progress. 1 2 3 4 5
2 I regard my union subscription as 1 2 3 4 5a goodinvestment.
3 Every employee should be 1 2 3 4 5compelled by law to join their union.
-
7/29/2019 Mearurement Measurement Scales
14/32
ADVANTAGE OF LIKERT
METHOD
1. Greater ease of preparation than the Thurstonetechnique.
2. The method is based entirely on empirical dataregarding subject's responses rather thansubjective opinions of judges.
3. This method produces more homogeneous scalesand increases the probability that a unitary attitude
is being measured, increasing validity (constructand concurrent) and reliability.
4. As a result most attitude researchers have reliedon easier to construct Likert scaling procedure to
measure attitudes.
-
7/29/2019 Mearurement Measurement Scales
15/32
DISADVANTAGE OF LIKERT SCALES
The Likert-type scale is only an ordinal scale, i.e. it makes possible theranking of individuals in terms of the favourableness of their attitude towarda given object, but it does not provide a basis for saying how much morefavourableone is than another. Whether this constitutes a disadvantage ofthe Likert scale in comparison with the Thurstone scale depends on one's
judgement of whether Thurstone scales really meet the criteria for interval
scales! Most attitude investigators do assume Likert scales provideinterval data
The total score of an individual has little clear meaning, since manypatterns of response to the various items may produce the same score.Thurstone-type scales are also subject to this criticism, but it applies even
more strongly to the Likert scales, since they provide a greater number ofresponse possibilities and combinations.
The midpoint suffers from problems of definition. Should we name it dontknow or no opinion or neutral etc. All these have slightly differentmeanings.
-
7/29/2019 Mearurement Measurement Scales
16/32
THE SEMANTIC DIFFERENTIAL
The Semantic Differential requires a list ofbipolar scales with usually seven rating points
lying between each end of the scale. They are
bipolar scales since each end is denoted by the
antonym of the other end.
Thus it is common to use adjectives like happy-
sad to characterise the opposite poles.Descriptive phrases too such as staff are
courteous - staff are not courteous are used
-
7/29/2019 Mearurement Measurement Scales
17/32
THE SEMANTIC DIFFERENTIAL
Bi-polar adjective or adjective phrases are
chosen as items on the basis of relevance to
the concept being rated
Concept to be Rated e.g. Supervisor A+3 +2 +1 0 -1 -2 -3
Good X Bad
Modern Old fashioned
Reliable X Unreliable
Responsible X Irresponsible
Uninterested in
employees
welfare
X Interested in
employees welfare
-
7/29/2019 Mearurement Measurement Scales
18/32
COMPARISON OF TWO BRANDS
Brand A versus Brand B (or ideal Brand A)
High price 1 2 3 4 5 6 7 Low price
High calories 1 2 3 4 5 6 7 Low calories
High fat 1 2 3 4 5 6 7 Low fat content
content
Highly sweet 1 2 3 4 5 6 7 Unsweetened
etc
Key: Rating of Brand A
Rating of Brand B (or ideal Brand A)
-
7/29/2019 Mearurement Measurement Scales
19/32
COMPARISON OF TWO BRANDS
Brand A Brand B (or ideal)
Price 2 5
Calories 6 7
Fat 5 7
Sweetness 3 5
Total 16 24
-
7/29/2019 Mearurement Measurement Scales
20/32
SEMANTIC DIFFERENTIAL PROFILE
ORGANISATION A
+3 +2 +1 0 -1 -2 -3
Good Bad
Modern Oldfashioned
Healthy Unhealthy
Energetic Lethargic
Responsible Irresponsible
Important Unimportant
-
7/29/2019 Mearurement Measurement Scales
21/32
KELLY'S REPERTORY GRIDTECHNIQUE
Devised as a means of mapping an
individual's personal constructs
a way in which two things are alike and inthe same way different from a third
Respondents consider three objects,
persons, etc., to determine in which way
two are alike( marked A) but also different
from a third (marked D)
-
7/29/2019 Mearurement Measurement Scales
22/32
KELLY'S REPERTORY GRIDTECHNIQUE
EXAMPLE: Repertory Grid for Brands of Beer
Constructs Brand A Brand B Brand C Brand D Brand E
Strong A A DMan's drink A A DReasonably priced A A D
Real ale A D AGood taste A A DArtificial taste A D AGood colour A A D
-
7/29/2019 Mearurement Measurement Scales
23/32
THE RELIABILITY AND VALIDITYOF ATTITUDE SCALES
The reliability of attitude scales is usually assessed via
the test-retest method
Internal reliability is also sought. Acceptable levels of
Cronbach alpha for attitudes scales is 0.7 and above
Alpha coefficient range Strength of association
-
7/29/2019 Mearurement Measurement Scales
24/32
VALIDITY
The validity of attitude scales is often checked byconcurrent validity using known criterion groups
Predictive validity is also possible by selecting some
criterion in the future such as product purchasingbehaviour
Construct validity is measured by correlating with otherknown measures of the same construct
Content validity is usually easily detectable by inspectionof item content
-
7/29/2019 Mearurement Measurement Scales
25/32
RELIABILITY AND VALIDITY
These important concepts relate to any measure/instrument
1. Validity of a measure: The degree to which a measureactually measures what we think it measures.
2. Reliability of a measure: The consistency of a measure overtime or under similar situations.
In social, or business research we cannot expect any measureto be perfectly valid or perfectly reliable. The best we can do
is to design our measures to be as valid and reliable as theycan be and where feasible run some statistical tests toevaluate their levels of reliability and validity.
