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Sampling Techniques

Choosing the Right Strategy

Purpose of Sampling

Sampling techniques are the specific strategies sociologists use to select participants from the target population. The choice of technique depends on research aims, resources, ethical issues, and the degree of representativeness required. Sampling techniques are broadly categorized into probability (random) and non-probability (non-random) methods.

Core Concept: Random Sampling

The foundation of generalizable research relies on probability sampling methods.

1

Equal Chance Selection

In random sampling, every member of the population has an equal chance of being selected.
2

Methods Used

Selection is achieved by methods such as using random number generators or drawing names out of a hat.

Random Sampling Analysis

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The Pros (Effectiveness) Because of its fairness, random sampling reduces bias and is highly representative, allowing generalization to the whole population.
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The Cons (Practicality) It may be difficult to implement without a complete sampling frame and can be costly.

Systematic Sampling Rule

N = Population Size / Sample Size
Systematic sampling selects sample members at regular intervals (N) from a complete list (sampling frame). Example: every 10th name is selected. It can introduce bias if the list has a hidden pattern.

Stratified Sampling Requirements

1

Strata Division

The population is divided into key strata (groups) such as gender, age, or social class.
2

Proportional Sampling

Researchers then randomly sample from each stratum proportionally to its size in the population.
3

Key Benefit

Stratified sampling increases representativeness by ensuring all important subgroups are included.

Non-Probability Glossary

These techniques do not rely on random selection and are often used in qualitative research.

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Snowball

Existing participants recruit future participants from among their acquaintances.
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Volunteer

Participants self-select to take part, often responding to advertisements or calls.
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Opportunity

Selecting participants who are easily accessible at the time of research (convenience sampling).
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Purposive

Selecting participants deliberately based on specific characteristics relevant to the research question.

Addressing Non-Random Bias

Understanding when non-random methods fail to reflect the population.

🤔
Snowball is good for hidden populations, but what is its main limitation?
⚠️
The sample may not be representative because participants likely share similar characteristics, introducing bias.

Practical Considerations & Bias

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Volunteer Sampling: It is easy and inexpensive but prone to bias since volunteers are typically motivated or interested in the topic, which may not reflect the wider population.

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Opportunity Sampling: It is convenient and quick but typically not representative, as it captures only those available and willing at that moment.

Quota Sampling Method

This non-probability technique attempts to mimic stratification.

Requirement Quota Selection Type
Male Interviewees 50% Non-Random
Female Interviewees 50% Non-Random
Key Limitation Selection bias can occur.
Total Result Straightforward but lacks representativeness goal of probability sampling.
Sampling Techniques Deck
Term
Sampling Techniques

What are sampling techniques?

Answer
Definition

Strategies sociologists use to select participants from the target population.

Term
Categories of Sampling

What are the two broad categories of sampling techniques?

Answer
Categories

Probability (random) and non-probability (non-random) sampling.

Term
Random Sampling

What is random sampling?

Answer
Definition

A method where every member has an equal chance of being selected.

Term
Disadvantage of Random Sampling

What is a disadvantage of random sampling?

Answer
Disadvantage

It can be costly and difficult without a complete sampling frame.

Term
Systematic Sampling

How does systematic sampling work?

Answer
Definition

Selecting members at regular intervals from a list, e.g., every 10th name.

Term
Risk of Systematic Sampling

What risk can systematic sampling have?

Answer
Risk

Bias if the list has a hidden pattern.

Term
Stratified Sampling

What is stratified sampling?

Answer
Definition

Dividing the population into groups (strata) and randomly sampling each proportionally.

Term
Purpose of Stratified Sampling

Why is stratified sampling used?

Answer
Purpose

To increase representativeness, especially for minority groups.

Term
Snowball Sampling

What is snowball sampling?

Answer
Definition

Participants recruit future participants from their acquaintances.

Term
Use of Snowball Sampling

When is snowball sampling useful?

Answer
Use

For studying hidden or hard-to-reach populations.

Term
Limitation of Snowball Sampling

What is a major limitation of snowball sampling?

Answer
Limitation

It may lack representativeness and introduce bias.

Term
Volunteer Sampling

What characterizes volunteer sampling?

Answer
Definition

Participants self-select to take part, often via advertisements.

Term
Drawback of Volunteer Sampling

What is a drawback of volunteer sampling?

Answer
Drawback

It can introduce bias due to self-selection.

Term
Opportunity Sampling

What is opportunity (convenience) sampling?

Answer
Definition

Selecting participants who are readily available and convenient.

Term
Representativeness of Opportunity Sampling

Why is opportunity sampling often not representative?

Answer
Reason

Because it includes only those accessible and willing at the time.

Term
Purposive Sampling

What defines purposive sampling?

Answer
Definition

Deliberately selecting participants with specific characteristics.

Term
Use of Purposive Sampling

When is purposive sampling mainly used?

Answer
Use

In qualitative research seeking detailed, specific information.

Term
Quota Sampling

What is quota sampling?

Answer
Definition

Filling predetermined quotas for subgroups using non-random methods.

Term
Limitation of Quota Sampling

What is a limitation of quota sampling?

Answer
Limitation

It can introduce selection bias.

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📊 Sampling Techniques Quiz

1. Which sampling technique ensures that every member of the population has an equal chance of selection?

Random sampling gives all members an equal chance, reducing bias.

2. In systematic sampling, participants are selected:

Systematic sampling uses a fixed step interval to select participants from a sampling frame.

3. Stratified sampling is particularly useful because it:

Stratified sampling divides the population into subgroups to sample proportionally.

4. Which sampling method is often used to study hidden populations?

Snowball sampling relies on participants to recruit others, useful for hard-to-reach groups.

5. What is a common criticism of quota sampling?

Quota sampling uses non-random methods, which can bias results.

📊 Results

  • Notes and Quiz
  • Sociology
  • AS Level
  • Research Methods
  • OCR