Hypotheses and Variables

• The aim of the study takes the form of a general statement covering the topic/theory/concept that will be investigated
• The aim identifies the purpose of the research and is a straighforward expression of what the researcher will attempt to find out be conductiong an experiment
• The aim outlines what is being studied and what the study is trying to achieve
• A hypothesis is a testable statement written as a prediction of what the researcher expects to find as a result of their experiment
• There are two types of hypothesis:

  • Null
  • Alternative
• The alternative hypothesis should include the independent variable and the dependent variable. Both should be operationalised.
• There are two different types of alterantive hypothesis:

  • Directional (one-tailed)
  • Non-directional (two-tailed)
• A directional hypothesis predicts the direction of the difference in conditions. It states that one condition will out-perform the other

  e.g. Participants who drink 200ml of caffeine before taking a memory test will correctly recall more items out of 15 than participants who drink 200ml before taking the same memory test
• A non-directional hypthesis does not predict the direction of the difference in conditions, it simply predicts that a diffrence will be shown.

  e.g. There will be a difference in the number of correctly recalled items out of 15 depending on whether participants have drunk 200ml of caffeine or 200ml of water before taking a memory test
• A null hypothesis begins with the idea that the independent variable will not affect the dependent variable
• When writing a hypthesis for a correlational investigation, instead of using the term 'difference', you must use the term 'relationship/correlation'.
• The independent variable is the only variable in an experiment that should be changed or manipulated throughout the experiment
• The dependent variable is the variable that is measured to determine the outcome of an experiment
• Operationalising variables refers to how both the independent and dependent variable are put to work/implemented by the researcher.
• Extraneous variables are any factors that intrude upon and adversely affect the dependent variable. These are usually controlled so they have the same effect across all conditions, which should stop them from affecting the dependent variable
• If extraneous variables are not controlled then they can become confounding variables
• Confounding variables can affect the dependent variable and negatively impact the research finding. The interference of these variables may not be apparent until after the research process has been completed