This document discusses validity and reliability in research methodology. It provides definitions and examples of validity and reliability, as well as the major types and methods used to measure them. Validity refers to how well a test measures what it intends to measure and includes content, criterion, and construct validity. Reliability concerns the consistency of test scores and encompasses test-retest, equivalent forms, and internal consistency methods. Validity and reliability are important concepts in research for reducing errors of measurement and ensuring accurate and consistent results.

2. RESEARCH
MEDTHODOLOG
Y

3. GROUP
MEMBERS
Sanaullah Mallah
Shazia Mallah

4. TOPIC
VALIDITY AND
RELIABLITY

5. OBJECTIVES
• What is validity and reliability
• How and why we use them as tools
• Methods , types, Factors
• Its importance and both concepts
together

6. AN OVERVIEW OF
PRESENTATION AS A WHOLE
AND RELIABILITY
by
SHAZIA MALLAH

7. ITS TYPES AND METHODES AS A
TOOLS TO KNOW HOW WE USE
IT AND FACTORS

8. Major types of
validityContent-related evidence of validity
Criterion-related evidence of validity
Construct-related evidence of validity
1
2
3

9. FACTORS AFFECTING
VALIDITY

10. Major Methods of
ReliabilityTEST-RETEST METHOD
EQUIVALENT-FORMS METHOD
INTERNAL-CONSISTENCY METHODS
1
2
3

11. FACTORS AFFECTING
RELIABILITY

12. VALIDITY AND RELAIBLITY
IMPORTANCE AND VALIDITY
AND RELIABILTY TOGETHER

13. EXAMPLE
if your scale is off by 5 pounds, it reads your
weight every day with an excess of 5pounds.
The scale consistently reports the same
weight every day, but it adds 5pounds to your
true weight.
•

14. EXAMPLE
• if your scale is off by 5 lbs, it reads your
weight every day with an excess of 5lbs. The
scale is reliable because it consistently reports
the same weight every day, but it is not valid
because it adds 5lbs to your true weight. It is
not a valid measure of your weight.
•

15. • The consistency of the scores obtained—how
consistent they are.
• the consistency of your measurement
instrument
• the degree to which an instrument
measures the same way each time it is used
RELAIBLITY
What do I mean by…?

16. © A. Taylor 16
• Reliability alone does not mean that you have
a good instrument however.
• Imagine the following reliable instrument:
0165
Every morning GALTON
gets on the scale and
every morning it reads
165 lbs.
It seems pretty reliable
since GALTON hasn’t
gained or lost any weight.
One day an elephant
got on GALTYON’s
scale and it still read
165 lbs.!
How is this scale
reliable?
It does measure the
same way under the
same conditions
(GALTON’s) – but a lot
of other conditions too
(the elephant and who
knows what else).
RELIABILITY

17. © A. Taylor 17
What in the world is a
measurement instrument?• Any tool that you use to measure with…
• What “instrument” might you use to measure the following
items?
1. How heavy the apples are
2. How hot the meat is
3. How much orange juice there is
a scale
a meat thermometer
a measuring
cup
a yardstick

18. © A. Taylor 18
Can it measure how
loud the radio is? how full the
glass is?
how smart
the girl is?
The ruler may be reliable (and perhaps
even valid) but not in these situations!
It is only valid for measuring length.
Reliable but not Valid

19. 19
What would the following instruments
measure?
The size of
someone’s foot
Eyesight
The perfect amount
of spaghetti!
More on
Instruments

20. © A. Taylor 20
What instrument you
choose depends on
several factors
• Ease of use – do you know how to use it?
.
• Access – do you have access to the instrument?
• Appropriateness – is it the best tool for what you are
measuring?
• Accuracy – how precise do your measurements have to
be?
• Cost – how expensive is it to use the instrument or
interpret the results?

21. SANAULLAH MALLAH

22. • Validity refers to how well a test measures
what it is purported to measure.
• appropriateness, correctness,
meaningfulness, and usefulness of the
specific inferences researchers make based
on the data they collect.
VALIDITY

23. © A. Taylor 23
Validity asks
if an instrument measures
what it is supposed to
how “true” or accurate the
measurement is.
W
h
a
t
i
s
V
a
li
d
i
t
y
?

