variables

• what is an independent variable?

  something that a researcher changed or manipulates

  • in order to test the affect of IV we need different experimental conditions and we need a comparison
• what is the dependent variable?

  the variable that is measured by the researcher.

  • any effect on the DV should be caused by the IV
  • a well written hypothesis should make it easy to tell what the IV and DV are
• operationalization of variables :

  we have to operationalise variables to make it testable so it needs to be very measurable, therefore very clear

  e.g use numbers (300ml) and names (lucozade)
• extraneous variables:

  any variables ,other than the IV, should be be controlled or removed as it can affect the dependent variable

  • unwanted, extra variables
  • are identified before the study by the researcher, who takes steps to minimise their influence
  • most are straightforward to control e.g age and lighting, but some so not vary systematically with the IV
• what are the two types of extraneous variables?

  participant variables

  situational variables
• what are participant variables?

  any individual differences between participants that could affect the DV
• what are situational variables?

  any features of the experimental situation that may affect the DV
• what variables are these examples of:

  • age
  • personality
  • motivation
  • intelligence

  participant
• what variables are these examples of:

  • noise
  • time of day
  • temperature
  • weather

  situational
• confounding variables:

  • they change systematically with the IV
  • we cannot tell if there are any changes in the DV and if it’s due to the IV or confounding variables - can become an unintentional IV
  • variables you find after the study that can influence the DV
• application to marshmallow test: participant variables

  • if the child is used to waiting for things normally
  • if they have a sweet tooth
  • if they were hungry or had eaten something previously
• application to the marshmallow test: situational variables

  • ensure they are tested in the same room
• demand characteristics:

  • participants are not passive within an experiment and are likely to spend a lot of the time trying to make sense of the situation
  • this is a significant extraneous variable in experimental research and is very difficult to control
  • cues may help ppts figure the aims of the study
  • as a result, they may act in a way they think is expected and over-preform (please U effect) or they may act in a way to sabotage the study (screw U effect)
  • therefore the behaviour is unnatural
• investigator effects:

  things that you do that could influence the participants of the behaviour

  • for example, if the researcher is smiling more at a certain participant, it may encourage behaviour, and cause the please U effect
  • it refers to the unwanted influence of the investigator on the research outcome
• randomization:

  in an investigation a researcher can take simple steps to minimize the effect of extraneous/confounding variables on the outcome

  • randomization= use of chance methods to reduce the researchers unconscious bias when designing an investigation (attempt to control investigator effects)
• standardization:

  • all participants should be subject to the same environment, information and experience
  • to ensure this , all procedures are standardized, so a list of ectactly what should be done in the study
  • e.g standard instructions to read to each ppt, so that there are no extraneous variables