variables

• • Extraneous variables : any variable other than the independent variable that may have an effect on the dependent variable 
• • Confounding variable : any variable other than independent that has not been controlled so affect DV
• • Randomisation:  is the use of chance in order to control for the effects of bias 
• • Standardisation : This is using exactly same procedures for all ppts
• validity : Refers to how accurate and representative the results are.
• internal validity:

  • Concern whether the results are due to the manipulation of the IV and not affected by confounding 
• external validity:

  • Refers to the extent to which the result can be generalised to other settings
• temporal validity:

  • Refer to how well we can generalise result across different time periods
• ecological validity:

  • Refer to whether the experimental results can be generalised to other settings 
• Reliability: Refers to how consistent the results are.
• internal reliabilty :

  •  refer to the extent to which a test is consistent within itself 
• • External reliabilty :  refers to extent its consistent over time
• • Inter-observer reliability:   refer to the extent to which two or more observers are in agreement on the behaviour they observe . check by correlating sets of data to see if it's positive: if its +0.8 or above the inter -observer reliability 
• • Test retest method : assesses external reliability by giving participants the same test on two occasions with normally a week or two apart so they don’t remember the answers. If the results are the same then external reliability is established.
• Demand characteristics: These are clues which participants respond to when in an experimental situation, in which they try to guess the aim or intended outcome of a study and therefore change their behaviour accordingly
• Investigator effects: These are any unwanted influences that the investigator/experimenter communicates to the participants which affects their behaviour
• Single and double-blind: The single-blind procedure is when the participant does not know the aim of the study. This helps reduce the possibility of demand characteristics from affecting the results. Double-blind is when where the investigator who deals with the participants also does not know the aim of the study. This helps reduce the chance of investigator effects, as the investigator will not unconsciously communicate the aim to the participants.