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  • 00:01


  • 00:10

    TARANI CHANDOLA: My name is Tarani Chandola.I'm a Professor of Medical Sociology at the Universityof Manchester.I'm also the director of the Cathy Marsh Institutefor Social Research, which is a Social Science ResearchInstitute that specializes in quantitative social sciencemethods.My own research expertise is on work and health, particularly

  • 00:32

    TARANI CHANDOLA [continued]: around stress at work and how that affects your health.So to help do this kind of research,I've helped to collect and analyzedata on stressful working conditionsas well as biological and physiological reactionsto stress.Today, I'll be talking about the methods involvedin measuring stress at work.Stress at work is a really key issue for work-related health

  • 00:55

    TARANI CHANDOLA [continued]: conditions because around 30% to 40%off all work-related illnesses is caused by stress,depression, or anxiety.Nearly all of us at work have been stressed outat some point or the other.But methodologically, it's really quite hardto measure stress at work.You can't just, for example, ask people

  • 01:16

    TARANI CHANDOLA [continued]: the question, are you feeling stress at work,because there are all kinds of methodological issueswith those kinds of responses to those kind of questions.They are maybe the negative effect bias .So people may have a negative kind of personalitythat gets them to respond negativelyto all kinds of questions.

  • 01:37

    TARANI CHANDOLA [continued]: So it might not be actually a stress-generating wordcondition that's making them feel stressed at work.But it might be their personality typethat causes them to respond negatively to the question.Yes.I'm feeling stressed at work.Another important limitation is that weneed to know what is it that causes the stress at work?Is it a work-related condition or is it

  • 01:60

    TARANI CHANDOLA [continued]: something else that is causing somebody to say, yes.I'm feeling stressed at work?It might be some sort of family issues or money issuesthat is causing them to be feeling stress at work.So we need to separate out the stress-generating condition,the stress-generating work condition from the stressreactions.

  • 02:20

    TARANI CHANDOLA [continued]: So the stress-generating work conditioncould be something related to your boss, for example,or something related to your low pay at work,or something related to bullying or harassment at work.And so it's quite important to separate out these workstressor conditions from your physiological, biological and

  • 02:45

    TARANI CHANDOLA [continued]: psychological stress reactions.And that's the key point in measuring stress at work,because all too often when you read researchabout work-related stress, they conflatethe stressor, the work-related stressor,with the stress reaction.So you're never quite sure what's being measured.Is it people's stress responses or is it

  • 03:07

    TARANI CHANDOLA [continued]: the work-related stressful condition?And that's the key mythological issuethat I wish to address in today's lecture.So first of all, we need to measure the work-related stresscondition, so the work stressors.And that's usually done through validated questionnaires.

  • 03:27

    TARANI CHANDOLA [continued]: We need to establish the measurementequivalents of these questions.So we need to make sure that these stressful workconditions mean the same thing in different cultures,in different languages, and different countries.But thankfully, there are quite a fewestablished and validated work-related questionnairesaround now that are being used in work stress research.

  • 03:48

    TARANI CHANDOLA [continued]: One example is the job demands control questionnaire,where you get people ask questions on their job control,such as to what extent they're able to do their work,when or how they wish to do their work.And the second aspect is the drop demands question,which is about asking people to what extent

  • 04:10

    TARANI CHANDOLA [continued]: they have to work very fast or very intensively.So the job demands control questionnaire has been aroundsince the 1980s.And that's a very established validated questionnaireon measuring work-related stressors.Another slightly more recent questioner,the effort-awarding imbalance questionnaire,has been around since the 1990s.

  • 04:30

    TARANI CHANDOLA [continued]: And that also measures stressful working conditionsby measuring how much effort people put in at work,and what rewards they get out from that work,and any imbalance between the efforts that they put in,and the rewards that they get out from work.So when you do have an imbalance,that's supposed to be a stress-generating workcondition.

