2. Unit 5 : Learning Outcomes
▪5.1 how to achieve reliability in research (similar results
achieved from a similar sample)
▪5.2 how to achieve validity (the research should
measure what it aimed to measure)
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3. Reliability
▪ The ability of a measuring instrument to
give consistent results on repeated trials.
▪ Repeated measurement reliability--the
degree of consistency among repeated
measurements of the same individual on
more than one occasion.
▪ There are degrees of reliability.
▪ For example one can perform triceps fat-
fold measures with great reliability in the
incorrect place on the arm. This target
illustrates good reliability with the darts
hitting nearly the same place. Reliability
has to do with the consistency or
repeatability.
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4. Ways to increase Reliability
▪Increase number of items (e.g., on test, survey)
▪Eliminate unclear items
▪Standardize conditions
▪Moderate the easiness and difficulty of tests
▪Minimize effects of external events
▪Standardize instructions
▪Maintain consistent scoring procedures (e.g., rubric for
essay or performance)
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5. Validity
▪ The ability of a measuring instrument
to give a true measure.
▪ Does it measure what it was intended
to measure?
▪ There are degrees of validity (not
yes/no).
▪ Can be evaluated only if an accepted
and independent method for
confirming the test measurement
exists. Since there is good reliability
(consistency), we have the potential for
strong validity; must be reliable to be
valid. If the center of the target
represents the ‘truth’ (or true measure),
this target illustrates high validity.
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6. Content Validity
▪ How well do the questions represent an adequate sample of the
potential items in the domain (comprehensive)? (Ask an expert)
▪ OR Content validity--the degree to which a measure covers the
range of meanings included within the concept.
▪ Format is an aspect of content validation:
▪ Is the language clear and appropriate?
▪ Is the type size appropriate?
▪ Does the format provide adequate work space (if needed), and
clear directions? Especially for achievement tests
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7. Ways to increase Validity
▪Careful planning and implementation of design.
▪Develop operational definitions.
▪Follow a standard study design Control group
Randomization Match subjects if needed ANCOVA –
analysis of covariance statistical technique
▪Search for discrepant evidence and negative cases
▪Triangulation by using multiple methods
▪“Member checks” by soliciting feedback from participation
about data and conclusions
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10. Ensuring Validity at the Design Stage
➢Avoid having biased researchers
➢Use appropriate methodology
➢Use an appropriate sample
➢Ensure adequate resources for the research
➢Choose and appropriate timescale
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11. Ensuring validity at the Data Collection
Stage
➢Avoid dropout rates from respondents
➢Take steps to avoid no return of questionnaires
➢Ensure standardized procedures for gathering data
➢Build on the motivations of respondents
➢Address researcher characteristics
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12. Lesson Title Unit Title
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Presented By : SUMUDU ANNE SAMARAKOON
MSc. in IT MBA University of Colombo MBCS UK
