Example Exam Essay: Prevalence rates of one health problem (IB Health Psychology)

Travis DixonHealth Psychology

Discussing prevalence "rates" of stress is literally impossible. So how do you answer this exam question? Here's how...

Discussing “prevalence rates” is easy when you’re writing about psychological disorders. That’s because these disorders have standardized diagnoses. You can calculate a specific % of the population who have depression, for example, and that is your “prevalence rate.” It might be more difficult in Health Psychology.

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For some health problems the same is true. Obesity, cardiovascular disease and addiction are examples of health problems that can be diagnosed and a % prevalence rate calculated. This data allows us to discuss changes over time and different %s in different groups (e.g. gender, socioeconomic status, countries, race, etc.)

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Stress, on the other hand, does not have a diagnosis. Psychologists don’t diagnose someone as “stressed.” There isn’t even a universally agreed upon definition of stress. This makes it difficult to compare across time and populations.

So how can we discuss prevalence rates of stress? This was actually the topic in the Nov 2020 exam question (the exact question was: Using one or more health problems as examples, discuss prevalence rates.) The marking guide defined “prevalence rate” as “the proportion of a population who have a specific characteristic at any given time.” We have literally no idea of what proportion of the population at any time is “stressed.” Disappointingly, the IB assessment team didn’t use the opportunity to address this issue in the marking guide. Also, despite stress being by far the most common health problem taught by teachers for this option, not a single study in their list of suggested studies was about stress.

So, I have attempted to demonstrate how you could answer this question in the following example essay. Here are the key points to remember:

  1. Identify the specific population(s) you’re discussing (e.g. gender, race, status, age, etc.)
  2. Describe who has higher levels of stress.
  3. Use the word “prevalent” where you can, instead of “prevalence rates.”
  4. Explain how and why they have higher levels of stress, using supporting evidence.
  5. Evaluate the studies.
  6. Address the issue of discussing “prevalence rates” when talking about stress and explain why it’s impossible to do so.


Discuss prevalence rates of one health problem.
One health problem is stress and the prevalence rates of this problem can be discussed by looking at social status. In particular, people with low socioeconomic and subjective social status have higher reported rates of stress than others. This is shown in studies like Steen and Rahal. However, the explanation might not just be about social factors, other factors like ACEs are also important to consider and are related to status. Furthermore, it’s difficult to discuss “prevalence rates” of stress, for reasons which will be discussed later in this essay. Question is restated in opening line. This guarantees 1 mark for Criterion A.  Introduction outlines the entire scope of the essay.
The prevalence rate of a psychological disorder or health problem refers to how common it is in a specific population. Higher levels of reported stress are more prevalent in people with low social status. Socioeconomic status (SES) is a type of social status which is measured by income, education, and occupation. People with higher social status tend to have lower levels of stress. They also have fewer health problems, they live longer and have lower rates of stress, cardiovascular disease and obesity. Prevalence rate is defined. The specific prevalence issue is outlined.
However, one problem with studying socioeconomic status and stress is that it’s not as reliable to study in teenagers. Researchers prefer to use Subjective social status (SSS), which is a person’s perceived social rank. It is used in studies of social status and stress in teenagers because SSS is a better predictor of health for teenagers compared to SES. Generally speaking, higher SSS is associated with better health. Knowledge is shown of the study through detailed description of relevant details of social status.

 Terminology is used appropriately.   

The prevalence of reported stress in teenagers and its link with subjective social status was studied by Steen et al. The aim of the study was to see if SSS is linked with perceived stress in school in Danish teenagers. The researchers measured the SSS in over 8,000 Danish 9th graders (15-16 years old). The Perceived Stress Scale (PSS) was used to assess stress levels and the scores showed an average score of 14.7/40. Girls were more stressed than boys (16.3 compared to 12.6) – a common finding in stress studies. Overall, low SSS (3% of participants) was associated with higher perceived stress averaging about 4-5 points higher on the Perceived Stress Scale, compared to medium and high SSS (97% of participants). The overall conclusion from the study is that lower SSS was linked with higher rates of perceived stress. The study is introduced with a topic sentence that highlights its relevance to the answer..


The study is described in detail and with accuracy.

This study shows how higher stress levels are more prevalent in teenagers with low status. It also shows another prevalence rate difference in stress levels – women and girls have higher levels of stress than men. The results of the study are explained and linked to the question.
However, one issue with this study is that it’s correlational. Could the relationship be explained in the other direction? Perhaps people who have high levels of stress are less inclined to socialize and spend time with friends, which might reduce their social status. The study is also limited because it doesn’t give an explanation for why status is linked with a higher prevalence of stress. To address this we can look at quasi experiments that compare participants in response to the trier social stress test (TSST), like Rahal et al.’s study. The limitation is explained. It also links well to the next answer, showing organization and clarity.
The aim of this study was to see if subjective social status (SSS) influences the stress response during acutely stressful situations. High schoolers from Los Angeles were the participants and data on SSS was collected using questionnaires and interviews and the TSST was conducted. The participants’ heart rate and salivary cortisol levels were checked before, during, and after the TSST. Emotional responses to the TSST were measured using a questionnaire The results showed there was a small but statistically significantly negative correlation (-0.08) between SSS and the fear response to the TSST (higher status, lower fear response). Most importantly, lower SSS was associated with greater fear reactivity as well as faster HPA axis reactivity and recovery (as measured through cortisol levels). This study is also described with good detail and accuracy.
This study provides some evidence that suggests higher status is linked with lower stress (and vice-versa) because of how it affects our physiological stress response. It makes sense that people with lower status would have a faster and more reactive stress response, since the activation of the HPA axis and the release of stress hormones will help them deal with stress. Why is this more important for people with low status? Because generally speaking, they are exposed to more stressors like poverty, abuse and violence, and so they need to be more ready to respond. Excellent knowledge and understanding is shown by explaining how social status is linked with biology. 
This is similar to other studies that have shown young children who grow up in violent families have more reactive amygdala than other children. Their brains have adapted to activate the stress-response system faster so they are able to deal with threats.

A major issue with Rahal’s study, though, is the strength of the correlation. -0.08 is a very weak correlation, even if it is statistically significant.

Relevant evaluative point identified. 
Another important fact to discuss is that these studies don’t address prevalence rates. That is because it’s impossible to discuss “prevalence rates of stress” since there is no objective diagnosis of “stress.” It is not like other health problems like cardiovascular disease that have a clear and distinct diagnosis so specific percentages of the population who have the problem can be identified and compared. This means we can discuss the prevalence of stress in different groups based on social status, but not prevalence rates. This shows excellent critical thinking and understanding of the issue. 
In conclusion, higher levels of reported stress and more responsive stress responses are common in teenagers with lower subjective social status. This could be because of the link between status and the HPA axis. However, these correlational studies have numerous limitations that need considering and compared to other health problems with objective diagnoses, discussing prevalence rates of stress is arguably impossible. Relevant conclusion. 
Mr Dixon’s Marks:A 2/2B 5/6C 5/6D 5/6E 2/2 19/22

This essay would score highly because of the detailed knowledge and understanding of prevalence rates and stress, the use of studies and the critical thinking.