Journal of Affective Disorders 132 (2011) 368–374

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Journal of Affective Disorders

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Research report

Psychometric properties of the Dickman Impulsivity Instrument in suicidevictims and living controls of rural China

Qi Gao a, Jie Zhang a,b,⁎, Cunxian Jia a

a Shandong University School of Public Health, Chinab State University of New York College at Buffalo, Buffalo, NY 14222, USA

a r t i c l e i n f o

⁎ Corresponding author at: Department of SociologNew York College at Buffalo, 1300 Elmwood Avenue, BTel.: +1 716 878 6425; fax: +1 716 878 4009.

E-mail address: zhangj@buffalostate.edu (J. Zhang

0165-0327/$ – see front matter © 2011 Elsevier B.V.doi:10.1016/j.jad.2011.03.002

a b s t r a c t

Article history:Received 25 August 2010Received in revised form 6 January 2011Accepted 2 March 2011Available online 25 March 2011

Background: We are not aware of any of impulsivity trait for Chinese rural youths. This studyevaluated the psychometric properties of Dickman Impulsivity Instrument in suicide cases andliving controls in rural China.Methods: The participants, 392 suicide victims and 416 controls were respectively selected, andthe psychological autopsy method was used to collect information. The Exploratory FactorAnalysis was processed to evaluate the construct validity. The Cronbach's alpha was computedto evaluate the internal consistency, and the Spearman rank correlation coefficients betweenSTAI Trait Anxiety Inventory, Coping Responses Inventory and Dickman Impulsivity Instrumentwere calculated to evaluate the convergent validity.Results:Dysfunctional and Functional impulsivity were extracted for both samples. Themean ofDI scores in suicide cases was larger than that in controls, but it was reversed for FI. There wereno significant differences between DI and FI in suicide cases, but in controls the mean of DIscores was significantly smaller than that of FI. The Cronbach's alpha was around .863 and .779respectively for DI and FI scales in suicides, and it was around .746 and .680 in controls. The DIand FI were significantly correlated with each other. Both the DI and FI were correlated withApproach and Avoidance Coping Response Inventory, and both of the scales were grosslyindependent with Trait Anxiety Inventory in two samples.Conclusion: The results indicated that the Dickman Impulsivity Instrument was adequate tomeasure impulsivity trait for suicide victims and living controls through proxy data in rural China.

© 2011 Elsevier B.V. All rights reserved.

Keywords:Dickman Impulsivity Instrument (DII)Psychometric propertiesPsychological autopsyChinese rural youthsSuicide

1. Introduction

Impulsivity can be defined as the tendency to deliberateless than most people of equal ability before taking action(Dickman, 1990), and it is considered as a major trait ofpersonality. High correlations were reported between impul-sivity and diverse suicide related disorders in differentpopulations. For example, independent impact of impulsivityon suicidality in borderline personality disorder (BPD) wasfound (Rihmer and Benazzi, 2010), high impulsivity was

y, State University ouffalo, NY 14222, USA

).

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f.

found in the etiology of suicide in schizophrenia (Iulian et al.,2010), and impulsivity could be one of the links betweenchildhood trauma and suicidal behavior (Braquehais et al.,2010). Impulsivity was found to be correlated with suicideideation and suicide attempt (Baca-Garcia et al., 2005; Carliet al., 2010; Conner et al., 2004; Dougherty et al., 2009; Hull-Blanks et al., 2004; Lester, 1993; Swann et al., 2005; Wyderand De Leo, 2007), and it was also discovered to be one of theprobable risk factors of suicide (Phillips et al., 2002b; Zhanget al., 2010). It indicated that the impulsivity trait might bedirectly or indirectly correlated with suicidal behaviors.

In China, suicide is the leading cause of death for 15–34-year-old rural people, and the Chinese suicide rate is 23.2 per100,000 people and a total of about 287,000 suicide deathsper year (Phillips et al., 2002a). Furthermore, the rural suicide

369Q. Gao et al. / Journal of Affective Disorders 132 (2011) 368–374

rate is three times higher than the urban suicide rate, which is27.1/100,000 versus 8.3/100,000 (Phillips et al., 2002a). From2005 to 2008, a case–control psychological autopsy (PA)study was conducted to investigate the mechanism behindthe suicide of youth in rural China. We wanted to comparesuicide risk factors between suicide cases and communityliving controls, and we tried to compare factors of suicide riskamong different subpopulations. In this study, the DickmanImpulsivity Instrument (DII) (Dickman, 1990)was adopted tomeasure the impulsivity personality for Chinese rural youths.

