The experimental method
Experimental method- The manipulation of an IV to measure effect on DV.
Aim- A general statement of what the researcher intends to investigate, the purpose of the study
Hypothesis- A clear, precise, testable statement that states the relationship between the variables to be investigated. stated at the outset of any study.
Directional hypothesis- States the direction of the difference or relationship
Non directional hypothesis- Does not state the direction
Variables- Any "thing" that can vary or change within an investigation. Variables are generally used in experiments to determine if changes in one thing result in changes to another.
IV- Independent variable. An aspect of the experiment that is manipulated by the researcher or changes naturally- you can measure the effect on the DV.
DV- The variable that is measured by the researcher.
Operationalisation- Clearly defining variables in terms of how they can be measured.
Control of variables
Extraneous variable- Any variable other than the IV that can have an effect on the DV
Confounding variables- As EV but effects whether we can be sure of the changes to the DV
Demand characteristics- Anything that may reveal the purpose of the investigation. May lead to a particpant changing their behaviour.
Investigator effects- Any effect of the investigators behaviour (intended or not) on the research outcome.
Randomisation- The use of chance in order to control the effects of bias when designing materials and deciding the order of conditions.
Standardisation- Using exactly the same formulised procedures and instructions for all participants in a research study.
Experimental design- The different ways in which the testing of participants can be organised in relation to the experimental conditions
Independent groups design- Participants allocated to different groups where each group represents on experimental condition.
Repeated measures- All participants take part in all conditions of the experiment
Matched pairs- Pairs of participants are first matched on some variables that may affect the DV. One member of the pair is assigned to condition A and the other to condition B.
Random allocation- An attempt to control the participant variables in an independent groups design which ensures that each participant has the same chance of being in one condition as another.
Counterbalancing- An attempt to control for the effects of order in a repeated measures design: half the participants experience the conditions in one order and the other half in the opposite order.
Types of experiment
Lab- An experiment in a controlled environment within which the researcher manipulates the IV and records the effect on the DV whilst maintaining strict control over extraneous variables
Field- An experiment that takes place in a natural setting within which the researcher manipulates the IV and records the effect on the DV
Natural- An experiment where the change in the IV is not brought about by the researcher but would have happened even if the researcher had not been there. The researcher records the effect on the DV.
Quasi- IV has not been determined. Variables simply exist. Not really an experiment.
Population- A group of people who are the focus of the researchers’ interest, from which a smaller sample is drawn.
Sample- A group of people who take part in research. The sample should be representative of the target population.
Sampling techniques- How to collect the sample.
Bias- Where certain groups may be over or under represented in the selected sample.
Generalisation- The extent to which findings and conclusions from a particular investigation can be broadly applied to the population.
Naturalistic observation- Watching and recording behaviour in the setting within which it would normally occur.
Controlled observation- Watching and recording behaviour within a structured environment.
Covert- Without participants knowing
Overt- Participants behaviour is watched with them knowing about it.
Participant- Researcher becomes a member of the group whose behaviour they are watching
Non participant- Researcher doesn’t become a member of the group whose behaviour they are watching
Behavioural categories- When a target behaviour is broken into components that are observable and measureable
Event sampling- A target behaviour or event is first established then the researcher records this event every time it occurs.
Time sampling- A target individual or group is first established then the researcher records their behaviour in a fixed time frame say every 60n seconds.