Goldbergs IPIP Big-Five factor markers: Internal

ndings using other inventories. One sample (N = 207) also completed two further personality measures

(the NEO-FFI and the EPQ-R Short Form). Conscientiousness, Extraversion and Emotional Stability/

* Corresponding author. Tel.: +44 131 651 1685.

E-mail address: alan.gow@ed.ac.uk (A.J. Gow).

www.elsevier.com/locate/paid

Personality and Individual Dierences 39 (2005) 3173290191-8869/$ - see front matter 2005 Elsevier Ltd. All rights reserved.Neuroticism scales of the IPIP were highly correlated with those of the NEO-FFI (r = 0.69 to 0.83,p < 0.01). Agreeableness and Intellect/Openness scales correlated less strongly (r = 0.49 and 0.59 respec-

tively, p < 0.01). Correlations between IPIP and EPQ-R Extraversion and Emotional Stability/Neuroticism

were high, at 0.85 and 0.84 respectively. The IPIP scales have good internal consistency and relatestrongly to major dimensions of personality assessed by two leading questionnaires.

2005 Elsevier Ltd. All rights reserved.

Keywords: Personality; IPIP Big-Five factor markers; Validationconsistency and concurrent validation in Scotland

Alan J. Gow *, Martha C. Whiteman, Alison Pattie, Ian J. Deary

Department of Psychology, School of Philosophy, Psychology and Language Sciences,

University of Edinburgh, 7 George Square, Edinburgh EH8 9JZ, Scotland, UK

Received 12 May 2004; received in revised form 16 July 2004; accepted 17 January 2005

Available online 2 March 2005

Abstract

Goldbergs (2001) IPIP Big-Five personality factor markers currently lack validating evidence. Thestructure of the 50-item IPIP was examined in three dierent adult samples (total N = 906), in each case

justifying a 5-factor solution, with only minor discrepancies. Age dierences were comparable to previousdoi:10.1016/j.paid.2005.01.011

settings. Individual dierences in human personality are often described as being quite compre-hensively described by 5 higher-order factors (Matthews, Deary, & Whiteman, 2003), although

site; the items are known collectively as the International Personality Item Pool (IPIP: Gold-berg, 2001).

The IPIP contains alternate versions of widely used inventories. For example, an IPIP version

of the NEO PI-R (Costa & McCrae, 1992) is available. The IPIP-NEO is available as a 50, 100, orfull 240-item questionnaire. The associations between the proprietary and IPIP versions have beenrecorded and are generally encouraging: in the short form of the IPIP-NEO, correlations rangefrom 0.70 to 0.82 (0.85 to 0.92 when corrected for unreliability) with the corresponding NEOPI-R factors (Goldberg, 2001). However, it has been suggested that even such high correlationsdo not imply that the dierent versions are truly equivalent (Costa & McCrae, 1999).

3. The IPIP Big-Five factor markers

The IPIP contains not only versions of proprietary scales, but also a number of items knownan increasing body of evidence suggests that additional factors are required to account for impor-tant individual variation beyond that assessed within more traditional 5-factor frameworks (Pau-nonen & Jackson, 2000); a recent review of 8 psycholexical studies found support for a 6-factormodel across seven languages (Ashton et al., 2004). For the purposes of the current study, how-ever, a 5-factor model is employed due to the general consensus that exists about what those fac-tors are; models with a higher number of factors are not entirely in agreement about what a 6th,7th or nth factor would be.

2. Recent debate and Goldbergs proposal

Goldberg (1999) has argued that scientic progress within the development of personalityinventories has been dismally slow (p. 7). He attributes this to the fact that most of thebroad-bandwidth personality inventories developed are proprietary instruments (such as theNEO PI-R/FFI: Costa & McCrae, 1992), possibly leading to a lack of improvement as research-ers require permission from the copyright holders and are charged for each questionnaire used.However, Costa and McCrae (1999) maintain that proprietary instruments are regularly revised(several changes were recently suggested to the short form of the NEO in response to a numberof criticisms of the scale (McCrae & Costa, 2004)). However, what may be hampering progressfurther is a dearth of comparative validity studies, where two or more inventories are evaluatedon their ability to predict a criterion variable (Goldberg, 1999). Goldberg therefore proposed aninternational collaboration to develop an easily available, broad-bandwidth personalityinventory. All researchers could freely use the items in the pool, and disseminate theirndings to improve these. Items were developed and subsequently presented on an internet web-1. Introduction

Personality assessment is important in a variety of situations, from academic research to clinical

318 A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329collectively as the Big-Five factor markers (Goldberg, 2001). The starting point for the creation

sistency renement (Saucier & Goldberg, 2002). The IPIP Big-Five factor markers are the result,with each factor measured by 10 or 20 items and mean internal consistencies of 0.84 and 0.90 for

4. The current studyGoldbergs IPIP Big-Five factor markers are examined in two stages. The 1st investigates thefactorial structure of the IPIP items and the internal consistency of the IPIP scales in three sam-ples of dierent ages. In addition, age dierences in IPIP scales are examined. The 2nd stagecorrelates IPIP scales with the NEO-FFI and the EPQ-R Short Form scales in a sample ofmiddle-aged individuals, in order to assess the IPIPs concurrent validity.

