2. experimental methods

Question 1

laboratory experiment

Answer 1

dirrect manipulation of iv: experimenter manipulates the IV and measures the DV

control: high levels of control aims to control extraneous/ cofounding variables so the only difference in conditions is the IV. control group acts as a control for a baseline comparison

randomisation: participants are randomly allocated to conditions to redues extraneous variables

Question 2

strengths of a laboratory experiment

Answer 2

easily replicated
high levels of control
allows experimenters to check reliability and if results are consistent

internal validity
easier to control potential confounding variable
increases the ability to establish between iv and dv

Question 3

weaknesses of a laboratory experiment

Answer 3

reduces ecological validity
high levels of control mean the environment has become artificial and different from everyday life situations
questions the accuracy to measure the complexity of human behaviour

demand characteristics
participants know they are being researched
reduces internal validity

Question 4

field experiments

Answer 4

investigations carried out in natural environment eg homes or school

situations where it is important research is carried out in natural environments

still manipulates iv and measure dv but can only attempt to control extraneous variables

participants are unaware are in an experiment

Question 5

field experiment strengths

Answer 5

high levels of ecological validity
in natural surroundings so behaviour is representative of real behaviour
more confident generalising findings to other situations

demand characteristics are lower
participants don’t know they are partaking so can’t guess the aims
increases internal validity as we are more sure the DV has measured what is aimed to

Question 6

field experiment weaknesses

Answer 6

time consuming
less participants being gathered
reducing population validity so difficult to generalise

difficult to have full control
not possible to predict everything that could occur and but controls in place more extraneous variables
reduces ability to establish cause and effect decreasing internal validity

Question 7

natural experiment

Answer 7

take advantage of naturally occurring events where the researcher has no direct control of the IV

participants are already assigned a condition eg researching the effects of a smoking ban and comparing smoking levels before and after

ethical and practical reasons this is sometimes the only experiment suitable

Question 8

natural experiment strengths

Answer 8

high levels of ecological validity
take place in natural setting so representative of behaviours naturally occurring
confident generalising results to other situations

Question 9

natural experiment weaknesses

Answer 9

behaviour being displayed is limited
researcher has no control over situation so the behaviour the researcher wants to study may only happen rarely
reduces available opportunities to replicate the research to test the reliability

event isn’t planed so no control of extraneous variables
not possible for researcher to predict everything
reduces confidence in establish cause and effect reducing internal validity

Question 10

what is a quasi experiment

Answer 10

use a pre-existing IV usually a character trait that doesn’t vary so aren’t randomly allocated eg age, gender

carried out in either controlled or more natural conditions