Validity
• Validity: A generic term used to define the
degree to which the test measures what it
claims to measure.
What is measurement validity?
• Validity refers to the accuracy of a measure.
• A measurement is valid when it measures
what it is suppose to measure and performs
the functions that it purports to perform.
• Does an indicator accurately measure the
variable that it is intended to measure?
VALIDITY
• The extent to which measures indicate what
they are intended to measure.
• The match between the conceptual definition
and the operational definition.
Validity
• validity types are attempting to assess the
degree to which you accurately
• Translated your construct into the
operationalization.
types of translation validity
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Face Validity
Content Validity
Criterion-Related Validity
Predictive Validity
Concurrent Validity
Convergent Validity
Discriminant Validity
Translational Validity
• Face/Logical Validity
–When the measure is that being tested,
i.e. the measure is valid by definition
• Content Validity
–Does the measure adequately sample
what is covered?
Face Validity
• Determined by judgements made by
the researcher and based on surface
appearance.
Content Validity
• Determined by expert judgements
of the appropriateness of the
contents of a measure.
Domain of Meaning
• Content validity refers to degree that one
has representatively sampled from that
domain of meaning.
• This type of validity receives the most
attention in construction of achievement &
proficiency measures with psychology &
education.
Criterion Validity
• Predictive Validity
–Can the measurement be used to predict
later reality?
• Discriminant Validity
–Is the measurement dissimilar to other
measures that it theoretically should be
dissimilar to?
Criterion Validity, 2
• Concurrent Validity
– Is the measurement correlated with a criteria
that is measured at the same time?
• Convergent Validity
– Is the measurement similar to other measures
that it theoretically should be similar to?
Construct validity
is an assessment of how well you
translated your ideas or theories into
actual programs or measures.
Why is this important?
Because when you think about the
world or talk about it with others (land of
theory) you are using words that
represent concepts
What is a criterion?
• This is the standard by which your
measure is being judged or
evaluated.
How to determine Criterion Validity
• Find alternative measurements
• Make alternative and your
measurements at similar times
• Compare results
• These methods work for Face/Logical &
Content Validity too!
Example: Reading Achievement Test
• A multiple choice test on reading
achievement (which is designed to measure
achievement at the time of testing and not
designed to predict any future behavior.)
might be validated by:
– comparing the scores on the test with
teachers’ ratings of students’ reading abilities.
• Teachers’ ratings are the criterion
Predictive Validity
• This is determined by correlating test
scores with criterion scores obtained
after examinees have had a chance to
perform what is predicted by the test.
• A measure is validated with reference
to future standing on criterion
variable.
Example: Employment Test
• The purpose of an employment test is to
predict success on the job.
• The most appropriate test of its validity is
predictive validity - to what extent does the
test predict what it is supposed to predict?
Reliability
WHAT IS RELIABILITY?
• A thermometer is Accurate if the actual body
temperature (98.6F) and what is registered on
the thermometer (98.6F) are the same
• A thermometer is Consistent if, for multiple
measures of body temperature, what is
registered on the thermometer (99F) is the same
each time (NOTE: a measure can be consistent
and inaccurate, but not the other way around!)
TEST RELIABILITY
• Remember. . .reliability deals with
measurement error; thus a “perfectly
reliable” measure is 100% error-free.
– We never know a person’s “true” score
• Therefore, all our selection tests will only be
estimates of reliability
Statistical Concept of Reliability
• Real Variance (Observed-Error)
• Observed Variance (Real+Error)
)‫واريانس واقعی (واريانس مشاهده شده – واريانس خطا‬
)‫ واريانس خطا‬+ ‫واريانس مشاهده شده (واريانس واقعی‬
Methods of reliability estimation
• 1-test---retest
• 2-Parallel forms/alternate forms
• 3-split half
• 4-Alfa Kronbach
WHAT FACTORS INFLUENCE
TEST RELIABILITY?
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•
Test question difficulty
Length of a measure
The method used to estimate reliability
Response format
How and by whom test is administered
How homogenous or similar the test items are
Physical conditions of testing location and physical
condition of test taker
Neither
Reliable
Nor
Valid
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Reliable
And
Valid

 
  
 

 

Reliable
But Not
Valid
aryousefy@edc.mui.ac.ir
Congratulation
Reliability
WHAT IS RELIABILITY?
• A thermometer is Accurate if the actual body
temperature (98.6F) and what is registered on
the thermometer (98.6F) are the same
• A thermometer is Consistent if, for multiple
measures of body temperature, what is
registered on the thermometer (99F) is the same
each time (NOTE: a measure can be consistent
and inaccurate, but not the other way around!)
TEST RELIABILITY
• Remember. . .reliability deals with
measurement error; thus a “perfectly
reliable” measure is 100% error-free.
– We never know a person’s “true” score
• Therefore, all our selection tests will only be
estimates of reliability
Statistical Concept of Reliability
• Real Variance (Observed-Error)
• Observed Variance (Real+Error)
)‫واريانس واقعی (واريانس مشاهده شده – واريانس خطا‬
)‫ واريانس خطا‬+ ‫واريانس مشاهده شده (واريانس واقعی‬
Methods of reliability estimation
• 1-test---retest
• 2-Parallel forms/alternate forms
• 3-split half
• 4-Alfa Kronbach
WHAT FACTORS INFLUENCE
TEST RELIABILITY?
•
•
•
•
•
•
•
Test question difficulty
Length of a measure
The method used to estimate reliability
Response format
How and by whom test is administered
How homogenous or similar the test items are
Physical conditions of testing location and physical
condition of test taker
Neither
Reliable
Nor
Valid














Reliable
And
Valid

 
  
 

 

Reliable
But Not
Valid
aryousefy@edc.mui.ac.ir
Congratulation