experimental research methods Flashcards
What are lab experiments conducted under?
highly controlled conditions , where accurate measurements are possible, a standardised procedure is used
What are some strengths of lab experiments
-A high degree of control over the variables minimises any extraneous variables - higher internal validity and establishes a cause-and-effect relationship
- more replicable as the variables are highly controlled
what are some limitations for lab experiments
-low ecological validity - low mundane realism
- high risk of demand characteristics
What are field experiments?
- field experiments are done in the everyday in the everyday environment of the participants
- the experimenter still manipulates the independent variable
-participants are often unaware they are participating
what are the strengths of field experiments?
- high ecological validity - research is conducted in the real world
- low risk of demand characteristics - unaware they are taking part in a study
what are the limitations are field experiments?
- less control over extraneous variables - reduces the internal validity
- potentially more time-consuming and expensive
- difficult to replicate precisely
what are natural experiments?
research is conducted in a natural setting
the experimenter does not manipulate the independent variable directly, it varies naturally
what are the strengths of natural experiments?
-high ecological validity
- low risk of demand characteristics
- can be used in situation in which it would be ethically unacceptable unacceptable to manipulate the independent variable
What are natural experiments?
-research is conducted in a natural setting
- the experimenter does not manipulate the independent variable directly, it varies naturally
what are the strengths of natural experiments?
- high ecological validity
- low risk of demand characteristics
- can be used in situations in which it would be ethically unacceptable to manipulate the independent variable
what are the limitations of the natural experiments?
- there is no control over extraneous variables
- its difficult for another research to replicate the study in the exact same way
What are quasi experiments?
the IV is naturally occuring but the DV may be measured in a laboratory setting
The IV is a difference between that existse.g gender or personality differences
What are the strengths of quasi experiments?
allows for comparisons between different types of people
quasi experiments are often carried out under controlled conditions and therefore share the strengths of a lab experiment
What are limitations of the quasi experiments?
- researcher cannot randomly allocate participants to conditions and therefore there may be confounding variables
-share limitations of a lab experiment if in controlled conditions
What is the dependent variable?
the variable that is being measured.
what is the independent variable?
the variable that is being manipulated.
What is the operationalisation of variables?
is crucial i.e. putting the variables into a form that can be easily tested or measured by defining them as precisely as possible.
What is the aim of an experiment?
is crucial i.e. putting the variables into a form that can be easily tested or measured by defining them as precisely as possible.
What is the hypothesis of a research study?
This is a precise and testable statement predicting the relationship between two variables. This is usually derived from a theoretical explanation.
What is a directional hypothesis?
predicts the direction in which any differences (/correlations/associations – Non-Experimental Methods) in the results of an investigation are expected to occur.A directional hypothesis should only be generated if there is previous research upon which to base that prediction – it cannot be based on the researcher’s hunch!
What is a non-directional hypothesis?
does not predict the direction in which any difference (/correlation/association – Non-Experimental Methods) in the results of an investigation are expected to occur.
This type of hypothesis would be generated if there is no previous research.
What is a null hypothesis?
predicts that there will be no significant difference (/correlation/association) found e.g. it predicts that the IV will not affect the DV.
What is the independent groups design?
This is where participants only take part in one of the conditions, so each group does one level of the IV.
Therefore, two entirely different groups of participants are compared against each other in terms of their performance.
How could you allocate participants fairly to conditions to reduce individual differences?
Random allocation: Use a random technique, such as picking names out of a hat, or using a random name generator.
Participants will then have an equal chance of being in either condition and participant variables should be evenly distributed
No order effects strength for IGD
No order effects: As different participants do each condition there are no order effects whereby the order in which the conditions are done may have an effect on the outcome. Practice and boredom effects are types of order effects and they also do not occur when using this design.
Practice effects – the participant becomes practiced at the task because they are doing it more than once, which leads to improved performance in the second condition.
Boredom effects – the participant becomes bored with the task, which leads to a deterioration in performance in the second condition.