5. Method

5.1. Questionnaires

5.1.1. IPIP Big-Five factor markers (Goldberg, 2001)

The IPIP Big-Five factor markers consist of a 50 or 100-item inventory that can be freely down-loaded from the internet for use in research (Goldberg, 2001). The current study makes use of the50-item version consisting of 10 items for each of the Big-Five personality factors: Extraversion(E), Agreeableness (A), Conscientiousness (C), Emotional Stability (ES) and Intellect (I). For eachof the items, which are in sentence fragment form (e.g., Am the life of the party), I was addedat the beginning so that the items would be easier to read, and more closely match the other inven-tories used. Participants were requested to read each of the 50 items and then rate how well theythe 50 and 100-item versions respectively. The items have been correlated with the adjectivemarkers, and average 0.67 and 0.70 for the short and long versions respectively (Goldberg,2001). Whilst there is some published work on the adjective markers, and the IPIP versionsof proprietary instruments, there seems to be little published research relating to the Big-Fivefactor markers, other than the information provided in Saucier and Goldberg (2002), and onthe IPIP website.of these items was Goldbergs (1992) 100 unipolar Big-Five factor markers (derived from earlylexical studies in English). These trait-descriptive adjectives had been used in a number of studies(Goldberg, 1992) and suggested 5 broad factors (very similar to those recovered from question-naire studies), namely Extraversion (or Surgency), Agreeableness, Conscientiousness, EmotionalStability (often regarded as the opposite pole of Neuroticism) and Intellect (or Imagination). Theadjective markers were related to the NEO-PI (an earlier version of the NEO PI-R), and corre-lations between corresponding scales ranged from around 0.46 to 0.69 (Goldberg, 1992). How-ever, Goldberg (1999) proposed that these adjectives might be improved upon to createquestionnaire items that would provide more contextual information than single words, but stillbe more succinct than items in many other inventories. A battery of IPIP items was thereforeadministered to a large adult sample, and those which had the highest correlations to the orthog-onal factor scores dened by the 100 adjective markers were chosen, with further internal con-

A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329 319believed it described them on a 5-point scale (very inaccurate to very accurate).

5.1.2. NEO Five Factor Inventory (NEO-FFI: Costa & McCrae, 1992)

This 60-item inventory consists of 12 items each for the 5 factors: Neuroticism (N), Extraver-sion (E), Openness (O), Agreeableness (A) and Conscientiousness (C). Participants were asked tomark each item on a 5-point scale (strongly disagree to strongly agree) according to how well itdescribed them.

5.1.3. Eysenck Personality Questionnaire-Revised Short Form (EPQ-R Short Form: Eysenck,

Eysenck, & Barrett, 1985)The EPQ-R contains 48 items, 12 each for the personality factors Extraversion (E), Psychoti-

cism (P) and Neuroticism (N), plus a Lie Scale (L). Participants were required to read each item,and circle either yes or no to show which best described them.

5.2. Participants and procedures

Participants were recruited in three groups.Student sample (N = 201). A student sample consisting of 201 participants (90 [44.8%] men and

111 [55.2%] women) was recruited, mostly undergraduates at the University of Edinburgh. Themean age of the sample was 25 years 6 months (sd = 10 years 2 months), ranging from 17 years9 months to 61 years 11 months. The participants were approached in lectures and asked to com-plete the IPIP.General population volunteers (N = 207). Members of the University of Edinburgh Psychology

Volunteer Panel were recruited into the study. These are individuals who responded to advertise-ments to be potential participants in psychology studies. The IPIP, NEO-FFI and EPQ-R ShortForm questionnaires were mailed to the participants. If there was no response after 5 weeks, areminder and a further copy of the questionnaires was mailed. Each returned questionnairewas checked for omissions or multiple answers. Where corrections were required, these were de-tailed in a letter sent to participants. Of 273 members of the Volunteer Panel sent the question-naires, 225 (82%) responded, although of these, 4 refused to complete the questionnaires, 9were no longer at the listed address and 5 had died. Corrections were requested from 54 partic-ipants, and reminders were sent to 83. This led to a nal return of 207 questionnaires (76% ofthe initial mailing), 61 (29.5%) men and 146 (70.5%) women. The mean age was 55 years 2 months(sd = 15 years 4 month), ranging from 18 years 7 months to 83 years 2 months (9 participants didnot record their age). Two questionnaires remained incomplete after corrections were requested: 2items were missing from one IPIP return, and 1 NEO-FFI item was missed by another partici-pant. As detailed in the manual (Costa & McCrae, 1992), the neutral response was imputed forthe missing NEO-FFI item.Lothian Birth Cohort 1921 (N = 498). Members of the Lothian Birth Cohort 1921 (LBC1921)

were assessed. Their recruitment is described extensively elsewhere (Deary, Whiteman, Starr,Whalley, & Fox, 2004). The LBC1921 are surviving participants of the Scottish Mental Surveyof 1932 and were mailed as part of an ongoing follow-up. All were aged around 81 at the timeof mailing. The procedure was the same as that described for the general population volunteersin the previous paragraph. The IPIP questionnaire was sent to 534 members of the LBC1921(from a list of 569, 32 had died and 3 were no longer contactable at the start of the current study;

