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Participants & Sampling Procedures

The Role of Participants

Key Context

Participants represent the human subjects involved in psychological research. The selection and sampling procedures affect the generalisability and validity of findings, as well as ethical considerations. We will focus on how different methods impact the representativeness of the sample.

Core Definitions

Understanding the sources from which samples are drawn.

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Target Populations

The entire group about which the researcher wants to draw conclusions (e.g., all teenagers in a country). Researchers rarely study whole populations due to size and logistical constraints.
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Sampling Frames

A list or source from which participants are drawn (e.g., school registers). The accuracy of this list influences sample representativeness.

Sampling Techniques Overview

Methods for selecting individuals from the target population.

1

Probability Sampling

Random Sampling: Every member of the target population has an equal chance of being selected.
2

Non-Probability Sampling

Opportunity, Quota, Self-Selected, Snowball. Based on convenience or specific criteria.

Random vs Opportunity Sampling

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Random Sampling: Minimises bias and enhances representativeness but can be practically difficult.
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Opportunity (Convenience) Sampling: Easy and economical but prone to bias and low generalisability.

Systematic Selection Rule

The core mechanism of systematic sampling.

Selecting every nth individual from a list.
More structured than opportunity but assumes list is random.

Stratified Sampling Requirements

Ensuring key subgroups (strata) are proportionally represented.

Stratum Definition Requirement
Key Characteristics Identified
Population Divided into Subgroups
Random Samples Taken Proportionally from each Stratum
Outcome: Increases representativeness across key variables.

Snowball Sampling Utility

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Is there a method for studying hard-to-reach groups?
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Yes, Snowball Sampling: Existing participants recruit others from their network. Useful for hidden or hard-to-access populations (e.g., drug users) but limited generalisability.

Observational Sampling Techniques

Choosing which behaviours to record in observational research.

✓

Event Sampling

Observing specific pre-defined events or behaviours (e.g., aggression incidents).
✓

Time Sampling

Observations made at specific time intervals (e.g., every 5 minutes) to capture ongoing behaviour.

Quota & Self-Selected Comparison

Comparing non-random methods based on trade-offs.

ID Technique Selection Basis Goal Ease Bias Risk Control Limitation
Q1 Quota Non-random within quotas Fill traits High High Controlled Bias may still exist
S2 Self-Select Volunteer (ads) Hard-to-reach Varies High Low Biased toward motivated individuals

Evaluation Summary

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The Researcher's Choice: Each sampling method has trade-offs between practical convenience, risk of sampling bias, representativeness, and ethical considerations. Researchers strive for balanced, ethically sound samples that align with research aims and resources.

Psychological Research Sampling Deck
Term
Participant

What is a participant in psychological research?

Answer
Definition

A human subject involved in a study.

Term
Target Population

What is the target population?

Answer
Definition

The entire group a researcher wants to draw conclusions about.

Term
Studying Whole Populations

Why do researchers rarely study whole populations?

Answer
Reason

Due to size and logistical constraints.

Term
Sampling Frame

What is a sampling frame?

Answer
Definition

A list or source from which participants are drawn.

Term
Random Sampling

What is random sampling?

Answer
Definition

Every member of the target population has an equal chance of selection.

Term
Opportunity Sampling

What is opportunity sampling?

Answer
Definition

Selecting participants based on availability and willingness.

Term
Systematic Sampling

How is systematic sampling conducted?

Answer
Method

Selecting every nth individual from a list.

Term
Stratified Sampling

What is stratified sampling?

Answer
Definition

Dividing the population into subgroups and randomly sampling proportionally from each subgroup.

Term
Quota Sampling

What is quota sampling?

Answer
Definition

Filling quotas to represent traits but selecting participants non-randomly within quotas.

Term
Self-selected Sampling

What is self-selected sampling?

Answer
Definition

Participants volunteer themselves, often through advertisements.

Term
Snowball Sampling

When is snowball sampling used?

Answer
Usage

For hidden or hard-to-access populations, when participants recruit others.

Term
Event Sampling

What is event sampling?

Answer
Definition

Observing specific pre-defined behaviours or events.

Term
Time Sampling

What is time sampling?

Answer
Definition

Observing behaviours at specific time intervals.

Term
Choosing Sampling Methods

What factors do researchers consider when choosing sampling methods?

Answer
Factors

Convenience, sampling bias, representativeness, and ethics.

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🌸 Sampling Techniques Quiz

1. Which sampling technique gives every member of the population an equal chance of selection?

Random sampling eliminates selection bias by giving all members an equal chance.

2. What is the main drawback of opportunity sampling?

It relies on participant availability, leading to unrepresentative samples.

3. In stratified sampling, why are subgroups (strata) created?

Stratification ensures important population traits are proportionally represented.

4. Which sampling method is best suited for accessing hidden populations like drug users?

Participants recruit others from their networks, useful for hard-to-reach groups.

5. What does time sampling involve?

Time sampling captures behaviour snapshots over set time periods.

📊 Results

  • Notes and Quiz
  • Psychology
  • AS & A Level
  • Relationships
  • WJEC