A Global Measure of Perceived Stress Author(S): Sheldon Cohen, Tom Kamarck and Robin Mermelstein Reviewed Work(S): Source: Journal of Health and Social Behavior, Vol

A Global Measure of Perceived Stress Author(s): Sheldon Cohen, Tom Kamarck and Robin Mermelstein Reviewed work(s): Source: Journal of Health and Social Behavior, Vol. 24, No. 4 (Dec., 1983), pp. 385-396 Published by: American Sociological Association Stable URL: http://www.jstor.org/stable/2136404 . Accessed: 24/10/2012 13:12

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http://www.jstor.org A GLOBAL MEASURE OF PERCEIVED STRESS 385

Richardson,Jean, and JulieSolis Wiggins,Jerry S. 1982 "Place ofdeath of Hispanic cancer patients 1973 Personalityand Prediction:Principles of in Los Angeles County." Unpublished PersonalityAssessment. Reading, MA: manuscript. Addison-WesleyPublishing Co. Stoddard,Sandol WilderFoundation 1978 The HospiceMovement. Briarcliff Manor, 1981 Carefor the Dying: A Studyof the Need for New York: Steinand Publishers. Hospice in RamseyCounty, Minnesota. A Valle, R., and L. Mendoza reportto the NorthwestArea Foundation 1978 The Elder Latino. San Diego, CA: Cam- fromthe AmherstH. WilderFoundation, panilePress. 355 WashingtonSt., St. Paul, MN.

A GlobalMeasure of PerceivedStress

SHELDON COHEN Carnegie-Mellon University

TOM KAMARCK Universityof Oregon

ROBIN MERMELSTEIN Universityof Oregon

Journalof Healthand Social Behavior1983, Vol. 24 (December):385-396

This paper presents evidencefrom threesamples, two of college studentsand one of participants in a communitysmoking-cessation program, for the reliabilityand validityof a 14-item instrument,the Perceived Stress Scale (PSS), designed to measure the degree to which situationsin one's lifeare appraised as stressful.The PSS showed adequate reliabilityand, as predicted, was correlated with life-eventscores, depressive and physical symptomatology, utilizationof health services, social anxiety,and smoking-reductionmaintenance. In all comparisons, thePSS was a betterpredictor of theoutcome in question thanwere life-event scores. When compared to a depressive symptomatologyscale, the PSS was found to measure a differentand independentlypredictive construct. Additionaldata indicateadequate reliability and validityof a four-itemversion of thePSS for telephoneinterviews. The PSS is suggestedfor examiningthe role of nonspecificappraised stress in the etiologyof disease and behavioral disorders and as an outcome measure of experiencedlevels of stress.

It is a common assumption among health -byone's perceptionsof theirstressfulness, researchers that the impact of "objectively" e.g., see Lazarus (1966, 1977). Surprisingly, stressfulevents is, to some degree,determined thistheoretical perspective has not been ac- companiedby developmentof psychometri- callyvalid measures of perceivedstress. This Researchreported in thispaper was supportedby grantsfrom the National Science Foundation (BNS articlediscusses the limitationsof objective 7923453)and the Heart,Lung and Blood Institute and subjectivemeasures of stressused in the (HL 29547). The authorsare indebtedto Edward assessmentof bothglobal and event-specific Lichtensteinand Karen McIntyrefor their collab- stresslevels. It arguesthat a psychometrically orationon thesmoking cessation project; the staff of soundglobal measure of perceived stress could Universityof Oregondormitory housing for their cooperationin securing Student Sample I; PamBirell providevaluable additional information about forher cooperation in obtaining class participantsfor therelationship between stress and pathology. SampleII; and to Susan Fiske,Lew Goldberg,Ed- Data are presented on the psychometric ward Lichtenstein,Karen Matthews, Michael propertiesof the Perceived Stress Scale (PSS), Scheier,and Tom Wills for commentson earlier draftsof thismanuscript. an instrumentdeveloped in responseto these Addresscommunications to: SheldonCohen, De- issues.The PSS measuresthe degree to which partmentof Psychology,Carnegie-Mellon Univer- situations in one's life are appraised as sity,Pittsburgh, PA 15206. stressful. 386 JOURNAL OF HEALTH AND SOCIAL BEHAVIOR

