Methods in Psychology

Probability (5% level)
1. Type I Error
  1. If HE is accepted and later turns out not to be true
  2. More likely if a lenient probability is used e.g. 10% level.
2. Type II Error
  1. If HE is rejected and it later turns out to be true
  2. More likely if a strict probability is used e.g. 1%
Parametric and Non-Parametric Tests
1. Non-Parametric
  1. Use nominal + ordinal data, simple, often subjective scales, tests for significance, convert scores to ranks
  2. sign test, Wilcoxon test, Mann-Whitney, chi-squared + Spearman's Rank Order Correlation test
2. Parametric
  1. Use interval/ratio data, contains info. about size of difference between scores, more powerful test of significance
  2. Related t-test, independent t-test, Pearson's Product Moment Correlation test
Correlations
1. Test for a link/ association between 2 key variables
  1. Research Hypothesis (instead of HE) used to predict relationship e.g. 'there will be a significant correlation between variable A and variable B'
2. Positive Correlation
  1. Variable A increases as variable B increases
3. Negative Correlation
  1. Variable A increases as variable B decreases
4. Zero Correlation
  1. No pattern/ relationship
Directional Hypotheses & Tails of Test
1. Non-directional Hypotheses
  1. There will be a significant difference in the DV when IV is changed
  2. Used by researchers to reduce experimenter bias (e.g. when rejecting anomalies
  3. 2-tailed statistical test
2. Directional Hypotheses
  1. Predict a significant increase or significant decrease in DV when IV is changed
  2. Only used when there is strong previous evidence about the direction of the results
  3. 1-tailed Statistical test
Reliability
1. External Reliability (test re-test)
  1. How consistent a method measures over time when repeated (same people under same conditions e.g. IQ test
  2. Correlate the results of a test conducted on one occaision with the results of a test conducted on a later occaision (with same subjects). High positive correlation = reliable method
2. Inter rater/ Observer Reliability
  1. content analysis/ observational studies
  2. 1.) Clearly describe behaviour to record (categorise)
    1. 2.) Observe same ppts. for same amount of time, independently
      1. 3.) Compare results, if 90% similar = reliable, consistent method
Validity
1. To what extent have you measured the factor you set out to measure; whether other factors have affected your results
2. e.g. Bigelow set out to measure children's understanding of friendship, but instead may have measured their language ability
3. Methods of establishing Validity::
  1. 1.) Face Validity: look at the method to see if it appears to measure what it is supposed to measure; open to bias
    1. 2.) Concurrent Validity: give same ppts. the new test, and an established test which measures the same thing (or questionnaire). Test scores for correlation - significant positive = valid
      1. 3.) Ecological Validity:where the conditions of a test are so controlled that they do not represent how a situation would occur naturally
Sampling
1. Target Population = people that your hypothesis relates to and from whom the sample is taken
2. Generalise = predict future behaviour of TP on basis of the result of sample
  1. Q-Sort Cards: used to measure self esteem, select 4 cards, convert into score of mood
    1. Reliability: test re-test = do test again on same ppts. after two weeks, same results = reliable
      1. Validity: Compare result's correlation with an established study (questionnaire), significant +ve correlation = valid
3. Random/ Systematic Sample: everyone in TP has an equal chance of being selected, assigned numbers
  1. Opportunity Sample: people who are willing and convenient, likely to be unrepresentative
    1. Stratified Sample: Divided into groups (e.g. gender, nationality, age) then random representative sample from each group
Ethical Guidelines
1. Informed Consent
  1. Verbal or written consent after information about task is explained, no deception
2. Consent for studies involving children
  1. Consent from parents (if under 16) and child wherever possible
3. Right of Withdrawal
  1. Informed of right to leave study at any time in brief, informed of right to withdraw information in debrief
4. Deceiving Participant
  1. Explained in debrief, consent to be deceived, knowing aim may affect behaviour
5. Protection from Physical and Psychological Harm
  1. Must be aware of consequences of investigation, should feel no worse about themselves after investigation, normalise by informing of other ppts., counselling
Hypotheses
1. Experimental (HE)
2. Null (Ho)
3. Alternative (H1)
4. Research (HR)
Descriptive Statistics
1. Averages
  1. summarise set of data into 1 value
    1. Compare 2 sets of scores
      1. Central point of 2 sets of scores
  2. Mean: interval/ratio data
  3. Median: Ordinal data
  4. Mode: Nominal data
2. Measures of Dispersal
  1. How spread out a set of scores are
  2. Tells yous if your ppts. scores are consistent or variable
  3. Range: largest - smallest value, affected by extreme scores
  4. Standard Deviation: uses all scores, use for interval/ ratio data, measures the deviation of each score from the mean
Quantitative & Qualitative Methods
1. Quantitative
  1. +Controls extraneous variables, +Establish C&E. +Can test hypothesis, +Can carry out statistical tests
2. Qualitative
  1. +Generates new theories, +High face validity, +High ecological validity, +High level of detail; understand behaviour better

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