This document discusses reliability and validity, which are important concepts for measuring instruments. Reliability refers to the consistency and accuracy of measurements from an instrument. There are several types of validity, including face validity, content validity, criterion validity, predictive validity, and construct validity. Validity determines if an instrument truly measures what it intends to. Factors like unclear directions, inappropriate test items, and language difficulties can impact an instrument's validity and reliability. Reliability is assessed through methods like test-retest reliability, internal consistency, and equivalence measures between raters. Both reliability and validity are necessary for a measuring instrument to provide accurate and meaningful results.

2. PRESENTED BY
S.Bhaktiswarup
a

3. INTRODUCTION
 Shall the instrument consistently yield similar scores on
repeated measurement? – Reliability
 Does the instrument measure what is actually intended to
measure? – Validity
Ex: Length measuring scale
Measuring instrument should be economical,
convenient and interpretable


4. VALIDITY
Validity deals with the
accuracy of the measurement
Validity of an instrument refers to
the degree to which an instrument
measures what is supposed to be
measuring

5. DEFINITION
 According to Treece and Treece ,Validity refers
an instrument or test actually testing what it
suppose to be testing.
 According to Polit and Hungler ;Validity refers
to degree to which an instrument measures
what it suppose to measuring .
 According to American psychological
foundation;Validity is an appropriateness
,meaning ,fullness and usefulness of
interference made from scoring of instrument

6. TYPES OF VALIDITY ;
FACE VALIDITY
 It involves an overall look of an
instrument regarding its appropriateness
to measure a particular attribute an
phenomenon.
 Though face validity is not considered a
very important and essential type of
validity for an instrument.
 However it may be taken in
consideration while assessing for other
aspect of validity of an instrument.
 In simple words this aspect of validity
refers to the face value or an outlook of

7. CONTENT VALIDITY
 It is concerned with scope of coverage with of
content area to be measured .
 Most upon it is applied in test of knowledge
measurement.It
 Mostly used in measuring included in the
research instrument to measure a particular
phenomenon.
 Judgement of content validity may be
subjective and are based on previous
researcher and experts opinion about the
adequacy ,appropriateness and
completeness of the content.
 Generally the validity ensure through the

8. CRITERION VALIDITY
 This type of validity is a relation in
between measurement of instrument
with some other external criteria.
 For exp - a tool is develop to measure e
the professionalism among nurses to
assess.
 The criterion validity nurse’s were
separately asked about the no. Of
research paper they published and the
no of professional conference they have
attended.

9. PREDICTIVE VALIDITY
 It is the degree of forecasting
judgement
 Example -some personality test on
academic future
 It is differentiation between
performances on some future criterion
and instrument ability.
 An instrument may have predictive
validity when its scores significantly
correlate with future criteria.

10. CONCURRENT VALIDITY
 It is the degree of measure in present .
 It relates to present specific behaviour
and characteristic.
 hence the difference between
predictive and concurrent
validity.refers to timing pattern of
obtaining measurement of criterion

11. CONSTRUCT VALIDITY
 A construct is founded in this type of
validity such as a nurse may have
designed an instrument to measure
the concept of pain in ambulatory
patient..
 The pain pattern may be due to
anxiety ,hence the result may be
misleading .Construct validity is a key
criterion for assessing the quality of a
study and construct validity has most
often been addressed in term of

12. FACTORS AFFECTING VALIDITY
Difficult sentences are difficult to understand
unnecessarily confused which will affect the validity of
the test.
Use of inappropriate items will lead to disorganisation
of matter lead to low validity.
Medium of expression ;English as a medium of
instruction and response for non English medium
creates more serious problem affects the validity of test.Unclear direction results to low validity.
If reading vocabulary is poor ,the student fail to
reply to the test item even if they know the answer.
Difficult level of items; Too easy or too difficult
test items would not discriminate among pupils
thereby the validity of a test will be lowered.

13. Cont..
Influence of extraneous factors –Style of
expression legibility,mechanics of
grammer ,handwriting,length of
answer,method of organising the matter.
Inappropriate time limits –If no time limit is
given the result will be invalidated.
Inadequate weightage to subtopics or
objectives forms a question of validity of
a test.
Quiz items;Sometimes student inability to
understand a test items guess and
respond .This would lower the validity of
a test items.

14. VALIDITY OF A SCALE
 LOGICAL VALIDITY
 The scale must conform to common sense
REASONING and therefore partly subjective.
 KNOWN GROUPS
 The scale is applied to known category of people
the result obtained is compared to known facts If
they are similar the scale is considered to be
valid.
 OPINION OF JURY
 The opinion of many jurist who will have no
biasness be considered I f several jurist are of
same opinion then it will be valid,
 INDEPENDENT METHOD
 Independent criteria will be used to measure a
thing and if the result are similar the scale is said
to be valid.

15. RELIABILITY
 Reliability deals with the consistency of
measurement in research.
 Reliability is the quality that guarantees us
that we will get similar results when
conducting the same test on the same
population every time.
Consider this ruler…

16. RELIABILITY
 Each ruler will give the same answer
each time…
But this one will be wrong each
time…

17. RELIABILYTY
 Each ruler is reliable
 But reliability doesn‘t mean much
when it is wrong…

18. RELIABILITY
 So, not only do we require reliability…
 We also need

19. GOOD RULER
BAD RULER

20. RELIABILITY
 The quality and adequacy of quantities
data only can be assessed by
establishing the reliability of an
instrument.
 RELIABILITY is the degree of
consistencies and accuracy with which
the variables are measured by
instrument.
 Reliability refers to the consistency of
measure .A test is considered reliable if
we get the same result repeated by.
 Reliability is defined as the ability of an
instrument to creat reproducible result.
 Therefore reliability concerned with
consistency of measurable tools.

