PSY 6430 Unit 5

1
PSY 6430 Unit 5

• Validity
• Determining whether the selection instruments are
  job-related

Today and Wednesday Lecture Exam Monday, 3/18
2
SO1 NFE, Validity, a little review

• Predictor test/selection instrument
• Use the score from the test to predict who will
  perform well on the job
• Possible confusion (again)
• You need to determine the validity of the test
  based on your current employees
• Then you administer it to applicants and select
  employees based on the score

(a few students had a problem distinguishing
between validity and reliability on E4, example
next)
3
SO1 NFE, Validity, example

• Administer a test to current employees
• Obtain measures of how well they perform on the
  job
• Correlate the test scores with the performance
  measures
• Assume The correlation is statistically
  significant
• Assume Current employees who score 50-75 also
  are performing very well on the job
• Now you administer the exam to applicants,
  predicting that those who score 50-75 will also
  perform well on the job

(main point next slide)
4
SO1 NFE, Validity main point

• You determine the validity of a selection test or
  instrument based on your current employees
• Then after establishing the validity or job
  relatedness of the test
• Give the test to applicants and select them on
  the basis of their test scores

5
SO2 Reliability vs. Validity

• Reliability
• Is the score on the measure stable and
  dependable?
• Are you actually measuring what you want to be
  measuring?
• Validity
• Is the measure related to performance on the job?

6
SO3 Relationship between reliability and validity

• A measure can be reliable, but not valid
• However, a measure cannot be valid unless it is
  reliable
• Reliability is a necessary but not sufficient
  condition for validity
• Text gives a perfect example
• You can reliably measure eye color, however, it
  may not be related to job performance at all

key point
7
Types of validation procedures

• Content expert judgment
• Criterion-related statistical analyses
  (concurrent predictive)
• Construct (but not practical-not covering this)
• Validity generalization (transportable, no local
  validity study jobs are similar)
• Job component validity (not covering this in this
  unit, but will return to it briefly in the next
  unit, transportable, job elements/components are
  similar but jobs are not)
• Small businesses Synthetic validity (not
  covering it, not very relevant now content
  validity)

(main types are the two kinds of
criterion-related and content validity construct
really a hold over from test construction - not
very relevant - I have only seen this used by a
few organizations create their own tests touch
on validity generalization, but right now while
validity generalization has excellent
professional support, may not be legal -
professional guidelines depart from legal in one
case, 6th Circuit Court ruled it illegal as a
matter of law based on Griggs/Duke and Albermarle
- 1987)
8
SO5 NFE but 7B is Difference between content and
criterion-related validity

• Criterion-related validity is also called
  empirical validity
• Concurrent validity
• Predictive validity
• This type of validity relies on statistical
  analyses (correlation of test scores with
  measures of job performance)
• Measures of job performance criterion scores

(content next slide)
9
SO5 NFE but related to 7B which is Difference
between content and criterion-related validity

• Content validity, in contrast, relies on expert
  judgment and a match between the content of the
  job and the content of the test
• Expert judgment refers to
• the determination of the tasks and KSAs required
  to perform the job via a very detailed type of
  job analysis
• linking the KSAs to selection procedures that
  measure them

10
NFE Intro to content validity

• You do NOT use statistical correlation to
  validate your tests
• Validation is based only on your job analysis
  procedures and matrix between KSAs and selection
  measures
• It is much more widely used than
  criterion-related validity
• Particularly since Supreme Court ruled it was OK
  to use for adverse impact cases (1995)

11
SO6 Two reasons why content validity is often
used

• It can be used with relatively small number of
  employees
• Large sample sizes are required to use
  criterion-related validity due to the correlation
  procedures
• The text later when talking about
  criterion-related validity indicates you may need
  over several hundred
• Dickinson usually 50-100 is adequate
• How many companies have that many current
  employees in one position?

