# Sampling techniques

> IB Psychology · IB Psychology 2027 First Assessment
> Source: https://www.owlsprep.com/study/ib-psychology-rm-sampling-techniques/

The advantages and disadvantages of different sampling techniques.

## Learning objectives

- The advantages and disadvantages of different sampling techniques.

## How often is this tested?

Based on OwlsPrep's analysis of official CIE IB_PSYCH P3 past papers (2019–2025): **Sampling techniques** appears **5 times** in the last 7 years — **20%** of all P3 questions (5 of 25).

Most-tested forms: Paper 3: research methods (3–6 marks) (5).

## Core concept

A sampling technique is the method used to select participants from a target population, and each has trade-offs. Random sampling gives every member an equal chance and reduces bias but is hard to achieve; opportunity (convenience) sampling is quick but often unrepresentative; volunteer (self-selected) sampling is easy but attracts a particular kind of person; stratified sampling divides the population into subgroups and samples each in proportion, improving representativeness; snowball sampling reaches hard-to-find groups through participant referrals at the cost of representativeness. The technique affects how far findings can be generalized, because it determines who ends up in the sample.

## Key studies

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

**Chang et al. (2023)** — In a sample of Chinese college students, trait mindfulness was negatively associated with social-media addiction, partly via attention control and reduced FOMO. — *A convenience/volunteer sample of students — fast to recruit, but its narrowness (one age group, one country, self-selected) is exactly the sampling limit that bounds generalization.*

## Evaluation (AO3)

**Strength — controls a key source of bias** — Choosing an appropriate technique — ideally random — reduces sampling bias and strengthens the case for generalization.

**Limitation — practicality wins in reality** — True random sampling is rarely feasible, so most psychology relies on convenience or volunteer samples, building in a bias that must be acknowledged.

## Scope

> **note**
>
> The sampling techniques and their trade-offs; the generalization consequence is RM_7 and the distinction from researcher bias is RM_8.

## Common pitfalls

- **Wrong:** Describing the sample (who took part) is the same as describing the sampling method (how they were chosen).
  - Why it fails: A frequently penalised misconception in IB Psychology exams.
  - Correct: The sampling METHOD is the selection procedure — self-selected (volunteer), opportunity, stratified, random, snowball — with its characteristics; listing participants' age or number describes the SAMPLE, not the technique. Name and describe the procedure.

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