320 A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329this number is greater than previous LBC1921 reports (e.g., Deary et al., 2004), as it includes indi-

highest with the Emotional Stability items.6.1.3. LBC1921The overall MSA was 0.85, and all individual items MSA were above acceptable levels. The

scree plot suggested the extraction of 6 factors, accounting for 45.2% of the variance. This solu-tion is available from the authors on request. A further PCA was conducted to determine whethera 5-factor structure also described the data eectively. The 5 factors extracted accounted forviduals who were subsequently ineligible or did not participate in the main study). Correctionswere requested from 135 participants, and reminders were sent out to 78. This procedure resultedin 498 returned questionnaires, a response rate of 93%. Of this number, 460 questionnaires werefully completed (86% of the original mailing), with 38 still partially completed even after correc-tions were requested or reminders sent.

6. Results

6.1. Structure of the IPIP items

6.1.1. Student sample

From the PCA, the overall measure of sampling adequacy (MSA) was 0.74, whilst the item val-ues were within acceptable limits (the lowest being. 59). This suggests the PCA could be conductedwithout having to remove any unsuitable items. The scree plot produced suggested the extractionof 6 factors accounting for 46.7% of the variance. This is not reported here (details are availablefrom the authors on request), as the 6-factor solution results mainly from a split of the Intellectfactor into two. In order to examine whether the item loadings were in accordance with the testconstruction and theory, 5 factors accounting for 42.6% of the variance were extracted from thestudent IPIP data (the loadings shown in Table 1) by PCA and subjected to varimax rotation. All10 Extraversion items loaded over 0.3 on the same factor, as did all the Emotional Stability items.Nine of the Agreeableness items loaded on the same factor, whilst one item (I make people feel atease) loaded highest with the Extraversion items. The 10 Conscientiousness items loaded to-gether, with 3 of the items having lower secondary cross-loadings (1 item loaded onto two otherfactors). Nine of the Intellect items had their highest loading on the same factor (with 1 lowercross-loading); I spend time reecting on things loaded highest with the Agreeableness items,with a smaller loading on the Intellect factor.

6.1.2. Volunteer panelThe overall MSA was 0.80, and all individual items MSA were above acceptable levels. The

scree plot suggested the extraction of 5 factors, accounting for 47.9% of the variance. This wasconducted, with varimax rotation, and the item loadings are shown in Table 1. The 10 EmotionalStability items loaded highest on the same factor. All the Intellect items loaded together, as did theExtraversion and Agreeableness items, with 1 Intellect, 1 Extraversion and 2 Agreeableness itemshaving a lower cross-loading of >0.3. Nine of the Conscientiousness items loaded together (1 itemhad lower cross-loadings on 2 other factors), whilst one item (I make a mess of things) loaded

A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329 32141.1% of the variance, with the varimax-rotated item loadings shown in Table 1. The 10

Table 1

Rotated IPIP item loadings in 3 samples

Component

E A C ES I

S V L S V L S V L S V L S V L

E1 .71 .68 .44 .09 .15 .30 .02 .02 .13 .03 .10 .07 .05 .14 .07E2 .66 .66 .68 .08 .15 .11 .04 .02 .08 .02 .02 .06 .09 .03 .08E3 .63 .60 .47 .21 .35 .57 .20 .05 .02 .16 .29 .25 .04 .03 .01E4 .60 .81 .72 .01 .02 .05 .03 .08 .04 .04 .05 .18 .18 .08 .00E5 .70 .64 .51 .18 .23 .43 .06 .08 .10 .01 .02 .19 .09 .13 .17E6 .65 .58 .67 .18 .24 .14 .03 .03 .19 .07 .16 .05 .08 .12 .11E7 .71 .75 .50 .10 .16 .46 .03 .06 .07 .00 .19 .20 .15 .13 .08E8 .54 .70 .50 .07 .12 .20 .18 .03 .20 .11 .01 .17 .06 .06 .16E9 .57 .75 .38 .02 .04 .22 .09 .04 .21 .04 .04 .14 .17 .19 .14E10 .68 .70 .71 .01 .11 .04 .13 .06 .02 .10 .17 .24 .11 .11 .01A1 .06 .22 .32 .51 .56 .14 .04 .03 .28 .00 .00 .03 .12 .20 .14A2 .13 .16 .21 .50 .58 .50 .04 .15 .01 .04 .05 .02 .17 .04 .15A3 .12 .24 .09 .46 .45 .16 .21 .01 .32 .15 .27 .09 .29 .15 .16A4 .10 .03 .15 .69 .80 .53 .16 .02 .14 .06 .04 .14 .10 .10 .06A5 .00 .17 .44 .63 .66 .11 .02 .05 .26 .01 .02 .11 .21 .08 .06A6 .19 .00 .00 .42 .57 .52 .19 .17 .11 .05 .02 .21 .24 .07 .07A7 .22 .31 .48 .68 .63 .22 .07 .18 .21 .05 .09 .00 .06 .03 .05A8 .25 .11 .21 .34 .70 .60 .18 .13 .17 .01 .08 .03 .02 .14 .15