IGD: reduced risk of demand characteristics:
Participants are only exposed to one of the experimental conditions, therefore they are less likely to guess the purpose of the study and change their behaviour accordingly.
IGD: No control of participant variables/individual differences
for example, participants in group 1 may have superior memory ability, therefore results might reflect group differences as opposed to the manipulation of the IV.
IGD: less economical:
Twice as many participants are needed.
What is the repeated measures design?
This is where participants take part in all conditions within the experiment i.e. all participants experience all levels of the IV.
Participants are therefore compared against themselves.
RMD: participant variables/ individual differences:
(the different abilities or characteristics of each participant) are controlled as the same participants are used in each condition i.e. participants are compared against themselves.
RMD: more economical
Fewer participants are needed, compared to an independent groups design.
RMD: order effects
The order of the conditions might affect performance (order effect), which can act a confounding variable:
Participants may perform better in the second condition because of a practice effect (they become practiced at the task), a positive order effect;
Participants may perform worse in the second condition because they have grown bored with the task (boredom effect), a negative order effect.
RMD: High risk of demand characteristics:
Participants are exposed to both conditions, so are more likely to guess the purpose of the study and change their behaviour to please the experimenter.
How could you deal with the issue of order effects when using a repeated measures design?
Counterbalancing is a technique that can be used to distribute order and practice effects. It involves changing the order of the conditions from one participant to the next, so half the participants experience the conditions in one order and the other half in the opposite order.
It ensures that each condition is tested first or second in equal amounts.
Other ways of dealing with the issues created from using a repeated measures design
Create a time interval between conditions (e.g. ask ppts to return two weeks later to complete the second condition).
Vary the stimulus material between conditions (e.g. use different word lists, but, they must be of equal difficulty to learn – words of a similar length/familiarity).
Use a different experimental design (e.g. independent groups or matched pairs, if appropriate).
What is the matched pairs design?
In a matched pairs design, participants are matched across the conditions according to certain relevant key characteristics (that might have an impact on the DV), such as IQ, age, memory ability.
MPD:Reduced participant variables:
By trying to ensure that the two groups are similar on some level e.g. age, IQ, age or memory ability, the results should be less affected by participant variables/individual differences and instead be due to the manipulation of the IV.
MPD:No practice or order effects and less likelihood of demand characteristics,
because participants only take part in one condition, therefore they are less likely to guess the aim of the study and alter their behaviour accordingly.
MPD: Difficult to match participants exactly:
It is impossible to control all participant variables because you can only match on variables known to be relevant, but an unmatched variable might be vitally important. Even two closely-matched individuals will have different levels of motivation or fatigue at any given moment in time.
MPD:Time consuming to match participants
: It can take some time for the researcher to identify pairs of participants that are well matched.
What is target population?
The group of people that the researcher is interested in, from which a sample is drawn - who they will generalise (apply) their findings to.
What is a sample?
The group of participants who take part in the study.
What is opportunity sampling?
The researcher selects participants who are available and willing to take part, asking whoever is around at the time of their study to take part
e.g. asking people in the street who are passing.
Opportunity sampling : strength: convenient
The most straightforward sampling technique - it is quick and easy for the researcher to obtain participants, because they simply select the first suitable participants readily available to them.
Opportunity sampling limitation: researcher bias
The researcher may avoid people they do not like the look of and approach those who have more desirable characteristics.
Opportunity sampling limitation: Unrepresentative sample
The sample is likely to be biased as it will undoubtedly exclude certain types of people, because it is drawn from a very specific area, such as one street in one town, so findings can’t be generalised to the target population.
e.g. if you select your sample from people walking around a town centre on a Monday morning, then it would be unlikely to include professional people or people from rural areas.
What is volunteer sampling?
Participants select themselves to be part of the sample, often by replying to adverts.
Volunteer sampling strength: easy
Creating the sample requires little effort from the researcher, other than creating an advert.