RM: Experimental methods Flashcards
What are the three key concepts?
The aim, hypothesis and experimental method.
What is the aim?
A general expression of what the researcher intends to investigate.
What is an hypothesis?
A statement of what the researcher believes to be true. Should be operationalised, i.e. clearly defined and measurable. Two types: directional and non-directional.
What are the two types of hypothesis?
Directional hypothesis and non-directional hypothesis.
What is a directional hypothesis?
States whether changes are greater or lesser, positive or negative etc.
What is a non-directional hypothesis?
Doesn’t state the direction, just that there is a difference, correlation, association.
What is an experimental method?
A researcher causes the independent variable (IV) to vary and records the effect of the IV on the dependent variable (DV). There are different levels of the IV.
What are the some research issues?
Extraneous variables, confounding variables, demand characteristics and investigator effects.
What are extraneous variables?
They are ‘nuisance’ variables that do not vary systematically with the IV. A researcher may control some of these.
What are confounding variables?
They change systematically with the IV so we cannot be sure if any observed change in the DV is due to the CV or the IV. CVs must be controlled.
What are demand characteristics?
Refers to any cue from the researcher or research situation that may reveal the aim of the study.
What are investigator effects?
Any effect of the investigator’s behaviour on the outcome of the research (the DV).
What are the research techniques?
Randomisation, standardisation, control groups, single blind and double blind.
What is randomisation?
The use of chance when designing investigations to control for the effects of bias.
What is standardisation?
Using exactly the same formalised procedures for all participants in a research study.
What are control groups?
Control groups are used for the purpose of setting a comparison. They act as a ‘baseline’ and help establish causation.
What is single blind?
A participant doesn’t know the aims of the study so that demand characteristics are reduced.
What is double blind?
Both participant and researcher don’t know the aims of the study to reduce demand characteristics and investigator effects.
What are the three experimental designs?
Independent groups, repeated measures and matched pairs.
Describe the independent groups experimental design.
One group do condition A and a second group do condition B. Participants should be randomly allocated to experimental groups.
What are the strengths of the independent groups experimental design?
NO ORDER EFFECTS: participants are only tested once so can’t practice or become bored/tired. This controls an important CV.
WILL NOT GUESS AIM: participants only tested once so are unlikely to guess the research aims. Therefore behaviour may be more ‘natural’.
What are the limitations of the independent groups experimental design?
PARTICIPANT VARIABLES: the participants in the two groups are different, acting as EV/CV. May reduce the validity of the study.
MORE PARTICIPANTS: need twice as many participants as repeated measures for same data. More time spent recruiting which is expensive.
Describe the repeated measures experimental design.
Same participants take part in all conditions of an experiment. The order of conditions should be counterbalanced to avoid order effects.
What are the strengths of the repeated measures experimental design?
PARTICIPANT VARIABLES: the person in both conditions has the same characteristics. This controls an important CV.
FEWER PARTICIPANTS: half the number of participants is needed than in independent groups. Less time spent recruiting participants.