  • 04:53

    TARANI CHANDOLA [continued]: Then we need to measure the biological or physiologicalstress response.And there are two main kinds or biological stress responsesthat have involved in humans and other animalsto deal with stressful situations, fight or flightconditions.These are the parasympathetic and sympathetic nervous system

  • 05:14

    TARANI CHANDOLA [continued]: and the hypokalemic pituitary adrenal, or HPA axis.And both these systems, both these biological systemsgive us the energy to either fightor run away from the potentially dangerous situation.However, measuring biological stress responsesit's not something you can easily to in a questioner.

  • 05:37

    TARANI CHANDOLA [continued]: It involves measuring these methods mechanisms,these biological mechanisms, indirectly through levelsof stress hormones.That's not easy to detect.So for example, the stress hormone adrenalineis very quickly dissipated throughout your bodyonce the stressful situation has occurred.So there's no point measuring adrenaline in your body

  • 06:00

    TARANI CHANDOLA [continued]: long after your work-related stressor has occurred.You can measure it in laboratory-type situationswhere you can sort of experiment and get people to respondto a stressful situation such as putting their handin a bucket of ice water.

  • 06:22

    TARANI CHANDOLA [continued]: So that's the core pressor test.That's quite stressful.Or else, getting people to do complicated arithmetic,asking them to subtract the numbers seven or 13from a very large number, and askingthem to do that repeatedly.So that's a physical as well as an example of a mental stressor

  • 06:43

    TARANI CHANDOLA [continued]: that corresponds directly to increase levelsof the stress hormone adrenaline circulatingin somebody's blood.But the thing is, once that stress-generating situationis finished, the levels of adrenaline in your bodyquickly reduce back to almost nothing.So it's very hard to detect these stress hormones

  • 07:08

    TARANI CHANDOLA [continued]: long after the stressful situation has occurred.The other thing is that these stressful tests,like the mental arithmetic test or the cold pressor tests,it's nothing to do with people's working conditions.So you're not really measuring work-related stressorsin a laboratory-type situation.

  • 07:31

    TARANI CHANDOLA [continued]: What you can measure is stress hormones like cortisolassociated with the HPA axis.And these stress hormones are slowerto dissipate throughout your body.So they remain in your body throughout the day.And in fact, cortisol, like nearly all the stresshormones, show a diurnal response.

  • 07:51

    TARANI CHANDOLA [continued]: So when you wake up in the morning,your cortisol levels are activated.And they peak to around about 20 to 30 minutes after awakening.And they return back to almost negligible levelswhen you're about to sleep at night-- so at bedtime.So it's this decline in your cortisol levels

  • 08:13

    TARANI CHANDOLA [continued]: from awakening that is a measure of your biological stressreactivity.So you're said to have a healthier stress profile whenyou have a steeper slope in your cortisol decline over today.And you're said to have an unhealthier stress profile whenyou have a less steep slope of cortisol decline

  • 08:37

    TARANI CHANDOLA [continued]: during the day, so that your bedtime cortisol levels remainquite high and elevated and not negligiblewhen you go to sleep.So how do you measure cortisol?Well, you can measure cortisol through people's blood.But asking people to get injected many times a day

  • 08:59

    TARANI CHANDOLA [continued]: is potentially quite stressful.And also it's not really a great way of measuring things.It's not convenient for the participant.And it's not convenient for the data collector.You can also measure cortisol in people's urine.But also, collecting bags of urine throughout the day thisalso not very easy.It's not an easy thing to do.

  • 09:19

    TARANI CHANDOLA [continued]: So a less invasive procedure has beendeveloped where we ask people where we collect cortisolfrom people's saliva.And we can do this by giving people little cotton swabsand asking them to put them into their mouthand saturated with their saliva for a couple of minutes or so.

