Clara A. Williams 

Raymond E. King

Civil Aerospace Medical Institute

Federal Aviation Administration

Oklahoma City, OK 73125

February 2010

Final Report

The Effects of Testing Circumstance

and Education Level on MMPI-2

Correction Scale Scores

DOT/FAA/AM-10/3

Office of Aerospace Medicine

Washington, DC 20591

OK-10-0077-JAH

Federal Aviation

Administration
NOTICE

This document is disseminated under the sponsorship 

of the U.S. Department of Transportation in the interest 

of information exchange. The United States Government 

assumes no liability for the contents thereof.

___________

This publication and all Office of Aerospace Medicine 

technical reports are available in full-text from the Civil 

Aerospace Medical Institute’s publications Web site: 

www.faa.gov/library/reports/medical/oamtechreports
i

Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. 

DOT/FAA/AM-10/3 

4. Title and Subtitle 5. Report Date 

The Effects of Testing Circumstance and Education Level on MMPI-2 February 2010 

Correction Scale Scores 6. Performing Organization Code 

 

7. Author(s) 8. Performing Organization Report No. 

Williams CA, King RE 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

FAA Civil Aerospace Medical Institute 

P.O. Box 25082 11. Contract or Grant No. 

Oklahoma City, OK 73125 

12. Sponsoring Agency name and Address 13. Type of Report and Period Covered 

Office of Aerospace Medicine 

Federal Aviation Administration 

800 Independence Ave., S.W. 

Washington, DC 20591 14. Sponsoring Agency Code 

15. Supplemental Notes 

Work was accomplished under approved task AM-523. 

16. Abstract 

The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) is used by the Federal Aviation Administration 

to assess psychopathology in air traffic control specialist applicants after a conditional offer of employment is 

extended. Two groups are compared in this study on their level of Scale K, which is used as a measure of 

defensiveness (putting one’s best foot forward – “faking good”), but which may be influenced by socioeconomic 

status and education. Group 1 had already been hired and took the MMPI-2 as part of a voluntary research 

protocol while in training. Group 2 took the MMPI-2 as part of their medical screening process for hiring. There 

was a significant difference between the two groups (2 indicated a higher level of K than 1) on the level of K, 

suggesting that K is likely measuring defensiveness. Group 1 faced no consequences for their results, while Group 

2 faced potential additional psychological assessment as a consequence of their MMPI-2 performance, and 

possibly even ultimate medical disqualification. While the hypothesis that groups would differ on K as a function 

of testing circumstances was supported, the hypothesis that K would rise as a function of education was not. 

 

17. Key Words 18. Distribution Statement 

 

 

Personnel Screening, Personnel Selection, Psychological 

Testing 

Document is available to the public through the 

Defense Technical Information Center, Ft. Belvoir, VA 

22060; and the National Technical Information 

Service, Springfield, VA 22161 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

Unclassified Unclassified 14 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

iii

Contents

Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

	 Testing Circumstance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

	 Education Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Appendix A: FAA Notice JO 3330.67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

1

The Effects of Testing Circumstance and Education Level

on MMPI-2 Correction Scale Scores

The Minnesota Multiphasic Personality Inventory-2

(MMPI-2)isusedby theFederalAviationAdministration

(FAA) as a screening method to detect psychopathology

in air traffic control specialist (ATCS) applicants (FAA

Notice JO 3330.67, see Appendix A). The MMPI-2 is

administered after a conditional offer of employment is

extended, in accordance with the Americans with Disabilities Act of 1990 (1991). Such a method is termed

“select out” and is part of theentry medicalexamination,

as described by King, Schroeder, Manning, Retzlaff, and

Williams (2008). Applicants are disqualified on the basis

of the presence of a personality disorder or other psychiatric conditions, including substance abuse, which poses

a “potential hazard to safety in the Air Traffic Control

System” (page 4, Appendix 1, FAA Order 3930.3A). The

MMPI-2 is only used as a screeningtool. Identified applicants are then assessed by a more comprehensive battery

of psychological tests, as well as a diagnostic interview

conducted by an independent-practice, licensed clinical

psychologist, paid by the FAA.

MMPI-2 profiles are interpreted by examining the

various clinical scales after a consideration of the validity indicators. One such validity indicator, the K scale,

is a measure of “faking good.”The K scale was originally

developed by Meehl and Hathaway (1946). Through

a series of analyses, Meehl and Hathaway determined

optimal “K corrections” to be made to selected clinical

scales in order to make the final scores more accurately

reflecttheknownpsychopathologyofthe criteriongroup. 

In other words, K was developed as a way to ensure that

those individuals with psychopathology would have appropriately elevated clinical scales. Greene summarizes

Meehl and Hathaway’s work as a way to accurately “differentiate persons known to have psychopathology who

were hospitalized and yet obtained normal profiles from

normalindividualswhoforsomereasonobtainedelevated

profiles” (Greene, 2000, p. 11). 

