RM: Experimental Method (year 1)

Aims

Hypothesis

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Variables

OIP Aim = purpose of the study


OIP (1) Hypothesis = clear statement of the relationship between 2 variables that can be tested


OIP (2) Variables = a 'thing that can change or vary within an investigation

developed from theories - narrows the focus of the research

a general statement that describes the purpose of the study

starts with: 'to investigate whether......'

an example of an aim for a study investigating the effects of watching aggressive behaviour = **to investigate whether investigating aggressive behaviour makes people more aggressive

this was developed from the theory: 'we learn from our experiences'

from the aim we formulate a hypothesis - what we expect to happen in the study

hypothesis - statement made at the start of the study and clearly states the relationship between variables as stated by the theory

e.g. observing aggressive behaviours will cause children to imitate those aggressive behaviours

hypotheses can be directional or non-directional

directional hypothesis (one-tailed)

  • clearly states the anticipated differences between the 2 conditions
  • e.g. more, less, higher, lower, faster, slower

non-directional (two-tailed)

  • simply states that there is a difference between conditions but doesn't specify the difference clearly

when and which hypothesis should be used when doing research?

  • non-directional = use this when there is no previous research or previous findings are contradictory
  • directional = use this when previous research suggests a particular outcome
  • independent variable (IV) = the 'thing' changed or manipulated by the researcher
  • dependent variable (DV) = the 'thing' which is effected by the IV (effects are recorded

e.g. observing aggressive behaviours causes children to imitate that aggressive behaviour


  • 'observing aggressive behaviours' = IV
  • 'imitate those aggressive behaviours' = DV
  • all other variables that may potentially effect the DV should remain constant in a properly run experiment. this is so the researcher can be confident that the cause and effect on the DV was the IV and the IV alone.
  • levels of the IV
  • to test the effect of the IV we need to different conditions, we can do this by:

~ comparing ppts before & after
~ comparing 2 groups of ppts

  • 2 levels of the IV:

~ control condition (e.g. before/group observe nice/no behaviours)
~
experimental condition (e.g. after/group observe aggressive behaviour)