(small number of incumbents and applicants)
12
SO6 Two reasons why content validity is often
used

• Many organizations do not have good job
  performance measures
• You need good performance criterion measures to
  do a criterion-related validity study because you
  correlate the test scores with job performance
  measures

13
SO7A Content vs. criterion-related validity and
the type of selection procedure

• If you use content validity you should write the
  test, not select an off-the-shelf test
• If you use criterion-related validity, you can do
  either
• It is much easier and less time consuming to use
  an off-the-shelf test than to write one!

(VERY IMPORTANT! book waffles on this a bit,
indicating that emphasis should be placed on
constructing a test, But only in rare situations
would I recommend selecting off-the-shelf test
with content validity - legally too risky why,
next slide)
14
SO7A Why should you write the test if you use
content validity? (this slide, NFE)

• Content validity relies solely on the job
  analysis
• The KSAs must be represented proportionately on
  the selection test as indicated in the job
  analysis in terms of
• Their relative importance to the job
• The percentage of time they are used by the
  employees
• It is highly unlikely that an off-the-shelf test
  will proportionately represent the KSAs as
  determined by your job analysis
• In some discrimination court cases, the judge has
  gone through the test item by item to determine
  whether the items were truly proportional to the
  KSAs as determined by the job analysis
• Both professional measurement reason and legal
  reason to write the test rather than using an
  off-the-shelf test

15
SO7B Content vs. criterion-related validity
Differences in the basic method used to determine
validity (review)

• Content validity
• Relies solely on expert judgment - no statistical
  verification of job-relatedness
• Criterion-related validity
• Relies on statistical prediction to determine
  job-relatedness

(I am not going to talk about SO8, face validity
very straightforward)
16
SO9 What is the heart of any validation study
and why?

• Job analysis
• The job analysis determines the content domain of
  the job the tasks and KSAs that are required to
  perform the job successfully

17
SO10 Major steps of content validity - very,
very specific requirements for the job analysis

• Describe tasks for the job
• Determine the criticality and/or importance of
  each of the tasks
• Specify the KSAs required for EACH task
• KSAs must be linked to each task (NFE)

Now because of ADA, is it an essential function?
(cont. next slide)
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SO10 Major steps of content validity, cont.

• Determine the criticality and/or importance of
  each KSA
• Operationally define each KSA
• Describe the relationship between each KSA and
  each task statement
• You can have KSAs that are required for only one
  or two tasks, or you can have KSAs that are
  required to perform several tasks
• The more tasks that require the KSAs, the more
  important/critical they are
• Describe the complexity or difficulty of
  obtaining each KSA (formal degree, experience)
• Specify whether the employee must possess each
  KSA upon entry or whether it can be acquired on
  the job (cannot test for a KSA if it can be
  learned within 6 months)
• Indicate whether each KSA is necessary for
  successful performance of the job
• Only the first major point will be required for
  the exam, but I want to stress how detailed your
  job analysis must be for content validity

(cont on next slide)
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SO10 Major steps of content validity, cont.

• Link important job tasks to important KSAs (FE)
• Reverse analysis you have linked the KSAs to the
  tasks, now you must link the KSAs to the tasks
  (NFE)
• KSA 1 may be relevant to Tasks 1, 6, 7, 10, 12,
  22
• KSA 2 may be relevant to Tasks 2, 4, 5
• Etc.
• (NFE) Develop test matrix for the KSAs
• If you want see how you go from the task analysis
  to the actual test, turn ahead to Figures 7.12,
  7.13, 7.14, 7.15, and 7.16 on pages 283-286 and
  Figure 7.17 on page 290

