AS RESEARCH METHODS- experimental methods- experimental design- controlling ev Flashcards
what do experiments study?
cause and effect relationship
what is a cause & effect rels?
changin 1 thing leads to another variable
what do experiments have?
iv & dv
what is an independent variable?
a variable that is manipulated by the experimenter in order to look at the effect that it has on dv
what is a dependant variable?
the variable that is measured by the experimenter
what is an iv in rels?
the cause in a cause and effect rels
what is a dv in rels?
the effect in a cause and effect rels
iv and dv in shorter?
iv is what we change and dv is what we measure
what are the types of experimental methods?
lab experiment, field experiment, natural experiment
what is a lab experiment usually?
usually artificial situations
define lab exp?
conducted in a controlled environment so we change the independent variable to see the effect on dv
advantages of lab experiment?
- high levels of control e.g investigate cause and effect
2. replicable = reliable
disadvantages of lab experiment?
- lack of ecological validity -artificial as people change behaviour for results
- dc
- p often try t make sense of exp could change p behaviour
define field experiment?
conducted in real life sit but still have control of iv and dv
advantages of field experiment?
- ecological validity higher as in real life sit so more likely real behaviour
- low demand c -more natural behaviour
disadvantages of field experiment?
- less control -less control so cant control ev so changes in dv may not be due to iv
- cost more expensive than lab exp
define natural exp?
investigation into totally naturally occurring situations
iv occurs naturally e.g gender age social backround
advantages of natural exp?
- improved validity real situations
2. research opportunities allow us to investigate situations that would be unethical to set up in labs
disadvantages of natural exp?
- less control on iv and dv so cant draw casual conclusions
2. not replicable usually are rare sit so we cant test reliability of findings
what are experimental designs?
how p’s are allocated to conditions of iv.
what are the different types of designs?
independent groups
repeated measures
matched pairs
what are independent group designs?
pps randomly allocated to diff groups which represent different conditions
advantages of independent groups?
1.less chance of order effects like learning etc
2.can use same stimulus materials
3/].less dc
disadvantages of independent groups?
- less effective for controlling p variables some diff abilities
- require more p
- takes more time to find p
what are repeated measures?
same pps are used in both conditions conditions have to be counterbalanced
advantage of repeated measures?
- p variables are elimated not diff abilities
2. fewer p need to be found = easier recruiting
disadvantages of repeated measures?
- order effects like fatigue(bored second time) and learning can occur
- dc due to more contact with researcher
- cannot use same stimulus material due to learning effects
what are matched pairs?
pairs of pp are closely matched and are then randomly allocated to one of the experimental conditions e.g characteristics like age intelligence iq test etc
advantages of match pairs?
- participant variation reduced
2. no order effects
disadvantages of matched pairs?
- costly and time consuming to find matched pairs
- need more p
- still gonna be p variation on other non matched factors
what are order effects?
completing 1 condition first may affect the p performance in another condition
what are ev’s?
variables other than iv that could affect dv and therefore confound the findings . they should be controlled to ensure that any changes in dv due to iv
examples of ev’s?
participant variables
situational variables
experimenter effects
dc’s
what are participant variables?
aspects of p characteristics or experience other than iv which may influence dv e.g motivation,age,intelligence,gender
what are situational variables ?
aspects of research situation other than iv which may influence dc e.g time of day,noise, temp
what are experimenter effects ?
effects of experimenters expectations which somehow communicated to p
how can a researcher control ev’?
situational variables
p variables
experimenter bias/dc
how can a researcher control situational variables?
keep sit same for everyone e.g lab ensure temp noise and pleasantness consistent
in a field try keep as many factors same e.g time of day
procedural controls ; specifically instruct p to avoid doing certain things that might influence dv
how can a researcher control participant variables?
use a matcher pairs or repeated measures design
in an indep make sure p are randomly allocated to each con this ensures that p variables randomly allocated equally distributes across conditions
how can a researcher control dc or experimenter bias?
single bind technique: p not told the aims of study so cannot alter b
double bind: researcher employs another who does not know aims of study to carry exp therefore cannot communication expectations about study to p
