Scientific processes

• Hypothesis

  A prediction or statement of what you think will happen in a piece of research
• Types of hypothesis

  Alternative and null
• Types of alternative hypothesis + explanation

  One-tailed/directional - when there is previous research that shows a particular effect

  Two-tailed/non-directional - when there is no previous research or the psychologist isn't sure what will happen
• Null hypothesis


  Predicts that there will be no change or difference
• Correlational hypothesis


  Predicting that there is a relationship between variable 1 and variable 2
• Sampling


  How psychologists choose participants to take part in research
• Population


  The group of people who are being studied
• Sample


  The group of people from the population who actually take part in the research
• Participant


  Each individual who takes part in a study
• Sampling technique


  The method used to select participants from the population
• Representative

  The sample has similar characteristics to the population
• Generalisation

  When findings can be applied back to the population
• Volunteer sampling


  Participants choose to take part in a study
• Random sampling


  everyone in the population has an equal chance of being selected
• Systematic sampling

  Selecting participants using a pre-determined system
• Stratified sampling


  Choosing participants based on the characteristics in the population
• Opportunity sampling

  Choosing whoever is available at the time
• 3 types of design

  - Independent measures

  - repeated measures

  - matched pairs
• Independent measures


  Different participants are used in different conditions
• Repeated measures


  The same participants are used in each condition
• Matched pairs

  Different participants are used but are similar to each other
• Strengths & weaknesses of independent measures

  Strengths - no order effects, less chance of demand characteristics

  Weaknesses - increased participant variables, requires more participants
• Strengths & weaknesses of repeated measures

  Strengths - less participant variables, requires fewer participants

  Weaknesses - order effects, more chance of demand characteristics
• Strengths & weaknesses of matched pairs

  Strengths - participant variables kept more constant, no order effects

  Weaknesses - cannot match perfectly, requires more participants
• Peer review


  Using independent experts to assess the quality and validity of research before it is published
• Process of peer review

  - research is submitted for publication in a scientific journal

  - other psychologists check the research e.g. validity, ethics

  - the reviewer can either accept or reject the report

  - the journal editor then makes the final decision based on the reviewer's comments
• Functions of peer review

  - ensures only high quality research is shared

  - ensures researchers do valid and ethical research

  - prevents poor research being shared
• Strengths of peer review

  - promotes high standards in research

  - prevents scientific fraud

  - contributes new knowledge to the field
• Weaknesses of peer review

  - hard to find an appropriate expert

  - experts in a similar area may have a conflict of interest

  - findings that aren't statistically significant are rejected to important findings may be overlooked
• Economy


  How much money we have as a society and what we choose to spend it on
• how does psychological health impact work & the economy?

  people who are happier are less likely to be dependent on state benefits and are 12% more productive
• reliability


  measuring something over and over and getting the same result
• the key to reliability

  consistency
• test for internal reliability + explanation

  split half method - compares performance on 2 halves on a questionnaire. there should be a correlation co-efficient of 0.8
• test for external reliability + explanation

  test-retest method - a test/experiment is carried out again using the same or similar ppt. if the same results are found, the study has high external validity
• internal validity 


  measure of the extent to which something is consistent within itself
• external validity 


  repeating a study on similar participants and getting the same results
• 2 ways of improving validity

  • conducting a pilot study to check for issues
  • standardising the way the study is done so it can be repeated in the same way
• inter-observer reliability 


  checking if observers are consistent in what they record
• 4 steps in establishing inter-observer reliability

  • discussing and agreeing on behaviour categories
  • 2 observers independently observing at the same time
  • compare and correlate data for agreement
  • is the correlation is 0.8 or greater, reliability has been established