A9 .22 .08 .18 .55 .80 .47 .05 .03 .17 .16 .04 .15 .08 .15 .12A10 .51 .45 .23 .10 .54 .57 .18 .07 .07 .11 .16 .22 .01 .13 .10

C1 .01 .07 .01 .07 .09 .17 .52 .53 .44 .10 .11 .07 .22 .08 .26

C2 .32 .03 .06 .12 .01 .09 .55 .71 .68 .07 .05 .04 .11 .13 .13C3 .17 .20 .04 .33 .03 .30 .38 .50 .41 .10 .03 .05 .34 .16 .31C4 .03 .04 .19 .01 .07 .06 .54 .26 .57 .39 .45 .22 .16 .01 .09C5 .09 .06 .11 .02 .07 .27 .67 .63 .45 .06 .15 .13 .11 .12 .01C6 .01 .01 .09 .01 .02 .17 .67 .68 .66 .01 .10 .13 .01 .14 .12C7 .01 .08 .14 .03 .06 .37 .61 .66 .46 .18 .18 .05 .05 .03 .23C8 .04 .03 .10 .10 .37 .18 .47 .49 .54 .19 .30 .17 .07 .00 .01C9 .11 .07 .12 .10 .06 .29 .75 .68 .40 .02 .07 .00 .04 .04 .17C10 .03 .22 .08 .03 .04 .38 .54 .53 .31 .01 .01 .09 .22 .28 .36ES1 .11 .09 .08 .04 .06 .00 .08 .00 .13 .73 .75 .71 .04 .09 .05ES2 .10 .03 .05 .18 .06 .23 .04 .12 .09 .58 .69 .60 .06 .04 .12ES3 .24 .05 .07 .29 .18 .14 .02 .16 .05 .57 .68 .68 .04 .13 .03ES4 .20 .10 .09 .17 .03 .17 .06 .01 .04 .60 .69 .58 .06 .11 .11ES5 .16 .21 .16 .18 .09 .09 .14 .14 .06 .37 .66 .71 .08 .07 .03ES6 .01 .19 .14 .25 .08 .15 .08 .12 .08 .66 .65 .76 .03 .13 .02ES7 .09 .01 .16 .08 .10 .07 .14 .04 .25 .75 .69 .61 .02 .05 .08ES8 .07 .07 .16 .19 .13 .05 .10 .07 .21 .75 .77 .65 .07 .04 .05ES9 .17 .01 .14 .06 .24 .11 .13 .00 .18 .70 .65 .62 .12 .03 .15ES10 .19 .07 .08 .05 .07 .03 .04 .06 .15 .72 .78 .69 .10 .03 .05I1 .08 .07 .13 .10 .13 .02 .03 .15 .02 .00 .04 .14 .57 .61 .63I2 .04 .08 .22 .10 .08 :34 .01 .02 .05 .16 .16 .16 .60 .65 .47I3 .20 .11 .16 .20 .19 .12 .21 .17 .06 .15 .18 .27 .46 .53 .56I4 .11 .02 .17 .39 .02 .42 .16 .08 .03 .07 .07 .10 .49 .63 .39

322 A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329

Emotional Stability items loaded onto the same factor. For Extraversion, Conscientiousness andIntellect, 9 of the items had their highest loading on the appropriate factor (with 3, 2 and 3 itemshaving lower cross-loadings of >0.3, respectively). The items loading on the wrong factor had asmaller loading on the appropriate factor. Six of the Agreeableness items loaded together, with afurther 3 which referred to an interest in others (such as I am not really interested in others)loading highest with the Extraversion items and the nal item (I insult people) loading highestwith the Conscientiousness items.In each sample, the factor structure appears to conform closely to that reported by Goldberg

(2001), with only minor discrepancies. As such, scale scores were produced for each of the 5 fac-tors, by summing the appropriate 10 items. Table 2 shows the internal consistencies in the 3 sam-ples. These were all acceptable to high, the lowest being 0.72. The mean scale scores in each of the3 samples are presented also.

6.1.4. Age dierences in IPIP scale scores

As the same factors were scored in the 3 samples, the data were combined in order to assess agedierences. The data were split into 3 age groups: early adulthood, which included all participantsup to the age of 30 (men: mean age 21.9 years, sd = 2.4, range 17.829.0 years; women: mean age21.4 years, sd = 2.3, range 17.829.8 years); middle adulthood, which consisted of those over 30 andunder 65 (men: mean age 47.8 years, sd = 11.1, range 30.064.9 years; women: mean age 49.8 years,sd = 10.3, range 30.063.7 years); and late adulthood, which was all participants over 65 althoughthe mean age was around 80 (men: mean age 80.5 years, sd = 2.2, range 66.981.0 years; women:

Table 1 (continued)

I5 .28 .18 .04 .16 .06 .26 .13 .23 .05 .04 .03 .01 .54 .57 .66I6 .22 .12 .34 .12 .17 .10 .02 .04 .23 .04 .04 .13 .53 .63 .43I7 .16 .11 .01 .03 .05 .25 .16 .14 .15 .14 .15 .09 .60 .55 .46I8 .02 .17 .11 .07 .12 .01 .13 .12 .14 .06 .09 .02 .72 .58 .50I9 .21 .22 .13 .43 .31 .31 .09 .01 .09 .21 .26 .13 .34 .37 .38I10 .29 .20 .08 .05 .05 .20 .08 .13 .02 .06 .01 .01 .51 .60 .67Note. S = student sample, V = Volunteer Panel, L = LBC1921, E = Extraversion, A = Agreeableness, C = Conscien-

tiousness, ES = Emotional Stability and I = Intellect. Numbers denote the order in which the IPIP items appear in

Goldberg (2001).

