research methods: experimental method Flashcards
what is an experimental method
involves the manipulation of iv to measure the effect on dv
what is an aim
a general statement of what the researcher intends to investigate, the purpose of the study
what is a hypothesis
a clear, precise, testable statement that states the relationahip between the variables to be investigated. stated on the onset of a study
what types of hypothesis can there be
directional and non-directional
d - the researcher makes clear the sort of difference that is anticipated between two conditions
nd - simply states that there is a difference between conditions but unlike directional, the nature of the difference is not specified
what are experimental designs
the different ways in which ppts can be organised in relation to the experimental conditions
what are three types of experimental designs
independent groups design - when 2 groups of ppts experience two different conditions of the experiment, the performance of both conditions will then be compared
repeated measures - all ppts experience both conditions of the experiment, two avergae score/measures from both conditions are compared
matched pairs - ppts are matched together based on variables or variables relevant to the experiment, attempt to control for the confounding variable of participant variables
evaluation of experimental designs
P - L - independent group - the ppts who are in different groups are not the same in terms of ppt variables
E - researcher finds a mean difference between groups on the dv but may be more to do with ppt variables than effects of iv
T - less valid
P - L - repeated measured every ppt has to do at least 2 tasks - may create order effects
E - could create boredom so this happens
T - order acts as a confounding variable
P - L - matched pairs - time-consuming and expensive
E - if a pre-test is needed
T - less economical
types of experiment
lab, field, natural, quasi
lab experiment
conducted in high environment - high control over extraneous variables -> high internal validity
low external validity -> unsual behaviour - low mundane realism
field experiment
IV is manipulated in natural, everyday setting - high mundane realism
- ethical issues - don’t know they’re there
natural experiment
researcher has no control over the IV and cannot change it eg. before and after a natural disaster - high external validity - involve real-world issues
- event may be rare, may mean that the findiings struggle to be generalised to other situations
quasi experiment
have an IV that is based on an existing difference between people , Iv cant be changed - carried out under controlled conditions
- cannot claim that the IV has caused any observed change as its not deliberately changed
sampling types
random, stratified, systematic, opportunity, volunteer
random sampling
all members of target population have an equal chance of being selected
P - + - unbiased
E - confounding V or EV’s equally divided
T- enhances internal validity
stratified sampling
composition of the sample reflect the proportions of people in certain subgroups in wider population
P - + - produces a representative sample - accurately reflects population
T - generalisable
