Measurement and Types of Scale for Data

1. MEASUREMENT AND
SCALING
Balaji.P

2. Measurement in Research
 Measuring so many things in day to day life (Ex:
Weight, height, how much love the song or movie (by
rating)., etc.
 Properties like weight, height measured by standard
unit of measurement. (so confident about accuracy of
the result of measurement)
 Properties like how much love the music or some
movies, intelligence, self confidence (No standard
scale, less confident about accuracy of result of
measurement)
 So We can’t measure everything in same scale.

3. Measurement
 Assign numbers in respect of properties of some
objects.
 Measurement is a process of mapping aspects
of a domain onto other aspects of a range
according to some rule of correspondence.
 So we need some scales to transform some
properties of object in to some number with
considering some rules.

4. Measurement Scales
 Nominal Scale
 Ordinal Scale
 Interval Scale
 Ratio Scale

5. Nominal Scale
 Nominal data are numerical in name only,
because they do not share any of the
properties of the numbers.
 For ex: Sex: Male as “0” and female as “1”. Marital
Status can be recorded as 1,2,3,4 depending on
whether person is single, married, widowed or
divorced.
 There is no meaning for 4-3, 4>3, 4/2

6. Ordinal Scale
 Ordinal scale places events in order, but there is
no attempt to make the intervals of the scale
equal in terms of some rule.
 For ex: Students rank in class. Mohan – 10th rank and
Krishna 40th rank.
 There is no meaning that “Krishna is 4 times better than
Mohan”. Difference between 11th and 10th rank may not be
equal to difference between other two ranks.
 Grater than or less than symbol acceptable. (first rank is
greater than second rank)

7. Interval Scale
 In the case of interval scale, the intervals are adjusted in
terms of some rule that has been established as a basis for
making the units equal.
 The primary limitation of the interval scale is the lack of a true
zero.
 For ex: Temperature (in degrees Fahrenheit): 58,63,78,100 etc. Its
true that 63>58, 90-70 = 108- 88 (same temperature change). But we
can’t say 126 is twice as hot as 63 even though126/63 =2.
 Because convert in to Centigrade scale (126 become 52) and (63
become 17). Now 53/17= 3. This is because of number 0 of neither
scale is indicative of the absence of whatever quantity we are trying
to measure.
 So no meaning of Quotient in interval scale.

8. Ratio Scale
 Ratio scales have an absolute or true zero of
measurement.
 For ex: Zero point in centimeter of length indicate
complete absence of Length (height, volume etc.)
 Ratio scale is allowed to do all arithmetic operation
which allowed for real number.

9. Sources of error in Measurement
 Respondent : Little Knowledge in that area and transient
factors like fatigue, boredom and anxiety etc.
 Situation: Situation demands respondent not to give
correct answer.
 Measurer: The interviewer can distort responses by
rewording or reordering questions.
 Instrument: Error may arise because of the defective
measuring instrument. (complex words, ambiguous
meanings, poor printing, inadequate space for replies,
response choice omissions)

10. Test of Measurement
 Test of Validity
 Test of Reliability
 Test of Practicality

11. Test of Validity
 Validity is the most critical criterion and indicates the degree
to which an instrument measures what it is supposed to
measure.
 Content Validity
 Extent to which a measuring instrument provides adequate
coverage of the topic under study. It determined by judgmental and
intuitive (Panel also decide sometime)
 Criterion related validity
 Measure of how well one variable or set of variables predicts an
outcome based on information from other variables. It measured by
correlation.
 Construct validity
 the degree to which a test measures what it claims, to be
measuring.it determined by various statistical

12. Test of Reliability
 A measuring instrument is reliable if it provides
consistent results.
 Reliable instrument need not be a valid instrument (For ex:
Scale that overweight 5 kg always give reliable).
 But Valid Instrument is always reliable.
 Two aspects of reliability
 Stability: Consistent results with repeated measurements of
the same person and with the same instrument.
 Equivalence: Considers how much error may get introduced
by different investigators or different samples of the items
being studied.

13. Test of practicality
 Practicality can judged in terms of economy,
convenience and interpretability.
 Length of measuring instrument, observation time, interview
time and data collection method are play important role in
economic.
 Convenience: measuring instrument should be easy to
administer (proper layout of the measuring instrument, clear
instruction to respondent)
 Interpretability: Persons other than the designers of the test
are to interpret the results . supplemented by (a) detailed
instructions for administering the test (b) scoring keys (c)
evidence about the reliability and (d) guides for using the test
and for interpreting results.

14. Quality of Good Measurement
 Precise
 Unambiguous
 Free from error
 Reliable
 Valid
 Practical

15. Development of Measurement
tool
 Concept Development
 Understand the major concept pertaining to studies.
 Specification of concept dimension
 It accomplish by deduction.
 Selection and development of indicators for
measuring each concept element.
 Use scales or question to measure knowledge, opinion etc.,
 Formation of index
 Combine different measurement in to single number or index.

16. Measurement Scales
 All the scales are broadly classified in to two
categories
 Comparative Scale ( the respondent is asked to
compare one variable against another)
 Non Comparative Scale ( respondents need only
evaluate a single variable)

17. Comparative Scale
 Paired comparison
 Every factor has to be paired with every other factor in
turn.
 Each of the objections is paired by the researcher so
that with 5 factors, as in this example, there are 10
pairs.
 n(n-1)/2

18. Non Comparative Scale
 Continuous rating scales: The respondents are
asked to give a rating by placing a mark at the
appropriate position on a continuous line.

19. Non Comparative Scale
 Itemized rating scale: With an itemized scale,
respondents are provided with a scale having numbers
and/or brief descriptions associated with each category
and are asked to select one of the limited number of
categories, ordered in terms of scale position.

20. Non Comparative Scale
 Semantic Scale: This type of scale makes extensive use
of words rather than numbers.
 Semantic Differential: The respondent is asked to choose
where his or her position lies, on a scale between two
bipolar adjectives. Semantic differentials can be used to
measure opinions, attitudes and values on a
psychometrically controlled scale.

21. Non Comparative Scale
 Likert scales: A Likert scale is what is termed a
summated instrument scale.

22. Guttman Scaling
 Also known as
 Scalogram analysis
 Cumulative scaling
 Purpose:
 Establish a one-dimensional continuum
 Perfectly predict item responses from total score
 Seldom perfect in practice

23. Gutman Scaling
 Start with a large set of items that you think all
reflect the same construct.
 Have many judges rate each statement with
respect to whether it is favorable with respect
to the construct - a yes/no rating.
 Lay out a table.