  • 09:40

    TARANI CHANDOLA [continued]: And once that's done, they put their saliva swabsinto a test tube.And they do that repeatedly when they wake up in the morning,20 or 30 minutes after they wake up,and at regular times during the day until they go to bed.So we get these swaps of cotton wool placed

  • 10:01

    TARANI CHANDOLA [continued]: in test tubes, which can then be placed in a padded envelopeand posted back to the data collectorsjust like they would do so with the postal questioner.And that's really quite a simple and non-invasive procedurethat can be done to collect the stress hormone, cortisol.And once those test tubes of cotton swabs of saliva

  • 10:24

    TARANI CHANDOLA [continued]: are sent back, they get sent to a lab to get processed.And we get back the results that tell uswhat the levels of cortisol were at particular timesduring the day.So once we get back these diurnal cortisol valuesthroughout the day, we then need to analyze these repeated

  • 10:46

    TARANI CHANDOLA [continued]: measures of cortisol.And there are two main ways of doingthis kind of repeated measures.Analysis, that's by using growth curve models.Or, we can use latent class or latent trait models.So I'll describe do the growth curve models, first of all.And that's a very popular method of analyzingrepeated measures such as repeated collections

  • 11:07

    TARANI CHANDOLA [continued]: of diurnal cortisol data.So we use growth curve models to estimate an average slopeof diurnal cortisol values.And we want to see to what extent certain groups of peoplehave a different diurnal slope than other groups of people.So we want to see in particular whether people

  • 11:28

    TARANI CHANDOLA [continued]: who score high on the work-related stressor questionnaires, such as the effort-reward imbalance,or job control-- job demands questionnaire,whether those groups of people havea higher than average slope of cortisol declinecompared to people who have a much steeper slopes of declineof diurnal cortisol decline, if they have

  • 11:51

    TARANI CHANDOLA [continued]: better work-related conditions.And so it's this difference in slopesthat growth curve models enables us to estimate.And we want to see whether the flatter slopes, so slopes whichdon't decline as fast, have a higher than average slope,

  • 12:12

    TARANI CHANDOLA [continued]: and whether these are really peoplethat have higher than average work stressor conditionscompared to the people who have a steeper slope of decline,and whether these are people thathave better working conditions.So in the paper that we've seen this slide,this is a paper that looked at the effort-reward imbalancequestionnaire in relation to the slope

  • 12:34

    TARANI CHANDOLA [continued]: of diurnal cortisol profile using growth models.So the green line denotes the groupof people with higher than average effort award imbalance.So these are people that have-- that'scalled more than two standard deviationsabove the mean effort-award imbalance.So these are people that put in too much effort at work

  • 12:57

    TARANI CHANDOLA [continued]: and get very little reward from their work.And this group of people we can seehave a flatter slope of the diurnal cortisol declinecompared to the people in the blue line who had a lowereffort award imbalance.In other words, they were getting a lot of rewardsfor much less effort at work.

  • 13:19

    TARANI CHANDOLA [continued]: So this is one kind of model that youcan use to look at the diurnal slope of cortisol decline,the growth curve model.And you look at different slopes of-- youuse it to estimate different slopesof diurnal cortisol decline for different groups of people,such as people who score high or low on the work stressorquestionnaires.

  • 13:45

    TARANI CHANDOLA [continued]: The other method of distinguishingbetween different groups or different patternsof diurnal cortisol decline is to use a latent class or latenttrait method.And here we don't directly estimate the slopeof diurnal cortisol decline.But instead, we try to observe from the patternof correlations in the data whether there

  • 14:06

    TARANI CHANDOLA [continued]: are some groups of people that havea higher than average cortisol levelsthroughout the day and other groups of peoplethat have lower than average cortisol levelsthroughout the day.So as I said, this is in contrastto the first method, the growth curve model method, wherewe directly estimate the slope.But in this method, we don't directly estimate the slope.

