research methods

• what are the 3 types of variable

  independent variable

  dependant variable

  extraneous variable
• independent variable

  the variable the experimenter changes or alters to see what the effect will be
• dependent variable

  what the experimenter measures
• extraneous variables

  anything other than the independent varibale that might effect the dependent variable
• what is operationalisation and why do we do it

  it means making the variables measurable

  we do this so that we can test our hypothesis about the effect of the IV on the DV
• hypothesis

  a prediction about what we think the outcome of a study be written as a testable statementtment
• null hypothesis

  a prediction that there will be no difference in the conditions of the iv being investigated
• experimental hypothesis

  a prediction that there will be a difference in the conditions if the iv
• 3 types of experimental design

  independent groups

  repeated measures

  matched pairs
• independent groups

  each ppt only takes part in 1 condition of the IV
• repeated measures

  each participant takes par in all conditions of the iv
• matched pairs

  each ppt only takes part in 1 condition of the independent variable but they are matched with a participant in the other condition on relevant characteristics and abilities
• What is a key advantage of independent groups design?

  Reduced order effects
• Why are order effects reduced in independent groups design?

  Participants only take part in one condition
• How does independent groups design affect participants' guessing of the experiment's aim?

  Participants are less likely to guess the aim
• What is a disadvantage of independent groups design?

  Increased participant variables
• How do participant variables affect results in independent groups design?

  Differences in characteristics may skew results
• What is a key advantage of repeated measures design?

  No participant variables
• Why are participant variables eliminated in repeated measures design?

  Each participant does both conditions
• What is a disadvantage of repeated measures design related to order effects?

  Increased chance of practice and fatigue
• How might participants change their behavior in repeated measures design?

  They may know what to expect in the second condition
• What is a key advantage of matched pairs design?

  Reduced participant variables
• How does matched pairs design reduce order effects?

  Each participant only takes part in one condition
• What is a disadvantage of matched pairs design?

  Time consuming and expensive
• Why is it difficult to completely match participants in matched pairs design?

  Some participant variables will still exist
• What are the advantages and disadvantages of independent groups, repeated measures, and matched pairs designs?

  Independent Groups:

  • Advantages: Reduced order effects
  • Disadvantages: Increased participant variables

  
  

  Repeated Measures:

  • Advantages: No participant variables
  • Disadvantages: Increased order effects

  
  

  Matched Pairs:

  • Advantages: Reduced participant variables
  • Disadvantages: Time consuming and expensive
• target population

  group of people a researcher wishes to study
• sample

  small group of people studied who represent the target population
• 4 types of sampling

  opportunity

  random

  systematic

  stratified
• opportunity sample

  members of the target population who are simply available and willing to take part are selected
• random sampling

  every member of the target population has an equal chance of being selected

  this can be done by putting names into a hat and picking out the no. required or a random name generator
• evaluation of opportunity samples

  -often don't represent all

  -have researcher bias = picks the sample that supports research

  +quick and easy
• random sample evaluation

  -may not be representative due to it being completely random (all footballers may still be picked)

  -time consuming for large populations

  +no researcher bias
• systematic sampling

  • pick every nth participant
  • generate a list of everyone in target population and pick every nth person
• systematic sampling evaluation

  + no researcher bias

  -may not be representative (it's random)

  -time consuming
• stratified sample

  • identify sub groups in target population
  • gill sample with sub groups relative to their numbers on the target population using a random sample
• stratified sample evaluation

  + representative

  + no researcher bias

  -time consuming
• volunteer sampling

  • advertise for a sample and they come to you
• volunteer sampling evaluation

  + can advertise for exact type of person wanted for the study

  + don't have to find they yourself

  -only get a certain type of person that will respond so unrepresentative

  -low response rate
• internal validity

  are you testing the effect of the IV on the DV