How to Write the Population and Sample for a Psychology Dissertation

How to Write the Population and Sample for a Psychology Dissertation

The population and sample section of a psychology dissertation explains who will participate in the study, how participants will be selected, and why the selected group is appropriate for investigating the psychological research problem. This section is typically included in Chapter 3 (Methodology) and helps establish the rigor, credibility, and ethical foundation of the study.

In psychology research, the population and sample section is especially important because researchers often study:

• Mental health experiences

• Human behavior

• Emotions and cognition

• Psychological interventions

• Social and developmental processes

A strong section clearly identifies:

• The target population

• Participant characteristics

• Sample size

• Sampling procedures

• Inclusion and exclusion criteria

• Recruitment methods

In simple terms, this section answers: “Who is being studied in this psychology dissertation, and how were participants selected?”

What Is the Population in a Psychology Dissertation?

The population is the larger group of people the researcher wants to study or understand.

In psychology dissertations, populations often include:

• College students

• Adults with anxiety or depression

• Healthcare workers

• Adolescents

• Therapy clients

• Online learners

• Parents or caregivers

The population should align directly with:

• The psychological problem

• Research questions

• Methodology and design

Example Population Statement

The target population for this study consisted of graduate students enrolled in online doctoral psychology programs in the United States.

What Is the Sample in a Psychology Dissertation?

The sample is the smaller group selected from the population to participate in the study.

Because it is usually impossible to study an entire population, researchers recruit a manageable sample that reflects the characteristics of the larger group.

Example Sample Statement

The sample included 20 doctoral students who reported experiencing academic burnout during online learning.

Why the Population and Sample Section Matters in Psychology Research

This section demonstrates:

• Methodological rigor

• Appropriate participant selection

• Ethical recruitment practices

• Alignment with the psychological research problem

Dissertation committees want to see that:

• Participants are appropriate for the study

• Sampling methods align with the research design

• The sample supports trustworthy findings

Where Is the Population and Sample Section Located?

This section is usually included in:

• Chapter 3: Methodology

Common headings include:

• Population

• Sample

• Participants

• Sampling Procedures

• Recruitment Procedures

Step-by-Step: How to Write the Population and Sample Section for a Psychology Dissertation

Step 1: Identify the Target Population

Clearly describe the larger psychological population relevant to the study.

Include:

• Participant type

• Relevant psychological or demographic characteristics

• Institutional or geographic context

Example:

The target population consisted of licensed mental health counselors working in outpatient clinical settings in the United States.

Step 2: Describe the Sample

Explain the specific group selected from the population.

Include:

• Estimated sample size

• Participant demographics

• Relevant psychological characteristics

Example:

The sample included 15 licensed counselors with at least three years of clinical experience treating anxiety disorders.

Step 3: Explain the Sampling Method

Describe how participants were selected.

Common Sampling Methods in Psychology Research

Quantitative Psychology Studies

Random Sampling

Participants selected randomly from the population.

Convenience Sampling

Participants selected based on accessibility.

Stratified Sampling

Participants selected from subgroups.

Qualitative Psychology Studies

Purposive Sampling

Participants selected because they have lived experience with the phenomenon.

Criterion Sampling

Participants must meet specific psychological or demographic criteria.

Snowball Sampling

Participants refer other participants.

Example:

Purposive sampling was used to recruit participants who had experienced symptoms of academic burnout while enrolled in online doctoral programs.

Step 4: Justify the Sample Size

Explain why the sample size is appropriate.

Quantitative Psychology Studies

Sample size may be justified using:

• Statistical power analysis

• Previous psychological studies

• Anticipated effect sizes

Example:

A sample size of 200 participants was selected to provide adequate statistical power for regression analysis.

Qualitative Psychology Studies

Sample size is often based on:

• Data saturation

• Depth of participant experience

• Methodological recommendations

Example:

A sample of 12 participants was considered sufficient to achieve thematic saturation.

Step 5: Define Inclusion Criteria

Inclusion criteria identify who is eligible to participate.

Examples:

• Adults age 18 or older

• Participants diagnosed with anxiety

• Full-time doctoral students

• Individuals currently receiving therapy

Example:

Participants were required to be currently enrolled in an online doctoral psychology program and over the age of 18.

Step 6: Define Exclusion Criteria

Exclusion criteria identify who cannot participate.

Examples:

• Individuals under age 18

• Participants without relevant psychological experiences

• Incomplete survey responses

• Individuals currently in crisis situations

Example:

Participants who had not completed at least one online doctoral course were excluded from the study.

Step 7: Describe Recruitment Procedures

Explain how participants will be recruited.

Common recruitment methods in psychology include:

• University participant pools

• Social media recruitment

• Mental health organizations

• Email invitations

• Professional networks

Example:

Participants were recruited through professional counseling organizations and university email announcements.

Step 8: Address Ethical Considerations

Psychology dissertations must carefully protect participants.

Discuss:

• Informed consent

• Confidentiality

• Voluntary participation

• Emotional risk considerations

• Data security

• IRB approval

Example:

Participation was voluntary, and all participant responses were kept confidential in accordance with Institutional Review Board (IRB) requirements.

Population and Sample Examples for Psychology Dissertations

Example for a Quantitative Psychology Study

The population for this study consisted of undergraduate students enrolled at public universities in the United States. A convenience sample of 250 students was recruited through online university announcements. Participants were required to be at least 18 years old and currently enrolled full-time.

Example for a Qualitative Psychology Study

The population for this phenomenological study included adults diagnosed with generalized anxiety disorder. Purposive sampling was used to recruit 10 participants who had received therapy for anxiety within the previous year.

Common Mistakes in the Population and Sample Section

Avoid:

• Vague participant descriptions

• No justification for sample size

• Misalignment between methodology and sampling method

• Weak recruitment explanations

• Missing inclusion or exclusion criteria

• Ignoring ethical protections for participants

Tips for Writing a Strong Psychology Population and Sample Section

• Align participants with psychological research questions

• Clearly define participant characteristics

• Use appropriate psychological sampling terminology

• Justify sample size logically

• Explain ethical protections carefully

• Ensure consistency with methodology and design

Quantitative vs. Qualitative Sampling in Psychology

Quantitative Psychology Research	Qualitative Psychology Research
Larger sample sizes	Smaller sample sizes
Statistical generalization	Depth of lived experience
Random or probability sampling	Purposive or criterion sampling
Statistical power important	Data saturation important

Final Thoughts on How to Write the Population and Sample for a Psychology Dissertation

The population and sample section is a critical part of a psychology dissertation because it explains who is being studied and how participants were selected. A well-written section demonstrates methodological rigor, ethical responsibility, and strong alignment between the psychological research problem and participant selection strategy.

Whether conducting qualitative, quantitative, or mixed methods psychology research, clearly describing the population, sample, sampling strategy, and recruitment procedures strengthens the credibility and trustworthiness of the dissertation.

If you need help selecting a methodology, consider qualitative dissertation tutoring! If you need help editing your Chapter 3, please visit our website.