Chapter 2 Psychology


Smaller group of research participants selected from a larger group of research interest


The entire group of research interest from which a sample is drawn.

Research hypothesis

A testable prediction of the relationship between two or more variables.


A general explanation of a set of observations about behaviour and/or mental processes which seem to be related.


A general explanation of a related set of observations or findings often including a representation in a diagrammatic form.


A research method in which a researcher tests whether one variable(s) influences or causes a change to another variable(s) under strictly controlled conditions.


Something in which individuals, animals or objects differ among themselves and that can change in amount or kind.

IV (Independent variable)

Variable that is manipulated in order to test its effects on the dependent variable.

DV (Dependent variable)

The variable in an experiment the researcher chooses to measure in order to assess the effect(s) of the independent variable(s).


Defining a variable in terms of the procedures or actions that can be observed and measured optic chias

Experimental group

The group exposed to the IV.

Control group

The group not exposed to the DV.

Extraneous variable

Any variable other than the IV that can cause a change in the IV and therefore affect the results in an unwanted way.

Confounding variable

A variable other than the IV that has had an unwanted effect on the DV, making it impossible to determine which of the variables has produced the predicted change in the DV.

Individual participant differences

The unique combination of personal characteristics, abilities and background each participant brings to an experiment.

Order effects

when a participant's response relevant to the dependent variable is influenced by the specific order in which an experimental task is presented rather than the independent variable

Experiment effect

An unwanted influence on the results produced by the person carrying out the research.

Placebo effect

Any change in a participant's behaviour due to their belief that they are receiving some kind of experimental treatment and they respond in accordance with that belief, rather than to the effect of the IV.


A fake treatment that is like the independent variable treatment but has no effect.


Process of selecting participants from a population of research interest.

Representive sample

A sample that is approximately the same as the population from which it was drawn in every important participant variable.

Random sampling

Sampling procedure that ensures every member of the population of research interest has a genuinely equal chance of being selected as a participant.

Stratified sampling

A sampling procedure which involves dividing the population to be sampled into different subgroups (strata), then selecting a separate sample from each subgroup (or stratum) in the same proportions as they occur in the population of interest.

Convenience sampling

Sampling procedure involving selection of participants who are readily available.

Random allocation

Procedure used to assign participants to experimental and control groups (or conditions) so that each one has a genuinely equal chance of being placed in any of the groups; ensures uniform distribution of participant characteristics.


Systematically changing the order of treatments or tasks for participants in a 'balanced' way to 'counter' the unwanted effects on performance of any one order.

Single-blind procedure

Participants do not know whether they are in an experimental or a control group.

Double-blind procedure

Neither the participant nor the researcher interacting with the participants knows which participants are in the experimental or control groups.

Standardized instructions and procedures.

Instructions and procedures are the same for all participants (except for variations required for experimental group participants exposed to the IV).

Non-standardized procedure

Research procedure/instructions that are not the same for all participants.

Independent groups

An experimental research design for which each participant is randomly allocated to one of two (or more) entirely separate conditions in the groups.

Repeated measures

An experiment research design for which each participant is in both the experimental and control conditions.

Matched participants

An experimental research design for which each participant in one participant "matches" another participant in another condition.

Cross-sectional study

Research method involving selection and comparison of groups of participants on one or more variables of interest.

Case study

An intensive, in-depth investigation of an individual, group, organisation or event.

Observational study

Collection of data by carefully watching and recording behaviour as it occurs.

Naturalistic observation

Naturally occurring behaviour of interest is viewed by a researcher in an inconspicuous manner so that the researcher's presence has no influence on the behaviour being observed.


A participant's written or spoken responses to questions, statements or instructions presented by the researcher.


written set of questions designed to collect self-report data


Questions asked by the researcher to obtain self-report data.

Rating scale

Fixed questions or statements for which participants rank each item by selecting from a number of choices.


Information collected through research.

Primary data

Data observed or collected from first-hand experience.

Secondary data

Information collected by someone other than the original user who did so for their own purpose.

Qualitative data

data (information) involving the 'qualities' or characteristics of a participant's experience of what is being studied

Quantitative data

numerical information on the 'quantity' or amount of what is being studied


An orderly arrangement and display of data in columns and rows.

Research integrity

Research that is carried out with a commitment to the search for knowledge and understanding, to following recognized research principles and standards for conducting research.


The extent to which the the results obtained from research are consistent.

Reporting conventions

Well-established and widely recognised standards about how a report is written and presented.

Respect for human beings

In relation to research ethics, when the researcher takes account of the rights, beliefs, perceptions and cultural backgrounds of all participant.

Standard deviation

Statistic that summarises how far scores within a set of scores spread out, or 'deviate', from the mean for those scores.

Research merit

research that is worthwhile and conducted appropriately to achieve the aim


a statistic that expresses a number as a proportion of 100

Measure of variation

Score that indicates how widely scores are distributed or spread around the central point.

Measure of central tendency

Score that indicates the central value of a set of scores.


The arithmetical average of all the individual scores in a set of scores.

Line graph

Uses points connected by lines to show how one variable changes as another variable changes.


In relation to research ethics, the use of fair procedures and ensuring fair distribution of the costs and benefits of the research.


A decision about how widely the findings of a research study can be applied, particularly to other members of the population from which the sample was drawn.

External validity

The extent to which the results obtained for a study can be generalized to the population from which the sample was drawn or to other people in other settings.

Internal validity

The extent to which the results obtained for a study are actually due to the variable(s) that was tested or measured and not some other factor.


A decision about what the results obtained from a research study mean.


The extent to which a research study has produced results that accurately measured what is claims to have measured.


Standards that guide individuals to identify good, desirable or acceptable behaviour.

Bar chart

A graph which uses a series of separate bars or rectangles next to, but not touching one another, so comparisons of different categories of data can be made; also called a bar graph.


In relation to research ethics, the potential benefits of the research to participants or the wider community.