2. Validity- How to show that the test truly measures
what it claims.
(Does it measure what it is suppose to measure)
Reliability- Produces stable, consistent
measurements.
(How representative is the measurement)
3. Validity
On a test with high validity the items will be closely
linked to the test’s intended focus.
Example: One common technique for demonstrating validity is
to use correlation.
If test measures intelligence than it should related to IQ,
performance on learning tasks, and problem-solving ability. If
all test scores correlate then new test is valid
4. Several ways to estimate validity
Content validity- related to objectives and their
sampling
Construct validity- theory underlying the target
Criterion related validity- concrete criteria in the real
world
Concurrent- correlating with another measure already
validated
Predictive- Capable of anticipating some later measure.
Face validity- related to test overall appearance
5. Validity vs. Reliability
Measures of validity are similar to measures of
reliability. With reliability, you compare one
measurement of a variable on a group of subjects
with another measurement of the same variable on
the same subjects. With validity, you also compare
two measurements on the same subjects.
6. Reliability
Reliability is the extent to which an experiment or
test shows the same result on repeated trails when
the same individuals are measure under the same
conditions.
7. Tests that Validity vs Reliability Matter
Acoustic Reflexes
MRIs
OAEs
Vemp
VNGs
ABR
ASSR
EcochG
8. Reliability Example
If your IQ was measured at 113 last week, Expect
nearly the same score if measured again this week.
9. Reliability and Error in Measurement
Measured score = true score + error
Example
For an IQ test
True score= actual level of intelligence
Error = current mood, fatigue, general health, etc.
10. Reliability
Equivalency: related to the co-occurrence of two
items
Stability: related to time consistency
Internal: related to the intruments
11. Practice Quiz
Reliability refers to whether we are truly measuring
the concept of interest in our study.
• True
• False
12. Practice Quiz
Reliability refers to whether we are truly measuring
the concept of interest in our study.
• True
• False
13. Practice Quiz
Researchers always try to maximize reliability and
validity in their research.
• True
• False
14. Practice Quiz
Researchers always try to maximize reliability and
validity in their research.
• True
• False
15. Practice Quiz
The validity of a measure refers to the:
a. comprehensiveness with which it
measures the construct.
b. particular type of construct
specification.
c. consistency of the measurement.
d. accuracy with which it measures the
construct.
16. Practice Quiz
The validity of a measure refers to the:
a. comprehensiveness with which it
measures the construct.
b. particular type of construct
specification.
c. consistency of the measurement.
d. accuracy with which it measures the
construct.
17. References
Cardozo, R., Magdalena, J., Validity, Reliability and Practicality Retrieved from
http://www.slideshare.net/songoten77/presentation-validity-reliability on
November 30, 2009
Gravetter, F., Wallnau, L. B., Essentials of Statistics for the Behavioral Sciences,
5th Edition, Thomson and Wadsworth, 2005
Writing Guides Reliabiltiy and Validity, Colorado State University, Retrieved
from http://writing.colostate.edu/guides/research/relval/index.cfm on Nov.
30, 2009