experimental method

• Aim - developed from theories and are general statements that describe the purpose of an investigation
• Hypothesis - a testable statement which states the relationship between the variables to be investigated
• there are 2 types of hypothesis: directional and non-directional
• Directional hypothesis - states the direction of the difference or relationship that is anticipated between two conditions. It includes words such as more, less, higher or lower
• We use a directional hypothesis when the findings of previous research suggest a particular outcome
• Non-directional hypothesis - simply states there will be a difference between conditions without direction
• We use a non-directional hypothesis when there is no previous research or the results are contradictory/inconsistent
• Variables - any ‘thing’ that can vary or change within an investigation
• Independent variable - the thing the researcher manipulates/changes naturally
• Dependent variable - the thing that is affected by what is changed (the independent variable) and is measured by the researcher
• Operationalisation - when broad categories are made into clearly defined and measurable variables
• In an experiment, the researcher changes or manipulates the independent variable and records/measures the effects this has on the dependent variable
• All other variables that might affect the DV should remain constant (control variables) so the researcher can be confident the cause of the effect on the DV is the IV
• Extraneous variable - any variable, other than the IV, that may have an effect on the DV, if it is not controlled. extraneous variables do not vary systematically with the IV. This can impact the researcher's interpretation or results
• Confounding variable - any variable, other than the IV, that may have an effect on the DV, so we cannot be sure of the true source of changes to the DV. does vary systematically with the IV
• Demand characteristics - any cue from the researcher or research situation that may be interpreted by pps as revealing the purpose of the investigation, which may lead to them changing their behaviour
• Investigator effects - any effect of the investigator’s behaviour on the research outcome (DV). This may include everything from the design of the study to the selection of and interaction with pps during the research process
• There are 2 ways to minimise the effect of extraneous/confounding variables on the outcome: randomisation and standardisation
• Randomisation - the use of chance in order to control for the effects of bias when designing materials and deciding the order of conditions.
• Standardisation - using exactly the same formalised procedures and instructions for all pps in a research study