Consideration of the K scale score can help to determine the extent to which an individual’s responses to

items are attempting to mask problems and difficulties. 

Certain clinical scales of the MMPI-2 can be adjusted or

correctedby addingthepredeterminedfractions(Butcher,

Graham, Ben-Porath,Dahlstrom, & Kaemmer, 2001) of

an individual’s K scale. The clinical scales and the fractionalraw-score additive values ofKareshown inTable 1.

Table 1. Descriptions of the five clinical scales that are K corrected and fractional values of K. 

Clinical Scalesa K valuesb

Scale 1 – Hypochondriasis. High scores reflect individuals who have an excessive 

number of vague nonspecific complaints and body concerns (G/I, fatigue, pain, and 

general weakness). 

.5 

Scale 4 – Psychopathic Deviate. High scores reflect difficulty in incorporating the values 

and standards of society, may exhibit asocial or antisocial behaviors, impulsiveness, and 

need for immediate gratification. May be a bit elevated in younger test takers as a normal 

function of late adolescence. 

.4 

Scale 7 – Psychasthenia. High scores reflect individuals experiencing a great deal of 

psychological turmoil and discomfort. They tend to be anxious, tense, and agitated. They 

are worrisome individuals with difficulty concentrating. 

1.0 

Scale 8 – Schizophrenia. High scores are reflective of bizarre mentation, delusions, and 

possibly hallucinations. Confused thinking, poor judgment, and alienation are common. 

1.0 

Scale 9 – Hypomania. High scores are suggestive of over-activity, poor impulse control, 

irritability, and possible aggressive outbursts. 

.2 

a

 Graham, 1990 

b

 Butcher, Graham, Ben-Porath, Dahlstrom, and Kaemmer, 2001 
2 

To gain an understanding of how a test-taker’s true

psychological functioning isestimated by correcting the

clinical scales, refer to Figure 1. As described above, a

fraction of the K score (see left margin for “Fractions of

K”) is added to the clinical scales (see bottom of pagefor

procedure to add fractions of K to the clinical scales) to

arrive at the K-corrected raw score, which is then plotted

to obtain theT score (normed to have a mean of 50 and

standard deviation of 10). 

Forexample,someonewith a rawK score of 25would

have 13 (.5K) points added to Scale 1, 10 (.4K) points

added to Scale 4, 25 (1K) points added to scales 7 and

8, and 5 (.2K) points added to Scale 9. The “Raw Score

with K” (bottom line) is then plotted to arrive at the Kcorrected T score for the clinical scale. The K scale is so

routinely used that it is included in the first 370 items

known as the “abbreviated version” of the MMPI-2. 

Administration of this shorter version permits scoring

of all clinical scales and allows K correction of scales 1,

4, 7, 8, and 9.

Graham(2006)reportsthatsomepractitioners caution

that onemust beespecially careful in using K corrections

in circumstances where defensiveness is common (e.g.,

employmentscreening), claiming that artificiallyinflated

profiles can result. Practitioners may, therefore, need to

avoid using K corrections in non-clinical evaluations. 

Butcher (1990) reports that other practitioners argue

that correcting MMPI-2 profiles gives a more accurate

measure of an individual’s defensiveness. While assessors

are interested in the level of an applicant’s defensiveness

to gain a truer functionalestimate, it is important to not

unnecessarily inflate clinicalscalesinnon-clinicalsettings. 

It is, therefore, important to understand thesource of the

K. If applicants are rendering profiles that are unduly

defensive, then it would be prudent to use modified

instructions to explain the role of the validity scales to

help the applicants answer in a more straight-forward

fashion (Butcher, Morfitt, Rouse, & Holden, 1997). 

According to Graham (1990), it is not unusual for

college-educated individuals who are not being defensive (masking problems) to obtain K-scale T scores in a

range of 55 to 60. Individuals with even more formal

education may obtain T scores in the range of 60 to 70

(Graham, 1990). According to Graham, the level of

K can be influenced by factors such as socioeconomic

status, as well as education, and is not strictly a measure

of defensiveness. 

The present study will gauge the influence of testing

circumstance(i.e.,researchparticipationvs. employment

screening) on K scores. Our hypothesis is that those who

arebeing screenedforemploymentwillbemoredefensive

and, thus, earn higher K scores than those who are only

participating in a research study with no job jeopardy. 

Theinfluence ofeducation on the value of K will also be

examined. We predict that the value of K will increasein

this sample as years of education increase, as predicted

by Graham (1990). 

