Research Methodology Example (Chapter 3): Design, Sampling, Slovin's Formula, Instrument and Data Analysis (2026)

Quick answer

Chapter 3 (Research Methodology) explains exactly how you will answer your research questions. It usually covers research design, research locale, respondents and sampling technique, research instrument (with validity and reliability), data gathering procedure, statistical treatment or data analysis, and ethical considerations. Below is a full annotated example with Slovin's formula worked out, plus a qualitative version.

What Is Chapter 3 (Research Methodology)?

Chapter 3: Research Methodology describes the plan for collecting and analyzing your data. A reader should be able to repeat your study just by following it. Panels check this chapter closely, because a weak method makes the results in Chapter 4 hard to trust.

Updated October 2026.

Chapter 3 must match Chapter 1. Every specific question in your statement of the problem needs a source of data (the instrument) and a way to analyze it (a statistic or a qualitative method). If you have not written Chapter 1 yet, start with our Chapter 1 research example.

This guide uses the same running examples as our other guides: "Study Habits and Academic Performance of Grade 12 STEM Students" for the quantitative version (see the quantitative research example) and "Lived Experiences of Working Students in Senior High School" for the qualitative version (see the qualitative research example).

Jump to: Structure · Quantitative example · Slovin's formula · Cronbach's alpha · Qualitative example · Weak vs strong · Checklist · FAQ

Chapter 3 Structure: Quantitative vs Qualitative

The headings are almost the same for both types of research, but the content is very different. Follow your school's template; some combine locale and respondents, or put ethics before data gathering.

Quantitative Research Methodology Example (Annotated)

Below is a complete, original illustrative Chapter 3 written by our team for "Study Habits and Academic Performance of Grade 12 STEM Students." It is not a real study: the school, numbers and results are invented to show the format. Do not copy it or cite it. In a proposal, write in future tense ("will"); in the final paper, most schools want past tense, as shown here.

Research Design Example

Research Design

This study used a descriptive-correlational research design. It is descriptive because it describes the level of study habits and academic performance of the respondents (Problems 1 and 2). It is correlational because it determines whether there is a significant relationship between these two variables without manipulating either of them (Problem 3). A correlational design was chosen because study habits cannot be ethically or practically assigned to students; the researchers can only measure them as they are.

Research Locale

Research Locale

The study was conducted at [School Name], a public senior high school in [City/Municipality, Province]. The school offers the Academic Track with STEM, ABM, HUMSS and GAS strands. It was chosen because it has four Grade 12 STEM sections and because teachers had observed late submissions and low periodical test scores among STEM students, as described in Chapter 1.

Respondents and Sampling Technique Example

Respondents and Sampling Technique

The population consisted of 172 Grade 12 STEM students enrolled in S.Y. 2025–2026, in four sections. The sample size of 120 was computed using Slovin's formula at a 5% margin of error. Stratified random sampling with proportional allocation was used so that each section was fairly represented. Within each section, respondents were drawn by lottery from the class list.

Table 1. Distribution of respondents (illustrative)

• Section A: population 44, sample 31
• Section B: population 44, sample 31
• Section C: population 42, sample 29
• Section D: population 42, sample 29
• Total: population 172, sample 120

Inclusion criteria: currently enrolled Grade 12 STEM students with a recorded first-semester GWA, who gave consent (and parental consent if below 18).

Slovin's Formula: Worked Example

Slovin's formula is the sample-size formula most often taught in Philippine senior high school and college research:

n = N ÷ (1 + N × e²)

where n is the sample size, N is the population size and e is the margin of error (usually 0.05, or 5%).

Step-by-step (illustrative numbers): N = 172, e = 0.05

1. Square the margin of error: e² = 0.05 × 0.05 = 0.0025
2. Multiply by the population: N × e² = 172 × 0.0025 = 0.43
3. Add 1: 1 + 0.43 = 1.43
4. Divide the population by this number: n = 172 ÷ 1.43 = 120.28
5. Round: n ≈ 120 respondents. Many teachers ask you to round up (121) so the sample is never smaller than the formula requires. Follow your teacher's rule and state it.

Proportional allocation per section: sample for a section = (section population ÷ N) × n.

• Section A: (44 ÷ 172) × 120 = 30.70 → 31
• Section C: (42 ÷ 172) × 120 = 29.30 → 29

Check that the section samples add up to your total (31 + 31 + 29 + 29 = 120).

A note on Slovin's formula. It is simple and widely accepted in Philippine schools, but it only uses the population size and margin of error. It does not consider the expected variability of your data or the statistical test you will use, so some statisticians prefer other methods, such as power analysis. For a school research project, use what your teacher requires and cite it in your paper.

