Research methods - Types of Experiment Flashcards
what is a lab experiment
an experiment that is conducted in a highly controlled, artificial environment. by creating the experiment artificially, the experimenter can control many variables, e.g by using standardised instructions to ensure each participant is treated in the same way
why may a researcher choose to conduct a lab experiment
control of extraneous variables means we can be confident that it is the manipulation of the IV that has caused the change in the DV
define internal validity
the extent to which a study is measuring what it set out to measure
what is external validity
the extent to which the results from the experiment can be generalised beyond the particular study to other people and settings
give four factors that could affect the internal validity of a study
demand characteristics, extraneous variables, researcher bias, researcher effects
define demand characteristics
cues in an experimental situation that communicate to participants what is expected of them, which can then lead to participants changing their behaviour to help or hinder the research
define extraneous variables
any variable other than the IV that could have an impact of the DV
define researcher bias
a researcher’s expectations or beliefs influence the design of the research or the collection of data
define researcher effects
anything that the researcher does that has an effect on the participant’s performance in a study - can be direct or indirect e.g way the study is designed
what are the two types of external validity
ecological validity and population validity
define ecological validity
the ability to generalise a research effect beyond the particular setting in which it is demonstrated to other settings
define mundane realism
the degree to which the task being completed is similar to events which occur in the real world
define population validity
the extent to which the results of a study can be generalised to other groups of people besides those who took part in the study
when would a study lack population validity
if the sample is not representative
what is reliability
a measure of consistency both within a study (internal reliability) and also over time such that is is possible to obtain the same results on subsequent occasions when exactly the same procedure is used (external reliability)
what does the standardisation of lab experiments allow
researchers can compare the results and test for internal reliability, as well as allowing for other researchers to replicate the study again in the future and test for external reliability
what are the strengths of lab experiments
high level of control over extraneous variables - increased internal validity and cause and effect can be established
standardised procedures which means that every participant will have the same experience (internal reliability) and allows for replication in the future (external reliability)
what are the weaknesses of lab experiments
due to being conducted in artificial settings, participants may not behave naturally - low ecological validity
participants are more likely to guess the aim of the study due to artificial settings and change their behaviour - decreases internal validity
risk of researcher bias as their expectations/beliefs may affect how they interact with participants or alter their interpretation of results
what is a field experiment
there is an IV that is manipulated by the researcher and a DV that is measured but the setting is the participant’s normal environment in relation to the behaviour being studied
what are the strengths of field experiments
behaviour is investigated in settings in which it would usually occur which means it is more likely to reflect real life - high ecological validity
ps are less likely to show demand characteristics as they often (but not always) don’t know they are being studied - increases internal validity
what are the weaknesses of field experiments
due to behaviour being investigated in natural settings, researcher has less control over extraneous variables - lower internal validity
ps are often unaware that they are being studied in a field experiment so ethical issues - lack of informed consent
replication may prove difficult as the naturalistic setting may be hard to repeat exactly - external reliability may be decreased
what are quasi experiments
where the IV is naturally occurring and cannot be manipulated by the experimenter - the IV is a difference between people that already exists ie gender and the researcher examines the effect this has on the DV
where can be quasi experiments be conducted
lab or field settings
why might it be useful to use a quasi experiment
allows research where an IV can’t be manipulated due to ethical or practical reasons
what are the issues of using quasi experiments
ps cannot be randomly allocated due to the conditions of the IV meaning there is less control over ps variables
may not be replicable as naturally occurring IV may be rare - lowers external reliability