Loadings over .3 are shown in bold.

A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329 323mean age 79.7 years, sd = 3.8, range 65.183.2 years). The mean scores for the 5 factors are shownin Table 3. The mean scale levels were compared using an ANOVA, with sex also included in theanalysis. There was a signicant main eect of sex for the Agreeableness, Emotional Stability andIntellect means (F(1,842) = 52.9, 6.9 and 4.8 respectively, p < 0.05). Women have signicantly higherAgreeableness scores, and lower Emotional Stability and Intellect means compared with the men.The main eect of age group was also signicant for each of the factors. Extraversion was signif-icantly higher in early adulthood compared with middle and late adulthood (p < .01 and 0.001respectively); the middle and late groups did not dier signicantly. The early adulthood groupwere signicantly lower in Agreeableness than the middle and late adulthood groups (p < 0.05and .001 respectively), and the middle and late groups did not dier. All groups were signicantlydierent with regard to Conscientiousness (p < 0.01), such that the late group had the highest level,followed by the middle adulthood and then the early adulthood groups. The early and middle

Table 2

Means and internal consistencies for IPIP factors

Factor Group

Student (N = 201) Volunteer (N = 207) LBC1921

Male

(N = 90)

Female

(N = 111)

Total Male

(N = 61)

Female

(N = 146)aTotal Male Female Total

Extraversion 25.2 (7.2) 24.1 (7.0) 24.6 (7.1) 21.2 (8.7) 22.5 (8.3) 22.1 (8.4) 19.9 (7.7) 21.2 (7.3) 20.7 (7.5)

0.87 0.90 0.84

Agreeableness 28.4 (4.8) 30.9 (4.8) 29.8 (5.0) 29.6 (6.4) 33.0 (5.5) 32.0 (6.0) 29.8 (5.0) 33.2 (4.8) 31.8 (5.2)

0.72 0.85 0.76

Conscien-

tiousness

22.1 (6.9) 22.5 (6.4) 22.4 (6.6) 26.7 (6.6) 26.9 (6.1) 26.8 (6.2) 28.6 (6.1) 28.8 (6.1) 28.7 (6.1)

0.80 0.79 0.77

Emotional

Stability

21.8 (7.2) 19.6 (7.7) 20.6 (7.5) 21.5 (8.3) 20.8 (8.3) 21.0 (8.3) 24.8 (8.5) 23.9 (7.9) 24.2 (8.1)

0.85 0.89 0.87

Intellect 28.3 (5.9) 25.9 (5.4) 27.0 (5.8) 27.5 (6.0) 27.4 (5.9) 27.4 (5.9) 23.9 (6.0) 23.4 (5.8) 23.6 (5.9)

0.77 0.79 0.73

Note. Means and standard deviations (in parenthesis) are shown in the top row for each factor.

Internal consistencies (Cronbachs alphas) are shown in italics.LBC1921 male N = 192 for Extraversion, Agreeableness and Intellect, 193 for Conscientiousness and 190 for Emotional

Stability; LBC1921 female N = 268 for Extraversion, 269 for Conscientiousness, 270 for Intellect, 271 for Emotional

Stability and 273 for Agreeableness.a N = 145 for Agreeableness and Conscientiousness.

324 A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329adulthood groups did not dier signicantly on their level of Emotional Stability, however, the lateadulthood group had a signicantly higher level than the 2 younger groups (p < 0.001). The resultwas similar for Intellect; however, in this case, Intellect was signicantly lower in late adulthood(p < 0.001), and did not dier signicantly from early to middle adulthood.

6.1.5. Correlations between measurement instrumentsTable 4 shows the internal consistencies for the factors from the 3 questionnaires completed by

the Volunteer Panel. These are all high in the NEO-FFI, the lowest value being 0.79. For theEPQ-R Short Form, the Cronbachs alphas for Extraversion and Neuroticism are high; however,the Psychoticism and Lie Scales are lower (0.56 and 0.66 respectively). The associations betweenthe scale scores of the dierent measures are shown in Table 5. The IPIP-NEO Extraversion cor-relation is 0.69 (p < .01), whilst the IPIP-EPQ and NEO-EPQ Extraversion correlations arer = 0.85 and 0.76, respectively (p < 0.01). Concerning the Emotional Stability/Neuroticism scalescores, the IPIP-NEO, IPIP-EPQ and NEO-EPQ correlated r = 0.83, 0.84 and 0.85, respec-tively (p < 0.01). The negative direction of the IPIP associations is due to the fact that this isscored towards the emotionally stable pole, as opposed to the emotionally labile pole in theNEO and EPQ. The IPIP-NEO Agreeableness correlation is r = 0.49 (p < 0.01). The Conscien-tiousness scale scores from the IPIP and the NEO correlated r = 0.76 (p < 0.01). The 5th factorsof the IPIP and NEO (Intellect and Openness respectively) correlate r = 0.59 (p < 0.01).Associations were examined within each of the measures. For the EPQ, no internal correlations

were above 0.3. The Extraversion and Agreeableness factors of the IPIP correlate r = 0.35(p < 0.01). None of the other factors correlated higher. With the NEO, Neuroticism correlated