1. e² = 0.0025 — 0.05 × 0.05
2. N × e² = 0.43 — 172 × 0.0025
3. 1 + 0.43 = 1.43 — Add 1
4. n = 120.28 — 172 ÷ 1.43
5. n ≈ 120 — Round as your school requires

Research Instrument, Validity and Reliability (Cronbach's Alpha)

Research Instrument

The researchers used a 20-item researcher-made Study Habits Questionnaire with four parts of five items each: time management (items 1–5), note-taking (6–10), test preparation (11–15) and concentration (16–20). Items were answered on a 4-point Likert scale: 4 – Always, 3 – Often, 2 – Sometimes, 1 – Never. Academic performance was taken from the first-semester GWA recorded by the registrar.

Validity. The questionnaire was checked by three validators: a research teacher, a guidance counselor and a STEM subject teacher. They rated each item for clarity and relevance, and two unclear items were revised based on their comments.

Reliability. The revised questionnaire was pilot-tested with 30 Grade 12 STEM students from another school who were not part of the sample. The internal consistency was computed using Cronbach's alpha, which was 0.86 (illustrative), indicating good reliability.

Interpretation of mean scores

• 3.26–4.00: Always – Very Good
• 2.51–3.25: Often – Good
• 1.76–2.50: Sometimes – Fair
• 1.00–1.75: Never – Poor

What Cronbach's alpha means. Cronbach's alpha (α) measures whether the items in a scale consistently measure the same idea. It ranges from 0 to 1. A common rule of thumb used in student research: 0.90 and above excellent, 0.80–0.89 good, 0.70–0.79 acceptable, 0.60–0.69 questionable, below 0.60 poor. Many teachers require at least 0.70. Compute it for each part of your questionnaire if the parts measure different things, using a spreadsheet, JASP, jamovi or SPSS.

Adapted questionnaires. If you adapt an existing questionnaire instead of making your own, cite the original author, ask permission when required, and still report validity and reliability for your version.

Data Gathering Procedure Example

Data Gathering Procedure

1. The researchers submitted a letter of request to the school principal and obtained written approval to conduct the study.
2. Informed consent forms were given to the respondents, and parental consent forms to those below 18 years old.
3. The validated questionnaire was administered in person during homeroom period, with the advisers' permission. The researchers explained the purpose of the study and the instructions, and answered questions.
4. Respondents answered the questionnaire in about 15 minutes, and the forms were retrieved the same day (120 of 120 retrieved).
5. With permission from the principal and the registrar, the respondents' first-semester GWAs were obtained and matched to questionnaires using code numbers, not names.
6. The data were encoded in a spreadsheet, checked twice for errors, and analyzed using the statistical tools below.

Statistical Treatment of Data Example

Statistical Treatment of Data

The following statistical tools were used to answer each problem. All tests were done at the 0.05 level of significance.

The key rule: one statistic for each research question, named in the same order as your statement of the problem. For a full guide to choosing statistics, see the statistics table in our quantitative research example.

Ethical Considerations

Ethical Considerations

The study followed basic research ethics. Participation was voluntary, and respondents could withdraw at any time without any effect on their grades. Informed consent was obtained from all respondents, and parental consent from minors. Questionnaires used code numbers instead of names, and GWAs were linked only through these codes. Data were stored in a password-protected file accessible only to the researchers and were used only for this study, in line with the Data Privacy Act of 2012 (Republic Act No. 10173). Results are reported only as group data, so no individual respondent can be identified. Sources and adapted items are properly cited.

Qualitative Research Methodology Example (Annotated)

Here is the same chapter for the qualitative running example, "Lived Experiences of Working Students in Senior High School." This is also an original illustrative example; the participants and details are invented.

Research Design. This study used a descriptive phenomenological design, because it aims to describe the lived experiences of working students as they themselves understand them, rather than to measure or compare them.

Research Locale. The study was conducted at [School Name], a public senior high school in [City/Municipality], where the guidance office reported a number of Grade 12 students who work after class or on weekends.

Participants and Sampling. Eight Grade 12 students were chosen through purposive sampling using these inclusion criteria: (a) enrolled in Grade 12 in the selected school; (b) working at least 15 hours a week; (c) has worked for at least six months; (d) willing to be interviewed and audio-recorded. Possible participants were identified with help from advisers. Interviews stopped at eight because the last interviews gave no new ideas (data saturation).

Research Instrument. A researcher-made semi-structured interview guide with ten main questions and follow-up probes, grouped by research question (experiences, challenges, coping). It was checked by three validators and tried in one pilot interview with a working student who was not part of the study.

