Takes place in an
environment controlled
by the experimenter
Takes place in the subject's
natural environment
IV is naturally occuring (also
called Quasi-Experiment)
RELIABILITY ISSUES - Analysing the data
from experiment could be subjective or human
error - participants have individual differences
so complete reliability hard to achieve
IMPROVED -
inter-rater
analysis - use
matched pairs
design
VALIDITY ISSUES - Does the test actually test the
dependent variable in relation to the independent
variable - lab experiments may not be ecologically
valid - are extraneous variables eliminated
IMPROVED -
conduct a pilot
study - use field
experiments or
Quasi-experiments
DESIGNS
Independent measures - groups include different participants
in each one which are not made to resemble each other
Lacks reliability
Repeated measures - groups are carried across between
conditions so the participants are exactly the same
Can result in order effects
Matched Pairs - groups include different participants in each one
but are made to resemble each other in their characteristics
Difficult to make them fully resemble
each other, time consuming
Null and alternative hypotheses
Null - saying there is will be no
difference between two conditions
Alternative - there will be a
difference between two conditions
OPERATIONALISE!
Displayed by frequency
polygons & histograms
CORRELATION
STRENGTHS - Shows the
relationship between two
co-variables and strength - not
unethical at all - starting point for
research
WEAKNESSES
- Cannot
assume cause
and effect -
secondary
data so risks
with validity
Positive or negative
correlation
ETHICS - good as all
data is secondary
and no participants
are involved
TYPES OF SAMPLE
Snowball - Investigator approaches
one participant who in turn
approaches several others and the
sample 'snowballs' to become a
large sample
Opportunity - Not really a
'technique', researcher uses
people that are readily available,
usually known to investigator prior
to experiment
Random - All target
population have an equal
chance of being selected,
usually using a computer to
ensure complete
randomness, very rarely used
Systematic - Finding a starting point
within a target population and then
obtaining subsequent participants by
using a constant interval e.g. every 10th
person
Stratified - Target population is
divided into subgroups and then
random samples are taken from
the subgroups