Experimental methods

• What are aims?

  + general statements of what researcher intends to investigate - purpose of the study

  + narrow focus of study to produce an aim

  + developed from theories
• What is a hypothesis?

  + a clear, testable statement done after an aim. at the start of a study

  + clearly describes the relationship between variables stated by the theory

  + can be directional or non-directional
• What is the difference between directional and non-directional hypotheses?


  + directional - researcher makes clear the difference that is anticipated between two conditions or groups of people e.g. less, more, etc.

  + non-directional - simple states that there is a difference between conditions or groups of people without specifying difference -> done when there is no previous research on the topic
• How is an experiment done?

  + two groups/ conditions

  + give each person in one group the IV

  + participants in other group are the control group

  + DV is then monitored and measured
• How is a hypothesis picked?


  + directional hypotheses are used when theory or findings of previous research studies suggest a particular outcome

  + non-directional hypotheses are used when no theory or previous research is present or findings from earlier studies contradict
• What are variables?

  + researcher changes or manipulates the IV and records or measures the effect of the IV on the DV

  + all other variables which may affect DV remain constant in properly run experiments

  + ensures researcher can be confident changes in DV was due to IV alone
• What are the levels of IV?

  + need comparison of different experimental conditions to test effect of IV on the DV

  + EITHER compare before and after IV added or compare two groups of participants

  + two levels of IV: control condition and experimental condition
• What is the operationalisation of variables?

  + ensure variables investigated are measurable

  + make sure variables have specific values
• What is the null hypothesis?

  The null hypothesis is a statement that assumes there is no significant relationship or difference on the DV when the IV is manipulated
• What is the Alternative hypothesis H1?


  + aka, research hypothesis

  + states that there is a change (difference) in measurement of the dependent variable due to manipulation of the IV