experimental design

• independent group design 


  the participants only person in one condition of the independent variable
• independent group design strengths

  there are no order effects and demand characteristics are eliminated as participants are less likely to guess the aims of the study
• independent design limitations 


  no control over participant variables whereby different abilities of participants in the various conditions can cause changes to the dependent variables
• independent design solution - random allocation

  it ensures that each participant has the same chance of being in one condition of the independent variable as another
• repeated measures 


  the same participant take part in all conditions of the independent variables
• repeated measures strengths 


  eliminates participant variables and fewer participants are needed so not time consuming
• repeated measures limitations 


  order effects such as boredom could occur meaning the participant could not do as well in the second variable
• repeated measures solution - counterbalancing 


  half of the participants do conditions in one order and the other half do it in an opposite order
• matched pairs


  pairs of participants are first matched on some variable that affects the DV then one member of each pair does one condition and the other does another
• matched pairs strength


  no order effects and demand characteristics
• matched pairs limitation


  can be time consuming and expensive to match participants
• pilot studies 


  a small scale version of an investigation which is done before the real investigation is undertaken, carried out to allow potential problems to occur