20
SO11 When you cant use content validity
according to the Uniform Guidelines

• When assessing mental processes, psychological
  constructs, or personality traits that cannot be
  directly observed, but are only inferred
• You cannot use content validity to justify a test
  for judgment, integrity, dependability,
  extroversion, flexibility, motivation,
  conscientiousness, adaptability
• The reason for that is that you are basing your
  job analysis on expert judgment - and judgment is
  only going to be reliable if you are dealing with
  concrete KSAs such as mechanical ability,
  arithmetic ability or reading blue prints
• The more abstract the KSA, the less reliable
  judgment becomes
• If you cant see it, if you cant observe it,
  then the leap from the task statements to the
  KSAs can result in a lot of error

(text mentions three I am having you learn the
first one and one I added in the SOs -- these are
the two that are most violated in practice the
second one is relevant to BOTH content and
criterion-related so shouldnt be listed under
when you cant use content validity cannot test
for KSAs that can be learned on the job)
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SO11 When you cant use content validity
according to the Uniform Guidelines, cont.

• When selection is done by ranking test scores or
  banding them (from U1)
• If you rank order candidates based on their test
  scores and select on that basis, you cannot use
  content validity - you must use criterion-related
  validity
• If you band scores together, so those who get a
  score in a specified range of scores are all
  considered equally qualified, you cannot use
  content validity - you must use criterion-related
  validity
• Why? If you use ranking or banding, you must be
  able to prove that individuals who score higher
  on the test will perform better on the job - the
  only way to do that is through the use of
  statistics
• The only appropriate (and legally acceptable)
  cut-off score procedure to use is a pass/fail
  system where everyone above the cut-off score is
  considered equally qualified

(only relevant if adverse impact)
22
Criterion-related validity studiesConcurrent
vs. predictive

• SO13A Concurrent validity
• Administer the predictor to current employees
  and correlate scores with measures of job
  performance
• Concurrent in the sense that you have collected
  both measures at the same time for current
  employees
• SO18A Predictive validity
• Administer the predictor to applicants, hire the
  applicants, and then correlate scores with
  measures of job performance collected 6-12 months
  later
• Predictive in the sense that you do not have
  measures of job performance when you administer
  the test - you collect them later

(comparison of the two, SO13A, describe
concurrent validity SO18A, describe predictive
validity)
23
Predictive Validity Three basic ways to do it

• Pure predictive validity by far the best
• Administer the test to applicants and randomly
  hire
• Current system next best, more practical
• Administer the test to applicants, use the
  current selection system to hire (NOT the test)
• Use test to hire bad, bad, bad both
  professionally and legally
• Administer the test, and use the test scores to
  hire applicants

(going to come back to these and explain the
evaluations text lists the third as an approach!
Click NO!!)
24
SO13B Steps for conducting a concurrent validity
study

• Job analysis Absolutely a legal requirement
• Discrepancy between law and profession (learn for
  exam)
• Law requires a job analysis (if adverse impact
  challenged)
• Profession does not as long as the test scores
  correlate significantly with measures of job
  performance
• Determine KSAs and other relevant requirements
  from the job analysis, including essential
  functions for purposes of ADA
• Select or write test based on KSAs (learn for
  exam)
• May select an off-the-shelf test or
• Write/construct one

25
SO13B Steps for conducting a concurrent validity
study

• Select or develop measures for job performance
• Sometimes a BIG impediment because organizations
  often do not have good measures of performance
• Administer test to current employees and collect
  job performance measures for them
• Correlate the test scores with the job
  performance measures
• (SO14 add this step) Determine whether the
  correlation is statistically significant at the
  .05 level
• (not necessary for exam) Administer test to job
  applicants and select on the basis of the test
  scores

26
SO15 The basic reason that accounts for all of
the weaknesses with concurrent validity

• All of the weaknesses have to do with differences
  between your current employees and applicants for
  the job
• You are conducting your study with one sample of
  the population (your employees) and assuming
  conceptually that your applicants are from the
  same population
• However, your applicants may not be from the same
  population - they may differ in important ways
  from your current employees
• Ways that would cause them (as a group) to score
  differently on the test or perform differently on
  the job, affecting the correlation (job
  relatedness) of the test

