Experimental Methods Flashcards
Lab experiment
Controlled artificial setting
Manipulate IV and measure DV
Strengths of lab
EV’s and DV’s are controlled - replicable and reliable
Weaknesses of lab
Low ecological validity
Field experiments
Natural environment
P’s often unaware
Strengths of field
Ecological validity
Weaknesses of field
Ethical issues e.g consent
Online research strengths
Large samples
Cheap
Diversity
Weaknesses of online research
Possible bias
Lies and social desirability
EV’s and DV’s
Quasi natural
IV not controlled
IV is naturally occurring event
Can be lab or field
E.g divorce or natural disaster
Quasi difference
IV not controlled
IV is a pre existing difference between p’s
E.g. sex, age
Strengths of quasi
Allows research of phenomena that for ethical reasons can’t be manipulated to study
Weaknesses of quasi
No definite cause and effect
Replication is nearly impossible
Experimental design - independent groups
2 separate conditions
Independent groups strengths
Less materials needed as the same test can be given to both groups
Independent group’s weakness
More p’s needed
Experimental design - repeated measures
Same p’s do both experiments
Repeated measures strengths
No individual differences
Repeated measures weaknesses
Order effects
Experimental design - matched pairs
Different p’s matched closely on personality, IQ etc
2 groups
Matched pairs strengths
Less chance of individual differences
Matched pairs weakness
Time consuming and matching can be difficult
What is a single blind procedure
The p’s don’t know what condition they’re in
What is a double blind procedure
Both researcher and p’s don’t know whose in which condition
What is target population
Large group of people that the researcher wishes to study
Sample
Small group who represent the target population and are studied
Population validity
How well the sample represents the target population
Opportunity sampling
People who are there, available and willing to
Strengths of opportunity
Quick and easy
Weaknesses of opportunity
Researcher bias as they pick p’s
Self selected sampling
Letter/flyer where people select/volunteer themselves
Strengths of self selected
Flyers can reach a diverse range of p’s
Weaknesses of self selected
Demand characteristics (more motivated)
Random sampling
Name generator
Strengths of random
No researcher bias + representative
Weaknesses of random
Time consuming
Systematic sampling
Selected in numerical intervals e.g every 8 people
Strengths of systematic
Quick,easy and unbiased
Weaknesses of systematic
May not be representative
Stratified sampling
Selecting in ratio to target population
Strengths of stratified
Most representative
Weaknesses of stratified
Time consuming
Quota sampling
Same as stratified but the researcher chooses the ratioed sub groups
Strengths of quota
Representative and can generalise
Weaknesses of quota
Time consuming and researcher bias
Snowball sampling
Current p’s recruit more through mutuals
Strengths of snowball
Can access hard to reach groups
Weaknesses of snowball
Not representative - too similar interests
What is internal validity
Does the study measure what it intends to measure
What is external validity
Whether the study paints a true picture of real life behaviours - mundane realism and would apply to different places, times or people - population validity
Word associated with validity
Accuracy
Validity issues
Researcher bias
Demand characteristics
Social desirability
Assessing validity - face validity
Whether the test appears at face value to measure what it claims to
Predicative validity
The degree to which a test accuractly forcasts a future outcome on a more broadly related topic
Content validity
Objectively checking whether the method of measuring behaviour is accurate and decides whether it is a fair test that achieves the aims of the study - this can be achieved by asking an expert of the specific area of behaviour to check validity
Concurrent validity
Comparing with an established measurement that has validity - If both test have similar results they have concurrent validity
Construct validity
Whether the overall results reflect the phenomena as a whole - this is achieved by checking the existing definitions of the behaviour
Word associated with reliability
Consistency
Internal reliability
If the test is consistent in itself
External reliability
Consistency over time
Ways to overcome reliability issues
Use more than one researcher
Repeat
Standardise procedures
Operationalise variables
Test retest
Repeated twice - if the same = reliable
Inter rater
Compare results from more than one researcher - high agreement = reliable
Split half
Splitting the test into two and comparing scores in both halves
What is temporal validity
Historic
What is ecological validity
Other settings/situations
What is falsifiability
Principle that a theory cannot be considered scientific unless it admits the possibility of being found false
Replicability
The extent to which scientific procedures and findings can be repeated by other researchers
Objectivity
All sources of personal bias are minimised so it can not distort or influence the research process
Situational variables
Anything to do with the environment e.g time of day, temperature or noise levels
Participant variables
Difference between participants e.g age, gender, intelligence
Investigator effects
How behaviour and language of experimenters will effect the participant - researcher bias (eg how the question is worded)
Demand characteristics
Participants searching for clues in order to act in a certain way for example if they subconsciously figure out the aim
Participant effects
Participants are aware they’re in the experiment so may behave unnaturally
Ethics
P - privacy
C - confidentiality
D - deception
R - right to withdraw
I - informed consent
P - protection from harm
Null hypothesis
Statement of no effect
- there will be no difference…
Alternative hypothesis
Any hypothesis except the null
Directional hypothesis- one tailed
There will be a direction - increase/decrease
Non directional hypothesis - two tailed
There will be a difference but does not state the direction
Confounding variable
Varies systematically with the IV that may impact the DV
Extraneous variable
Do not vary systematically however impact DV - e.g weather
Ethics - brief
Must infirm p’s of purpose - be clear
Erasure confidentiality
Give them the right to withdraw
Provide an opportunity for question
Ethics - debrief
Inform p’s of purpose
Ensure no undue stress
Ensure p’s leave in ‘same frame of mind’ as they entered
Right to withdraw and access to report if asked
Opportunity for questions
Thank the p’s for taking part
What is privacy
A persons right to control the flow of information about themselves
What is confidentiality
Communication of personal info from one person to another - the trust that this will be protected
What is deception
P’s not aware of the study so can’t give informed consent
What is right to withdraw
P’s understanding that they have the right to leave the study at any point and remove data when the study is over
What’s informed consent
P’s given info regarding the experiment so they can choose whether to participate or not
What’s protection from harm
Should not experience negative physical or psychological harm beyond normal day to day lives
