Methods of Enquiry in Psychology

The One Thing

Psychology develops dependable knowledge through systematic enquiry: researchers formulate questions, collect and analyse evidence, and evaluate conclusions. The strength of psychological research depends on selecting an appropriate method, controlling bias, interpreting data carefully, and protecting participants’ rights and wellbeing.

Who and What

• Scientific enquiry: A systematic process of asking questions, forming explanations, collecting evidence, analysing data, and reaching conclusions. Its usual stages are identifying a problem, reviewing existing knowledge, stating objectives or questions, forming a hypothesis when appropriate, selecting participants and methods, collecting data, analysing data, interpreting results, communicating findings, and considering replication.
• Research problem: A clearly stated question or issue that the researcher intends to investigate.
• Hypothesis: A tentative, clear, specific, and testable statement about the expected relationship between variables. It must be capable of being supported or rejected by evidence.
• Variable: Any characteristic or condition that can take different values.
• Independent variable: The variable changed or controlled by the researcher.
• Dependent variable: The variable measured to observe the effect of the independent variable.
• Extraneous variable: A factor other than the independent variable that may influence results.
• Operational definition: A precise description of how a variable will be measured or manipulated.
• Objectivity: Collecting and interpreting evidence without personal opinions or bias affecting the results.
• Reliability: The consistency of a method or measurement under similar conditions.
• Validity: The extent to which a method measures what it is intended to measure.
• Replication: Repeating a study to assess whether its findings remain consistent.
• Theory: An organised set of evidence-supported ideas used to understand behaviour.
• Naturalistic observation: Studying behaviour in its usual setting without deliberately changing the situation.
• Participant observation: Observation in which the researcher becomes part of the group or situation.
• Non-participant observation: Observation in which the researcher watches without becoming involved.
• Controlled observation: Observation conducted under planned and controlled conditions.
• Experimental method: Manipulating an independent variable and measuring its effect on a dependent variable. It is particularly useful for examining cause and effect.
• Experimental group: The group receiving the treatment or experiencing the change in the independent variable.
• Control group: The comparison group that does not receive the experimental treatment or receives a standard condition.
• Random assignment: Placing participants into groups by chance to reduce pre-existing differences.
• Survey method: Collecting information about opinions, attitudes, experiences, or behaviour through questions.
• Questionnaire: A written or digital set of questions used to gather information from respondents.
• Interview: Direct verbal interaction between researcher and participant. Interviews can provide detailed information and allow clarification, but may be time-consuming and affected by interviewer bias.
• Case study: An intensive study of one person, group, institution, or unusual event. Case studies provide rich understanding but may not generalise to larger populations.
• Psychological testing: The use of standardised tools to measure abilities, personality, interests, attitudes, or other psychological characteristics.
• Standardisation: Using identical instructions, conditions, scoring rules, and interpretation procedures for all participants.
• Population: The complete group about which the researcher wants to draw conclusions.
• Sample: The smaller group selected for actual study.
• Representative sample: A sample reflecting important characteristics of the population.
• Random sampling: Selecting participants so that each population member has a known chance of selection.
• Qualitative data: Descriptive, non-numerical information, including words, explanations, observations, and personal experiences.
• Quantitative data: Numerical information that can be counted, measured, and statistically analysed.
• Frequency: The number of times a score, response, or category occurs.
• Mean: The arithmetic average:

Mean = Sum of all scores divided by the number of scores.

• Median: The middle score in an ordered data set. With an even number of scores, it is the average of the two central values.
• Mode: The score or category occurring most frequently.
• Range: The difference between the highest and lowest scores:

Range = Highest score minus lowest score.