(text lists several weaknesses and all of them
really relate to one issue dealing with
inferential statistics here)
27
SO16 Restriction in range

• With criterion-related validity studies the
  ultimate proof that your selection test is job
  related is that the correlation between the test
  scores and job performance measures is
  statistically significant
• A high positive correlation tells you
• People who score well on the test also perform
  well
• People who score middling on the test also are
  middling performers
• People who score poorly on the test also perform
  poorly on the job
• In order to obtain a strong correlation you need
• People who score high, medium, and low on the
  test
• People who score high, medium, and low on the
  performance measure

(before really understanding the weaknesses
related to concurrent validity and why pure
predictive validity is the most sound type of
validation procedure, you need to understand what
restriction in range is and how it affects
correlation coefficient related to some of the
material from the last unit on reliability - so
if you understood it in that context, this is the
same conceptual issue)
28
SO16 Restriction in range, cont.

• That is, you need a range of scores on BOTH the
  test and the criterion measure in order to get a
  strong correlation
• If you only have individuals who score about the
  same on the exam, regardless of whether some
  perform well, middling, and poorly, you will get
  a zero correlation
• Similarly if you have individuals who score high,
  medium, and low on the test, but they all perform
  reasonably the same, you will get a zero
  correlation
• Any procedure/factor that decreases the range of
  scores on either the test or the performance
  measure
• Reduces the correlation between the two and,
  hence,
• Underestimates the true relationship between the
  test and job performance
• That is, you may conclude that your test is NOT
  valid, when in fact, it may be

29
SO16 Restriction in range, cont.

• Restriction in range is the technical term for
  the decrease in the range of scores on either or
  both the test and criterion
• Concurrent validity tends to restrict the range
  of scores on BOTH the test and criterion, hence
  underestimating the true validity of a test

(cont on next slide)
30
SO16 Restriction in range, cont.

• Why? You are using current employees in your
  sample
• Your current employees have not been fired
  because of poor performance
• Your current employees have not voluntarily left
  the company because of poor performance
• Your current employees have been doing the job
  for a while and thus are more experienced
• All of the above would be expected to
• Result in higher test scores than for the
  population of applicants
• Result in higher performance scores than for the
  population
• Thus, restricting the range of scores on both the
  test and the performance criterion measure

(diagrams on next slide)
31
SO16 Restriction in range, cont.

• Top diagram
• No restriction in range
• Strong correlation
• Bottom diagram
• Restriction in range
• Test scores and
• Performance scores
• Zero correlation

(extreme example, but demonstrates point -
concurrent validity is likely to restrict range
on both, underestimating true validity)
32
SO17AB Factors that affect concurrent validity

• A. Why the length of employment of current
  employees may affect the results of a concurrent
  validity study
• An aging, experienced work force has been
  performing the job for a long time, thus
• You would expect them to score better on an
  ability test than inexperienced job applicants
  AND
• You would expect them all to perform reasonably
  well on the job
• Thus, you have restricted the range on both your
  test and performance scores, which would result
  in a lower correlation coefficient than would
  occur with applicants
• Underestimate the job-relatedness of the test

(17ab are really questions about restriction in
range)
33
SO17AB Factors that affect concurrent validity

• Why rejected applicants, turnover and promotions
  would affect the results of a concurrent validity
  study
• Rejected applicants and those that leave are
  likely to be poorer performers your most skilled
  workers are promoted what is left are employees
  who perform similarly on the test performance
  measure
• You would expect the remaining, current employees
  to score more similarly on an ability test than
  job applicants AND
• You would expect them to perform similarly on the
  job
• Thus, you have restricted the range on both your
  test and performance scores, which would result
  in a lower correlation coefficient than would
  occur with applicants
• Underestimate the job-relatedness of the test

(b same logic as A both have to do with
restriction in range)
34
SO18 Predictive validity