24. EXAMPLE

25. EXAMPLE

26. SABA PERVEZ

27. VALIDITY TYPES AS A TOOL
AND ITS FACTORS

28. Major types of
validityContent-related evidence of validity
Criterion-related evidence of validity
Construct-related evidence of validity
1
2
3

29. Major types of
validityContent-related evidence of validity1
the content and format of the instrument. How
appropriate is the content? How comprehensive?
Does it logically get at the intended variable? How
adequately does the sample of items or questions
represent the content to be assessed? Is the format
appropriate?

30. Major types of
validityCriterion-related evidence of validity2
the relationship between scores obtained
using the instrument and scores obtained
using one or more other instruments or
measures

31. Major types of
validityConstruct-related evidence of validity3
The nature of the psychological construct or
characteristic being measured by the instrument.
How well does a measure of the construct explain
differences in the behavior of individuals or their
performance on certain tasks.

32. FACTORS AFFECTING
VALIDITY
1. Test-related factors
2. The criterion to which you compare
your instrument may not be well
enough established
3. Intervening events
4. Reliability

33. MUHIBULLAH

34. RELIABILITY METHOEDS AS A
TOOL
AND ITS FACTORS

35. Major Methods of
ReliabilityTEST-RETEST METHOD
EQUIVALENT-FORMS METHOD
INTERNAL-CONSISTENCY METHODS
1
2
3

36. Major Methods of
ReliabilityTEST-RETEST METHOD1
The test-retest method involves administering the
same test twice to the same group after a certain
time interval has elapsed

37. Major Methods of
ReliabilityEQUIVALENT-FORMS METHOD2
When the equivalent-forms method is used, two
different but equivalent (also called alternate or
parallel ) forms of an instrument are administered
to the same group of individuals during the same
time period

38. Major Methods of
ReliabilityINTERNAL-CONSISTENCY METHODS3
Internal consistency reliability is a measure of how
well the items on the test measure the same
construct or idea.

39. FACTORS AFFECTING
RELIABILITY
1. Test length
2. Test-retest interval
3. Variability of scores
4. Guessing
5. Variation within the test situation

40. ZAINAB YOUNIS

41. VALIDITY AND RELAIBLITY
IMPORTANCE

42. IMPORTANCE
Reliability and validity are important concepts
in research. The everyday use of these terms
provides a sense of what they mean (For
example, your friends are reliable. Your
opinion is valid). In research, their use is a little
more complex

43. IMPORTANCE
RELIABILITY
TEST-RETEST METHOD
EQUIVALENT-FORMS
METHOD
INTERNAL-CONSISTENCY
METHODS
VALIDITY
Content-related
evidence of validity
Criterion-related
evidence of validity
Construct-related
evidence of validity

44. IMPORTANCE
ERRORS OF MEASUREMENT

45. VALIDITY AND RELIABILTY
TOGETHER

46. Putting Reliability
and Validity
Together
Every instrument can be evaluated on two
dimensions:
Reliability
How consistent it is given the same conditions
Validity
If it measures what it is supposed to and how
accurate it is

47. Putting
Reliability and
Validity
Together
Imagine that I have 3 fish tank thermometers, a
blue one, a red one, and a green one.
 The blue one always reads the same temperature no
matter how hot or cold the water is.
 The red one shows a different temperature every time even
if I just measured it 5 seconds earlier.
 The green one seems to read accurately, warm when the
water is warm and cold when the water is cool.

48. © A. Taylor
Do not duplicate without
48
Is it consistent?
Is it measuring what
it is supposed to? Is it reliable?
Is it valid?
Blue always reads the
same temperature no
matter what
Red different
temperature every time
even if nothing has
changed
Green warm when the
water is warm and cold
when the water is cool
Complete the chart below

49. 49
Is it consistent?
Is it measuring what
it is supposed to? Is it reliable?
Is it valid?
Blue always reads the
same temperature no
matter what
Red different
temperature every time
even if nothing has
changed
Green warm when the
water is warm and cold
when the water is cool
Yes
No
Yes, the thermometer
only changes if the
temperature changes
No
No
Yes
Reliable but
Not valid
Not reliable
Not valid
Reliable and
Valid
Complete the chart below