Researchon the role of psychosocialand "event"is thecognitively mediated emotional environmentalstressors as riskfactors in both responseto theobjective event, not the objec- physicaland psychological illness has typically tiveevent itself (Lazarus, 1977;Mason, 1971). employedrelatively objective stressor mea- An importantpart of thisview is thatthis re- sures.This work includes studies of the effects sponseis notbased solelyon theintensity or of specificstressful events, such as unem- any otherinherent quality of the event,but ployment(Cobb and Kasl, 1977;Dooley and ratheris dependenton personaland contextual Catalano, 1980; Gore, 1978), bereavement factorsas well. (Stroebeet al., 1982),and exposureto intense The assumedcentrality of thecognitive ap- levels of noise (Cohen and Weinstein,1981) praisal process suggeststhe desirabilityof and high levels of population density measuringperceived stress as opposed or in (Sundstrom,1978). In addition,there is an additionto objective stress. For example, abundantliterature on thecumulative effect of comparisonof the predictivevalidities of ob- objective stressfullife events (Dohrenwend jectiveand subjectivemeasures could help to andDohrenwend, 1974, 1981). In thesestudies, clarifythe role of theappraisal process in the variousversions of life-eventscales (original relationshipbetween objective stressors and scale developedby Holmes and Rahe, 1967) illness.Perceived stress scales could also be are used to producea cumulativestress score. used in conjunctionwith objective scales in an These scores are usuallybased on eitherthe effortto determinewhether factors such as numberof events that have occurred within the social support(Pearlin et al., 1981),hardiness specifiedtemporal framework (in mostcases, (Kobasa, 1979),and locus of control(Johnson six to 12months) or on a sumof event weights and Sarason, 1979) protectpeople fromthe thatare based on judges' ratingsof thediffi- pathogeniceffects of stressfulevents by alter- cultyof adjustingto theseevents. ingstressor appraisal or by altering the process Thereare some clear advantages to objective or processesby whichappraised stress results measuresof stressfulevents. First, such mea- in physiologicalor behavioraldisorders (Gore, surespermit an estimateof theincreased risk 1981).Finally, perceived stress can be viewed fordisease associatedwith the occurrenceof as an outcomevariable-measuring the experi- easily identifiableevents. Second, the mea- encedlevel of stressas a functionof objective surementprocedure is oftensimple, e.g., did stressfulevents, coping processes, personality thisevent occur duringthe last six months?, factors,etc. and in manycases, personsexperiencing a Previouswork has employeda numberof particularevent can be identifiedwithout the approachesto assess bothglobal and event- necessityof asking them about the occurrence specificlevels of perceivedstress. For exam- of the event, e.g., personsliving in noise- ple, severalinvestigators have modifiedlife- impactedcommunities. Third, these measure- eventscales in an attemptto measureglobal menttechniques minimize the chance of vari- perceivedstress. The modificationinvolved ous subjectivebiases in the perceptionsand askingrespondents to ratethe stressfulness or reportingof events. impactof each experiencedevent. In general, On theother hand, the use ofobjective mea- life-stressscores based on self-ratingsofevent suresof stress implies that events are, in and of stressfulnessare betterpredictors of health- themselves,the precipitatingcause of pathol- relatedoutcomes than are scoresderived from ogy and illnessbehavior. This implicationis either a simple countingof events (unit- counterto theview that persons actively inter- weighting)or normativeadjustment ratings act withtheir environments, appraising poten- (Sarason et al., 1978; Vinokurand Selzer, tiallythreatening or challengingevents in the 1975).However, the increases in predictability lightof availablecoping resources (Lazarus, providedby these ratingsare small. It is 1966, 1977). From this latterperspective, noteworthythat any increasein predictability stressoreffects are assumed to occur only ofa weightedevent score over a simplecount when both (a) the situationis appraisedas of eventsis likelyto be smallsince alternative threateningor otherwisedemanding and (b) in- weightingschemes yield composite scores that sufficientresources are availableto cope with are substantiallycorrelated with the event the situation.The argumentis thatthe causal count(Lei and Skinner,1980). In short,cal- A GLOBAL MEASURE OF PERCEIVED STRESS 387 culatingglobal perceived stress levels on the ical scalethat can be administeredinonly a few basis ofreactions to individualevents assumes minutesand is easyto score.Because levels of thatperceived stress levels are very highly cor- appraisedstress should be influencedby daily relatedwith the numberof reportedevents. hassles,major events, and changesin coping Otherweaknesses of global perceivedstress resources,the predictive validity of the PSS is scalesthat are basedon a specificlist of events expectedto falloff rapidly after four to eight includean insensitivityto chronicstress from weeks. ongoinglife circumstances,to stress from Evidence is presented from three eventsoccurring in the lives of close friends samples-twoof college students and one ofa and family,from expectations concerning fu- more heterogeneouscommunity group-for tureevents, and fromevents not listed on the theconcurrent and predictive validities and the scale. internaland test-retestreliabilities of thenew Subjectivemeasures of responseto specific scale. The paper also examinesthe relative stressorshave also been widelyused, e.g., predictivevalidity of the PSS and two life- measures of perceived occupationalstress eventinstruments. Our premise is thatthe PSS (Kahnet al., 1964).There are, however, some shouldprovide a betterpredictor of health out- practicaland, theoretical limitations of mea- comesthan does a globalmeasure of objective suresof specific stressors. Practically, it is dif- stressors,such as life-eventscales. This should ficultand time-consumingto adequatelyde- occur because a perceivedstress instrument velop and psychometricallyvalidate an indi- providesa moredirect measure of the level of vidualmeasure every time a new stressoris stressexperienced by the respondent. Presum- studied.Theoretically, there is an issue of ably,it is thislevel of appraised stress, not the whethermeasures of perceivedresponse to a objectiveoccurrence of the events, that deter- specificstressor really assess a person'sevalu- minesone's responseto a stressor(s)(Lazarus, ationsof thatstressor. There is, in fact,evi- 1966, 1977).Also, the new measureis more dence that people often misattributetheir globalthan life-event scales. Thatis, it is sen- feelingsof stressto a particularsource when sitiveto chronicstress deriving from ongoing thatstress is actuallydue to anothersource lifecircumstances, to stressfrom expectations (Gochman, 1979; Keating, 1979; Worchel, concerningfuture events, to stressfrom events 1978; Worcheland Teddlie, 1976). Another notlisted on a particularlife-events scale, and problemwith measures of response to specific to reactionsto thespecific events included on stressorsis thatsuch measures imply the inde- any scale. pendenceof thatevent in theprecipitation of disease. However,it is likelythat the illness processis affectedby a person'sglobal stress METHODS level,not just by his/herresponse to a particu- lar event. Validationdata werecollected in threesam- The above discussion indicates the de- ples - two consistingof collegestudents and sirabilityof developingan instrumentto mea- one consistingof a moreheterogeneous group enrolledin sure a global level of perceivedstress. This a smoking-cessationprogram. The and articlepresents data on the PerceivedStress samples assessmentprocedures are de- Scale, a 14-itemmeasure of the degree to scribedbelow. whichsituations in one's lifeare appraisedas stressful.PSS itemswere designed to tap the Perceived Stress Scale (PSS) degreeto whichrespondents found their lives unpredictable,uncontrollable, and overload- The 14 itemsof the PSS are presentedin ing.These threeissues have been repeatedly AppendixA. PSS scores are obtainedby re- foundto be centralcomponents of theexperi- versingthe scores on theseven positive items, ence of stress (Averill,1973; Cohen, 1978; e.g., 0=4, 1=3, 2=2, etc., and thensumming Glass and Singer,1972; Lazarus, 1966,1977; acrossall 14 items.Items 4, 5, 6, 7, 9, 10,and Seligman,1975). The scale also includesa 13 are thepositively stated items. numberof directqueries about current levels The PSS was designedfor use withcommu- of experiencedstress. The PSS is an econom- nitysamples with at leasta juniorhigh school 388 JOURNAL OF HEALTH AND SOCIAL BEHAVIOR education.The itemsare easy to understand thathad occurredon a scale rangingfrom -3 and the responsealternatives are simpleto (extremelynegative) to +3 (extremelyposi- grasp. Moreover,as notedabove, the ques- tive),the format used by Sarasonet al. (1978). tions are quite generalin natureand hence Separatescores were generated based on self- relativelyfree of contentspecific to any sub- ratedimpact and unweightedevents. The un- populationgroup. weightedscore was the totalnumber of life The data reportedin this articleare from eventschecked. The score based on impact somewhatrestricted samples, in thatthey are ratingswas the summedimpact of checked younger,more educated,and containfewer events.The impactscore is nota puremeasure minoritymembers than the general population. of the occurrenceof objectiveevents, but In lightof thegenerality of scale contentand rathertakes into account the respondents' per- simplicityof languageand responsealterna- ceptionsof the events. tives, we feel thatdata fromrepresentative The Centerfor Epidemiologic Studies De- samplesof the generalpopulation would not pressionScale (CES-D) was employedas a differsignificantly from those reported below. measureof currentlevel of depressivesymptomatology(Radloff, 1977). Twentyitems, each representinga state characteristic or not College Student Sample I characteristicof a depressedperson, are rated on a four-pointscale to indicatethe frequency The respondentswere 332 (121 male, 209 of theiroccurrence during the last week. Re- female,two withsex not specified)freshman sponseoptions range from "rarely or noneof college studentsliving in dormitoriesat the thetime" to "mostor all of thetime." Universityof Oregon.The mean age of the Physicalsymptomatology was measuredby samplewas 19.01with a standarddeviation of the Cohen-HobermanInventory of Physical 2.75. All respondentsgave writtenconsent Symptoms(CHIPS). The CHIPS is a listof 39 allowingaccess to theirstudent health center common physical symptoms(Cohen and records. Hoberman, 1983). Items were carefully Measures. Respondents completed five selectedto excludesymptoms of an obviously scales: one measuredlife events; another so- psychologicalnature, e.g., feltnervous or de- cial anxiety; a third depressive symp- pressed.The scale,however, is primarilymade tomatology,fourth, physical symptomatology; up ofsymptoms, such as headache,back ache, and finallyperceived stress (the PSS). All in- acid stomach,that have been traditionally strumentswere completedduring a one and viewedas psychosomatic.Each itemis rated one-halfhour session. forthe degree to whichthat problem bothered A modifiedversion of the College Student or distressedthe individual during the past two Life-EventScale (CSLES) was used as a mea- weeks.Items are ratedon five-pointscale from sureof stressfullife events; the original scale "not at all" to "extremely."The CHIPS has was developedby Levine and Perkins(1980). beenfound to have adequatereliability and to This scale is composedof 99 itemsthat repre- predictuse of studenthealth services in the sentevents that fall into 14 different categories seven-weekperiod following completion of the characterizingthe adjustment demands of col- scale(r = .29and .22in independent samples). lege students,e.g., academic affairs,male- The Social Avoidanceand DistressScale femalerelationships, and familymatters. Nine (SADS) was used to measuresocial anxiety itemsdealing with health-related issues were (Watson and Friend, 1969). This 28-item not used in calculatinglife-stress scores be- true-falsescale taps boththe desireto avoid cause of the possibilitythat these items were others(social avoidance) and the experience of measuringthe same thingas items in the distressin social interactions(social distress). symptomchecklists. Analyses including the Utilizationof thestudent health center was studentsare re- unuseditems indicated that their exclusion - did also monitored.All university notaffect the results reported below. quiredto paya feethat provides for outpatient Respondentswere asked to indicatewhether medicalcare. The physiciansat the student each eventhad occurredduring the last year. healthcenter routinely fill out a standardized Theywere asked to ratethe impact of events formdescribing the problem(s)for which the A GLOBAL MEASURE OF PERCEIVED STRESS 389