• SO18A Predictive validity (review)
• Administer the predictor to applicants, hire the
  applicants, and then correlate scores with
  measures of job performance collected 6-12 months
  later
• Predictive in the sense that you do not have
  measures of job performance when you administer
  the test - you collect them later, hence, you can
  determine how well your test actually predicts
  future performance

35
SO18B Steps for a predictive validity study

• Job analysis Absolutely a legal requirement
• Determine KSAs and other relevant requirements
  from the job analysis, including the essential
  functions for purposes of ADA
• Select or write test based on KSAs
• You may select an off-the-shelf test or
• Write/construct one
• Select or develop measures for job performance

Learn this point for the exam
(first four steps are exactly the same as for a
concurrent validity study)
36
SO18B Steps for a predictive validity study

• Administer the test to job applicants and file
  the results away
• Do NOT use the test scores to hire applicants
  (Ill come back to this later)
• After a suitable time period, 6-12 months,
  collect job performance measures (or training
  measures)
• Correlate the test scores with the performance
  measures
• (SO18B add this step) Determine whether the
  correlation is statistically significant
• (NFE) If so, administer test to new job
  applicants and select on the basis of the scores

37
SO19 Two practical (not professional) weaknesses
of predictive validity

• Time it takes to validate the test
• Need appropriate time interval after applicants
  are hired before collecting job performance
  measures
• If the organization only hires a few applicants
  per month, it may take months or even a year to
  obtain a large enough sample to conduct a
  predictive validity study (N50-100)

38
SO19 Two practical (not professional) weaknesses
of predictive validity

• Very, very difficult to get managers to ignore
  the test data (politically very difficult)
• Next to impossible to get an organization to
  randomly hire - some poor employees ARE going to
  be hired
• Also difficult to convince them to hire without
  using the test score (but much easier than
  getting them to randomly hire)

(I dont blame them admissions process for I/O
program)
39
SO20A Best predictive validity design

• Figure 5.5 lists 5 types of predictive validity
  designs
• Follow-up Random selection (pure predictive
  validity)
• Best design
• No problems whatsoever from a measurement
  perspective completely uncontaminated from a
  professional perspective
• Follow-up Use present system to select
• OK and more practical, but
• It will underestimate validity if your current
  selection system is valid and the more valid it
  is the more it will underestimate the validity of
  your test
• Why?

(answer not on slide)
40
SO20C Predictive validity, selection by scores

• Select by test score Do NOT do this!!!
• Professional reason
• If your selection procedure is job related, it
  will greatly underestimate your validity - and,
  the more job related the selection procedure is,
  the greater it will underestimate validity.
• In fact, you are likely to conclude that your
  test is not valid when in fact it is
• Why? You are severely restricting the range on
  both your test and your job performance measures!

(professional and legal reasons not to do this)
41
SO20C Predictive validity, selection by scores

• Legal reason
• If adverse impact occurs you open yourself up to
  an unfair discrimination law suit
• You have adverse impact, but you do not know
  whether the test is job related

42
SO20 NFE, Further explanation of types of
predictive validity studies

• Hire, then test and later correlate test scores
  and job performance measures
• If you randomly hire, this is no different than
  pure predictive validity 1 previously,
  Follow-up Random selection
• If you hire based on current selection system,
  this is no different than 2 previously,
  Follow-up Select based on current system

(one more slide on this)
43
SO20 NFE, Further explanation of types of
predictive validity studies

• Personnel file research - applicants are hired
  and their personnel records contain test scores
  or other information that could be used as a
  predictor. At a later date, job performance
  scores are obtained.
• This is no different than Follow-up Select based
  on current system

44
For exam Rank order of criterion-related
validity studies in terms of professional
measurement standards

• 1. Predictive validity (pure) - randomly hire
• 2.5 Predictive validity - current selection
  system
• 2.5 Concurrent validity
• 4. Predictive validity - test scores to hire

45
Which is better Predictive vs. concurrent,
research results (NFE)

• Data that exist suggest that
• Concurrent validity is just as good as predictive
  validity for ability tests (most data)
• May not be true for other types of tests such as
  personality and integrity tests
• Studies have shown differences between the two
  for these type of tests - so proceed with caution!

