Hypothesis and variables

• Research methods (RM)

  • How psychologists carry out research.
  • Important in understanding why studies are designed the way they are.
• Scientists will often draw on a number of different methods as part of their research but one of the most often used is the experimental method
• Experimental methods

  • Involves the manipulation of an independent variable (IV) to measure the effect on the dependent variable (DV)
  • Experiments may be laboratory, field, natural or quasi
• Developing a design

  • We have a theory that energy drinks affect how much people talk.
  • This is based on our having read a few research studies that energy drinks contain sugar and caffeine, and that these substances increase alertness, making people ‘chattier’.
  • A new energy drink - Speedupp- has come on in the market and we are keen to know if it will affect the talkativeness of those who drink it.
• Aims

  • A general statement of what the researcher intends to investigate, the purpose of the study.
• Aims

  • We have an initial idea (caffeine=more chatty), the next step is to narrow the focus of our research to produce an aim.
• Hypothesis

  • A hypothesis is a statement that is made at the start of a study and clearly describes the relationship between variables as stated by the theory. 

  Hypotheses can be directional or non-directional.
• Directional Hypothesis

  • In a directional hypothesis the researcher makes clear the sort of difference that is anticipated between two conditions or two groups of people. 
  • For this reason, directional hypotheses include words like more or less, higher or lower, faster or slower, etc.
• Non-directional Hypothesis

  • A non-directional hypothesis simply states that there is a difference between conditions or groups of people but, unlike in a directional hypothesis, the nature of the difference is not specified.
• Deciding which type of hypothesis to use

  • Researchers tend to use a directional hypothesis when a theory or the findings of previous research studies suggest a particular outcome. 
  • When there is no theory or previous research, or findings from earlier studies are contradictory, researchers instead decide to use a non-directional hypothesis.
  • Even though SpeedUpp is a new energy drink, the effects of caffeine and sugar on talkativeness are well-documented. 
  • Therefore, we will opt for a directional hypothesis on this occasion.
• Variables

  • Independent variable (IV) 
  • The aspects of the experimental design which is manipulated by the researcher - or changes naturally
  • Dependent variable (DV). 
  • The variable that is measures by the researcher. 
  • Any effect on the DV should be caused by a change in the IV.
  • All other variables that might affect the DV should remain constant. So the researcher can be confident that any change in the DV was due to the IV, and the IV alone.