Chapter 1 - Key science skills

Controlled experiment

An experiment in which only one variable is manipulated at a time.

Case study

in-depth investigation of an individual, group, or particular phenomenon that contains a real or hypothetical situation

Correlational study

non-experimental study in which researchers observe and measure the relationship between two or more variables without any active control or manipulation of them

Simulation

the process of using a model to study the behaviour of a real or theoretical system

Within-subjects design

experimental design in which participants complete every experimental condition

Between-subjects design

experimental design in which individuals are divided into different groups and complete only one experimental condition

Convenience sampling

involves selecting readily available members of the population, rather than using a random or systematic approach.

• e.g. a psychology professor asking her students to participate in an interview.

Random sampling

uses a procedure to ensure every member of the population has the same chance of being selected.

• e.g. using a random generator to select a set of names for the sample

Stratified sampling

involves selecting people from the population in a way that ensures that its strata (subgroups) are proportionally represented in the sample

Extraneous variables

any variable that is not the independent variable but may cause an unwanted effect on the dependent variable

Confounding variables

a variable that has directly and systematically affected the dependent variable, may be an extraneous variable that was not controlled or cannot be controlled.

Accuracy

refers to how close a measurement is to the true value of the quantity being measured

Precision

how closely a set of measurement values agree with each other

Repeatability

The extent to which the same study or measure used under the same conditions will produce the same results

Reproducibility

the extent to which the same study or measure, used under different conditions or with different people or procedures, will produce the same results