46
SO21 Sample size needed for a criterion-related
validity study (review)

• Large samples are necessary
• The text indicates that frequently over several
  hundred employees are often necessary
• Dickinson maintains that a sample of 50-100 is
  usually adequate - learn Dickinsons number
• What do companies do if they do not have that
  many employees?
• They use content validity
• They could possibly also use validity
  generalization or job component validation, but I
  want to hold off on that for a moment these are
  legally risky

47
SO23 NFE, Construct validity

• Every selection textbook covers construct
  validity
• I am not covering it for reasons indicated in the
  SOs, but will talk about it at the end of class
  if I have time
• Basic reason for not covering it is that while
  construct validity is highly relevant for test
  construction, very, very few organizations use
  this approach - its too time consuming and
  expensive
• First, the organization develops a test and
  determines whether it is really measuring what it
  is supposed to be measuring
• Then, they determine whether the test is job
  related

48
SO27 Validity generalization, what it is

• Validity generalization is considered to be a
  form of criterion-related validity, but you dont
  have to conduct the validity study in your
  organization for your employees
• Rather you take validity data from other
  organizations for the same or very similar
  positions and use those data to justify the use
  of the selection test(s)
• Common jobs computer programmers and systems
  analysts, set-up mechanics, clerk typists, sales
  representative, etc.

(I am skipping to SO27 for the moment, SOs24-26
relate to statistical concepts about correlation
organization of this chapter Is just awkward. I
want to present all of the validity procedures
together, and then compare them with respect to
when you should/can use one or the other. Then,
Ill return to SOs 24-26 cont on next slide)
49
SO27 Validity generalization, what it is

• Assumption is that those data will generalize to
  your position and organization
• Thus, you can use this approach if you have a
  very small number of employees and/or applicants
• Note this point well

50
SO28 Validity generalization, cont.

• Testing experts completely accept the legitimacy
  of validity generalization
• Primarily based on the stellar work of Schmidt
  and Hunter (who was a professor at MSU until he
  retired)
• Gatewood, Field, Barrick believe this has a
  bright future
• Frank Landy (also a legend in traditional I/O) is
  much more pessimistic about it
• Wording of the CRA of 1991 may have made this
  illegal
• There has not been a test case
• No one wants to be the test case (you should not
  be the test case)

(this slide, NFE, cont. on nxt slide)
51
SO28 Validity generalization, cont.

• Actually have come full circle with respect to
  validity generalization and its acceptance by
  testing specialists
• In the early days of testing, validity
  generalization was accepted
• If a test was valid for a particular job in one
  organization it would be valid for the same or a
  similar position in another organization
• It then fell into disfavor, with testing
  specialists reversing their position, and
  adhering to situational specificity
• Now, based on Schmidt and Hunters work, it is
  again embraced by testing specialists

(this slide, also NFE)
52
SO29 FE Two reasons why CRA 1991 may make
validity generalization illegal

• Both reasons relate to the wording in the CRA
  that the only acceptable criterion measure (job
  performance measure) is actual job performance
• Criterion-related validity studies have often
  included the use of personnel data such as
  absenteeism, turnover, accident rates, training
  data, etc. as the criterion or in multiple
  regression/correlation studies as one or more of
  the criteria this may not be considered job
  performance under CRA 1991
• If courts interpret actual in actual job
  performance literally, then the courts could
  maintain that only the performance of the workers
  who participate in the study would be an
  acceptable criterion measure
• Could ban the use of data from other
  organizations and require local validity studies
  (local meaning in your own organization)

