????? (validity)

1
????? (validity)
2
?????

• ??????? ??? ?? ?? ???? ?? ???????? ???? ????
  ?????? ?? ?? ???? ??? ??? ?????? ?? ???.

3

• A measure is valid when the differences in
  observed scores reflect true differences on the
  characteristic that we are attempting to measure
  and nothing else.

4

• ?????? ????? ????? ??? ?? ???? ?????? ???? ????
  ???? ??? ??? ?
• ???? ? ????? ????.

5
????? ?????

• ????? ???????(content-related validity)
• ????? ????
• ????? ?????(????? ?????)Criterion-related
  validity
• ????? ??? ????predictive
• ????? ??????Concurrent
• ????? ????Construct
• Convergent
• Discriminate

6

• ?????? ?? ??? ????? ? ???????? ?? ??? ????? ????
  ????? ? ???? ??? ??? ?? ??? ? ?? ????? ?????? ???
  ??? ????? ?? ???????? ?? ?????? ?? ???? ?? ??
  ????? ????? ?? ?? ???? ????? ? ??? ??? ?????? ???
  ?????? ??? ??? ?????? ?? ????.

7

• ??????? ???? ? ??????? ????? ?? ?? ?? ?? ??????
  ????? ? ???? ????? ??????? ???.

8

• ????? ??????? ?? ??? ???? ?????
• ?? ??? ?? ????? ???? ??? ????? ?? ?? ????? ?? ??
  ?? ???? ?? ????? ???? ??? ???? ??? ?? ?? ???? ??
  ????? ?? ????? ???? ??? ???? ???.
• ???? ????? ?? ??? ???? ???? ????? ????? ?????
  ?????? ???.

9
Nunnalypsychometric theories 1994, P.103

• In spite of efforts to settle every psychological
  measurement issue by flight into statistics,
  content validity is mainly settled in other ways.
  Although helpful hints are obtained from analysis
  of statistical findings, content validity
  primarily rests upon an appeal to the property of
  content and the way it is presented.

10

• It was argued that the sampling adequacy of
  test content, the relevance of test content, and
  the clarity of domain definitions should be
  associated with the terms content
  representativeness, content relevance,
  respectively, rather than with the term content
  validity, because these notions do not refer to
  any kind of test validity. Also, it was indicated
  that the sampling adequacy of test responses and
  the relevance of these responses are matters
  already encompassed by the concept of construct
  validity.
• Since no appropriate means of defining this type
  of validity is therefore found, it is concluded
  that content validity is not a useful term for
  test specialists to retain in their vocabulary.

11
????? ????? ??????? ?? ????? ?? ???????? ?? ?????
?? ??????? ???????????????????????????????????????
??? ??????????????????????????????????????????
??????????????????????????????????????????????????
????

• ???????? ??? ????? ???? ????? ???? ????? ???????
  ???? ?????.
• ? ???? ????? ????? ??????? ?? ????? ?? ?????
  ??????? ?? ??? ???? ?? ???? ??? ????? ?? ?? ?????
  ???? ????? ? ??? ??? ?????? ?? ???? ???????
• (content domain) ????? ???????? ?? ???.

12

• For example, a depression scale may lack content
  validity if it only assesses the affective
  dimension of depression but fails to take into
  account the behavioral dimension

13

• ????? ??? ????? ?? ????? ??????? ?? ???? ????? ?
  ?? ??????????????? ?? ?? ???? ????? ?????
  ??????????? ??????? ?? ????? ??? ??? ????? ?? ??
  ????? ??? ??????.

14

• Validity is usually a matter of degree rather
  than an all-or-none property Nunnaly P. 84

15
????? ????(?????) Face validity

• ????? ???? ?? ?????? ????? ??????? ??? .
• ????? ???? ?? ??? ???? ????? ?? ??? ?? ???? ???
  ?? ????? ?? ?? ?? ?? ???? ???? ?? ?????? ????? ??
  ???? ?????? ???? ?? ???? ??? ???.

16

• According to Nunnaly the face validy may best
  be understood as reflecting the extent to which
  someone who is not trained to look for formal
  evidence of validity feels the instrument
  measures what it is intended to measure.