studentwas treatedat each visit.The formis ing-ControlProgram. Participants were solic- based on the International Classification of itedthrough newspaper, television, and radio Diseases, 9thRevision (Commissionon Profes- advertisements.To qualifyfor participation in sionaland Hospital Activities, 1980) and allows theprogram, subjects either had to be married each visit to be classifiedas illness-relatedor livingwith a partner.The meanage of the (codes 001-779),injury- and poisoning-relatedsubjects was 38.4 years (s = 11.57). Thirty- (codes 800-999),or "other"(V codes), e.g., sevenpercent of the sample made over $25,000 receiveprophylactic vaccination. peryear, and 74 percenthad formaleducation For each student,the numberof visitsin beyondhigh school. They had been smoking each of thethree categories was recorded.Up foran averageof 20.9 years(s = 11.82).Only to three symptomsor problemscould be threeof the participantswere students;all of checkedfor any individualvisit. If the prob- thesewere graduatestudents, 25 to 31 years lems were all in the same category,only one old. Themean self-monitored baseline smoking visit was recordedfor thatcategory. If the ratewas 25.6 cigaretsa day. problemswere in differentcategories, a sepa- Treatment.Treatment groups met for six ratevisit was recordedfor each of the pertinent consecutiveweekly sessions lastingapprox- categories.When total visits (collapsing over imatelytwo hourseach. The targetquitting categories)were calculated,each visit was dateoccurred on thefourth session. Interven- countedas one, irrespectiveof whetherthere tion strategies included behavioral self- was a singleproblem or a numberof problems managementtechniques, nicotine-fading, and a in differentcategories. Both the number of ill- cognitive-behavioralrelapse preventionpro- ness visitsand the numberof totalvisits are gram.Overall, 64 percent(N = 41) ofthe sub- analyzedin thisreport. jects wereabstinent at the end of treatment. The numberof visits was calculatedfor each Measures. Duringa pretreatmenttesting of two independenttime blocks: the 44 days session,subjects completed a life-eventscale, precedingthe testingsession and the46 days a physical-symptomchecklist (CHIPS), and followingthe testing session. The initial44-day the PSS. The life-eventscale consistedof 71 periodwas usedas an indicatorof the base-rate normativelynegative events chosen from the of visits. UnpleasantEvents Schedule (Lewinsohn and Talkington,1979). This scale replacedthe one College Student Sample II used withstudent samples because it provided an itempool appropriateto the community Respondentsin thesecond sample were 114 population.Subjects identify the eventsthat membersof a class in introductorypersonality have happenedto themin thelast six months psychology(53 females,60 males,and one with and ratethe impact of each eventon a seven- sex notspecified) who received class creditfor pointscale, ranging from extremely negative to participatingin thestudy. The meanage ofthe extremelypositive. As in the collegestudent samplewas 20.75with a standarddeviation of samples,both the numberof eventsand the 4.41. These studentscompleted the samefive event-impactscores were analyzed. questionnairesas thosein the previousstudy Subjectscompleted the PSS and theCHIPS duringa one and one-halfhour session during priorto the firsttreatment session and at the the second week of the SpringQuarter. For endof the six-week treatment. Both tests were thissample, the data on healthservices utiliza- administeredin the same manneras withthe tionwere dividedinto the 90 days preceding collegestudent samples, except that with the the testingsession and the 46 days following groupof smokers,a one-weektime frame was thetesting session. The 90-day period was used used forthe CHIPS. as an indicatorof thebase-rate of visits. RESULTS Smoking-CessationSample Means, Variance and ReliabilityEstimates Subjects.Subjects were 27 malesand 37 fe- malesparticipating ina smoking-cessationpro- Mean scores on the PSS forthe complete gramrun by the Universityof OregonSmok- samples(males and femalescombined) were 390 JOURNAL OF HEALTH AND SOCIAL BEHAVIOR