There are various questionnaires fromdifferent theoreticalpoints of view, for example, Barratt Impulsivity Scale wasdeveloped to measure impulsivity involving behavioral,cognitive and physiological components (Barratt and Patton,1983), and Impulsiveness–Venturesomeness–Empathy ques-tionnaire was used to process conception of impulsivityinvolving Venturesomeness and Impulsiveness as twodistinctcomponents (Eysenck et al., 1985). Dickman stressed thatthe consequences of impulsivity are not always negative(Dickman, 1990). He proposed that individual differences inimpulsivity would reflect differences in the degree to whichattention tends to remain fixed once it is directed to aparticular source of information (Dickman, 1996). Highimpulsive subjects' rapid responding has little cost in errorswhen the experimental task is very simple (Dickman, 1985),and high impulsive subjects are more accurate than otherswhen the available time for making a decision is short(Dickman and Meyer, 1988). Dickman hypothesizes theexistence of two different traits: Functional Impulsivity (FI)and Dysfunctional Impulsivity (DI). FI results in rapid, inac-curate performance in situations where this is optimal and DIresults in rapid, inaccurate performance in situations wherethis is non-optimal. He successfully constructed the DII todiscriminate within the self-report domain between thosetwo traits, and demonstrated that both differ in their per-sonality and cognitive correlates.

The DII was proved to have stable reliability and validity.The Cronbach's alpha was used to assess the internalconsistency and it was .74 and .85 respectively for FI and DIscales in original American version. The correlation betweenFI and DI scales was significant (r=.23), and both FI and DIscales were correlated with all of the other impulsivity scales(Dickman, 1990). The DII was also translated and adapted indifferent language context within high reliability and validity.Two factors were also recovered both in males and femalesin French version, and the DI scale was correlated with theBarratt Impulsiveness Scale and both scales were grosslyindependent from Spielberger's Trait-Anxiety Inventory (Caciet al., 2003). The internal consistency was sufficient for Dutchversion, which congruence coefficients were .88 for FI scaleand .92 for DI scale, and the factors were also similar with theoriginal version (Claes et al., 2000). It also showed goodreliability and validity for Spanish version (Chico et al., 2003).All of the evidence seems to suggest that the DII is quite stableacross languages and populations.

Though there were many studies on the quality of theDickman Impulsivity Instrument, there were few studiesconcerning the impulsivity trait inChinese rural youthsespeciallyin suicide victims. In this study, we wanted to evaluate thepsychometric properties of DII in two Chinese rural youngsamples: suicide victims and community living controls.

2. Methods

2.1. Design

Psychological autopsy (PA) method was used to collectinformation of target persons. The psychological autopsy studyis one of the best ways to disclose the official reason frombiological, psychological, and social aspects by interviewinginformants of suicidevictims. It is a goodandpopularmethod insuicide researchwith high reliability and validity (Phillips et al.,2002b; Zhang et al., 2002). The case–control studymethodwasalso used in the study to optimize scientific validity, and suicidevictims were compared to living and non-suicidal people thatwere the same as or equal to the population fromwhich suicidevictims originated. To decrease discrepancies between theEnglish and Chinese measurements, the 23 items of the DII (12DI itemswhichwereoddnumbered and11FI itemswhichwereeven numbered) were translated into Chinese and then back-translated into English by independent English native colla-borators. Differences between the original versions and theretranslationswere discussed in order to improve the quality ofthe Chinese translations.

2.2. Study population

Liaoning Province, Hunan Province and Shandong Prov-ince in China were chosen as the research sites, and a total of16 counties were randomly selected to recruit cases. In eachcounty, we had a project coordinator in charge of the sur-veillance and the report of the suicide cases. Suicide cases thataged 15–34 years were selected consecutively from suicidevictims which happened from October 2005 to June 2008. Foreach suicide case, we randomly selected community livingcontrols from the same area aged between 15 and 34 years. Atlast, 392 suicide cases that consisted of 214 men and 178women with a mean age of 26.8±6.4 were selected, and 416controls that consisted of 202 men and 214 women with amean age of 25.7±6.2 were selected from the same counties.

