scientific processes

• Aim


  A generic statement about what the researcher intends to study, which is generated from a theory that they want to test
• The aim outlines what is being studied and what the study is trying to achieve
• Hypothesis


  A specific, testable statement that references the operationalised variables being investigated
• The aim is generic and outlines the focus of the study, the hypothesis is precise and should not have any ambiguity
• Experimental hypothesis


  A hypothesis which directly predicts the effect of the independent variable on the dependent variable
• Directional experimental hypothesis


  Predicts the direction of the change/difference
• Non-directional experimental hypothesis


  Does not predict the direction of the change/difference
• Null hypothesis


  States that the independent variable will have no effect on the dependent variable
• All published psychology research must include the null hypothesis
• To turn a non-directional hypothesis into a null hypothesis, only one word needs to be changed: 'a' into 'no'
• Sampling


  Obtaining the participants who will take part in the research
• Sample


  Taken from the population that is relevant to the research topic
• Target population


  The specific population the researcher wants to investigate
• Generalised population


  A population that is more broad than the target population
• Sampling techniques


  • Stratified
  • Random
  • Volunteer (self-selected)
  • Systematic
  • Opportunity
• Stratified sampling


  • Small-scale reproduction of the target population, dividing and categorising the population by characteristics important to the research
• Random sampling


  • Selecting people in a way that everyone has a fair chance of being selected
• Volunteer (self-selected) sampling


  • People volunteer (choose) to take part, selecting themselves as participants
• Systematic sampling


  • Selecting every nth person from a list to make a sample
• Opportunity sampling


  • Selecting those who are most convenient, willing and available to take part
• Pilot study


  A small scale trial investigation that tests some or all aspects of the intended investigation, carried out prior to the research
• Pilot studies


  • Identify problems in the design, method or analysis, allowing them to be altered and fixed
  • Participants can help identify issues and propose changes that stop demand characteristics from happening
  • Changes are then made before the full research takes place to try and ensure a higher level of validity
  • Pilot studies are able to identify if the research is 'worth' conducting
• Independent groups design


  Experimental design where participants only experience one condition of the independent variable
• Independent groups design


  • Generates unrelated data
  • Compares the performance of the group in one condition to the performance of the group in another condition
• Strengths of independent groups design

  • Less likely to have demand characteristics
  • Less likely to have order effects
• Limitations of independent groups design


  • Participant variables/individual differences
  • More participants are needed
• Repeated measures design


  Experimental design where participants experience all conditions of the independent variable
• Repeated measures design


  • Generates related data
  • Participants act as their own control group
  • Counterbalancing is used to avoid order effects
• Strengths of repeated measures design

  • No individual differences
  • Fewer participants are required
• Limitations of repeated measures design


  • Order effects
  • Demand characteristics are more likely
• Matched pairs design


  Participants are assessed and matched on important characteristics, then randomly allocated to conditions
• Matched pairs design produces related data
• Balancing


  Splitting the participants into groups and changing the order of the conditions per group
• Fewer participants are required


  Each participant generates (at least) two scores
• Demand characteristics are more likely


  Participants are more likely to guess the purpose of the research due to taking part in multiple conditions
• Matched Pairs Design


  Participants (usually) achieve just one score as they (usually) only take part in one condition
• Matched Pairs Design


  • Participants are assessed and matched on the characteristic(s) that are important for the particular research they are taking part in, e.g. age, ethnicity, gender etc.
  • Often MZ (Monozygotic/ identical) twins are used for this design as they create the perfect matched pair (one twin can be assigned the experimental condition and the other twin the control condition)
  • The matched participants are then randomly allocated to one condition each
• In an experiment on the social learning of aggression, participants would be matched on a scale according to how aggressive they already are


  Any difference in scores should be due to the effect of the IV and not on natural aggression levels
• Strengths of Matched Pair Design

  • Due to participants only taking part in one condition, it means there are less likely to be order effects
  • Almost factors out individual differences as a confounding variable as the researchers have striven to find a 'match' per participant i.e. participant variables are controlled for to some extent
• Limitations of Matched Pair Design

  • Matching is difficult and it is often impossible to match all characteristics, especially when the unmatched characteristic could be important to the results of the research. Also, even well matched participants could have different levels of motivation in the study, affecting the outcome.
  • More participants are need to ensure there are enough to take part in the different conditions.
  • Matching participants is very difficult and time consuming