Method

Testing Circumstance

Group 1 consisted of 1,014 FAA ATCS students in

training at the FAA Academy in Oklahoma City, OK,

who voluntarily completed the MMPI-2 as part of a

research project. Therewere 794 (78.3%)males and 220

(21.7%)femalesinGroup1. Theywere administeredthe

standard567-itempaper-and-penciltest. This grouphad

notpreviouslybeenadministeredtheMMPI-2;theywere

medically screened using the FAA-modified 16PF with

nonstandardscoringmethod,whicheliminatedvirtually

no candidates (King, Retzlaff, Detwiler, Schroeder, &

Broach, 2003; King, Schroeder, Manning, Retzlaff, &

Williams, 2008).

Group 2 consisted of 2,374 tentatively hired ATCS

candidates who completed the MMPI-2 as part of their

medical screening process. This group of 1,914 (80.6%)

males and 460 (19.4%) femalesreceived the abbreviated

computerized administration of the MMPI-2 via the

FAA Intranet. All the K-scale items were present in the

abbreviated test administration. All clinical and K-scale

items were presented in the same order for each version

of the test.

Education Level

Having a high school diploma is a pre-requisite to be

hired as an ATCS. Many applicants attended College

Training Initiative (CTI) programs, which are hosted

by two-year (community) and four-year colleges. For

Group 1, years of education were not reported consistently due to a misunderstanding of the demographics

portion of the MMPI-2 by the participants. Therefore,

the analysis on level of education was not conducted on

Group 1. Most members of Group 2 more accurately

reported their level of education due to an explicit chart

the authors developed. This chart demonstrated how to

converteducationattainmentinto anumber(highschool

diploma equals 12 years ofeducation, one year of college

equals 13 years of education, etc.) and was included in

the instructions introducing the MMPI-2.

Sixteen of 2,374 total caseswereexcluded fromGroup

2 because they had failed to identify their level of education. Non-gender norms were used because the purpose

of this research is to support personnel selection. The

Civil Rights Act of 1991 states that it is an unlawful

employment practice to use gender-specific norms in

personnel selection.
3

Figure 1. MMPI-2 Profile. Used by permission of the University of Minnesota Press. All rights reserved. “MMPI-2” and “Minnesota Multiphasic 

Personality Inventory-2” are trademarks owned by the Regents of the University of Minnesota.
4 

Results

The overall mean (with standard deviations in parentheses) of the K scale for Group 1 was 57.15 (9.295);

for Group 2 it was 62.10 (7.526). This difference was

significant, t (1,609.77) = -14.97, p = .0001. There was

approximately half of a standard deviation (-4.95) difference between the groups. According to Cohen (1988),

this is a small-to-medium effect size.

Table 2 shows that 2,358 candidates in Group 2 indicated their level of education. There were 1,904 males

and 454 females. Two thousand forty-one candidates

indicated that they had more than 12 years of education

(indicating some college). Theremaining 333 candidates

indicated 12 years of education. 

The group’s K scaleT-scores ranged from 32 to 81. An

analysis using Pearson’s correlation coefficient (2-tailed)

indicated no significantlinearrelationship between theK

scalescores and years ofeducation (r=.04, p=.06). Figure

2 shows a plot of the relationship between K scale scores

and years of education for the group.

Discussion

ThisresearchsuggeststhatKdidnotincrease aslevel of

educationincreased, atleastwhenmeasuredforATCSjob

applicants. Thelevel ofeducation in this group, however,

was relatively range-restricted, as every participant had

at least 12 years of education, and most had either 14 or

16 years of education as a function of their hiring source

(the CollegeTraining Initiative). While it is unfortunate

that this research effort could not gauge the effect of

education in the voluntary research participants due to

their misunderstanding of how to convert grade level to

number of years of education, in all likelihood, the level

of education was roughly equivalent between Groups 1

and 2, as they were recruited from similar sources.

This research was also not ableto measurethe participants’socioeconomic status. Inonesense,theyweremore

alike than different as they were young job applicants

who presumably were not particularly financially secure. 

Nevertheless, the applicants likely camefrom a variety of

backgrounds, fromrelatively financially insecureto quite

well-off. Perhaps these unmeasured differences exerted

Table 2. Descriptive statistics for K by Years of Education for Group 2. 

Years of Education Number K - Mean K - Std. Deviation 

12 333 61.5 7.5 

13 279 61.5 7.4 

14 453 62.6 7.4 

15 251 61.9 7.8 

16 894 62.2 7.5 

17 80 62.8 8.5 

18 68 63.3 7.3 

Figure 2. Relationship between K scale scores and years of education for Group 2.
5

an influence on Scale K. Future research should measure

socioeconomic status (SES) as directly as possible (considering background SES, as well as current SES) and

compare it to level of K. 

The hypothesis that there is a significant difference

between the two groups in terms of their scale K scores

was supported. Job applicants were likely much more

motivated to present themselves favorably, due to the

effects of the score on their chance of being hired. “Passing” the MMPI-2 meant that there would be one fewer

obstacle to secure employment in a lucrative profession. 

