object, quality or event that changes or
varies some way e.g. aggression,
intelligence, height, attraction
have to operationalise variables,
physically measurable or testable
Investigating Varibales
observations,
case studies,
surveys -
precisely
measured in
varying amounts
of detail
correlations - measured and
compared to see how they co-vary
with each other
experiment - IV is altered to see effect on
DV (IV is manipulated, DV is measured
outcome
EV - extraneous variables influence DV -
could spoil experiment can be random
(reduce accuracy) or constant (truly
confound experimental methods
Experimental Designs
Repeated Measures -
same participants in
each condition
Strengths - participant variables
are constant between conditions,
better statistical tests are used
because of less varieties between
conditions, fewer participants are
needed
Weaknesses - order effects, learning fatigue and
bordem, demand characteristics people guess the
aim of the study, different tests might be needed
Matched Pairs - different but
similar participants in each
condition
Strengths - variables are more
constant, better statistical tests
there are less variations between
conditions, no order effects, no
demand characteristic, same test
is used
Weaknesses - it is time consuming, more
participants are required, variables can
never be matched perfectly
Independent Measures - different
participants in each condition
Strengths - order effects do not
influence second condition,
demand characteristics are less
of a problem, same test is used
Weaknesses - participant variables
differ, worse statistical tests means
there are more variation between
conditions, more participants are
required
Reliability and Validity
Reliability - how consistent or dependant a test
is, reliable test carried out in same
circumstances should always produce same
results
Internal - should give consistent results, can be assessed
using split half method, results from each half should produce a
high positive correlation. e.g. IQ test = equal difficulty should
achieve similar scores on all sections
External - should produce consistent results
regardless of when its used, can be assessed using
test retest method, should produce high positive
correlation between 2 scores. e.g. took same IQ test
on 2 different days should get same results
Validity - how well a test measures to
what it claims to e.g. IQ test with only
maths q's is not a valid test of general
intelligence
Internal - extent to which results are
caused by variables being
measured rather than extraneous
variables
External - extent to which
results of test can be
generalised e.g. to a
larger population
Ecological - extent to
which results can
reflect real life
Assessed? - comparing
results with results an
existing measure, make a
judgement on whether it
measures what it claims
Improved?
Standardising Research
Specific procedures are
created, followed every
time is carried out,
ensures test is carried
out, ensure researchers
are testing participants in
the same way
e.g. same sequence,
same time of day,
same environment with
participants receiving
same instructions,
reduces the possibility
of EV affecting
research help improve
IV and ER
Pilot studies
Small scale trial runs of test, used to check for any
problems before test is carried out for real, gives researchers
practice at following procedures, allow validity and reliability
of test to be assessed in advance, opportunity for
improvements to be made
Operationalising variables
clearly defining all
research variables.
clarifying improves
reliability and validity
e.g. watching aggressive TV influences
aggressive behavior, aggressive TV and
aggressive behavior need to be defined
Experimental Methods
Lab - research deliberately
manipulates the independent variable
while maintaining strict control over
extraneous variables through
standardised procedures in a
controlled environment
Strengths - high external validity
as extraneous variables are
controlled, greater ability to
replicate, can establish cause
and effect
Weaknesses - reduces
ecological validity and mundane
realism, possibility of demand
characteristics and experimenter
bias
Field - deliberately
manipulates the independent
variable does so in participants
natural environment