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Research Methods (Types of Experiment (Laboratory Experiments
The aim of…
Research Methods
Types of Experiment
Laboratory Experiments
The aim of laboratory experiments is to control all relevant variables except for one key variable, which is altered to see what the effect is. The variable that you alter is called the independent variable. Laboratory experiments are conducted in an artificial setting
Control - the effects of confounding variables are minimised.
Replication - strict controls mean you can run the study again to check the findings
Causal relationships - ideally it's possible to establish whether one variable actually causes a change in another.
Artificial - experiments might not measure real-life behaviour
Demand characteristics - participants may respond according to what they thing is being investigated, which can bias the results.
Ethics - deception is often used, making informed consent difficult.
Field Experiments
Field experiments are conducted outside the laboratory. Behaviour is measured in a natural environment like a school, the street or on a train. A key variable is sill altered so that its effect can be measured.
Causal relationships - you can still establish causal relationships by manipulating the key variable and measuring its effect, although it's very difficult to do in a field experiment.
Ecological validity - field experiments are less artificial that those done in a laboratory, so they relate to real life better.
Demand characteristics - these can be avoided is participants don't know they're in a study.
Less control - confounding variables may be more likely in a natural environment.
Ethics - participant who didn't agree to take part might experience distress and often can't be debriefed. Observation must respect privacy.
Natural Experiments
This is where the researcher looks at how an independent variable, which isn't manipulated be the researchers, affects a dependent variable. The independent variable isn't manipulated because it's an event which occurs naturally. An example is research into the effect of a single-sex school and a mixed-sex school on behaviour. Participants are usually allocated to the conditions randomly.
Ethical - it's possible to study variables that would be unethical to manipulate
Demand characteristics - participants might not know that they're in a study, so their behaviour is likely to be more natural.
Ecological validity - they tend to be less artificial than laboratory experiments
Causal relationships - because you don't manipulate the independent variable, and because other variables could be having an effect, it's hard to establish causal relationships.
Ethics - deception is often used, making informed consent difficult. Also, confidentiality may be compromised if the community is identifiable.
Quasi Experiments
In a quasi experiment, the researcher isn't able to use random allocation to put participants in different conditions. This is usually because the independent variable is a particular feature of the participants, such as gender or the existence of a mental disorder.
Control - quasi experiments are often carried out under controlled conditions
Ecological validity - the research is often less artificial than laboratory studies, so you're more likely to be able to generalise the results to real life.
Participant allocation - you can't randomly allocate participants to each condition, and so confounding variables may affect results.
Causal relationships - it can be hard to establish cause and effect because the independent variable isn't being directly manipulated.
Correlational Research
Correlational research looks for a relationship between two variables. As these variables aren't manipulated as in an experiment, it's not possible to state the just these two variables rise and fall together, or that one variable is causing the change in the other - the pattern may be a result of a third unknown variable or just be a coincidence.
Causal relationships - these can be ruled out if no correlation exists
Ethics - you can study variables that it would be unethical to manipulate.
Causal relationships - these cannot be assumed from a correlation, which may be caused by a third unknown variable.
Ethics - misinterpretation can be an issue. Sometimes the media infer causality from a correlation.
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Observational Techniques
Naturalistic Observation
Naturalistic observation involves observing subjects in their natural environment. Researchers take great care not to interfere in any way with the subjects they're studying.
Ecological validity - the participants' behaviour is natural and there are no demand characteristics, as the participant is unaware of being observed.
Theory development - these studies can be a useful way of developing ideas about behaviour that could be tested in more controlled conditions later.
Extraneous variables - you can't control variables that may affect behaviour.
Observer bias - the observers' expectations may affect what they focus on and record. This means the reliability of the results may be a problem - another observer may have come up with very different results.
Ethics - you should only conduct observations where people might expect to be observed by strangers. This limits the situations where you can do a naturalistic observation. Debriefing is difficult. Observation bust respect privacy. Getting informed consent can be tricky.
Controlled Observation
This is where the situation is carried out in conditions set up by the researcher.
Replicability - controlled observations can be easily replicated by other researchers by using the same observation schedule. This means it is easy to test for reliability.
Efficiency - the data obtained from structured observations is easier and quicker to analyse as it is quantitative (i.e. numerical) - making this a less time-consuming method compared to naturalistic observations.
Ease of use - controlled observations are fairly quick to conduct which means that many observations can take place within a short amount of time. This means a large sample can be obtained resulting in the findings being representative and having the ability to be generalised to a large population.
Validity - controlled observations can lack validity due to the Hawthorne effect/demand characteristics. When participants know they are being watched they may act differently.
Self-Report Techniques
Questionnaires
Questionnaires can be written, face-to-face, on the phone or via the internet.
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Bad questions - leading questions or unclear questions can be a problem.
Biased samples - some people are more likely to respond, making a sample unrepresentative.
Self-report - people often wish to present themselves in a good light. What they say and what they actually think could be different, making any results unreliable.
Ethics - confidentiality can be a problem, especially around sensitive issues.
Interviews
Structured interviews follow a fixed set of questions that are the same for all participants. Unstructured interviews may have a set of discussion topics, but are less constrained about how the conversation goes.
Rich data - you can get detailed information, as there are fewer constraints that with a questionnaire. Unstructured interviews provide richer information than structured interviews.
Pilot study - interviews are a useful way to get information before a study.
Self-report - the results can be unreliable and affected by social desirability bias.
Impractical - conducting interviews can be time-consuming and requires skilled researchers.
Data analysis - analysing the data can be hard, particularly for unstructured interviews, because there could be a huge amount of qualitative data, which can be tricky to analyse.
Ethics - confidentiality can be a problem, especially around sensitive issues.