23.18and 23.67 in the student samples and 25.0 and femalesin each sample.The relativemag- in thesmoking-cessation sample. Standard de- nitudesof the correlationsfor males and fe- viationswere 7.31, 7.79, and 8.00,and ranges maleswith each ofthe criteria were compared were6 to 50, 5 to 44, and 7 to 47. Mean PSS by transformingthe correlationsto z scores scoresfor females were 23.57 and 25.71in the (Fisher'stransformation) and dividingthe dif- studentsamples and 25.6 in the communityference between the z scoresby the standard sample.Standard deviations were 7.55, 6.20, errorof the differencebetween the z coeffi- and 8.24. Mean PSS scores for males were cients(cf. Guilford,1965). None of theresult- 22.38and 21.73 in the student samples and 24.0 ingz scoreswere significantly different from 0 in thecommunity sample. Standard deviations at thep < .05 level. Since therewere no dif- were 6.79, 8.42, and 7.80, respectively.Al- ferencesbetween males and females, only data thoughthe mean PSS score forfemales was forthe entiresample are reportedbelow. slightlyhigher than the mean score for males in Separatecorrelations between the PSS and all threesamples, this difference did not ap- validitycriteria were also calculatedfor those proachstatistical significance in any sample. below and above medianage in the smoking Age was unrelatedto PSS in all threesam- cessationsample. These analysesseemed un- ples. Since the age distributionin thecollege ncessaryin thestudent samples, since 98 per- studentsamples was severelyskewed, a cor- centof the studentswere between 16 and 25 relationbetween the PSS andage was unlikely. years old. The 31 persons in the "young" Thecorrelations between age andPSS were.04 communitygroup ranged from 22 to 35. The 33 and -.08 in the college samples and -.02 in the personsin the"old" groupranged from 36 to smoking-cessationsample. 70. Correlationsfor young and old werecom- Coefficientalpha reliability for the PSS was paredwith the same procedure described in the .84, .85, and .86 in each of thethree samples. foregoing.Only one ofthese comparisons indi- For a state measure,test-retest correlations cateda statisticallysignificant difference at the shouldbe muchhigher for short retest intervals p < .05 - actuallyp < .01 - level. Data on thanfor longer ones. For thePSS, two inter- thiscomparison are presentedin theappropri- valsare available, two days and six weeks. The ate sectionin the following and addressed in the PSS was administered,on twooccasions sepa- discussionsection. ratedby two days,to 82 collegestudents en- Correlations between PSS and Life-Event rolledin coursesat theUniversity of Oregon; Scores. Since perceivedstress should gener- when respondingto the retest,the subjects ally increase with increases in objective wereasked to strivefor accuracy rather than cumulativestress levels, the PSS shouldbe for consistencyacross time. The test-retestrelated to thenumber of life events. Moreover, correlationin this sample was .85,whereas the thesecorrelations should be higherwhen the correlationwas only.55 forthe 64 subjectsin life-eventscores are based on the self-rated thesmoking study who were retested after six impactof the events,since impact scores re- weeks. flectsome of thesame stressorappraisal measuredby thePSS. As apparentfrom Table 1, Evidence for Concurrentand thereis a small to moderatecorrelation be- Predictive Validity tweennumber of life events and thePSS in all threesamples. Moreover, in all butone case, Separatecorrelations between the PSS and thatcorrelation increases when the scale score the validitycriteria were calculated for males takesinto account the respondent's perception