• Standard deviation: A measure of how much scores vary around the mean.
• Correlation: A statistical relationship showing how two variables change together.
• Positive correlation: Increases in one variable are generally associated with increases in the other.
• Negative correlation: Increases in one variable are generally associated with decreases in the other.
• Causation: A relationship in which a change in one variable produces a change in another. Correlation alone does not prove causation.
• Correlation coefficient: Generally ranges from −1.00 to +1.00. A value near +1 indicates a strong positive relationship, a value near −1 a strong negative relationship, and a value near 0 little or no linear relationship.
• Ethical guidelines: Rules requiring responsible research and protection of participants’ rights, safety, dignity, wellbeing, and privacy.
• Informed consent: Voluntary agreement after receiving understandable information about the study.
• Confidentiality: Keeping participants’ personal information and individual responses private.
• Debriefing: Explaining the purpose, procedures, and findings after participation.
• Right to withdraw: The freedom to leave a study at any time without penalty.
• Deception: Withholding or misrepresenting information; it should be avoided unless strongly justified and must be followed by debriefing.
• Researcher bias: The influence of the researcher’s expectations, beliefs, or preferences on the study or interpretation of findings.
• Data presentation: Tables organise data in rows and columns; bar graphs compare categories, histograms display continuous numerical data, and pie charts show parts of a whole.

Causes and Consequences

• A clearly defined research problem leads to a suitable research design. Researchers review existing knowledge, state objectives or questions, form a hypothesis when appropriate, and select participants and methods accordingly.

• Manipulation of the independent variable permits stronger causal investigation. In a simple experiment, an experimental group is compared with a control group while extraneous variables are controlled. Random assignment reduces pre-existing differences between groups.

• Experimental control strengthens causal conclusions. Experimental research is especially useful for cause-and-effect relationships, whereas correlation demonstrates association only. A third variable may influence both measured variables, or the direction of influence may be uncertain.

• Observation provides access to actual behaviour. Naturalistic, participant, non-participant, and controlled observation can reveal behaviour in different contexts. However, participants may change their behaviour when observed, and observer bias may affect records.

• Surveys increase efficiency but may reduce accuracy. Questionnaires and interviews can collect information from many people, but responses may be affected by poor wording, social desirability, memory errors, interviewer bias, or an unrepresentative sample.

• Sampling determines the scope of conclusions. A population is studied through a sample, ideally a representative sample selected through random sampling. Sampling bias occurs when some population members have a greater chance of selection than others, limiting generalisability.

• Case studies produce depth rather than broad generalisation. Intensive study of one person, group, institution, or unusual event can provide detailed understanding, but findings may not apply to larger populations.

• Psychological tests require consistent and appropriate procedures. Tests should be reliable, valid, standardised, and suitable for participants’ age, language, culture, and the purpose of assessment.

• Statistical analysis organises evidence but does not determine its meaning independently. Frequency, mean, median, mode, range, and standard deviation summarise quantitative data. Tables, bar graphs, histograms, and pie charts communicate patterns, but numbers must be interpreted in relation to the research design and limitations.

• Ethical safeguards protect participants and the quality of research. Research requires informed consent, voluntary participation, protection from physical or psychological harm, privacy, confidentiality, the right to withdraw, debriefing, and responsible use of deception when unavoidable. Children and other vulnerable participants require special care and appropriate permission from parents, guardians, institutions, or relevant authorities.

• Methodological limitations qualify psychological conclusions. Difficulties include measuring private mental processes, the influence of culture and context, participant reactivity, researcher bias, ethical restrictions, and limited generalisability.

• Replication and transparent reporting strengthen knowledge. Findings become more credible when studies are repeated, use diverse samples, and produce converging evidence from different methods. Researchers should report methods, limitations, unexpected results, and sufficient detail for others to evaluate or repeat the study.

What Gets Asked

• Explain why no single research method is best for every psychological question, comparing experiments, observations, surveys, interviews, case studies, and psychological testing.
• Distinguish the independent, dependent, and extraneous variables, and explain how experimental and control groups, random assignment, and control of conditions support causal conclusions.
• Compare correlation with causation, including the meaning of positive and negative correlations and the interpretation of correlation coefficients from −1.00 to +1.00.
• Explain how sampling, representativeness, and sampling bias affect the generalisability of psychological findings.
• Calculate and interpret the mean, median, mode, range, frequency, and standard deviation, and select appropriate forms of data presentation.
• Evaluate ethical and methodological limitations, including informed consent, confidentiality, debriefing, the right to withdraw, deception, researcher bias, participant reactivity, cultural influence, and the protection of children or other vulnerable participants.