Research methods · Class practicals and the research proposal

IB Diploma Programme Psychology SL (the course first assessed in 2027). This topic covers how psychologists collect evidence. You need it for three parts of the assessment. In your class practicals 课堂实践 you carry out at least four small studies, one with each of four methods: an experiment, an interview or focus group, an observation, and a questionnaire. Paper 2 Section A asks four questions about one of your practicals, and Section B asks you to discuss an unseen study using the concepts. The internal assessment 内部评估 is a research proposal 研究计划书: you plan a study for a population of interest 目标人群 but do not carry it out.

In 2015, 270 researchers tried to repeat 100 published psychology studies. Only about a third (36%) found a significant result again. Some of the original studies had small samples, flexible analyses or biased designs. Research methods are not a list to memorise; they decide which findings you can trust.

Must-know for this topic:

Six methods placed by control and by kind of data; the four ringed ones are used in class practicals

Quantitative data 定量数据 are numbers; qualitative data 定性数据 are words, pictures or descriptions. Experiments and questionnaires mostly produce quantitative data; interviews mostly qualitative data.

An experiment 实验 changes the independent variable 自变量 (IV) and measures the effect on the dependent variable 因变量 (DV), while keeping other variables the same. A variable that changes with the IV and also affects the DV is a confounding variable 混淆变量.

Hypotheses must be precise. For a study on music and memory:

• Research hypothesis 研究假设: students who learn 20 words in silence will recall more words than students who learn them with music playing.
• Null hypothesis 零假设: there will be no difference in recall, or any difference will be due to chance.

There are three experimental designs 实验设计:

Sampling chooses who takes part; allocation decides which condition each person does

A laboratory experiment 实验室实验 has high control but may not feel real (low ecological validity 生态效度). A field experiment 现场实验 happens in a real setting. In a natural experiment 自然实验 the researcher does not choose the IV (for example, a new school timetable), and in a quasi-experiment 准实验 the IV is a fixed trait such as age or gender, so participants cannot be randomly allocated.

Purposive and snowball sampling are common for interviews, when the researcher needs people with a special experience.

A questionnaire 问卷 can use closed questions (yes/no, or a Likert scale 李克特量表 from 1 "strongly disagree" to 5 "strongly agree") or open questions. Closed answers are easy to count; open answers give reasons. People may give the answer that sounds good: social desirability bias 社会期望偏差. Anonymous questionnaires reduce it.

An interview 访谈 can be structured (fixed questions), semi-structured (an interview guide, with follow-up questions) or unstructured. A focus group 焦点小组 is an interview with about 6 to 10 people at once, where people's answers spark each other's ideas, but a strong speaker can lead the group. Interviews are recorded, transcribed and analysed by finding themes.

An observation 观察 can be naturalistic (a real setting) or controlled, overt (people know) or covert (they do not), and participant or non-participant. Observers use a behaviour checklist 行为清单 with clear categories, for example "hits", "shares a toy", "helps". Two observers record the same sessions, and high agreement shows inter-rater reliability 评分者间信度.

Every study must follow ethical rules. The main ones are informed consent 知情同意 (people know what they agree to; parents consent for children under 16), the right to withdraw 退出权 at any time, no deception 欺骗 unless it is necessary and harmless, debriefing 事后说明 (telling participants the true aim afterwards), protection from harm 免受伤害 and confidentiality 保密 (no names in the report). Responsibility, one of the six concepts, asks you to apply these rules to a particular study.

Section A asks four questions about one class practical: describe what you did (4 marks), explain a concept in relation to it (4 marks), compare it with another method (6 marks) and design a study with a different method on the same topic (6 marks).

Worked example. Describe how you used an interview or focus group in your class practical. (4 marks)

Our aim was to find out how IB students experience stress before mock exams. We used purposive sampling to choose four DP2 students who had just taken mocks. Each gave informed consent. We ran semi-structured interviews of about 15 minutes with six open questions, such as "What did you do the evening before your first exam?", and recorded them. We transcribed the recordings and coded them, and two themes appeared: lack of sleep and comparing scores with friends.

Section B (15 marks) gives you an unseen study. You discuss it with two or more of four concepts: bias, causality, measurement and responsibility. For each concept: point to a detail in the study, explain its effect on the conclusion, and suggest a better design.

The internal assessment is a research proposal of 24 marks. You choose a topic and a population of interest (for example, international students in their first year in China), and plan a study with one of the four class-practical methods. You argue for every choice, but you do not collect data.

The four parts of the research proposal

Example plan: How do first-year international students in Ningbo experience making friends? Method: semi-structured interviews, because the question is about experience and needs rich data. Sample: purposive sampling of eight students, through the university's international office. Ethics: informed consent, a right to withdraw, no names, and information about counselling services. Discussion: the researcher's own views could shape the questions (bias), so a second researcher codes the transcripts; eight students from one university may not transfer to other cities.

• The six methods, with a strength and a limit of each; quantitative and qualitative data.
• IV, DV, confounding variables; research and null hypotheses; the three designs, counterbalancing and random allocation; types of experiment.
• Five sampling techniques with their problems.
• Questionnaires (Likert, social desirability), interviews and focus groups, observations (checklists, inter-rater reliability).
• Participant and researcher bias; generalisability, credibility, transferability, triangulation.
• The ethical rules, and how responsibility applies them.
• Paper 2 Section A (4, 4, 6, 6 marks) and Section B (15 marks, two or more concepts).
• The research proposal: four parts, one class-practical method, planned but not carried out.