Research Methods

Notes on Research Methods

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Investigation Designs (1)


  • Independent variable (IV) - the variable that you are in control of. The one the experimenter manipulates. The one that you change.
  • Dependent Variable (DV) - The variable that you measure. The one that changes because of the IV.
  • Confounding Variable - An extraneous variable that affects the out-come of the DV
  • Extraneous Variable - An unwanted variable that the experimenter may or may not be aware of.

Operationalisation of Variables

How the variables are measured - The process by which the variables are measured       E.g. using laughing as a measure of happiness


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Investigation Designs (2)

Aims and Hypothesis

Experimental Hypothesis - When the IV is manipulated there will be a change in the DV

    • Non-directional (2 tailed) - The IV has an effect of the DV but it is not know what direction is it.       e.g. 'Background Music affects the recall of a word list'
    • Directional (1 tailed) - The IV has an expected directional effect on the DV      e.g. 'Background music aids recall of a word list'

Null Hypothesis - When the IV is manipulated there will not be a change in the DV any difference will be due to chance or individual difference.

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Investigation Designs (3)

Experimental Designs

Repeated Measures - All do one condition and then all do the other. Then compare the results at the end.

  • Strengths - No individual differences, Less pps.
  • Weaknesses - Order effects
  • Remedy - Counter Balance

Matched Groups - Recruit a group of pps that are as similar as possible. One group does one condition and the other group does the other.

  • Strengths - Reduces individual differences, No order effects
  • Weaknesses - hard to find twins
  • Remedy - Use Monozygotic twins
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Investigation Designs (4)

Experimental Designs Continued...

Independent Groups - Pps are randomly allocated to either one or other of the conditions

  • Strengths - No order effects, reduced chances of Demand Characteristics
  • Weaknesses - More pps are required, more individual differences than the other experiments designs.
  • Remedy - Pps need to be randomly allocated.

Pilot Studies... These are basically practice studdies to make sure that no external or internal variables are going to change the outcome

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Investigation Designs (5)

Types of Sampling

Opportunity sample: Choosing thoes that are immediately available to you to participate in your experiment... e.g. thoes walking the street.

  • Strength - Easy method to operate
  • Weakness - A biased sample

Volunteer sample: Advertise for Pps.. e.g. in a newspaper or notice board

  • Strength - Access to a wider variety of pps
  • Weakness - They are more likely to be highly motivated (Volunteer Bias)

Random sample: All the target population are put into a hat and are chosen at random.

  • Strength - This is unbaised
  • Weakness - If the sample is too small there will still be bias.

Stratified sample: If equal numbers of boys and girls are required these are put into a hat.

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Investigation Designs (6)

Observational Methods

Naturalistic... Involves the researcher observing naturally occuring behaviour.

  • Strengths - High levels of ecological validity, Pps could be unaware they are being observed there-fore acting even more natural.
  • Weaknesses - No controll over extraneous variables, Ethical issues

Controlled... Where the researcher trys to control certain variables.

  • Strengths - Higher levels of controll over Extraneous variables
  • Weaknesses - pps may be effected by the fact they are being observed, behaviour may not be natural, Low ecological validity.
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Investigation Designs (7)

Observational Methods - Dimensions

Pps Vs. Non-pps

  • Pps... requires the researcher to actually join the group or take part in the situation being studdied
  • Non-pps... observations being made from outside the group

Disclosed Vs. Undisclosed

  • Disclosed... pps are aware they are being observed
  • Undisclosed... pps are unaware they are being observed

Structured Vs. Unstructured

  • Structured... Clear plan of what the researcher is going to measure and how.
  • Unstructured... records behaviours as they occur
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Investigation Designs (8)

Surveys + Interviews 

Surveys... Involves asking a large amount of people for information on a specific top at a particular moment in time. Involves asking both open and closed depending on what the researcher wants to find out.

  • Open Questions... Allows pps. to expand on their answer rather than just yes or no or tick this box questions (Qualitative Data)
    • Strengths - Provides qualitative data, much more realistic.
    • Weaknesses - difficult to analyse
  • Closed Questions... The pps. chooses from a selection of choices (Quantitative Data)
    • Strengths - Provides quantitative date which can be easily analysed.
    • Weaknesses- Artificial (not realistic), Not sure whether the respondent has understood the question

Interviews... Involves a conversational exchange between the interviewer and one or more individuals. Asks certain topic starters and records the reactions.

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Investigation Designs (9)

Surveys + Interviews 


  • Strengths - 
    • Can be used to question a large amount of people, quickly
    • Used to collect a large amount of in debth data
    • Researcher does not need to be pressent
    • A reduced investigator effects.
  • Weaknesses - 
    • Social Desirability - dont want to make yourself look bad
    • Untruthful responces
    • Distortion of sampling frame - Eg. only people who can read and write can take part
    • Difficult to frase questions. Different people interperate different ways.
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Investigation Designs (10)

Surveys + Interviews 


  • Strengths - 
    • Detailed information can be obtained
    • Allows pps to free express themselves
    • Unstructure, encourages the pps to honnest
  • Weaknesses - 
    • More time consuming
    • Greater chance of interpersonal variables e.g. Risk of investigator effects
    • Statistical analysis may be difficult
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Investigation Designs (11)

Surveys + Interviews 

Quantitaitve Data...  Information in numerical form, e.g. number of students in a class, Average scores on a quiz

Qualitative Data...  Information in Non-numerical form e.g. speach, written words, Pictures.

Experimental Validity

Internal Validity...  concerns what goes on inside the experiment.

    • E.g. Extraneous Variables, Confounding Variables, Poorly Operalationalised, IV + DV, Order Effects, Experimentor Bias, Sampling

External Validity... concerns what goes on outside the experiment.

    • E.g. Ecological validity (Applied to real life and like real life), Population validity, Historical validity and Cultural validity
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Methods and Techniques (1)

Experimental Methods...

Lab Experiments...

  • Strengths... Cause + Effect can be established, Can be easily replicated, Control of variables
  • Weaknesses... Not very ecologically valid, Demand characteristics cannot be controlled very well, Bias sampling.

Field Experiments...

  • Strengths... High in ecological validity, Less demand characteristics
  • Weaknesses...Less control of variables, Not very ethically sound, Hard to replicate
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Methods and Techniques (2)

Experimental Methods Continued...

Natural/Quasi Experiments...

  • Strengths... No demand characteristics,
  • Weaknesses... Lack of control, Hard to replicate, Hard to determine cause + effects
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Methods and Techniques (3)

Correlational Methods...

Positive...  the most common; as one variable increases so does the other, as stress goes up the amount of ilness increases.

Negative... as one variable increases the other decreases, e.g. e.g. it might be fair to assume that the higher your stress levels the lower your life expectancy.

Case Studies...

  • A case study can involve a whole host of techniques including observations, questionnaires, surveys, interviews, testing and even on occasion experiments. 
  • They are frequently longitudinal in nature and may also involve asking others, such as friends and associates.
  • You cannot generalise the findings to make a general theory
  • You may get Social Desireablity amongst the families responces
  • Can get Experimentor Bias
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