Data Gathering Procedure. (1) Approval from the principal. (2) Consent from participants and parental consent for minors. (3) Face-to-face interviews of 30–45 minutes in a private room after class, in English or Filipino based on the participant's choice. (4) Audio recording with permission. (5) Verbatim transcription and translation where needed.

Data Analysis. Transcripts were analyzed using thematic analysis following Braun and Clarke's (2006) six phases: familiarizing with the data, generating initial codes, searching for themes, reviewing themes, defining and naming themes, and writing the report.

Trustworthiness. Credibility was supported by member checking (participants reviewed a summary of themes); dependability by keeping an audit trail of codes; confirmability by having two researchers code separately and compare; and transferability by describing the participants and setting in detail.

Ethical Considerations. Voluntary participation, informed consent and assent, pseudonyms (P1 to P8), recordings stored on a password-protected device and deleted after the study, and referral to the guidance office if a participant felt distressed.

Weak vs Strong Chapter 3 Writing

These are the most common Chapter 3 problems panels point out. All samples are illustrative.

Learn From Methods in Real Studies

The best way to write a strong Chapter 3 is to read the Methods sections of published studies on your topic and see how they report design, sampling, instruments and analysis. On Ocean of Papers you can search 250M+ papers from OpenAlex, PubMed, arXiv, bioRxiv, medRxiv and Europe PMC for free, and open legal free PDFs where they exist.

Search "study habits academic performance questionnaire" free, then open a citation map on a good study to find similar studies whose questionnaires you might adapt (with citation). For your Chapter 2 sources, see our review of related literature example. For full published papers to study, browse our research paper samples.

Chapter 3 Checklist

Check these before submitting Chapter 3:

• The research design is named, explained and justified, and linked to the research questions.
• The locale is described with a reason for choosing it.
• Quantitative: population, sample size computation (formula, values, rounding) and sampling technique are clear; the respondents table adds up.
• Qualitative: number of participants, purposive sampling, inclusion criteria and saturation are stated.
• The instrument is described (items, parts, scale) with validity (validators) and reliability (pilot test, Cronbach's alpha) or, for qualitative, expert validation and a pilot interview.
• The Likert interpretation ranges are given.
• The data gathering procedure is in numbered steps, from permission to analysis.
• Each research question has one matching statistic or analysis step; the level of significance is stated.
• Qualitative: the analysis method is named and trustworthiness steps are described.
• Ethics covers consent (and parental consent for minors), voluntary participation, confidentiality and data privacy.
• Numbers match Chapter 1 (scope and delimitation) and will match Chapter 4.
• Tense is consistent: future for the proposal, past for the final paper (if your school requires it).

FAQ

What is included in a Chapter 3 methodology example?

A Chapter 3 usually includes the research design, research locale, respondents and sampling technique, research instrument, data gathering procedure, statistical treatment or data analysis, and ethical considerations. The annotated example above shows each part for a quantitative and a qualitative study.

What is a research design example?

"This study used a descriptive-correlational design" is a research design example for a study that describes two variables and tests their relationship. Other designs are descriptive, causal-comparative, experimental and quasi-experimental for quantitative studies, and phenomenology or case study for qualitative ones.

What is a sampling technique example?

Stratified random sampling by section is a common quantitative example: the population is divided into sections and respondents are randomly drawn from each in proportion to its size. For qualitative studies, purposive sampling with clear inclusion criteria is the usual example.

How do I compute Slovin's formula?

Use n = N ÷ (1 + N × e²). With N = 172 and e = 0.05: 172 × 0.0025 = 0.43; 1 + 0.43 = 1.43; 172 ÷ 1.43 = 120.28, so about 120 respondents (or 121 if your teacher asks you to round up).

What is a data gathering procedure example?

A good example lists numbered steps: asking permission from the principal, getting consent, administering the instrument, retrieving it, collecting secondary data like GWA with permission, and encoding the data. See the full example above.

What Cronbach's alpha is acceptable?

Many teachers accept 0.70 or higher. As a common rule of thumb, 0.80–0.89 is good and 0.90 or higher is excellent. Report the value from your pilot test for each part of your questionnaire.

Does qualitative research need Slovin's formula?

No. Qualitative studies use small purposive samples and stop when no new ideas come up (data saturation). Explain your inclusion criteria and why your number of participants is enough.

Can I copy this methodology example?

No. It is an illustrative example with invented numbers. Use the structure, then write your own Chapter 3 with your real population, instrument and procedures.

Related guides

• Chapter 1 research example (background of the study)
• Review of related literature (RRL) example
• Quantitative research example (Chapters 1–5)
• Qualitative research example (Chapters 1–5)
• Statement of the problem examples

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