.
-
7/29/2019 Mearurement Measurement Scales
26/32
DETERMINING RELIABILITY
1. Test-retest reliability. The degree to which themeasure returns the same value from the same
respondents on a second occasion. Temporal
reliability or stability over time
2. Parallel-form reliability. When two equivalent (butdifferent) forms of a measure are developed (e.g.
two equivalent forms of a single personality scale
are developed), it is the degree to which the same
value is returned from the same respondents for
the two different equivalent forms.
-
7/29/2019 Mearurement Measurement Scales
27/32
DETERMINING RELIABILITY
3. Split-Half or Inter-Item Method A measure of reliability reflecting the degree to which
one half of the items is the same as that for the otherhalf of the items (like a test-retest, but can beperformed on a single occasion).
Problem how do we determinewhich items should be in each half?
Often worked on the odd-even items on a scale/test.
4. Internal Consistency Method (Cronbachs Alpha) A measure of reliability that is equivalent to the
mathematical average of all possible split halfcombinations.
-
7/29/2019 Mearurement Measurement Scales
28/32
CRONBACH ALPHA INTERNAL
RELIABILITY ANALYSIS Select Analyze, choose Scaleand click on Reliability
Analysisto open the Reliability Analysis dialoguebox.
Transfer all the scale or subtest items to the Itemsbox.
Ensure Alphais chosen in the Modelbox Click on Statisticsto open the Reliability Analysis
Statistics dialoguebox.
In the Descriptivesfor area, select Item, Scaleand
Scaleif item deleted. In the Inter-itemarea choose Correlations
Select Continuethen OKto produce the output
-
7/29/2019 Mearurement Measurement Scales
29/32
Cronbach Alpha Analysis Printout
Item-total Statistics
Scale Scale Corrected
Mean Variance Item- Alpha
if Item if Item Total if Item
Deleted Deleted Correlation Deleted
Q1 34.1939 32.3228 .6455 .8462
Q2 34.2755 33.1914 .5686 .8525
Q3 34.2653 31.4959 .7414 .8383Q4 34.1531 32.6258 .6756 .8445
Q5 34.3878 32.1368 .7492 .8392
Q6 34.2347 32.1196 .7459 .8393
Q7 34.2245 31.9903 .6860 .8429
Q8 34.1837 31.7391 .7225 .8400
Q9 34.1735 31.0727 .7082 .8402
Q10 35.5612 40.7436 -.1369 .9175
Reliability Coefficients
N of Cases = 98.0 N of Items = 10
Alpha = .8647
This item
stands out
This will be
the alpha ifwe leave this
item out
-
7/29/2019 Mearurement Measurement Scales
30/32
CRONBACH ALPHA INTERNAL
RELIABILITY ANALYSIS The two columns to focus on are the last two. The Corrected Item-Total Correlation reveals those items
that have low correlations with the test or scale as awhole. Here item 10 stands out as the correlation is notonly lower than the rest but it is also negative.
The last column shows the overall scale alpha or internalreliability if that item is removed. If item 10 is removedthe overall scale alpha rises to .9175, much higher thanthe current alpha and indicative of a scale with very highinternal consistency, i.e. all items measuring the same
concept. The overall alpha is .8647, printed below the bottom sub-
table. This is quite acceptable but by eliminating item 10we do have the option of an even higher value.
-
7/29/2019 Mearurement Measurement Scales
31/32
GENERAL CRITICISMS OF ATTITUDE SCALES
Attitude scales can be easily faked self report measures are limited by what a
subject is willing to reveal about themselves
and depends on such factors as
willingness to cooperate,
social expectancy,
feelings of personal adequacy,
feelings of freedom from threat,
dishonesty, carelessness, ulterior
motivation,
interpretation of verbal stimuli.
-
7/29/2019 Mearurement Measurement Scales
32/32
GENERAL CRITICISMS OFATTITUDE SCALES
Response sets such as acquiescence (thetendency to agree with items irrespectiveof their content) and social desirability (the
tendency to agree to statements whichsocial consensus would support) fog thedata derived from attitude scales.
The best way of eliminating acquiescence
and social desirability is to order randomlypositive and negative items to prevent asubject ticking madly away down the same
column