Agreeableness 28.3 (4.7) 30.9 (4.6) 29.8 (4.8) 29.5 (6.2) 32.5 (6.1) 31.5 (6.3) 29.8 (5.2) 33.2 (4.8) 31.9 (5.2)

Conscien- 21.6 (6.7) 22.5 (6.6) 22.1 (6.6) 26.7 (6.1) 26.6 (6.0) 26.6 (6.0) 28.5 (6.2) 28.4 (6.2) 28.5 (6.2)above 0.3 with both Extraversion and Conscientiousness (r = 0.42 and 0.31 respectively,tiousness

Emotional

Stability

22.0 (6.7) 18.6 (7.3) 20.1 (7.2) 21.0 (8.5) 20.2 (8.3) 20.5 (8.4) 24.7 (8.5) 24.0 (7.9) 24.2 (8.1)

Intellect 27.9 (5.7) 26.8 (5.1) 27.3 (5.4) 28.5 (6.1) 26.6 (6.0) 27.2 (6.1) 24.0 (6.1) 23.9 (6.0) 23.9 (6.0)

Note. The age groups are dened as follows: Early = up to 30 years old (mean = 21.6 years, sd = 2.4), Middle = from 30

to 65 years old (mean = 49.1 years, sd = 10.6), and Late = 65 years and above (mean = 80.0 years, sd = 3.3).

Standard deviations are shown in parenthesis.

Late adult male, N = 204 for Emotional Stability, 206 for Extraversion, Agreeableness and Intellect and 207 for

Conscientiousness; Late adult female, N = 313 for Extraversion, 314 for Conscientiousness, 315 for Emotional Stability

and Intellect and 318 for Agreeableness.a For Agreeableness and Conscientiousness, N = 106.Table 3

Mean IPIP scale scores by age group

Factor Age group

Early adult (N = 178) Middle adult (N = 162) Late adult

Male

(N = 78)

Female

(N = 100)

Total Male

(N = 55)

Female

(N = 107)aTotal Male Female Total

Extraversion 25.4 (7.6) 24.3 (7.1) 24.8 (7.3) 21.7 (8.0) 21.9 (8.5) 21.8 (8.3) 20.0 (7.7) 21.6 (7.3) 21.0 (7.5)

A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329 325p < 0.01).

6.1.6. Joint PCA of the IPIP, NEO and the EPQ scalesThe scale scores for the IPIP and the NEO-FFI, plus the EPQ-R Short Form Extraversion and

Neuroticism scales, were analysed by PCA (the EPQ Psychoticism and Lie Scale were excluded asno corresponding factors exist in the IPIP and NEO). The overall MSA was 0.74 and all scalescores MSA were above acceptable levels. The scree plot suggested the extraction of 5 factorsaccounting for 85.9% of the variance. The loadings in Table 6 show that the 1st rotated compo-nent is described by the Neuroticism/Emotional Stability scale scores, the 2nd by the Extraversionscores, followed by Conscientiousness, then Openness/Intellect and nally Agreeableness. No sub-stantial cross-loadings were observed.

7. Discussion

The results of the current study are encouraging with regard to the IPIP 50-item Big-Five factormarkers. In the 3 samples the 5-factor structure proposed by Goldberg has been conrmed, withonly minor deviations from the expected item loadings. The 5 IPIP scales have high internal con-sistencies comparable to those previously cited (Goldberg, 2001). Cross-sectional changes withage are reported for the scales for the rst time, and these generally follow the patterns seen inprevious work using alternative inventories.

Table 4

Mean scale scores for the IPIP, NEO-FFI and EPQ-R questionnaires in the Volunteer Panel

Factor Questionnaire

IPIP NEO-FFI EPQ-R Short

Male Female Total Male Female Total Male Female Total

Extraversion 21.2 (8.7) 22.5 (8.3) 22.1 (8.4) 26.3 (7.6) 26.7 (7.3) 26.6 (7.4) 6.3 (4.1) 7.1 (3.7) 6.9 (3.8)

0.90 0.85 0.89

Agreeableness 29.6 (6.4) 33.0 (5.5) 32.0 (6.0) 29.9 (5.9) 34.8 (5.9) 33.4 (6.3)

0.85 0.80

Conscien-

tiousness

26.7 (6.6) 26.9 (6.1) 26.8 (6.2) 32.6 (7.1) 33.4 (6.5) 33.2 (6.7)

