Control of Variables

Control of Variables

1. Extraneous Variable (EV) ~ Any variable other than the Independent Variable that may have an effect of the dependent variable (What we are measuring) if it isn't controlled. Therefore it is a nuisance

2. Confounding Variables ~ Any other variable other than the IV that may of effected the DV so we cannot be sure of the true changes upon the DV. This varies systamaticlly with the Iv.

3. The only thing that should be effecting the DV is the IV

4. EVs are exposed initially so that their effect can be reduced before the experiment starts. EVs make it harder to detect the result. An example is testing soda.

5. Extraneous Variables are variables that are nusiances and are unwanted. It is any other variable that the independent variable that may have an effect on the dependant variable.

6. Confounding Variables ~ Anything other than the independent variable that may of effected the DV. Therefore we do not know the true change of the DV as there could be a misconception.

   • Standardisation ~ Using exactly the same formalised approach/instructions for all participants in a study.
     • Randomisation ~ The use of chance in order to control effects of bias when designing materials or conditions

7. Demand characteristics ~ Any cues from the researcher that may be interpreted by the participants as revealing the purpose of the investigation. This may lead to the participant changing their behaviour to meet an ideology or expectation (The please - u effect). Therefore false participant reactivity is an extraneous variable

   • Similarly, the cues could sabotage the study subconsciously or purposely
   • Situational Variables ~ Time, Weather, Temperature

8. The investigator effect ~ Any effect of the researchers behaviour (conscious or unconscious) that will effect the outcome of the DV. This involves the design of the experiment to the interaction.

   • An example of the investigator effect is in an energy drink experiment. A hypothesis states people who drink more energy drink will becomes more chatty than those who don't drink energy drinks. Therefore, an investigator may prompt/encourage participants to becomes more talkative as that is what they expect.

9. Participant Variables ~ Age, Gender, Personality, Intelligence, Concentration