17

• Face validity is the extent to which a test
  appears to measure what it is supposed to measure

18

• ??? ???? ????? ???? ??? ????? ???? ????? ????
  ????? ???? ?? ????? ????? ??? ?? ?? ???? ?? ?????
  ???? ?? ???? ?? ??? ?? ???.
• ? ???? ??? ????? ????? ?? ???? ?? ????.
• ? ?? ??? ???? ???? ???? ????? (????? ???? )??
  ???? ?????? ????? ? ????? ???? ????? ???? ?????
  ??????? ? ????? ????? ???.

19
????

• ???????? ??????? ?? ????? ????? ?? ?? ?? ?? ?????
  ????? ?? ????? ??? ? ???? ????? ??? ??? ??? ? ??
  ????? ????? ????? ?? ????? ?? ?? ???? ????? ????
  ?? ????? ???? ??? ???? ???? ???? ?????? ????
• ?? ???? ?? ??? ?? ????.
• ???????? ?? ???? ??? ?? ?? ?????? ?? ???? ?????
  ??
• ?????? ? ????? ????? ??? ?? ??????????? ????
• ?? ????? ??? ????.

20

• ?? ??? ?? ????? ???? ?? ????? ????? ????? ???
  ?????? ??? ?? ???? ????? ?? ??? ????? ?? ????
  ????? ???? ???? ??????? ?? ???? ?????? ????? ??
  ????? ???? ??? ??? ?????? ?????? ????? ?? ???????
  ????? ??? ? ???? ??? ?????? ?? ?? ??? ???? ??
  ????? ???? ????? ????.

21
??? ????? ????? ????

• ?? ???? ?? ????? ???? ??? ???? ?? ????? ???????
  ??? ????? ???? ?? ???? ????? ????? ??????? ?? ???
  
• ?? ??? ? ???? ??????? ?? ??? ???????? ????
  ??????? ???.

22

• ?????? ?? ????? ???? ?????? ?????? ??? ????? ????
  ?? ?? ????? ?? ????? ???? ?? ?? ????? ???????
  ?????? ???? ???? ???.
• ? ???????? ?????? ?? ?? ????? ?? ????? ???? ???
  ???? ?????? ????? ?? ?????? ????(????? ????)
  ??????? ???? ?? ????? ???? ?? ?????????.
• ? ????? ??? ?? ????? ??? ??? ? ????? ??? ??
  ?????? ??? ???? ??? ???? ?? ??? ?????? ???? ???
  ????.

23

• ???? ????? ??? ?? ?? ?? ????? ????? ?? ????? ???
  ????? ?? ?? ????? ??? ???? ???? ?? ???.
• ? ?????? ??? ???? ?? ??? ?? ????? ?? ????? ??????
  ???? ?? ????? ?????? ?????? ???? ????? ?? ?????
  ?????? ???? ?????(???? ????? ? ???? ??????) ?????
  ?? ?? ????? ?????? ???? ?? ???.

24
????

• Researchers have found that the amount of words a
  child reads correctly in one minute is a good
  indicator of general reading ability.

25
?? ???? ????? ????? ?????????? ? ?????

• ?????? ??????? ?? ????? ?? ????? ???? ????? ??
  ???????.

???? ??? ?????

• ????? ??????? ?? ????? ?? ????? ???? ????? ??
  ????? ??????.

???? ??? ?????
26
?????? ? ?????
????
????? ???
????
27
?????? ? ?????
???? ?????
???? ????
???? ????
???? ?????
28
?????? ? ?????
a c
b d
29
?????? ? ?????
a c
b d
30
?????? ? ?????
31
???? ??????

• ????? ?? ???? ????? ???(????? ???? ?? ?????) ??
  ??? ????? ?????.

• ?????? ????? ???? ??? ????? ?? ????? ????? ????
  ???.

???? ?????? ????

• ?????? ????? ????? ??? ????? ?? ????? ????? ????
  ???.