2.3. Informants and data collection

For each of the suicide victims we had two informantswho knew the deceased person well. We selected the in-formants based on the context or environment, and the firstinformant was generally a relative of the deceased and thesecond informant was a good friend or neighbor in the case.For each control, we also interviewed two informants, and theprinciples of selection for control informants were the sameas that for the suicide cases. The village doctors were trainedto identify and report suicide cases to the county level ofCenter for Disease Control and Prevention (CDC) whichmonthly reported these suicide victims to the principalinvestigator in each province. All the informants should signon the informed consent form or agreed to inform orally. Eachinterview was completed by one interviewer and one in-formant without the third person present.

2.4. Data analysis

In this research, the information of two informants wascombined as the proxy data for suicide victims and living

370 Q. Gao et al. / Journal of Affective Disorders 132 (2011) 368–374

controls. Then, the combined data were adopted to evaluatethe Psychometric Properties of DII for different populations.

The Exploratory Factor Analysis was used to assessConstruct Validity of the DII in this study. The criterion fordetermining the number of extracted factors was ParallelAnalysis, which was one of the best methods for determiningthe number of components to retain (Glorfeld, 1995; Haytonet al., 2004; Zwick and Velicer, 1986). The principle of theParallel Analysis was to compare the eigenvalues derivedfrom actual data sets with the 95th percentile of thedistribution of eigenvalues (Glorfeld, 1995) that wasextracted from random data sets that parallel the actualdata sets with regard to the number of cases and variables. Allof the procedures could be processed by SPSS 16.0 (O'Connor,2000).

Cronbach's alpha was computed to evaluate the internalconsistency, and the correlation coefficients between CopingResponse Instrument (CRI) (Moos et al., 1990), Spielberger'sTrait-Anxiety Inventory (TAI) (Spielberger et al., 1983) andDII were calculated to evaluate the convergent validity. TheCRI (48 items, true/false format) is used for measuring theindividuals' coping skills, which includes two dimensions:Approach and Avoidance methods. The Trait-Anxiety Inven-tory (20 items) was part of State Trait Anxiety Inventory,which was used to measure trait anxiety personality.

In this study, all of the scores of reversely narrative itemsfor each scale were reversely coded before analysis, and all ofthe data analysis was processed by SPSS 16.0.

3. Results

3.1. Demographic characteristics

Altogether 392 suicide victims and 416 living controlswere obtained for this study. As shown in Table 1, suicide caseswere slightly older than controls (P=.010), while there wasno gender differences between cases and controls (P=.086).Suicide cases were less educated than controls (Pb .001), andtheywere less likely to bemarried than the controls, but it wasnot significant at the .05 level. More suicide victims were at alower family annual income level than controls (Pb .001).

Table 1Demographic characteristics of the samples.

Demographic variable Suicide group(n=392)

Control group(n=416)

P

Age 26.84±6.37 25.69±6.17 .010Gender

Male 214 (54.59%) 202 (48.56%) .086Female 178 (45.41%) 214 (51.44%)

Education level (years) 7.38±2.77 9.15±2.40 b.001Marital status

Never married 161(41.07%) 144 (34.62%) .058Ever married 231(58.93%) 272 (65.38%)

Family annual incomeLow (RMB b10,000) 158 (40.31%) 79 (18.99%) b.001Middle (10,000R ≤RMB b20,000)

134 (34.18%) 126 (30.29%)

High (RMB ≥20,000) 91 (23.21%) 169 (40.63%)

3.2. Construct validity

3.2.1. Construct validity in suicide victimsThe Kaiser–Meyer–Olkin (KMO) measure of sampling

adequacy and the Bartlett's Sphericity Test were computedto evaluate whether Factor Analysis could be used for thisdata. The KMOmeasure of sampling adequacywas .905whichwas close to 1 and the Chi-Square for Bartlett's Sphericity Testwas significantly 2944, all of which indicated that FactorAnalysis could be taken in the case group.