0.79 0.85

Emotional

Stability/

Neuroticism

21.5 (8.3) 20.8 (8.3) 21.0 (8.3) 20.8 (10.1) 21.9 (10.2) 21.5 (10.2) 4.8 (3.6) 5.2 (3.5) 5.1 (3.6)

0.89 0.92 0.86

Intellect/

Openness

27.5 (6.0) 27.4 (5.9) 27.4 (5.9) 29.3 (8.2) 32.1 (5.9) 31.3 (6.8)

0.79 0.79

Psychoticism 2.1 (1.9) 1.7 (1.5) 1.8 (1.6)

326 A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329The IPIP Big-Five factor markers correlate highly with the appropriate scales of the NEO-FFIand the EPQ-R, providing concurrent validity for the IPIP. The associations are particularly highfor N/ES, E and C. With regard to Intellect and Openness, it is unsurprising these factors are re-lated to a smaller degree (Goldberg, 1992), although still at 0.59. The IPIP Intellect factor seemsmore reliant on items assessing ideas and imagination, whilst NEO Openness items appear slightlybroader in their scope, encompassing willingness to try new experiences.In the current study, mean levels of Extraversion and Intellect decrease with age, whilst Agree-

ableness, Conscientiousness and Emotional Stability increase. These cross-sectional changes withage are similar to those noted in previous research with other 5-factor inventories (McCrae et al.,2000; Srivastava, John, Gosling, & Potter, 2003), providing further evidence for the concurrentvalidity of the IPIP. It is often stated that personality changes little after the age of about 30(McCrae et al., 2000); however, signicant dierences were noted with Emotional Stability andIntellect in late adulthood. The reasons for this are still unclear and it might be due to a combi-nation of actual changes in personality, as well as cohort dierences.Goldberg (2001) states that all the IPIP items are preliminary, and are to be modied when nec-

essary. The current studys ndings suggest a number of possible item alterations to improve thereliability of the IPIP 50-item Big-Five factor markers. These are available from the authors on

0.56

Lie Scale 4.2 (2.5) 4.8 (2.3) 4.6 (2.4)

0.66

Note. Blank cells denote no corresponding value for the scale.

Emotional Stability is an IPIP factor, whilst Neuroticism is the equivalent factor (negative pole) in the NEO-FFI andEPQ-R.

Intellect is the 5th IPIP factor, whilst Openness is the 5th NEO-FFI factor.

Factor scores can range between 0 and 40 for the IPIP, 0 and 48 for the NEO-FFI, and 0 and 12 for the EPQ-R.

Means and standard deviations (in parenthesis) are shown in the top row for each factor.

Internal consistencies (Cronbachs alphas) are shown in italics.For all means, N = 207 (61 male, 146 female), except IPIP A and IPIP C where N = 206 (61 male, 145 female).

Table 5

Associations between the IPIP, NEO-FFI and EPQ-R Short Form factors

1 2 3 4 5 6 7 8 9 10 11 12 13

1. IPIP E

2. IPIP A 0.35**

3. IPIP C 0.02 0.17* 4. IPIP ES 0.25** 0.14* 0.16*

5. IPIP I 0.27** 0.12 0.03 0.01 6. NEO E 0.69** 0.41** 0.18* 0.35** 0.17*

7. NEO A 0.20** 0.49** 0.08 0.32** 0.09 0.26**

8. NEO C 0.02 0.17* 0.76** 0.21** 0.07 0.26** 0.15*

9. NEO N 0.30** 0.12 0.23** 0.83** 0.04 0.42** 0.25** 0.31** 10. NEO O 0.17* 0.19** 0.21** 0.05 0.59** 0.04 0.24** 0.12 0.05 11. EPQ E 0.85** 0.42** 0.07 0.23** 0.26** 0.76** 0.22** 0.10 0.28** 0.16* 12. EPQ N 0.31** 0.06 0.16* 0.84** 0.01 0.37** 0.21** 0.23** 0.85** 0.09 0.27** 13. EPQ P 0.03 0.27** 0.16* 0.11 0.26** 0.06 0.33** 0.20** 0.09 0.23** 0.06 0.08 14. EPQ L 0.06 0.16* 0.28** 0.21** 0.06 0.00 0.20** 0.38** 0.19** 0.12 0.04 0.20** 0.15*

Note. E = Extraversion, A = Agreeableness, C = Conscientiousness, ES = Emotional Stability, I = Intellect, N = Neuroticism, O = Openness,

P = Psychoticism, L = Lie Scale.

For all correlations, N = 207, except those with IPIP A and IPIP C where N = 206.*p < 0.05, **p < 0.01.

A.J.Gowet

al./Perso

nality

andIndivid

ualDieren

ces39(2005)317329

327

ing dierent inventories to assess concurrent validity. With the information reported in the currentstudy, this next stage in the validation is now possible.