???? ?????? ????
32
2 X 2 tables

• Gold standard
• -
• New True False
• test
• - False - True -

33
Calculating SN and SP

• Gold standard
• -
• New
• TP FP
• test
• - FN TN
• Sensitivity Specificity
• TP/TPFN
  TN/FPTN

34
Pos and Neg Predictive Value

• Gold standard
• -
• New PV
• TP FP
  TP/TPFP
• test
• - FN TN - PV
• TN/TNFN
• Sensitivity Specificity

35
???? ?????? ????

• ?????? ????? ???? ??? ????? ?? ????? ????? ????
  ???.

HIV
36
???? ?????? ????

• ?????? ???? ???? ??? ????? ?? ????? ????? ????
  ???.

HIV -
37
???? ??????
a b
c d
38
???? ??????
a b
c d
39
Consider 1000 patients 500 with a disease, 500
without
40
Consider 1000 patients 500 with a disease, 500
without

• 4 possible types of diagnostic testing
  classifications 2 correct, 2 incorrect

41
Correct Classification True Positive (TP)
Definition Sensitivity TP / (TP FN)
probability of a test among diseased
Example Sensitivity 400 / 500 80
42
Correct Classification True Negative (TN)
Definition Specificity TN / (FP TN)
probability of a - test among healthy
Example Specificity 450 / 500 90
43
Incorrect Classification False Positive
Definition False Positive Fraction FP / (FP
TN) probability of test among healthy
Example FPF 50 / 500 10
44
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45

• ????? ????
• ???? ????? ??? ?? ?? ??? ?????? ?? ????? ????
  ?????? (???? ?? ??? ???? ?? ?? ??????? ??????
  ????)?? ?? ???? ????? ??? ???? ????? ???? ???????
  ???.
• ???? ??? ? ?????? ?????...

46

• Construct validity seeks agreement between a
  theoretical concept and a specific measuring
  device or procedure.

47

• For example, a researcher inventing a new IQ test
  might spend a great deal of time attempting to
  "define" intelligence in order to reach an
  acceptable level of construct validity.

48

• Construct validity can be broken down into two
  sub-categories
• 1- Convergent validity
• 2- Discriminate validity

49
????? ????? ???? ?? ????? ?? ?????
? ???? ???? ?? ???? (?? ????? ???? ??? )??
????? ??????. ? ??? ???? ?????? ???? ?? ???? ?
?????? ??????. ? ????? ??? ????? ???? ?? ???
????? ?????????? ?? ??? ????? ??? ???? (?????
???? ????? ??? ?????????? ? ?????? )?? ???? ? ??
(??? )???? ???? ???(????????? ?????????????
?????? ???????..)????? ?? ??????.
50

• ?? ??? ???? ?? ???? ???????? ???? ????? ?????
  (SF36) ?????? ?? ?? ??? ?? ???? ???????? ?? ???
  ???? ???? ?? ????? ???????? ???? ?? ?????? ????.

51

• ??? ??? ????? ????? ????? ???? ?? ????? ???
  ?????-????
• 1-????? ??????? ????? ?????? ????? ??? ???
• ????? ????? ???? ????? ???? ?? ????? ?????? ??
  ???? ?????? ???? ???? ???? ????? ??? ?????????
  ??????? ????? ????? ????? ???? ??? ???? ??????
  ???? ?? ???? ?????. ??? ????? ?? ????? ?????
  ?? ?????.
• ????? ????? ?? ?????
• ????? ???? ??? ????? ?? ????? ??? ???? ?? ????
  ??? ??????? ?? ?????? ???? ?? ???? ???????? ?????
  ????.??? ?? ????? ????? ?? ?????.

52

• 2- ????? ???
• (??? ?? ?? ???? ??? ????? ???? ?????? ????
  ????(????? ????? ??? ?????)? ????? ????? ?? ?????
  ???? ?? ???? ???? ?? ??????? ???? ???).
• 3 ????? ????? (factor analysis)
• 4- ????? ?????? ?????
• ?????? ??????? ????? ????? ??? ???? ?? ???? ??
  ?????(???? ???? ????? ?? ????? ???????? ???????
  ????? ????? ?????????? ?? ???? ????? ??? ? ????
  ?? ??? ?? ?????? ???? ?? ????).

53
(No Transcript)