RESEARCH METHODS YEAR 1 – SAMUEL NESBITT
Experimental Method Variables Controlling Variables
Directional Hypothesis IV and DV Operationalisation Extraneous variables Demand Characteristics Randomisation
Aims • Any variable other than IV • Pps second guess the aims • The use of chance to
• One tailed: stating the direction • IV is manipulated, DV is • Clearly defining
• The purpose of the which might influence DV, but of the study and alter their reduce the researcher’s
of difference or relationship measured. variables in terms of
investigation is randomly distributed. behaviour. influence
how they can be
Hypothesis Non- Directional Hypothesis Levels of the IV measured.
• The formulation of a • Two tailed: stating there is a • Having more than one Confounding variables Investigator Effects Standardisation
testable statement difference or relationship condition; experimental • A variable which may have • When a researcher's • Ensuring all pps are
Null Hypothesis and control influenced DV, but varies behaviour influences the subject to the same
• Stating there is no difference systematically with IV. outcome of the study. experience.
or relationship
Experimental Design Types of Experiments
Independent Groups Repeated Measures Matched Pairs Lab Experiments Field Experiments Natural Experiments Quasi Experiments
• Pps in each condition of an • All pps take part in all • Similar pps are paired (e.g. • IV is manipulated in a • IV is manipulated in a • IV in the environment has • IV is based on an existing
experiment are different. conditions. IQ) and allocated to different controlled setting natural setting been manipulated naturally; difference between
experimental conditions. effect on DV is recorded. people; effect on DV is
Strengths Strengths Strengths Strengths recorded.
• No order effects • No pp variable problems Strengths • High internal validity • High ecological validity Strengths
• More economical • No order effects (control of extraneous • High external validity Strengths
Limits Limits • High external validity
Limits Limits variables) • Unique research –
• Less economical • Low internal validity
• • Can see cause and effect opportunities may be rare
• PP variables not controlled – • Demand characteristics Cannot match pps exactly (control of extraneous Limits
• • Replication
Deal with this using random • Order effects – Deal with Time-consuming and less variables) Limits • Low internal validity
allocation this using counterbalancing economical Limits • Ethical issues • Low internal validity (no
- half do condition A then B, • Low ecological (external) random allocation)
other half do B then A. validity, artificial setting
• Demand characteristics.
Sampling Research techniques
Selecting pps for an investigation
Random Sampling Systematic Sampling Stratified Sampling Opportunity Sampling Volunteer sampling
• All members of the • Selecting every nth • PPs are selected according • Choosing whoever is • Participants select Pilot studies Control group/condition
population have an person from a list to their proportion in a themselves. • Checking procedures • Used as a comparison
available
equal chance of target population. and materials
Strengths Strengths Strengths • Making modifications
selection
• No research bias Strengths • Convenient and quick • Less time-consuming
Strengths • No research bias • Participants are willing
• Limits Double-blind
No researcher bias Limits • Representative of target Limits Single blind
• Researcher biased •
Limits • May end up with biased population • Biased - Attracts a certain • Participants aren’t Neither participants nor
• Unrepresentative as it the individual conducting
• May end up with biased sample profile of people, e.g. curious made aware of research
Limits uses a specific location. the research know the aim
sample • Time consuming aims until the end.
• Cannot reflect all the ways beforehand..
• Time consuming in which people are
different
1
Experimental Method Variables Controlling Variables
Directional Hypothesis IV and DV Operationalisation Extraneous variables Demand Characteristics Randomisation
Aims • Any variable other than IV • Pps second guess the aims • The use of chance to
• One tailed: stating the direction • IV is manipulated, DV is • Clearly defining
• The purpose of the which might influence DV, but of the study and alter their reduce the researcher’s
of difference or relationship measured. variables in terms of
investigation is randomly distributed. behaviour. influence
how they can be
Hypothesis Non- Directional Hypothesis Levels of the IV measured.
• The formulation of a • Two tailed: stating there is a • Having more than one Confounding variables Investigator Effects Standardisation
testable statement difference or relationship condition; experimental • A variable which may have • When a researcher's • Ensuring all pps are
Null Hypothesis and control influenced DV, but varies behaviour influences the subject to the same
• Stating there is no difference systematically with IV. outcome of the study. experience.
or relationship
Experimental Design Types of Experiments
Independent Groups Repeated Measures Matched Pairs Lab Experiments Field Experiments Natural Experiments Quasi Experiments
• Pps in each condition of an • All pps take part in all • Similar pps are paired (e.g. • IV is manipulated in a • IV is manipulated in a • IV in the environment has • IV is based on an existing
experiment are different. conditions. IQ) and allocated to different controlled setting natural setting been manipulated naturally; difference between
experimental conditions. effect on DV is recorded. people; effect on DV is
Strengths Strengths Strengths Strengths recorded.
• No order effects • No pp variable problems Strengths • High internal validity • High ecological validity Strengths
• More economical • No order effects (control of extraneous • High external validity Strengths
Limits Limits • High external validity
Limits Limits variables) • Unique research –
• Less economical • Low internal validity
• • Can see cause and effect opportunities may be rare
• PP variables not controlled – • Demand characteristics Cannot match pps exactly (control of extraneous Limits
• • Replication
Deal with this using random • Order effects – Deal with Time-consuming and less variables) Limits • Low internal validity
allocation this using counterbalancing economical Limits • Ethical issues • Low internal validity (no
- half do condition A then B, • Low ecological (external) random allocation)
other half do B then A. validity, artificial setting
• Demand characteristics.
Sampling Research techniques
Selecting pps for an investigation
Random Sampling Systematic Sampling Stratified Sampling Opportunity Sampling Volunteer sampling
• All members of the • Selecting every nth • PPs are selected according • Choosing whoever is • Participants select Pilot studies Control group/condition
population have an person from a list to their proportion in a themselves. • Checking procedures • Used as a comparison
available
equal chance of target population. and materials
Strengths Strengths Strengths • Making modifications
selection
• No research bias Strengths • Convenient and quick • Less time-consuming
Strengths • No research bias • Participants are willing
• Limits Double-blind
No researcher bias Limits • Representative of target Limits Single blind
• Researcher biased •
Limits • May end up with biased population • Biased - Attracts a certain • Participants aren’t Neither participants nor
• Unrepresentative as it the individual conducting
• May end up with biased sample profile of people, e.g. curious made aware of research
Limits uses a specific location. the research know the aim
sample • Time consuming aims until the end.
• Cannot reflect all the ways beforehand..
• Time consuming in which people are
different
1
