# Prevalence of health problems

> IB Psychology · IB Psychology 2027 First Assessment
> Source: https://www.owlsprep.com/study/ib-psychology-hwb-prevalence-of-health-problems/

One or more factors that may explain changes in the prevalence of one or more health problems in a population. One or more factors that may explain differences in the prevalence of one or more health problems between populations.

## Learning objectives

- One or more factors that may explain changes in the prevalence of one or more health problems in a population. One or more factors that may explain differences in the prevalence of one or more health problems between populations.

## How often is this tested?

Based on OwlsPrep's analysis of official CIE IB_PSYCH P2 past papers (2019–2025): **Prevalence of health problems** appears **46 times** in the last 7 years — **16%** of all P2 questions (46 of 288).

Most-tested forms: Essay: To what extent (22 marks) (14), Essay: Discuss (22 marks) (14), Essay: Evaluate (22 marks) (10), Essay: Contrast (22 marks) (6), Essay (22 marks) (2).

## Core concept

Prevalence is how common a health problem is in a population. It changes over time and differs between populations — obesity, for example, has risen steeply in many countries over recent decades, while estimates of newer problems like 'social media addiction' vary enormously. Two kinds of factor drive the numbers: real changes (environment, diet, technology, age structure) and measurement changes (what criteria and questionnaires define a 'case', and how the sample was drawn). A rising or differing prevalence figure therefore has to be read carefully — part real trend, part artefact of definition.

## Key studies

IB Psychology answers must be supported by named studies. Learn these to cite as evidence:

**Schramm et al. (2023)** — Obesity prevalence in Denmark rose from 6.1% to 18.4% between 1987 and 2021, with strong period effects (rising across all age groups) but no cohort effects. — *Anchors a real change in a health problem's prevalence over time and distinguishes period from cohort explanations.*

**Cheng et al. (2021)** — A meta-analysis estimated social-media-addiction prevalence at ~25%, but with wide variation driven by diagnostic criteria, questionnaire quality, culture and sampling. — *Anchors a second health problem and shows how much a prevalence figure depends on measurement, not just reality.*

## Evaluation (AO3)

**Strength — reveals genuine trends** — Population data over time (Schramm) and pooled across studies (Cheng) can expose real trends in a health problem and the factors behind them.

**Limitation — only as good as the case definition** — Differing criteria, self-report questionnaires and sampling make figures hard to compare, so apparent differences or increases can be measurement artefacts.

## Scope

> **note**
>
> This card covers changes in, and differences in, the prevalence of non-disorder HEALTH PROBLEMS (obesity, social-media addiction). Cultural differences in DISORDER prevalence are HWB_3. Prevention/treatment of these problems is HWB_9.

## Common pitfalls

- **Wrong:** Reading a rising or higher prevalence figure as purely a real increase in the problem.
  - Why it fails: A frequently penalised misconception in IB Psychology exams.
  - Correct: Prevalence depends on how a 'case' is defined and measured — changed criteria, greater awareness, and different questionnaires or samples can inflate or deflate the number independent of any real change.

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