53
SO30 Correction!!

• The material in this study objective relates to
  synthetic validity (pages 199-201) in the section
  Validation Options for Small Businesses not job
  component validity
• I am going to talk about job component validity
  in the next unit because it is tied to a
  particular type of job analysis procedure the
  Position Analysis Questionnaire

54
SO30NFE Synthetic validity (briefly)

• This is a way to conduct a criterion-related
  validity study with small samples as long as you
  have related jobs in the organization
• Jobs that require some of the same KSAs
• I believe it has become obsolete since the
  Supreme Court ruled in 1995 that content validity
  is an acceptable defense for adverse impact
• Criterion-related studies are simply more costly
  than content validity
• Selection experts, however, will always prefer
  criterion-related studies

55
SO31 Interesting fact (and for the exam)

• In a 1993 random survey of 1,000 organizations
  listed in Duns Business Rankings with 200 or
  more employees, the percentage of firms
  indicating that they had conducted validation
  studies of their selection measures was

24
In todays legal environment, the other
organizations could find themselves in a whole
world of hurt!
(click, click!)
56
Factors that affect the type of validity study
When to use which validity strategy

• Four main factors that influence the type of
  validity study you can do
• Sample size
• Cut-off score procedures
• Type of attribute measured observable or not
• Type of test write or off-the-shelf

(on the exam, I am likely to give you situations
and ask you, given the situation, what type of
validity strategy could you use and why That is,
what options do you have? Thats exactly the type
of decision you are going to have to make in
organizations. So, to make it easier, and
summarize things Include validity generalization
in your answers
57
Factors that affect the type of validity study
When to use which validity strategy

• Sample size
• Large employees Concurrent
• (all forms, OK) Predictive
• Content
• Validity generalization
• Small employees Content
• Validity generalization

(its OK to use content and validity gen with
large sample sizes many orgs do use content!)
58
Factors that affect the type of validity study
When to use which validity strategy

• Cut-off score procedures
• Minimum (pass/fail) Concurrent
• (all forms, OK) Predictive
• Content
• Validity generalization
• Ranking or banding Concurrent
• (only criterion-related- Predictive
• all but content) Validity generalization

(validity generalization is based on correlation,
even if you dont do the study yourself, so
remember it is considered a type Of
criterion-related study)
59
Factors that affect the type of validity study
When to use which validity strategy

• Attribute being measured
• Observable Concurrent
• (all forms, OK) Predictive
• Content
• Validity generalization
• Not observable Concurrent
• (only criterion-related- Predictive
• all but content) Validity generalization

(personality, extraversion, social sensitivity,
flexibility, integrity, etc.)
60
Factors that affect the type of validity study
When to use which validity strategy

• Type of test
• Write/construct Concurrent
• (all forms, OK) Predictive
• Content
• Validity generalization
• Off-the-shelf Concurrent
• (only criterion-related- Predictive
• all but content) Validity generalization

(next slide, back to SO 24 interpretation of
validity correlation)
61
SO24 Statistical interpretation of a validity
coefficient

• Recall, r correlation coefficient
• r2 coefficient of determination
• Coefficient of determination
• The percentage of variance on the criterion that
  can be explained by the variance associated with
  the test
• r .50, to statistically interpret it
• r2 .25
• 25 of the variance on job performance can be
  explained by the variance on the test
• Less technical, but OK
• 25 of the differences between individuals on
  the job performance measure can be accounted for
  by differences in their test scores

62
SO25 Validity vs. reliability correlations

• You interpret a validity correlation coefficient
  very differently than a reliability correlation
  coefficient
• You square a validity correlation coefficient
• You do NOT square a reliability correlation
  coefficient
• Why?
• With a reliability correlation coefficient you
  are basically correlating a measure with itself
• Test-retest reliability
• Parallel or alternate form reliability
• Internal consistency reliability (split half)

(I am not going to go into the math on that to
prove that to you)
63
SO25B Validity vs. reliability correlations,
examples for test

• You correlate the test scores from a mechanical
  ability test with a measure of job performance
• The resulting correlation coefficient is .40
• How would you statistically interpret that?