A series of random data matrices (392×23) for suicidegroup were generated, and all the eigenvalues were comput-ed for the correlation matrices for the actual data and for therandom data sets. The third eigenvalue (1.374) of randomdata sets was larger than the third eigenvalue (1.333) ofactual data sets. Therefore, two components were retainedthrough Parallel Analysis, which explained 40.4% of the totalvariance and represented the two expected factors of DII.Principal Component Analysis was used to extract commonfactors (number of factors=2), and the Varimax method wasused to rotate these common factors. All of 12 DI items anditem 22 were gathered together in factor 1, and 10 FI itemswere gathered in factor 2. More details were shown inTable 2.

3.2.2. Construct validity in community living controlsSimilarly, we conducted Exploratory Factor Analysis in

control group. The KMO measure of sampling adequacy was.800. The Chi-Square for Bartlett's Sphericity Test was 1760and it was also significant, which indicated that it was ade-quate to conduct Factor Analysis in control group.

A series of random data matrices (416×23) for controlswere also generated. The third eigenvalue (1.36) of randomdata sets was larger than the third eigenvalue (1.275) ofactual data sets. So, two components were also retained withthe interpretation of 36.9% of the total variance, which alsorepresented the two expected components of DII. Eleven DIitems and item 22 were gathered together in factor 1, and 10FI items and item 21were gathered in factor 2. More detailswere shown in Table 2.

3.3. Reliability

The mean of DI score in suicide cases (around 6.78) waslarger than that in controls (around 3.70), but it was reversedfor FI (7.11 vs. 7.63). There were no significant differencesbetween DI and FI in suicide cases, but in controls themean ofDI score was significantly smaller than that of FI. More detailswere shown in Table 3–5.

3.3.1. Reliability for suicide casesThe results showed satisfactory internal consistency both

for DI and FI scales for suicide group. As shown in Table 3, themean of total score for the DI scale was 6.78±3.67, and it was6.73±3.73 and 6.84±3.60 respectively for males andfemales. The Cronbach's alpha for the DI scale equaled .863in the entire sample, .868 in males and .860 in females. Themean of total score for the FI scale was 7.11±2.86, and it was6.98±2.87 and 7.29±2.83 respectively for males andfemales. The Cronbach's alpha for the FI scale was respec-tively .779 in the entire sample, .774 in males and .786 in

Table 2Rotated component matrix: factor loadings for suicide and control samples.

Items Suicide Control

DI FI DI FI

Item 11 Without thinking carefully before acting .790 .677Item 23 Without considering consequences before acting .762 .561Item 9 Without considering situation to make up mind .741 .558Item 13 Get in trouble because of no thinking .737 .619Item 15 Plans failed because of careless thinking .675 .578Item 19 Carefully weigh pros and cons before acting .663 .524Item 1 Speak without thinking .662 .509Item 7 Shop without thinking about whether affordable .621 .445Item 3 Enjoy working out problems slowly and carefully .455 .426Item 21 Good at careful reasoning .441 −.481Item 17 Get involved in projects without considering .431 .367Item 5 Make appointment without thinking .424 .381Item 22 Avoid activities that people have no time thinking .364 .354Item 20 Admired by others because of thinking quickly .739 .677Item 6 Put thought into words quickly .736 .661Item 4 Good at taking advantage of opportunities .711 .632Item 12 Not like doing things quickly .595 .349Item 10 Like taking part in fast-paced conversation .505 .515Item 14 Enjoy jobs that required making fast decision .492 .566Item 2 Not like making decision quickly .491 .327Item 16 Like sports or games that required fast move .459 .593Item 18 Miss out opportunities because of no fast mind .371 .310Item 8 Feel uncomfortable if making up mind quickly .355 .341

Extraction method: Principal Component Analysis. Rotation method: Varimax.Lower loadings in each component were excluded.

371Q. Gao et al. / Journal of Affective Disorders 132 (2011) 368–374

females. It was also shown that the scores were not normallydistributed according to Kolmogorov–Smirnov test (D value)and Shapiro–Wilk test (W value).

