scientific processes

• Aim

  A generic statement about what the researcher intends to study, which is generated from a theory that they want to test
• Aim

  Outlines what is being studied and what the study is trying to achieve
• Aim


  • To investigate the effect caffeine has on memory recall
• Hypothesis


  A specific, testable statement that references the operationalised variables being investigated
• Aim


  Generic and outlines the focus of the study
• Hypothesis

  Precise and should not have any ambiguity about it
• Hypothesis


  A testable statement written as a prediction of what the researcher expects to find as a result of their experiment
• Hypothesis


  • No more than one sentence long
  • Includes the independent variable (IV) and the dependent variable (DV)
  • Both IV & DV need to be operationalised - giving specifics on how each variable is to be manipulated or measured
• Operationalising variables


  • Exposing some children to an aggressive adult model whilst other children are not exposed to an aggressive adult model (operationalisation of the IV)
  • Number of imitative and non-imitative acts of aggression performed by the child (operationalisation of the DV)
• Experimental Hypothesis


  Hypothesis which directly predicts the effect of the IV on the DV
• Directional Experimental Hypothesis


  Predicts the direction of the change/difference (anticipates more specifically what might happen)
• Directional Experimental Hypothesis


  • Participants who drink 200ml of an energy drink 5 minutes before running 100m will be faster (in seconds) than participants who drink 200ml of water 5 minutes before running 100m
  • Participants who learn a poem in a room in which loud music is playing will recall less of the poem's content than participants who learn the same poem in a silent room
• Non-Directional Experimental Hypothesis


  Does not predict the direction of the change/difference (an 'open goal' i.e. anything could happen)
• Non-Directional Experimental Hypothesis

  • There will be a difference in time taken (in seconds) to run 100m depending on whether participants have drunk 200ml of an energy drink or 200ml of water 5 minutes before running
  • There will be a difference in recall of a poem depending on whether participants learn the poem in a room in which loud music is playing or in a silent room
• Null Hypothesis


  What all research starts with as it is 'ground zero' of the research process - the idea that the IV will have no effect on the DV
• Turning a non-directional hypothesis into a null hypothesis

  Change 'a' into 'no'
• All published psychology research must include the null hypothesis
• To accept or reject the null hypothesis is why the null hypothesis is so important - it tells the researcher whether or not their experiment has shown a difference in conditions
• 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 wishes to investigate
• Generalised population

  A population that is more broad than the target population
• Researcher draws sample from target population

  Generalises the findings across 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 (strata), e.g. age, gender, education etc.
  • The sample is representative of the target population
  • Easy to generalise as the sample is representative
  • Selection is unbiased as it is based on the sub groups in society
  • Time consuming, knowing the subgroups and dividing the population into categories, then selecting participants to match these, can be very time consuming
  • The researcher requires knowledge of the subgroups and categories of the population, which may not be available
• Random sampling

  • Selecting people, in a way that everyone has a fair chance of being selected, this could be done by having all names in a hat and pulling them out or by using a computer generator
  • Unbiased selection, meaning it is more likely to be a representative sample
  • As the results are fairly representative, it means the results are able to be generalised to the target population
  • Time consuming and impractical, it is not always a possibility to be able to have all of the information on a target population, or, for all of the target population to want to take part in the study
  • It may be non-representative as all of one gender could be selected randomly, which would not be a true example of the target population
• Volunteer (self-selected) sampling

  • People volunteer (choose) to take part, selecting themselves as participants of a study often by replying to adverts
  • Willingness of participants as they are choosing to take part so participants are less likely to want to jeopardise the study and its results
  • Not much effort is required to obtain the sample e.g. put up a poster, put out an ad on social media etc.
  • Volunteer bias, which means the results will not be able to be generalised as volunteer participants often have personality traits in common e.g. sociable, out-going etc.
  • Volunteers are often eager to please, which causes demand characteristics, which means that they may behave how they think the researcher wants them to
• Systematic sampling

  • Selecting every nth person from a list to make a sample. The researcher has to calculate how many people they need to know which nth they need
  • Unbiased selection, meaning it is more likely to be a representative sample
  • As the sample is likely to be reasonably representative it means that the results can be generalised to the target population
  • Not always truly unbiased as the selection process can interact with a hidden periodic trait, if every 10th person is a 19 year old shop worker, then they are the only people in the sample
  • It may be non representative as all of one gender could be selected systematically, which would not be a true example of the target population
• Opportunity sampling

  • Selecting those who are most convenient, willing and available to take part. This could be asking people who are passing in the street to take part
  • Natural experiments use opportunity sampling as the researcher has no control over who is being studied
  • Quick and easy way to get information as it is using people who are readily available to use
  • Cannot generalise as the sample is like to be unrepresentative, as it is likely to miss whole sections of the population, students could be at school for example or people who are at work can not be in the sample
  • It is a self selected sample as participant have the option to agree or decline to join in at the time of the study
• Experimental design

  How the participant sample is used in combination with the different levels of the independent variable (IV)
• Types of experimental design

  • Independent Groups design
  • Repeated Measures design
  • Matched Pairs design
• Independent Groups design

  • Participants only experience one condition of the IV
  • Participants are randomly allocated to each condition to avoid researcher bias
  • Generates unrelated data (because the two groups are separate to one another)
• Independent Groups design procedure

  1. Participants in condition 1 learn a poem with music playing

  2. Participants in condition 2 learn the same poem in silence

  3. Measure the dependent variable (DV) as the number of words correctly recalled from the poem

  4. Compare the performance of the group in condition 1 to the group in condition 2
• 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 can affect results
  • More participants are needed
• Repeated Measures design

  • Participants experience all conditions of the IV
  • Generates related data (because the two scores come from the same participant)
  • Participants act as their own control group
• Repeated Measures design procedure

  1. Participant learns a poem with music playing (condition 1)

  2. Participant learns a different poem in silence (condition 2)

  3. Measure the DV as the number of words correctly recalled from each poem

  4. Compare the participant's performance in condition 1 to condition 2

  5. Use counterbalancing to avoid order effects
• Strengths of Repeated Measures Design

  • No individual differences affecting results
  • Fewer participants required
• Limitations of Repeated Measures Design

  • Order effects can be a problem
  • More likely to have demand characteristics
• Matched Pairs design

  • Participants are assessed and matched on important characteristics
  • Participants are randomly allocated to one condition each
  • Produces related data