Research methods and Statistics in Psychology

1. Psychology Uses Science to Understand People

Science is a system of thought that leads us to a rational explanation of how things work in the world and a process of getting closer to truths and further from myths, fables and unquestioned or ‘intuitive’ ideas about people.

Moving beyond intuition. Psychology relies on the scientific method to move beyond intuition and common sense, which are often based on myths, stereotypes, and unchecked wisdom. Empirical research, gathering evidence-based facts, is crucial for understanding human behavior. For example, research has shown that text abbreviations do not necessarily harm a child's standard of English, contrary to popular belief.

Science as a thought system. Science is not merely a body of technical knowledge but a way of thinking that leads to testable explanations of observed phenomena. It involves rational explanations and a process of refining our understanding of the world, distinguishing it from reliance on intuition or unchecked assumptions.

Everyday scientific thinking. People use the logic of scientific thinking in their daily lives, such as forming hypotheses and testing them. The difference between ordinary and professional scientific thinking lies in practice and the acquisition of formal concepts and procedures. This includes questioning assumptions, gathering evidence, and modifying beliefs based on findings.

2. Scientific Thinking Extends Common Sense

A study of methods and statistics, at the very least and done properly, will enhance your ability to spot gross errors in the statistical arguments of advertisers, politicians and charlatans who try to use numbers or ‘findings’ to bamboozle you.

Enhancing predictive power. Psychological science aims to enhance our ability to predict, understand, and control human action beyond what common sense can achieve. Prediction involves observing patterns and regularities, while understanding seeks to explain why these patterns occur.

Benefits of scientific thinking. By understanding and controlling events, science can improve people's lives. In psychology, this includes improving teaching and learning, reducing antisocial behavior, and alleviating disturbed behavior.

Checking the evidence. Scientific thinking involves checking evidence and not just trusting intuitive guesses. It enhances the ability to spot errors in statistical arguments and assumptions made from findings that have made the news.

3. Theories Guide Psychological Research

Research supplies evidence which might support or contradict a theory.

Theories and hypotheses. Psychological research begins with a theory, a general explanation that requires evidence. From this, a hypothesis is derived, which is a testable statement. A research question is then posed, leading to a specific research prediction.

The hypothetico-deductive method. Mainstream psychological research relies on the hypothetico-deductive method, which involves developing explanatory theories and testing hypotheses derived from those theories. This method includes observation, data gathering, induction of generalizations, and deduction of testable hypotheses.

Falsifiability. A key aspect of scientific theories is that they must be falsifiable, meaning that there must be a way to show that the theory is wrong. This does not mean the theory must be proven wrong, but that it is possible to conduct tests that would disprove it if it were false.

4. Variables Are Measured to Test Hypotheses

A VARIABLE is anything that varies.

Defining variables. A variable is anything that can change and be measured. Variables can be explanatory concepts, and in psychology, these concepts are often hypothetical constructs. Precise operational definitions are needed to measure these variables.

Types of variables. Variables can be categorical, where data points are placed into qualitatively different categories, or measured, where data points appear along a scale. Measured variables can be discrete or continuous.

Operational definitions. To measure psychological constructs, researchers use operational definitions, which specify the activities required to measure a construct. These definitions provide a method for measuring some part of a hypothetical construct, ensuring precision and replicability.

5. Sampling Impacts Research Generalizability

In psychological research studies we are usually not specifically interested in the sample that we study... We study a sample because we cannot study the entire population and we assume that the sample is a small representation of the sorts of humans in general that we are interested in.

Samples and populations. Psychological research often involves studying a sample to make generalizations about a larger population. The goal is to select a sample that is representative of the population to which the results may be generalized.

Sampling bias. Sampling bias occurs when certain sub-groups of the target population are under- or over-represented in the sample. To avoid bias, researchers use equal probability selection methods (epsem), where every case in the target population has an equal chance of being selected.

Random sampling methods.

• Simple random sample: Every case has an equal chance of selection.
• Systematic random sample: Every nth case is selected, with a random starting point.
• Stratified sampling: The population is divided into strata, and samples are randomly selected from each stratum in proportion to their size in the population.