3.3.2. Reliability for controlsThe results showed sufficient internal consistency both for

DI and FI scales for control group. As shown in Table 4, themean of total score for the DI scale was 3.70±2.73, and it was7.63±2.32 for the FI scale. The Cronbach's alpha in the DIscale equaled .746 in the entire sample, .and it was .680 forthe FI scale. It was also shown that the scores were notnormally distributed according to D and W values.

3.4. Convergent validity

3.4.1. Convergent validity for suicide casesAs both the DI and FI scales were not normally distributed,

Spearman rank correlation coefficients were computed toevaluate the convergent validity for DI and FI scales. The

Table 3Total mean scores and the Cronbach's α of the DII for suicide group.

DI

Entire sample Male Femal

Mean 6.78 6.73 6.84Std. deviation 3.67 3.73 3.60α .863 .868 .860D .137 ⁎⁎⁎ .153 ⁎⁎⁎ .127W .925 ⁎⁎⁎ .922 ⁎⁎⁎ .927

⁎⁎⁎ Pb .001.

correlation between DI and FI was significant (r=.513) insuicide cases. The DI scale was significantly correlated withtwo subscales of the CRI and the TAI, and FI was justsignificantly correlated with CRI Approach and CRI Avoid-ance. More details were shown in Table 6.

3.4.2. Convergent validity for controlsThe Spearman rank correlation coefficients were also

calculated for controls. As shown in Table 6, the correlationbetween DI and FI was also significant (r=.250). The DI wassignificantly correlated with two subscales of CRI and the TAI,and FI was significantly correlated with two subscales of CRI.

Both DI and FI were negatively correlated with age insuicide and control groups. The DI for suicide was negativelycorrelated with education level, but the correlation for FI waspositive. Both DI and FI for controls were not significantlycorrelated with education level. There were no significantcorrelations between impulsivity and family annual income.More details were shown in Table 6.

FI

e Entire sample Male Female

7.11 6.98 7.292.86 2.87 2.83.779 .774 .786

⁎⁎⁎ .118 ⁎⁎⁎ .121 ⁎⁎⁎ .130 ⁎⁎⁎⁎⁎⁎ .942 ⁎⁎⁎ .944 ⁎⁎⁎ .939 ⁎⁎⁎

Table 4Total mean scores and the Cronbach's α of the DII for control group.

DI FI

Entire sample Male Female Entire sample Male Female

Mean 3.70 3.69 3.71 7.63 7.88 7.39Std. deviation 2.73 2.87 2.59 2.32 2.24 2.38α .746 .770 .720 .680 .660 .696D .166 ⁎⁎⁎ .188 ⁎⁎⁎ .170 ⁎⁎⁎ .141 ⁎⁎⁎ .140 ⁎⁎⁎ .140 ⁎⁎⁎

W .915 ⁎⁎⁎ .911 ⁎⁎⁎ .911 ⁎⁎⁎ .942 ⁎⁎⁎ .934 ⁎⁎⁎ .948 ⁎⁎⁎

⁎⁎⁎ Pb .001.

372 Q. Gao et al. / Journal of Affective Disorders 132 (2011) 368–374

4. Discussion

This study was designed to assess the reliability andvalidity of Dickman Impulsivity Instrument for its use amongtwo sources of Chinese rural young people: suicide victimsand community living controls. The results were similar towhat had been reported in previous studies, which indicatedthat the Chinese adaption of the DII had satisfactory reliabilityand validity.

FI was described as a useful trait that enabled people tofunction better, and it is associated with enthusiasm andactivity. In contrast, DI was described as a bad trait thatleads to problems for the individual, and it is more stronglyassociated with disorderliness, and a lack of concern abouthard facts (Brunas-Wagstaff et al., 1995; Dickman, 1990). Inthis study, themeanof FI scoreswas around7.63 and themeanof DI scores was around 3.70 in controls, all of which wasanalogouswithin other normal people. For example, in Spanishcollege students the mean of FI and DI scores respectivelyranged from 4.76 to 5.58 and from 2.55 to 2.98 (Chico et al.,2003; Vigil-Colet, 2007; Vigil-Colet and Codorniu-Raga, 2004);in French college students themeanof FI scorewas around 7.12among different subgroups and it was around 2.85 for DI scale(Caci et al., 2003); in English adults, it was 6.27 for FI scale and2.84 for DI scale (Miller et al., 2004); it also showed similarresults in Dutch adults (Claes et al., 2000).