16 of the differences in the job performance of
individuals can be accounted for by the
differences in their test scores
64
SO25B Validity vs. reliability correlations,
examples for test

• You administer a computer programming test to a
  group of individuals, wait 3 months and
  administer the same test to the same group of
  individuals.
• The resulting correlation coefficient is .90
• How do you statistically interpret that
  correlation coefficient?

90 of the differences in the test scores
between individuals are due to true differences
in computer programming and 10 of the
differences are due to error
65
Different types of correlation coefficients or
why it is a good idea to take Huitemas
correlation and regression

• The most common type of correlation to use is the
  Pearson product moment correlation
• However, you can only use this type of
  correlation if
• You have two continuous variables, e.g., a range
  of scores on both x and y
• If the relationship between the two variables is
  linear
• Some have shown a curvilinear relationship
  between intelligence test scores and performance
  of sales representatives

(NFE, I think)
66
Different types of correlation coefficients or
why it is a good idea to take Huitemas
correlation and regression

• Point biserial coefficient is used when one
  variable is continuous and the other is
  dichotomous
• High school diploma vs. no high school diploma
  (X)
• Number of minutes it takes a set-up mechanic to
  set up a manufacturing line (Y)
• x is dichotomous, y is continuous
• Phi coefficient is used when both variables are
  dichotomous
• High school diploma or no high school diploma (X)
• Pass or fail performance measure (Y)
• Both x and y are dichotomous

(NFE, I think, one more slide on this)
67
Different types of correlation coefficients or
why it is a good idea to take Huitemas
correlation and regression

• Rho coefficient - Spearmans rank order
  correlation - when you rank order both x and y,
  and then correlate the ranks
• Rank order in test scores
• Rank order number of minutes it takes set-up
  mechanics to set up a manufacturing line
• Use rank order when either your x or y scores are
  not normally distributed - that is, when there
  are a few outliers - either very high scores on
  either or very low scores on either

(NFE, I think,last slide)
68
End of Unit 5

• Questions?
• Comments?

69
NFE Back to construct validity

• Construct validity
• Does the test actually measure the construct
  you think it is measuring?
• This is a hold-over from the more traditional
  cognitive psychology and psychometrics field that
  philosophically believes in mind-body dualism
  (mentalism)
• That is, there really is something called
  general intelligence that is more than just the
  sum of what you ask on an exam and it is
  different than a behavioral repertoire
• One of the reasons I like this text so much is
  that it is clear that the authors are not from
  this old school
• This will become more obvious when you read the
  material related to ability testing

70
NFE Back to construct validity

• But, back to the question you are asking with
  construct validity
• Does the test actually measure the construct
  you think it is measuring?

• Is your measure of extroversion really
  measuring
• extroversion?
• Is your measure of creativity really measuring
• creativity?
• Is your measure of ability to work with others
  (agreeableness) really measuring the ability to
  work with others?

71
NFE Construct validity, cont.

• You construct a test
• You correlate your test with other tests that
  supposedly measure the same thing (or a very
  similar construct) and other measures that might
  get at that construct
• Correlations are not going to be perfect because
  your measure is not measuring exactly the same
  thing as those other measures, but should be
  reasonably correlated with those measures
• Continue to do that until you have pretty good
  evidence that your test is indeed measuring what
  it is supposed to be measuring

72
NFE Construct validity, cont.

• But notice, for validation purposes, you are NOT
  done yet
• You have evidence that the test is supposedly
  measuring what you say it is, but
• You still need to conduct a criterion-related
  validity study to determine whether the test is
  related to the job
• Thus, you end up doing a lot of time-consuming
  work
• The ONLY reason you would do this was if you
  could not locate a test that measured what you
  want and had to create your own (not likely, by
  the way)