TABLE 1. Correlationsbetween Life-Event Scores and PSS

Smoking-CessationStudy College Student College Student Beginningof End of Sample I Sample II Treatment Treatment Number of Life Events .20* .17 .38* .39* Impact of Life Events .35* .24* .49* .33* *p<.Ol. A GLOBAL MEASURE OF PERCEIVED STRESS 391

TABLE 2. Correlationsof Stress Measures with De- than that the stress caused the symp- pressiveSymptomatology tomatology. In regard to establishingthe validityof the CollegeStudent College Student SampleI SampleII PSS, it is importantto note the substantialcor- relations between the scale and both symp- Numberof Life Events .18* .14 tomatologymeasures. There is probablysome Impactof overlap between what is measured by the de- Life Events .29* .33* pressive symptomatologyscale and what is Perceived measured by the PSS, since the perceptionof StressScale .76* .65* stress may be a symptomof depression. This *p<.001. may, to some degree, account for the mag- nitude of that correlation.In lightof the very of the events. Hotelling t-tests, testing the high correlation between the PSS and the statisticalsignificance of differencesbetween CES-D (depressive symptomscale), it is desir- correlations,indicate that this increase is sig- able to demonstratethat these scales are not nificant(p < .05) forStudent Sample I and for measuringthe same thing.Hence, partialcor- the smoking-cessationsample at the beginning relationswere calculated; in these, depressive of treatment. symptomatologywas partialledout of the cor- There was a differencein the correlation relationsbetween the PSS and physical symp- between PSS and numberof negative events tomatology,and the PSS was partialledout of for young and old participantsin the smoking the correlation between depressive symp- cessation sample. For the young, the correla- tomatologyand physical symptomatology.In tion was .65 (p < .05); forthe old, it was .19. the case of PSS and physical symptomatology, PSS Versus Life Events as a Predictor of the correlationwas .16, p < .01, for sample I Symptomatology. As noted earlier, we ex- and .17, p < .07, for sample II. In the case of pected thatthe PSS would be a betterpredictor the CES-D and physical symptomatology,the of the various health outcomes than would correlationwas .31, p < .01, in sample I and stressfullife-event scores. The data presented .38,p < .01, in sample II. Hence, even withthe in Tables 2 and 3 supportthis prediction in the very high correlation between the PSS and case of both depressive and physical symp- CES-D, both scales still independentlypre- tomatology.Hotelling t-test (p < .05) provide dicted physical symptomatology. statisticalsupport for these differencesin all PSS Versus Life Events as a Predictor of cases. Since these are cross-sectionalcorrela- Utilization of Health Services. Table 4 pre- tions, no causal inferencesare implied. For sents the correlations between the PSS and example, it is possible that increased symp- utilizationof health services, both before and tomatology caused increased stress, rather afteradministration of the scale. In Sample I, the PSS significantlypredicted utilization during the five-weekperiod aftercompleting the TABLE 3. Correlations*of StressMeasures with PhysicalSymptomatology TABLE 4. Correlationsof PSS and HealthCenter College College Smoking- UtilizationBefore and AfterCompleting Student Student Cessation Scale SampleI SampleII Studya Numberof Student Student Life Events .31 .36 .40 SampleI SampleII Impactof BeforeScale Administration Life Events .23 .32 .51 PhysicalIllness Visits .08 -.06 Perceived All Visits .11* -.05 Stress Scale .52 .65 .70 AfterScale Administration a Sincethe life-events questionnaire was adminis- Physical Illness Visits .17** .04 tered only at beginning of treatment,only All Visits .20*** .12 beginning-of-treatmentdata are presentedso that *p<.05. PSS and life-eventcorrelations are equivalent. **p<.0l. * p <.001 forall correlations. ***p <.001. 392 JOURNAL OF HEALTH AND SOCIAL BEHAVIOR scale. In SampleII, therewas a nonsignificantcoefficient alpha reliabilityestimate for the correlationbetween the PSS andall visitsafter four-itemPSS was .72. The test-retestreliabil- administrationof the scale. Correlationbe- ity of the four-itemscale over a two-month tweenthe PSS and physicalillness visits after intervalwas .55. administrationof the scale, withbefore-ad- The four-itemscale at one monthwas corre- ministrationvisits partialled out, was .15,p < lated(.3 1,p < .01) withthe average number of .007, for Sample I and -.02 for Sample II. cigarettessmoked per day at one month;the Similarpartial correlation for the PSS and all latterinformation was froma self-reportcon- visitsafter administration, with all preadmin- firmedwith a carbon monoxidemeasure. istrationvisits partialled out, was .16,p < .01, Similarly,the four-item scale at threemonths forSample I and .13 forSample II. Thesecor- was correlated(.37, p < .001) withsmoking relationssuggest that the PSS is predictiveof rate at threemonths. Finally, the shortPSS changesin healthcenter utilization. Correla- scale at one monthafter treatment predicted tionsof life-eventscores with utilization were smokingrate three months after treatment (.39, notsignificant in bothsamples for both physi- p < .001). In all cases, the greaterthe PSS cal illness and all visits; these correlations score,the more cigarettes smoked. A number rangedfrom -.04 to +.03. ofpartial correlations were calculated to clarify PSS Versus Life Events as a Predictor of the natureof the relationshipbetween the Social Anxiety.Levels of perceivedstress in abridgedversion of the PSS and smokingrate. collegestudents, especially freshmen, should In the firstpartial correlation, the end-of- be relatedto theirability to becomeintegrated treatmentPSS score and smokingrate were intothe university community. We wouldex- partialledout of the correlationbetween the pectthat the poorer the integration, the greater four-itemPSS and smokingrate at one month theperceived stress. The social anxietyscale followingtreatment. The partialcorrelation providesa traitmeasure that presumably taps was .29,p < .01. In thesecond correlation, the difficultyinmaking friends and social contacts, four-itemPSS and smokingrate at one month i.e., theability to integrate into the community. following treatment were partialled out of the In bothstudent samples, increases in social correlationbetween the four-itemscale and anxietywere associated with increases in per- smokingrate at threemonths. The partialcor- ceivedstress (.37 and .48,p < .001for both). relationwas .34,p < .01. These analysesindi- Althoughnumber of lifeevents was unrelated cate thatchanges-in perceived stress as mea- to social anxietyin bothsamples, there were suredby thePSS are predictiveof changesin smallcorrelations between event impact and smokingrate. Another partial correlation indi- social anxiety (-.13, p < .02, -.26, p < .01). catedthat the abridged PSS predictedchanges Again,these are cross-sectionaldata and no in smokingrate over a two-monthperiod. Spe- causal inferencesare implied. cifically,a correlationof .26 (p < .05) was PSS and Smoking-ReductionMaintenance: foundwhen smokingrate at the one-month The Four-Item Scale. To examine the role of follow-upwas partialledout of thecorrelation the PSS as a predictorof maintenanceof betweenthe four-item PSS at one monthand smoking-ratereduction, perceived stress level smokingrate at threemonths. These data sug- was also assessed one and threemonths fol- gestthat the four-item scale providesa useful lowing treatment.Since posttreatmentdata measureof perceivedstress for use in tele- werecollected by telephoneinterview, a short phoneinterviews and othersituations where a versionof the scale, consistingof the four veryshort scale is required. items(numbers 2, 6, 7, and 14) thatwere cor- relatedmost highly with the 14-item scale, was employed.The mean score on the four-itemDISCUSSION scale was 5.6 at one monthand 5.9 at three months.Standard deviations were 3.6 and4.0, The PSS has adequate internaland test- and thescores ranged from 0 to 15and 0 to 14. retestreliability and is correlatedin the ex- Mean PSS scores formales were 4.8 at one pectedmanner with a rangeof self-reportand monthand 5.9 at three,while mean scores for behavioralcriteria. Moreover, the PSS is more femaleswere 6.2 and 5.9, respectively.The closely relatedto a life-eventimpact score, A GLOBAL MEASURE OF PERCEIVED STRESS 393 whichis to somedegree based on therespon- eventscales willbe predictiveover fairly long dent'sappraisal of theevent, than to themore periods,such as several monthsto several objectivemeasure of the number of events oc- years.2 We have examined the predictive curringwithin a particulartimespan. The PSS abilityof the PSS overfour to 12week periods also provedto be a betterpredictor of health afteradministration. These data suggestthat and health-relatedoutcomes than either of the the best predictionsoccur withina one- or two life-eventscales. Finally,the PSS, al- two-monthperiod. It is ourfeeling that as this though highlycorrelated with depressive periodis lengthened,the predictive validity of symptomatology,was foundto measurea dif- thescale willfall. After all, perceivedlevels of ferentand independentlypredictive construct. stressshould be influencedby dailyhassles, It is noteworthythat the level of correlation major-events,and changes in the availability of betweenthe life-eventscales and the symp- copingresources, all of whichare quitevari- tomatologicaloutcomes (.18 to .36 range)is able over a shortperiod. In fact,test-retest equivalentto,'if not better than, similar corre- reliabilityanalyses indicate that test-retests in- lationsreported in the literature(cf. Rabkin volvinga veryshort time (two days) resultin and Struening,1976; Tausig, 1982). Hence, the fairlysubstantial correlations, whereas admin- superiorpredictability ofthe PSS is notattrib- istrationssix weeks later produce more moder- utableto psychometricweaknesses in thelife- ate test-retestcorrelations. eventscales thatwere employed or to idiosyn- As mentionedearlier, the PSS can be usedto cratic aspects of the samples under study. determinewhether "appraised" stressis an Moreover,from an absoluteperspective, the etiological(or risk)factor in behavioraldis- PSS correlationswith symptomatological mea- ordersor disease. It can also be used to look suresare quitehigh (.52 to .76). However,in moreclosely at theprocess by whichvarious the case of depressivesymptomatology, the moderatorsof the objective stressor/pathology correlationmay be somewhatinflated by the relationshipoperate. For example,we could overlapin the operationaldefinitions of per- determinewhether social support protects one ceived stress and of depressive symp- fromthe pathogenic effects of stressfulevents tomatology(cf. Dohrenwend et al., 1978;Gore, by alteringthe appraisal of thoseevents or by 1981). alteringthe process by whichappraised stress In general,the relationshipsbetween PSS causes an illnessoutcome. This second kind of and thevalidity criteria were unaffected by sex analysis,however, is limitedto thedegree that or age. The one exceptionwas the strongre- thePSS reflectsresponses to eventsoutside of lationshipbetween the PSS and numberof life thosemeasured by theobjective event instru- eventsfor the youngand the lack of such a ment.That is, it is limitedto thedegree that it relationshipfor the old. Thesedata may reflect is moreglobal than the objective stressor mea- a differencein therole of lifeevents in deter- sure.Finally, the PSS can be used as an out- miningstress levels for these two age groups. come variable, measuringpeople's experi- Thatis, otherchronic stressors, expectations, encedlevels of stress as a functionof objective etc. maybe moreimportant for the olderre- stressfulevents, coping resources, personality spondents. factors,etc. The PSS differsfrom life-event scales in a The four-itemversion of the PSS providesa numberof ways. First,the PSS asks abouta usefultool whendata mustbe collectedover shorterperiod, one monthas opposedto the the phone. This scale makes repeatedmea- usual six to 12 monthscovered by typicallife- sures of perceivedstress in large samples event scales.1 It is worthnoting that with a feasible.It shouldbe noted,however, that be- subjectivescale, the shorterperiod should be cause of the limitednumber of items,the sufficientsince perceived stress during the last abridgedscale suffersin internal reliability and monthshould reflect any objective events that thusprovides a less adequateapproximation of are stillaffecting respondents' stress levels. perceivedstress levels than the entire scale. A seconddifference between the PSS and a Althoughnot testedin thisstudy, the PSS life-eventscale is theperiod of timeafter ad- may also providean economicaltool foras- ministrationthat the scale providespredictions sessing chronic stress level. Either the of health-relatedoutcomes. Presumably, life- abridgedversion of the PSS or the complete 394 JOURNAL OF HEALTH AND SOCIAL BEHAVIOR