In this study, the means of FI score in suicide cases (around7.11) were similar to those in controls and other normalpopulations, but for DI scale the scores (around 6.78) weremuch larger than those in controls (around 3.70) and in otherpopulations (range from 2.84 to 3.71). In other words,dysfunctional impulsivity was lower than functional impulsiv-ity in controls but not in suicide victims, and dysfunctionalimpulsivitywashigher in suicide victims than in controls,whilefunctional impulsivity was lower in suicide victims than incontrols. All of the evidence indicated dysfunctional impulsivityrather than functional impulsivity might be correlated withsuicidal behaviors, and lack of functional impulsivitymight alsobe an important risk factor for suicide. We could also find that

Table 5Comparing total mean scores for DI and FI in suicide and control groups.

DI FI Suicide Control

Suicide Control Suicide Control DI FI DI FI

Mean 6.78 3.70 7.11 7.63 6.78 7.11 3.70 7.63t 13.26 2.72 1.87 26.21P b.001 .007 .063 b.001

dysfunctional impulsivity was increased with reducing educa-tion level,while functional impulsivitywasdecreased in suicidegroup. In this study, suicide victims had completed less edu-cation than controls. So, it might be inferred that educationlevel was one of the causes that impulsivity differed betweensuicide and controls. Further evidencewas required on this.Wealso found that as age increased impulsivity (both DI and FI)was decreased both for suicide victims and controls.

In this study, Exploratory Factor Analysis was adopted toassess the construct validity of Chinese adaption of DII, andParallel Analysis was applied to determine the number offactors before conducting a factor analysis. There were somemethods for determining the number of components to retainin an exploratory factor analysis, such as Horn's ParallelAnalysis, Cattell's scree test, Bartlett's chi-square test, Velicer'sminimum average partial and Kaiser's eigenvalues greaterthan 1, among which Parallel Analysis was the most nearlyaccurate one (Hayton et al., 2004; Zwick and Velicer, 1986).We applied modified Horn's Parallel Analysis in this study(Glorfeld, 1995).

The two-factor structure of the DII was found for bothsuicide and control groups, which showed that the functionaland dysfunctional constructs were valid in both populations.In suicide group, all of 12 odd items and item 22 were gath-ered together in factor 1 which clearly stood for theDysfunctional Impulsivity, and the rest 10 even items weregathered in factor 2, which represented the FunctionalImpulsivity. It was similar to previous studies (Caci et al.,2003; Chico et al., 2003; Claes et al., 2000; Dickman, 1990;Pedrero Perez, 2009). Item 22 “I try to avoid activities whereyou have to act without much time to think first” belonged toFI subscale in Dickman's study but it was extracted in DIsubscale with the lowest loading value of .364 in this study.

In control group, 11 odd items (except for item21) and item22 were gathered together in factor 1 which represented DI,and the other 10 even items and item 21 were gathered infactor2which representedFI. The loadingvalueof item21 “I amgood at careful reasoning” was −.481 in FI component whichwas .389 in DI component for control sample. The loadingvalues of item 21 in FI and DI components for suicide samplewere also similar (.441 in DI factor and .411 in FI factor).

The factors in which items 21 and 22 were grouped weredifferent with that of Dickman's American version. One of thepossible reasonswas that the depiction of item21might lead tobidirectional understanding both for suicide victims and livingcontrols in rural China or it might be because the relativelyformal expressionwasadopted for Chineseversion. For item22,the double negative was used and it might cause confusion forChinese rural youth. TheChineseversionof the two itemsmight

Table 6Spearman rank correlation coefficients for suicide and control groups.

DI FI CRI Approach CRI Avoidance TAI Age Education Family income

Suicide group DI 1 .513 ⁎⁎ −.267 ⁎⁎ .260 ⁎⁎ −.108 ⁎ −.158 ⁎⁎ −.103 ⁎ .024FI .513 ⁎⁎ 1 −.100 ⁎ .241 ⁎⁎ −.046 −.209 ⁎⁎ .104 ⁎ .079

Control group DI 1 .250 ⁎⁎ −.297 ⁎⁎ .235 ⁎⁎ −.117 ⁎ −.153 ⁎⁎ −.080 −.033FI .250 ⁎⁎ 1 −.124 ⁎ .300 ⁎⁎ −.088 −.152 ⁎⁎ −.079 −.002

⁎ Pb .05.⁎⁎ Pb .01 (two tailed).