  • 14:29

    TARANI CHANDOLA [continued]: But instead, we use a pattern of correlationsin the data, the repeated measures of cortisol declineto try and get at distinguishing between twoor more groups or people with different patternsof diurnal cortisol values throughout the day.In the slide that we're seeing right now,we actually found two potential groups

  • 14:49

    TARANI CHANDOLA [continued]: of latent classes of diurnal cortisol declinethroughout the day.The class that's denoted by the pink lineare the ones with elevated stressresponses throughout the day.And this is using the latent traitmethod, which is in contrast to the growth curve model method.Using this particular method, we didn't observe any correlations

  • 15:10

    TARANI CHANDOLA [continued]: with work-related stressors unlike using the growth curvemodel in the previous slide.Now, it's really important to keep confounders in mindwhen you're doing this kind of analysis.We always need to remember that we're reportingwhat we hear are correlations.So we are reporting correlation between somebody's responses

  • 15:32

    TARANI CHANDOLA [continued]: to a work-related stress questionnaireand the correlation with their cortisol levelsduring the day time.Now, there may be all kinds of reasons or constant factorswhy somebody has elevated stress levels of hormone circulatingin their system throughout the day.There may be problems at home in their family life.

  • 15:54

    TARANI CHANDOLA [continued]: They may have money problems thatis causing their elevated stress levels of cortisol thatis nothing to do with their work-related stress generatingcondition.Sometimes we can measure some of these background confoundingfactors.But it's very unlikely that we'llmeasure all the background potential confounding factors.

  • 16:16

    TARANI CHANDOLA [continued]: So it's always important to keep in mind that we're justlooking at observational data here,not experimental data here, and that we're never really quitesure whether the work stress-generating condition isgenerating the stress hormone cortisol response.

  • 16:37

    TARANI CHANDOLA [continued]: So even though we've been really careful in measuring the stresshormone cortisol and we've been really careful measuringthe work-related stressful condition,we can never be entirely sure whether oneis cause of the other.The key conclusion here is whenever

  • 16:58

    TARANI CHANDOLA [continued]: you read a piece of research on work-related stress or stressat work, you really need to ask the question,has this piece of research measured work stress properly?Have they managed to separate outthe stress-generating working conditionfrom the stress response?Another method that I didn't mentioned earlier--you can also measures cortisol through people's hair samples--

  • 17:19

    TARANI CHANDOLA [continued]: is becoming-- these kinds of biomarkers of stressare becoming more and more available in surveys,in standard surveys.So there's no excuse why we shouldkeep relying on using questionnaires to just measurework-related stress when there areall kinds of problems with people's answers

  • 17:40

    TARANI CHANDOLA [continued]: to a questionnaire.So the key thing to remember now isthat even though you're running a surveyand you're interested in stress, youmight feel that how do I measure a biological stress reaction?The answer is that it's become even morefeasible to do that because they'restandardized ways of collecting these biological stress

  • 18:01

    TARANI CHANDOLA [continued]: responses, which can be analyzed in lab.And you can get these objective markersof people's biological stress responsesand separate out the stress responsefrom people's stress-generating conditionthat you can measure in a question.[MUSIC PLAYING]

Video Info

Publisher: SAGE Publications Ltd.

Publication Year: 2017

Video Type:Video Case

Methods: Measurement, Psychometrics, Growth curve modelling, Survey research

Keywords: cortisol; cortisol and stress; diurnal rhythm; effort-reward imbalance; parasympathetic nervous system; physiological stress; Stress (psychological); Stress at work; Stress: biological aspects; Stressors; Sympathetic nervous system ... Show More

Segment Info

Segment Num.: 1

Persons Discussed:

Events Discussed:



Professor Tarani Chandola explains how stress at work can be measured. He discusses different methods for collecting data about the stress levels of workers, and he points out inaccuracies that can occur when performing stress research.

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Measuring Stress at Work: Combining Biological and Social Science Data

Professor Tarani Chandola explains how stress at work can be measured. He discusses different methods for collecting data about the stress levels of workers, and he points out inaccuracies that can occur when performing stress research.

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