14-itemscale couldbe used. Monthlyadminis- independentpredictive validities of the PSS trationsof the scale couldbe summedor aver- and a depressive symptomatologyscale. aged,providing a reliable,i.e., based on more Hence, thePSS can be viewedas assessinga samples,measure of chronic stress, as wellas a statethat places people at riskof, i.e., is an- predictorthat represents a longer term than the tecedentto, clinicalpsychiatric disorder even one-monthperiod covered by the scale. thoughthat state is also partof a diverseset of Two commonly used measures of feelingsand statesthat are characteristicof nonspecificpsychological distress, the nine- disorder. scale, 54-itemPERI DemoralizationMeasure In sum, the PSS is a briefand easy-to- (Dohrenwendet al., 1980) and the 28-item administermeasure of the degree to which General Health Questionnaire(Goldberg, situationsin one's lifeare appraisedas stress- 1972),include a numberof items that are simi- ful.It has been provento possess substantial larto thosein the PSS. Thesescales, however, reliabilityand validity;thus, it providesa are muchbroader in scope. Theyare designed potentialtool forexamining issues aboutthe as epidemiological measures of symp- roleof appraised stress levels in the etiology of tomatology,and bothinclude a broadrange of disease and behavioraldisorders. itemstapping common psychiatric symptoms, such as hostility,diminished self-esteem, de- NOTES pression,and anxiety,as well as psychosomatic complaints.Although appraised stress 1. There are two recentlydeveloped life-event scales thatassess eventsover a one-monthpe- maybe symptomaticof psychologicaldisorder riod,the Hassle Scale (Kanneret al., 1981)and when viewed in combinationwith elevated the UnpleasantEvents Scale (Lewinsohnand scoreson otherpsychiatric symptoms, itis our Talkington,1979). contentionthat the perception of stressitself, 2. Pearlinet al. (1981)have pointed out that there is no singletime frame that is optionalfor observ- as assessed by the PSS, is not a measureof ingthe effects of diverselife events. However, psychologicalsymptomatology. This conten- existingworks, includingthe Pearlin et al. tionis, infact, supported by the data indicating study,examine rather long periods.