373Q. Gao et al. / Journal of Affective Disorders 132 (2011) 368–374

be too obscure for rural youth who did not have much formaleducation. A very low coefficient of similarity for item 22 wasalso reported in French (Caci et al., 2003).

The Cronbach's alphas or KR-20 coefficients for DI and FIscales were also similar among different populations. In thisstudy, the Cronbach's alpha was around .863 in the entiresample, males and females for DI scale and it was around .779for FI scale in suicide group. The Cronbach's alphawas relativelylower in control group and it was around .746 and .680 re-spectively for DI and FI scales. In American undergraduatestudents, the Cronbach's alpha was .85 and .74 respectively forDI and FI scales (Dickman, 1990). In adults of United Kingdom,it was .84 and .78 respectively for DI and FI scales (Miller, et al.,2004). In French undergraduate students, the Kuder–Richard-son KR-20 coefficient was around .79 for DI scale and it wasaround .75 for FI scale (Caci et al., 2003). All of the evidenceindicated that the internal consistency reliability of DII wasquite stable among different populations.

The DI and FI scales exhibited relatively low correlationswith each other. It was .513 for suicide group and .250 forcontrol group. It was similar to that in Spanish adaption (.32)(Chico et al., 2003), in United Kingdom adaption (.25) (Milleret al., 2004), in French version (.23) (Caci et al., 2003) and inAmerican version (.23) (Dickman, 1990).

The CRI and TAI were used as the criterion measures toevaluate the convergent validity for DII. The CRI Approach wasused to assess positive approach coping response and the CRIAvoidance was used to assess negative avoidance copingresponse for individuals (Moos et al., 1990). The TAI was usedto assess trait anxiety personality which denoted stableindividual differences in anxiety proneness and referred to ageneral tendency to respond with anxiety to perceived threatsin the environment (Spielberger et al., 1983).

The Spearman rank correlation coefficients between thesescaleswere computed to assess convergent validity. Both theDIand FI scales were negatively and significantly correlated withCRI Approach and both of them were positively and signifi-cantly correlated with CRI Avoidance in suicide victims andliving controls. It demonstrated that impulsivity, no matter DIor FI, was negatively correlated with positive coping responses,and it was aligned with negative coping responses. It alsoindicated that though the FI might lead to positive conse-quences, the coping responses might be negative, which wasalso described by Dickman (1990). Caci et al. (2003) found thatDI was slightly and positively correlated with anxiety andFI was slightly and negatively correlated with anxiety. In ourstudy, both the DI and FI scales were slightly and negativelycorrelated with TAI. It indicated that impulsivity might be,in a minor extent, negatively correlated with trait anxietypersonality.

The main shortcomings of our study might be that thesample sizewas relatively small and the reliability and validityresults might differ while two samples (the suicide victimsand community living controls) with different dysfunctionalimpulsivity levels were used. Some of other researchers haveused many other impulsivity instruments as criterion mea-sures to assess convergent validity, such as Eysenck Impul-sivity Scale, Barratt Impulsiveness Scale and BIS/BAS scale, etc.Due to time and financial constrains, we could not apply somany measures.

The current studyprovidedpreliminaryevidenceconcerningthe reliability and the validity of the Chinese adaption ofDickman Impulsivity Instrument. Its validation in both suicidevictims and living control sampleswas generally similar to thosereported in the international literatures. The Chinese version ofDickman Impulsivity Instrument, with a littlemodification,maybe used appropriately and successfully to measure impulsivitytrait for Chinese rural people.

Role of funding sourceThis research was supported by the United States National Institute of

Mental Health (NIMH): R01 MH068560.

Conflict of interestThe authors had no conflicts of interest to declare in relation to this

article.

Acknowledgments

This research was supported by US Public Health ServiceGrant R01 MH068560. We thank the US National Institute ofMental Health for funding this research, and our researchcollaborators, interviewers and interviewees in China.

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