Research MethodologyFor IB Psychology Students

Empirical Investigation

The collecting of objective information firsthand, by making careful measurements based on direct experience.

You must collect the evidence yourself.You cannot rely on the opinion of experts.

Scientific Method

•1. Develop a Hypothesis•2. Perform a Controlled Test•3. Gather Objective Data•4. Analyze the Results•5. Publish the results (which can then be

analyzed, criticized, and replicated by others)

•Hypothesis – a prediction of the outcome of an experiment

Terminology

•Reliability – consistency in measurement. Does it yield the same results every time?

•Validity – actually measuring what you intend to measure.

•Independent Variable – the variable that causes change (ie: studying for an exam)

•Dependent Variable – the variable that changes (ie: the exam grade)

•Confounding/Extraneous Variable – a variable that has unwanted influence on the outcome of an experiment.

•Correlation – a relationship in which two or more variables change together.

•Replication – repetition of research by other researchers.

•Construct – something that we can think about & talk about. It is an abstract concept (not tangible)

•Operationalize – to turn a construct into an observable or measurable form.▫Ie: Intelligence = IQ Test

Demand Characteristics•Confounding/Extraneous variables that are

present when an experiment is conducted. These variables can cause bias.▫Ie: What the researcher is expecting to find,

What people think the true purpose of the experiment is

•Demand characteristics can be present in the words used to describe the purpose of the study, the appearance or conduct of the researcher, or the environment in which the research is conducted.

Controlling for Bias

• Single-Blind Experiments – the participants don’t know if they’re in the experimental group or control group.

• Double-Blind Experiments – neither the experimenter nor the participants know whether the participants are are in the experimental or control group.

• Placebo – an intervention (ie: sugar pill) that is expected to have no effect. Any change that occurs with a placebo is thought to be due to the person’s expectations of change.

Types of Experimental Design•Between-Subject Designs – studies in which

comparisons are made between groups of people assigned to different levels of the Independent Variable (IV) such as research conditions or treatments.

•Within-Subjects Designs (Repeated Measures Designs) – studies in which comparisons are made between two or more scores for each person. This involves repeated administration of the same measure to the same participant.

•Matched-Pairs Design – subjects are matched in pairs according to criteria considered important by the researcher (ie: age, gender). Each member of the pair is randomly assigned to one condition while the other member is assigned to a different condition.

•Single-Subject Design – a within-subjects design in which a single participant appears in each condition of the IV. Multiple measures are taken from a single participant.

Sampling• Random Sampling - sampling in which every

member of a population has an equal chance of being selected.

• Systematic Sampling – choosing every 3rd, 10th, 25th ,etc. case/member of a population.

• Stratified Sampling – the population is first divided into sub-populations according to a chosen criteria (ie; age, gender). Groups/Cases are then chosen from each sub-population.▫ Ie: if an age group makes up 10% of the population,

then 10% of cases from that subpopulation are chosen

•Ad-Hoc (opportunity & convenience) Sampling – samples are assembled on the basis of availability. This sampling type is typically used by psychology students.

Descriptive Statistics

•Variables- are the measures such as scores on a test, gender, age, etc.

•Quantitative - data in the form of numbers.

•Qualitative – data in the form of text or images.