Basic research methods Flashcards
What is an independent variable
the variable that is manipulated by the researcher
one that changes
what is a dependent variable
the variable that is being measured
what is an extraneous variable
a variable that might affect the DV
what is a confounding variable
a variable that interacts with the IV and affects the DV
what are demand characteristics
when a participants works out the aims of an experiemtn and behaves in a way they think the experimenter wants them to
what is a lab experiment
an experiment that has control of all variables
Evaluation of a lab experiment
strengths- high control means findings are reliable
- high internal validity
- cause and effect can be established
weaknesses
- low ecological validity
- demand characteristics
what is a field experiment
an experimental investigation carried out in a natural environment e.g. school
evaluation of field experiement
strenghts
- high ecological valdity
- low demand characteristics
weaknesses
- time-consuming, small sample size, low pop validity
- do not have full control of extraneous variables
what is a natural experiment
experimenter takes advantage of a naturally occurring event, does not have control of the IV
Evaluation of natural experiment
strenghts
- high ecological valdity
- low demand characteristics
weaknesses
- no control, less reliable as hard to replicate
- no control of extraneous variables, low internal validity
what is a quasi-experiment
an experiement which uses a pre-existing IV that does not vary
usually a character trait e.g. phobia, age, gender
what are the 3 types of experimental design
- matched pairs
- independent groups
- repeated measures
what are repeated measures
where participants take part in all all levels of the IV and the results of the DV. in both conditions are compared
take part in both conditions
what are independent groups design
when participants are split into different conditions, so different participants take part in each levels of the IV
What is matched pairs design
when different participants are used in each level of the IV but they are matched as similarly as possible, they are similar on key characteristics that are likely to affect the DV
evaluation of repeated measures
strengths
- less participants needed so cheaper
- less participant variables
weaknesses
- demand characteristics
- order effects, acting as a confounding variable
evaluation of independent groups design
strengths
- less demand characteristics
- no order effects
weaknesses
- more participant variables as they are not matched
- more participants needed
evaluation of match pairs
strengths
- less demand characteristics
- less order effects
- less participant variables
weaknesses
- time consuming
- more participants needed
- still some participant variables
way to overcome limitations in repeated measures
counterbalancing- half participants experience the conditions in one order, the half experience them in a different order
way to overcome limitations in independent groups
random allocation- each participant has the same chance of being in each condition