research methods key terms

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experimental method

experimental method

involves the manipulation of an independent variable to measure the effect on the dependent variable

may be: laboratory, field, natural or quasi

aim

general statement of what the researcher intends to investigate, the purpose of the study

hypothesis

clear, precise, testable statement that states the relationship between the variables to be investigated.

stated at the outset of any study

directional hypothesis

states the direction of the difference or relationship

non directional hypothesis

does not state the direction of the difference or relationship

variables

any ‘thing‘ that can vary or change within an investigation

used in experiments to determine if changes in one thing result in changes to another

independent variable

some aspect of the experimental situation that is manipulated by the researcher- or changes naturally- so the effect on the DV can be measured

dependent variable

variable that is measured by the researcher

any effect on DV should be caused by the change in IV

operationalisation

clearly defining variables in terms of how they can be measured

extraneous variable

any variable other than the independent variable that may affect the dependent variable if it is NOT controlled

essentially nuisance variables that do not vary systematically with the IV

confounding variables

kind of extraneous variable

varies systematically with the IV

we can’t tell if any change in the DV is due to the IV or the confounding variable

demand characteristics

cue from the researcher or from the research situation that may be interpreted by participants as revealing the purpose of an investigation

may lead to a participant changing their behaviour within the research situation

investigator effects

any effect of the investigator’s behaviour (conscious or unconscious) on the research outcome (the DV)

may include everything from the design of the study to the selection of/interaction with/participants during the research process

randomisation

use of chance methods to control for the effects of bias when designing materials and deciding the order of experimental conditions

standardisation

using exactly the same formalised procedures and instructions for all participants in a research study

extraneous variable examples:

participant reactivity

confounding variables examples:

metabolic rate

age

physical activity

height

sex/gender

experimental design

different ways in which participants can be organised in relation to the experimental conditions

independent groups design

participants are allocated to different groups where each group represents one experimental condition

repeated measures

all participants take part in all conditions of experiment

matched pairs design

pairs of participants are first matched on some variables that may affect the DV

one member of the pair is assigned to condition A and the other condition B

random allocation

attempt to control for participant variables in an independent groups design which ensures that each participant has the same chance of being in on condition as any other

counterbalancing

attempt to control for the effects of order in a repeated measures design

half participants experience the conditions in one order and the other in the opposite order