6. Qualitative Methods Offer Alternative Insights

There is too much measurement going on. Some things which are numerically precise are not true; and some things which are not numerical are true.

Limitations of quantitative methods. Many researchers reject the application of conventional scientific methods to the study of people and society. They argue that human behavior is not susceptible to precise measurement and that quantification can distort the richness of human experience.

Qualitative data. Qualitative approaches gather meaningful verbal data, providing a richer, fuller description of phenomena. Qualitative data can be text-based or pictorial and are often the contents of interviews or observer's notes.

The qualitative-quantitative debate. The qualitative-quantitative dimension represents a fundamental division within the theory of methods in contemporary psychological research. This dimension influences the extent to which research employs aspects of either approach.

7. Ethical Research Protects Participants

The real purpose of the scientific method is to make sure nature hasn’t misled you into thinking you know something you actually don’t know.

Ethical responsibilities. Psychologists have responsibilities to publish well-founded results and to protect research participants from harm. This includes obtaining informed consent, ensuring confidentiality, and minimizing stress and discomfort.

Deception. Deception is only used when scientifically justifiable and when no feasible non-deceptive alternative exists. Debriefing is essential to inform participants of the true purpose of the study and to address any negative effects.

Ethical principles. The British Psychological Society's Code of Ethics and Conduct is based on four major principles: respect, competence, responsibility, and integrity. These principles guide researchers in conducting ethical and responsible research.

8. Research Designs Balance Control and Realism

The essence of scientific research is to relate these changes in variables to changes in other variables.

True experiments. A true experiment attempts to isolate cause and effect by manipulating an independent variable and controlling all other variables. This includes the random allocation of participants to conditions and measuring the effect on a dependent variable.

Quasi-experiments. Quasi-experiments lack some essential features of a true experiment, such as random allocation of participants. These designs are often used in field settings where full control is not possible.

Non-experiments. Non-experimental methods investigate variables that exist among people without researcher intervention. These studies often involve correlating variables or investigating existing group differences.

9. Experiments Demonstrate Cause and Effect

The essence of studying anything (birds, geology, emotion) is the observation of changes in variables.

Isolating cause and effect. Experiments are designed to demonstrate a relatively unambiguous connection between cause and effect. This is achieved by manipulating an independent variable and controlling all other salient variables.

Independent and dependent variables. The independent variable (IV) is manipulated by the experimenter, while the dependent variable (DV) is measured to see if it has changed as a result of the IV manipulation. The goal is to establish that changes in the DV depend on changes in the IV.

Alternative explanations. A key aspect of experimental design is to eliminate alternative explanations for observed relationships. This involves controlling for confounding variables and ensuring that any observed effect is genuinely due to the manipulation of the IV.

10. Data Analysis Validates Research Findings

The real purpose of the scientific method is to make sure nature hasn’t misled you into thinking you know something you actually don’t know.

Statistical analysis. Decisions about design and measurement directly affect the statistical analysis that is possible at the end of data collection. It is important to consider the statistical analysis while designing the study and its measures.

The role of statistics. Statistics are used to summarize data and to show relationships between data that support a particular view or theory. They are essential for obtaining a clear, objective, and fair conclusion about the area of psychological research.

Findings and conclusions. It is important to distinguish between findings, which are what actually occurred in a study, and conclusions, which are what the researcher may conclude as a result of considering findings in the light of background theory.

11. Report Writing Communicates Research Clearly

The real purpose of the scientific method is to make sure nature hasn’t misled you into thinking you know something you actually don’t know.

Report structure. Research reports typically include an abstract, introduction, method, results, discussion, and references. Each section serves a specific purpose in communicating the research process and findings.

Quantitative vs. qualitative reports. Quantitative reports emphasize objective measurement and statistical analysis, while qualitative reports focus on meaningful verbal data and rich descriptions of phenomena. Both types of reports require careful planning, clear writing, and attention to detail.

Ethical considerations. Throughout the research process, it is essential to adhere to ethical principles, such as obtaining informed consent, ensuring confidentiality, and minimizing harm to participants. These principles guide researchers in conducting responsible and ethical research.

Last updated: February 27, 2025