21. TEST-RETEST RELIABILITY
 The same scale can be applied twice to
the same population to achieve the
same objective and if the two result are
similar The scale is regarded as reliable.
The test can be done on two similar
group also.
MULTIPLE FORM
 The same population is subjected to
2 or more types of scales will be
administer in the case the result are
more or less similar.this scale may be
regarded as reliable.

22. SPLIT HALF METHOD
 The scale may be divied into two equal
parts.
 Each part is taken as a complete scale and
measurement is made separated
 The correlation between the two scores
obtained If digree of correlation is high The
scale may be regarded as reliable.

23. STABILITY
 The stability aspect of reliability means research
instrument provides same result when it is used
consequitively for two or more times
 It is also known as test re test reliability the test is
adminstred twice at two different points in time .Its
used to asses the consistency of a test across time.
 This type of reliability assumes that there will be no
change in the quality or construct being measured
.Test retest reliability is the best used for things that are
stable overtime
 .Generally reliability is higher when little time has
passed between test.The test retest method is a
relatively easy and straight forward approach to
establish reliability.
 It is used for questionnaires observation ,checklist.

24. STATISTICALCALCULATION
 Adminstration a research instruments to
a sample of subject one or two different
occasions.
 Serves of the tool admistrated at two
different occasions is compared and
calculated by using following formula of
correlation coefficient.
 The correlation co- efficient revals the
magnitude and direction of relationship
between scores generated by research
instrument at two separate occations.

25. INTERPRETATION OF RESULT
Result ranges from -1.00- +1.00 and as
follows
 +1.00 scores indicate perfect
reliability.
 0.00 score indicates no reliability
 A score above 0.70 indicates an
acceptable level of reliability of a
tool.

26. SPLIT HALF METHOD
 Procedure of calculating split half
reliability of research instrument
involves following step.
 Divide item of a research instrument in
two equal parts through grasping either
in odd number question and even
number question or first half and second
item groups .
 Administer two sub parts of the tools
simultaneously,scores them
independently and compute the
correlation coefficient on the two
separate scores by using following
formula.

27. CNT,,
 In the split half to overcome the
underestimation of reliability of entire
scale as the formula given above has
estimated reliability of only half items
the following formula is used to
estimate reliability of entire test.
 r¹=2r/1+r
 r’=the estimated reliability of entire
test
 r=the correlation coefficient computed
on split halfs

28. EQUIVALENCE
.
 This aspect of reliability is estimated when a researcher is
testing the reliability of a tool which is used by two different
observer to observe a single phenomenon simultaneously
and independently on two presumably parallel instrument and
administer to an indivisual at same time .
 Example-
 A rating scale developed to asses clear lines of the bone
marrow transplantation unit ,this rating may be administrative
to observe the cleanliness of the bone marrow transplantation
until by two different observer simultaneously but
independently.
 This reliability may be computed by using following
formula
 R=number of agreements/number of agreements +no.
of disagreements


29. FACTORS INFLUENCING
RELIABILITY
. EXTRINSIC FACTORS
1. Group variability
Group which is homogeneous in their ability
will get lower reliability score and Heterogenous
group will get high reliability
2. Guessing of Examinees
Some may get high score on testing and low
score on retesting
3. Environmental conditions
Like light, sound and other comforts
4. Momentary fluctuations
a broken pencil, sudden sound, fear of giving
wrong answer, knowing no way to change it

30. 1. Length of the test
Longer tests yields a higher reliability
2. Range of total scores
The range of the total scores is less then the reliability will be low
3. Difficulty index
If the difficult index is around 0.50 then reliability will be more
4. Discrimination value
More the discriminatory items more will be the reliability
INTRINSIC FACTORS

31. Relationship between
Reliability and Validity
A valid test is generally reliable. A test
which is not valid, may not be reliable
A test which is reliable may or may not
be valid
A high degree of reliability does not
necessarily lead to high validity. It may
reflect a high degree of constant error
A test that is not reliable, is never valid

32. Cont..
 Validity is truthfulness while reliability is
trust worthiness.
 A tests must not valid unless it is reliable .
 A test has single reliability co-efficient
estimated by statistical procxedures where
as no single validityindex for a test
 Validity and reliability are degree of each.
 Validity includes reliability.


33. SUMMERISATION

34. REFERENCES
 Sudha R. Nursing Education Principles and
concepts, 1st edition, New delhi :Jaypee Brothers
Medical publishers (p) ltd, 2013.
 Sharma suresh k. Nursing Research $ statistics,
1st Edition
 Basavanthappa BT, Nursing Education, 2nd
Edition, New Delhi; Jaypee Brothers Medical
Publishers (P) Ltd: 2009.
 Borich Gary, Kubiszyn Tom,Educational testing
and measurement, 7th edition,kundli;Replika
press Pvt Ltd:2004.


35. Basavanthappa BT, Nursing Education, 2nd
Edition, New Delhi; Jaypee Brothers
Medical Publishers (P) Ltd: 2009.
Borich Gary, Kubiszyn Tom,Educational
testing and measurement, 7th
edition,kundli;Replika press Pvt Ltd:2004.