Under these conditions, it is understandable that a scale

that measures “faking good” would be elevated. Thus,

Group2likelyhadelevatedlevelsofKduetodefensiveness. 

Modifying the instructions that introduce the MMPI-2

might help reduce the level of K by reducing defensiveness (Butcher, Morfitt, Rouse, & Holden, 1997), either

on initial presentation or on re-tests during second-tier

assessment.

This research suggests that elevations of K in ATCS

applicants are more likely due to defensiveness, rather

than years ofeducation. Theimplications of thisresearch

include some support for using the K scale to correct the

clinical scales with ATCS applicants. Continuing to use

K to correct the clinical scales would be in keeping with

the intent to correct for defensiveness when a test taker

is asked to report his or her psychiatric symptoms and

other potentially embarrassing information. Defensivenessresultsin under-reporting ofsymptoms;therefore,K

correctionserves ausefulfunctionbybringing the clinical

scalestothelevelthattheywouldbe atifthetesttakerwere

not being defensive. Futureresearch should investigateif

the K fractional values that have been traditionally used

(and reported in Table 1 and Figure 1 here) are optimal

when the MMPI-2 is being used as part of a selection

procedure, rather than in a clinical setting. 

It istruethat a job applicant’s defensivenessmay result

in profiles that suggest more psychopathology, whereless

actually exists due to the K correction. That is why no

applicant is ever eliminated on the basis of the results of

the MMPI-2 alone. All applicants identified with the

MMPI-2 are afforded, at the FAA’s expense, a more extensive assessment that may include a re-administration

of the MMPI-2 (with explicit instructions on how to

respondina lessdefensivefashion), aswell as othertesting

and a clinical interview. It is important to keep in mind

that K correcting has long been an accepted practice; the

point of this study was for practitioners to better understand the sources and utility of K when dealing with an

employment applicant population.

References

Americans with Disabilities Act of 1990, Pubic Law

No.101-336, §2, 104 Stat. 328 (1991). (www.

ada.gov)

Butcher,J.N. (1990). The MMPI-2 in psychological treatment. NY: Oxford.

Butcher,J.N.,Graham,J.R.,Ben-Porath,Y.S.,Dahlstrom,

W.G.,&Kaemmer,B. (2001). MMPI-2 (Minnesota

Multiphasic Personality Inventory-2) manual for

administration, scoring, and interpretation, revised

edition. Minneapolis, MN: NCS Pearson.

Butcher, J.N., Morfitt, R.C., Rouse, S.V., & Holden,

R.R. (1997). Reducing MMPI-2 Defensiveness:

Theeffect ofspecialized instructions on retest validity in a job applicant sample. Journal of Personality

Assessment, 68, 385-401.

CivilRightsAct of 1991, Public LawNo 102-166 (1991). 

(www.eeoc.gov/policy/cra91.html)

Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd Ed.). Hillsdale, NJ: Erlbaum.

Federal Aviation Administration (1980, May 9). FAA

Order 3930.3A - Air traffic control specialist health

program. Washington, DC: U.S. Government

Printing Office.

Federal Aviation Administration (2008, February 28). 

FAANoticeJO3330.67 -Guidancefor administering

psychological screening evaluations of tentatively selected airtrafficcontrol specialistcandidates. (https://

employees.faa.gov/tools_resources/orders_notices/

index.cfm?fuseaction+c.dspDocumentInformation

&documentID=73513)

Graham, J.R. (1990). MMPI-2: Assessing personality

and psychopathology, 2nd edition. New Haven, NY:

Oxford.

Graham, J.R. (2006). MMPI-2: Assessing personality

and psychopathology, 4th edition. New Haven, NY:

Oxford.

Greene, R.L. (2000). The MMPI-2: An interpretive

manual, 2nd Edition. Needham Heights, MA: Allyn & Bacon.

King,R.E.,Retzlaff,P.D.,Detwiler,C.A., Schroeder,D.J.,

& Broach, D. (2003). Use of personality assessment

measures in the selection of air traffic control specialists. (DOT/FAA/AAM-03/20). Washington, DC:

FAA Office of Aerospace Medicine.
6 

King, R.E., Schroeder, D.J., Manning, C.A., Retzlaff,

P.D., & Williams, C.A. (2008). Screening air traffic

control specialists for psychopathology using the Minnesota Multiphasic Personality Inventory-2. (DOT/

FAA/AM-08/13). Washington, DC: FAA Office

of Aerospace Medicine.

Meehl, P.E., & Hathaway, S.R. (1946). The K factor as a

suppressor variablein theMMPI. Journal ofApplied

Psychology, 30, 525-564.
A-1

Appendix A

FAA Notice JO 3330.67 - Guidance for Administering Psychological Screening Evaluations of

Tentatively Selected Air Traffic Control Specialist Candidates

A-3
A-4 
A-5