Research methods- Experimental method Flashcards
Aim
Purpose of study
To investigate…
Experimental hypothesis
Clear precise, testable statement that states the relationship between the variables to be investigated. - Outset of study.
Directional hypothesis (one tailed)
difference anticipated made clear between the two conditions
: more, less, higher, lower, faster, slower
Non-directional hypothesis (two tailed)
Nature of difference not specified.
Null hypothesis
No significant difference between two groups.
Independent Variable
Manipulated by researcher or changes naturally
Dependent variable
Measured by the researcher
Conditions
Different testing groups which reflect what independent variable is.
Operationalisation
Clearly defining variables into measurable factors.
Variables ‘operationalised’ when writing hypothesis
Extraneous variable
Additional unwanted variables that might potentially interfere or change the Dv.
Confounding variables
Extraneous variables that have systematically changed with the Iv.
Investigator effects
Any effect of the investigator’s behaviour on the research outcome.
Demand characteristics
Participants picking up cues from the researcher or research situation, revealing the purpose of the investigation may lead to the participant changing their behaviour.
Please you, screw you affect.
Randomisation
The use of chance wherever possible to control for the effects of bias.
Standardisation
As far as possible all participants should be subject to the same environment, information and experience.
Standardised instructions read to each participant.
Experimental Design
The way in which participants are used in experiments.
How participants are assigned to different conditions.
Order effects
Any effect of doing one condition followed by another.
Order in which info is presented influences participant’s response.
Independent groups
Participants take part in only one condition.
Results then compared.
ADV:
- No order effects (only take part once)
-Participants less likely to guess aim
- Only one test needed
DISADV: Not the same participants so differences between the two groups may be because of individual differences.
- Two groups of participants needed.
Repeated Measures
Participants experience both conditions
Results then compared
Weaknesses:
- Order effects are a problem
- Demand characteristics are a problem as participants guess the aim
- More than one test needed
Strengths:
- Participant variables not an issue as same participants in both conditions
- Less participants needed so more economical
Matched paris
2 separate groups of participants
Paired on key characteristics
Tries to control participant variables
STRENGTHS:
- No order effect as participants only in one condition
- Less demand characteristics
WEAKNESSES:
- Still participant variables as cant match exactly
- Matching is time consuming and expensive
- Less economical
Counterbalancing
An attempt to minimise the effects of order effects in a repeated measure design.
Attempts to balance out order effects but can’t get rid of them.
Half participants do condition A then B.
Half participants do condition B then A.
Random allocation
Used in independent groups
Participants randomly allocated to conditions using random techniques to address the problem of participant variables in the two conditions.
Avoids bias
Evenly distributes participant characteristics across the conditions of the experiment using random techniques
4 types of experiment
lab, field, nature, quasi
lab experiments
Researcher manipulates the IV.
Takes place in artificial, controlled setting
STRENGTHS:
- high control over extraneous variables
- more confidence that Iv has affected Dv
- replication is possible because of control
WEAKNESSES:
- lack generalisability to other settings
- in particular, lacks generalisability to real life
- participants more likely to act unnaturally- demand characteristics
- lacks mundane realism
field experiments
iv manipulated by researcher
setting more natural
STRENGTHS:
- higher mundane realism than lab
- behaviour more valid and authentic
- participants may be unaware they’re being studied
WEAKNESSES:
- less control over extraneous variables
- cause and effect between iv and dv more difficult to establish
- precise replication not possible
- ethical issues
- possible invasion of privacy
natural experiments
Researcher doesn’t manipulate IV.
IV is an event which occurs naturally
STRENGTHS:
- Provides opportunities for research that may not be otherwise undertaken.
- high external validity as they study real-life issues and problems e.g. natural disaster
WEAKNESSES:
- natural disasters only happen rarely, reducing opportunities for research
- Generalising findings to other similar situations will be limited
Quasi experiment
Researcher doesn’t manipulate IV.
IV is a feature of the participants e.g. gender
STRENGTHS:
- Often carried out under controlled conditions, therefore share same strengths as lab experiment
WEAKNESSES:
- Cannot randomly allocate participants to conditions (already in them)
- Therefore may be confounding variables.
Single-blind procedure
Participants not told aim of study + not told what condition of experiment they are in.
An attempt to control the effects of the demand characteristics
Double-blind procedures
Neither researcher or participants know the aim.
Often third party conducts the investigation without knowing its purpose.
Control groups and conditions
(Drug Trial Example)
Experimental condition- real drug
Control condition- Placebo
Pilot studies
Small scale trial run of the actual investigation
Handful of participants
Helpful with other methods
Observation studies: provides a way of checking behavioural categories in use
Researcher can identify potential issues, modify procedure to save time + money.