APPENDIX A: Items and Instructionsfor PerceivedStress Scale

The questionsin thisscale ask youabout your feelings and thoughtsduring the last month. In each case, youwill be askedto indicatehow often you felt or thought a certain way. Although some of the questions are similar,there are differencesbetween them and youshould treat each one as a separatequestion. The best approachis toanswer each question fairly quickly. That is, don'ttry to countup thenumber of times you felt a particularway, but rather indicate the alternative that seems like a reasonableestimate. For each questionchoose fromthe following alternatives: 0. never 1. almostnever 2. sometimes 3. fairlyoften 4. veryoften 1. In thelast month, how often have you been upset because of something that happened unexpectedly? 2. In the last month,how oftenhave you feltthat you wereunable to controlthe importantthings in yourlife? 3. In thelast month,how oftenhave you feltnervous and "stressed"? 4*a In thelast month,how often have you dealtsuccessfully with irritating life hassles? 5.a In thelast month, how often have you felt that you were effectively coping with important changes that wereoccurring in yourlife? 6.a In the last month,how oftenhave you feltconfident about yourability to handleyour personal problems? 7.a In thelast month,how oftenhave youfelt that things were going your way? 8. In thelast month,how often have youfound that you could not cope withall thethings that you had to do? 9.a In thelast month,how oftenhave you been able to controlirritations in yourlife? 10.a In thelast month,how often have you feltthat you wereon top of things? A GLOBAL MEASURE OF PERCEIVED STRESS 395

APPENDIX A (Continued)

11. In the last month,how oftenhave you been angeredbecause of thingsthat happened thatwere outside of your control? 12. In thelast month,how oftenhave you foundyourself thinking about thingsthat you have to accomplish? 13. aIn the last month,how oftenhave you been able to control the way you spend your time? 14. In the last month,how oftenhave you feltdifficulties were pilingup so highthat you could not overcome them? a Scored in the reverse direction.

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