IB Psych Unit 1: Research Methodology

Independent variable

the variable that is manipulated by the researcher.

Dependent variable

the variable that is measured by the researcher. It is assumed that this variable changes as a result of the manipulation of the independent variable.

Confounding variables

any variable that you're not investigating that can potentially affect the outcomes of your research study

Controlled variables

variables that are kept constant in order to avoid influencing the relationship between the IV and the DV.

Target population

The group of people to which the findings of the study are expected to be generalized.

Stratified sample

a method where a population is divided into subgroups (strata) based on shared characteristics, and then random samples are drawn from each stratum to ensure representation of all subgroups in the overall sample.

Random sampling

every individual in a population has an equal chance of being selected for a sample

Convenience sample

A non-probability sampling method where participants are selected based on their accessibility and ease of recruitment, rather than random selection

Self-selected sample

Involves recruiting people who volunteer to participate in a study

Matched pairs design

Members of the sample are not randomly allocated to conditions.

Independent measures design

Members of the sample are randomly allocated to conditions and only participate in one condition.

Repeated measures design

The same participants would take part in both conditions.

Construct validity

The extent to which the experiment is measuring what it is intended to.

Internal validity

The extent to which the researcher is certain that the independent variable is causing the dependent variable to change.

Population Validity

The extent to which the experiment can be generalized to fit a larger population.

Ecological validity

The extent to which the experiment can be generalized to fit a larger population.

When the experiment is done in a controlled environment (lab setting), it automatically has low ecological validity.

Hypothesis

a testable prediction about the relationship between two or more variables

Null hypothesis

states that there is no significant relationship or difference between the variables being studied

Standardized procedures

the process of establishing common procedures and criteria for measuring psychological constructs, ensuring consistency and reliability across different assessments.

Lab experiment

a controlled research method where the experimenter manipulates one or more independent variables to observe their effects on a dependent variable, all while maintaining strict control over extraneous variables

Quasi experiment

a research design that aims to establish cause-and-effect relationships, but unlike a true experiment, participants are not randomly assigned to conditions, often due to practical or ethical constraints.

Correlational studies

Correlational studies are different from experiments in that the researcher does not manipulate any variables (there are no IVs or DVs). Variables are measured and the relationship between them is quantified.

Case studies

an in-depth investigation of an individual or a group. Can involve a variety of other methods (observations, interviews, and so on), anything that deepens our understanding of an individual or a group of interest.

Observation

the systematic and careful study of behavior, typically involving watching and recording actions or interactions without directly manipulating the situation

Interview

a research or clinical tool where a researcher or clinician engages in a directed conversation with an individual to gather information about their thoughts, experiences, and behaviors

Strengths + limitations of case studies

STRENGTHS:

• they can provide new knowledge that applies beyond a single person.

• provide important evidence in support of an existing theory

LIMITATIONS:

• Case studies can't be replicated. No other person in the world will have exactly the same pattern of brain damage as S.M., and even people with a similar condition may be very rare.

• Findings from one case might not apply to everyone. It’s mistaken to assume that the results from one case can be generalized to all people.