research methods 1 - the experimental method Flashcards
pages 13-41
What is an experiment?
The manipulation of variables to establish cause-and-effect.
What is standardisation?
This means that procedures, materials and instructions within a study are kept the same for ALL participants (except for the independent variable).
What is an aim?
A broad statement based on what is going to be investigated in the study.
What is a hypothesis?
A precise, testable statement of what the researcher predicts will be the outcome of the study.
What is an independent variable?
A variable that is manipulated by a researcher to investigate whether it consequently brings change in another variable.
What is a dependant variable?
What is measured and is “dependent” on the independent variable.
What is an alternative (experimental) hypothesis?
The alternative hypothesis is a prediction of what the researcher thinks will happen to the DV when the IV changes.
What is a Null Hypothesis?
The null hypothesis states that the IV will have no effect on the DV and any observed differences will be due to chance.
Define: Operationalised
phrasing variables as specific as possible
What are the two types of experimental hypothesis?
Non-Directional: predicts that there will be a difference between two conditions without stating the direction.
Directional: states the direction of the predicted difference between two conditions or two groups of participants
What is an extraneous variable?
Variables which must be eliminated or controlled otherwise they may affect the DV and damage the validity of results.
2 types of extraneous variable:
Participant Variable (Internal): variables to do with participants eg: age, ethnicity, intelligence etc
Situational Variable(external): variables to do with the situation which might affect the behaviour of participants in an experiment eg: time of day, lighting temperature, instructions etc.
How can extraneous variables be controlled?
Standardised procedures and standardised instructions
What is a confounding variable?
an extraneous variable which hasn’t been controlled by standardised procedures or standardised instructions.
What are demand characteristics?
Demand characteristics can affect the DV and therefore are an example of an extraneous variable.
What are the two different types of demand characteristics?
- If the participant pleases the experiment because they know they are in an experiment.
- If the participant deliberately behaves in a way which spoils the experiment.
How can demand characteristics be controlled?
- Deception: this is where the participants aren’t told the research aim
- Single blind method
What is the investigator effect?
the investigator may unknowingly suggest to the participants how they are expected to behave
How can investigator effects be controlled?
Double blind method:
What is internal reliability?
- refers to the extent the experiment was conducted consistently
- checked if there are standardised procedures put in place or if the study is replicable
What is external reliability?
- refers to the extent which the study is consistent over time
- test-retest( pts are tested once then the same pts at a later date)
What is internal validity?
- whether or not we can say for certain that the IV has caused the effect seen in the DV
What is external validity?
- the extent to which results can be generalised to
- temporal validity, ecological validity(settings) and population validity are all different types
what are 5 features of a lab experiment?
- conducted in a fully controlled environment
- experimenter deliberately changes the independent variable
- measures the dependant variable in quantitative data
- experimenter controls the extraneous variables(participants)
- procedures and instructions are standardised
what are 2 strengths and 2 weaknesses of a lab experiment?
Strengths:
- cause and effect can be established due to high control
- reliability can be checked as experiments can be replicated using standardised procedures
Weaknesses:
- they are artificial and lack ecological validity
- more prone to bias from demand characteristics
what are 4 features of a field experiment?
- conducted in a more natural environment
- experimenter deliberately changes the independent variable
- experimenter measures the dependant variable
- experimenter controls SOME of the extraneous variables
what are 2 strengths and 2 weaknesses of a field experiment?
Strengths:
- more realistic than lab experiments, greater ecological validity
- less bias from demand characteristics
Weaknesses:
- less control means its harder to establish cause and effect
- harder to check reliability as its harder to replicate because of less standardised procedures that can be put into place
what are 3 features of quasi and natural experiments?
- no control over the independent variable
- the dependent variable is measured
- no control over extraneous variables
what is a quasi experiment?
where the independent variable is naturally occurring INTERNAL differences eg age or gender
what is a natural experiment?
investigates naturally occuring external situations ( eg bank robbery) where independent variable can’t be directly manipulated but occurs naturally.
what are 2 strengths and 2 weaknesses of natural/quasi experiments?
Strengths:
- most realistic, greatest ecological validity
- least likely to suffer bias from demand characteristics
Weaknesses:
- least control means its hardest to establish cause and effect
- most difficult to check reliability
what is the independent measures experimental design?
involves using different people in each condition of the IV
evaluate independent measures design
strengths:
- less demand characteristics
- avoids practice and order side effects
weaknesses:
- you need lots of participants and lots of time and resources
- may be some individual differences ( some in one group may be better than others)
what is the repeated measures design
involves using the same people in each condition of the IV
evaluate the repeated measures design
strengths:
- less participants are needed
- results won’t be contaminated by individual differences
weaknesses:
- demand characteristics may change the behaviour
- order and practice effects will be present
what is the matched pairs design
participants are matched with another who is similar in a relevant variable. each person from a pair goes in a different condition.
evaluate the matched pairs design
strengths:
- completely avoids practice and order as participants won’t get tired or bored
- results won’t be contaminated by individual differences
weaknesses:
- needs lots of participants and time and resources
- participants are never perfectly matched
what is the double blind method?
- neither the researcher nor the participants know what the hypothesis is about or which condition they’re in.
- a researcher assistant is hired to conduct the investigation and collect data
what is the single blind method?
this is where the participants aren’t told the condition they’re in.
how are practice and order effects reduced
counterbalancing
what is counterbalancing
where the participants are split into two and perform the tasks in a different order. it means that each condition is tested first and second in equal amounts