IPIP Intellect 0.00 0.20 0.09 0.90 0.06NEO Openness 0.06 0.02 0.18 0.86 0.24

328 A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329Acknowledgement

The authors would like to thank Christine Braehler, Sarah Chalmers, Helen Fletcher and Ruthrequest, and have been forwarded to Goldberg. Whilst the current study provides concurrent val-idation for the IPIP Big-Five factor markers, Goldberg (1999) points to a lack of studies compar-

NEO Agreeableness 0.24 0.04 0.03 0.11 0.87IPIP Agreeableness 0.06 0.37 0.14 0.04 0.78

Note. Loadings over 0.3 are shown in bold.Table 6

Loadings for the IPIP, NEO and EPQ scale scores

Component

1 2 3 4 5

EPQ Neuroticism 0.93 0.18 0.08 0.04 0.00IPIP Emotional Stability 0.93 0.11 0.06 0.02 0.16NEO Neuroticism 0.91 0.19 0.17 0.00 0.06EPQ Extraversion 0.11 0.93 0.02 0.12 0.14IPIP Extraversion 0.16 0.90 0.08 0.14 0.08NEO Extraversion 0.24 0.83 0.18 0.01 0.17IPIP Conscientiousness 0.08 0.03 0.93 0.10 0.06NEO Conscientiousness 0.16 0.04 0.92 0.03 0.08Turner for their assistance in distributing the IPIP to the student sample, and collating theresponses. Alan Gow holds a Royal Society of Edinburgh/Lloyds TSB Foundation for ScotlandStudentship. Ian Deary is the recipient of a Royal Society-Wolfson Research Merit Award.

References

Ashton, M. C., Lee, K., Perugini, M., Szarota, P., de Vries, R. E., Di Blas, L., et al. (2004). A six-factor structure of

personality-descriptive adjectives: Solutions from psycholexical studies in seven languages. Journal of Personality

and Social Psychology, 86, 356366.

Costa, P. T., Jr., & McCrae, R. R. (1992). Revised NEO personality inventory (NEO PI-R) and NEO ve-factor

inventory (NEO-FFI) professional manual. Odessa, FL: Psychological Assessment Resources.

Costa, P. T., Jr., & McCrae, R. R. (1999). Reply to Goldberg. In I. Mervielde, I. J. Deary, F. de Fruyt, & F. Ostendorf

(Eds.), Personality psychology in Europe (Vol. 7, pp. 2931). Tilburg: Tilburg University Press.

Deary, I. J., Whiteman, M. C., Starr, J. M., Whalley, L. J., & Fox, H. C. (2004). The impact of childhood intelligence

on later life: Following up the Scottish Mental Surveys of 1932 and 1947. Journal of Personality and Social

Psychology, 86, 130147.

Eysenck, S. B. G., Eysenck, H. J., & Barrett, P. (1985). A revised version of the Psychoticism scale. Personality and

Individual Dierences, 6, 2129.

Goldberg, L. R. (1992). The development of markers for the Big-Five Factor Structure. Psychological Assessment, 4,

2642.

Goldberg, L. R. (1999). A broad-bandwith, public-domain, personality inventory measuring the lower-level facets of

several Five-Factor models. In I. Mervielde, I. J. Deary, F. de Fruyt, & F. Ostendorf (Eds.). Personality psychology

in Europe (Vol. 7, pp. 728). Tilburg: Tilburg University Press.

Goldberg, L. R. (2001). International Personality Item Pool. Web address can be obtained from authors.

Matthews, G., Deary, I. J., & Whiteman, M. C. (2003). Personality traits (2nd ed.). Cambridge: Cambridge University

Press.

McCrae, R. R., & Costa, P. T. Jr., (2004). A contemplated revision of the NEO Five-Factor Inventory. Personality and

Individual Dierences, 36, 587596.

McCrae, R. R., Costa, P. T., Ostendorf, F., Angleitner, A., Hrebickova, M., Avia, M. D., et al. (2000). Nature over

nurture: Temperament, personality, and life span development. Journal of Personality and Social Psychology, 78,

173186.

Paunonen, S. V., & Jackson, D. N. (2000). What is beyond the Big Five? Plenty! Journal of Personality, 68, 821835.

Saucier, G., & Goldberg, L. R. (2002). Assessing the big ve applications of 10 psychometric criteria to the development

of marker scales. In B. De Raad & M. Perugini (Eds.), Big ve assessment (pp. 2958). Seattle, WA: Hogrefe &

Huber.

Srivastava, S., John, O. P., Gosling, S. D., & Potter, J. (2003). Development of personality in early and middle

adulthood: Set like plaster or persistent change? Journal of Personality and Social Psychology, 84, 10411053.

A.J. Gow et al. / Personality and Individual Dierences 39 (2005) 317329 329

Goldberg " s " IPIP " Big-Five factor markers: Internal consistency and concurrent validation in ScotlandIntroductionRecent debate and Goldberg rsquo s proposalThe IPIP Big-Five factor markersThe current studyMethodQuestionnairesIPIP Big-Five factor markers (Goldberg, 2001)NEO Five Factor Inventory (NEO-FFI: Costa & McCrae, 1992)Eysenck Personality Questionnaire-Revised Short Form (EPQ-R Short Form: Eysenck, Eysenck, & Barrett, 1985)

Participants and procedures

ResultsStructure of the IPIP itemsStudent sampleVolunteer panelLBC1921Age differences in IPIP scale scoresCorrelations between measurement instrumentsJoint PCA of the IPIP, NEO and the EPQ scales

DiscussionAcknowledgementReferences