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CONCEPTS TO BE INCLUDED

CONCEPTS TO BE INCLUDED. Factor analysis as a data reduction technique Factors/ dimensions Factor loadings Exploratory factor analysis Eigenvalues and Kaisers criterion Scree plot and elbow criterion ( very short: rotation and interpreting factor loadings ).

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CONCEPTS TO BE INCLUDED

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  1. CONCEPTS TO BE INCLUDED • Factor analysis as a data reductiontechnique • Factors/dimensions • Factor loadings • Exploratory factor analysis • Eigenvalues and Kaiserscriterion • Scree plot and elbowcriterion • (very short: rotation and interpreting factor loadings)

  2. SelecTing factors in Factor analysis

  3. AIM Selectingtheappropriatenumber of factors/dimensions in exploratory factor analysis. Three criteria: • EigenvaluesandKaiser’scriterion • Scree plot and elbowcriterion • Interpreting factor loadings (afterrotation)

  4. EXAMPLE: THE BIG FIVE NEO-PI-R personality scales measure five domains of personality describing normal adults

  5. EXAMPLE: THE BIG FIVE Five constructs/dimensions/factors: • Openness (closed minded – intellectual curiosity) • Conscientiousness (sloppy/unreliable – highly organized) • Extraversion (reflective – attention seeking) • Agreeableness (suspicious – compassionate) • Neuroticism (emotionally stable – emotionally unstable)

  6. SIX ITEMS DESCRIBING ASPECTS OF PERSONALITY • Even minor annoyances can be frustrating to me (N) • Sometimes I feel completely worthless (N) • I really enjoy talking to people (E) • I often try new and foreign foods (E) • I try to be courteous to everyone I meet (A) • Most people I know, like me (A)

  7. MANY ITEMS, SMALLER SETS OF FACTORS Item O1 Item O2 Item O3 … Item C1 … Item E1 … Item A1 … Item N1 Item N2 Item N3 Openness Conscientiousness Extraversion Agreeableness Neuroticism ETC…

  8. CONFIRMATORY OR EXPLORATORY? Item O1 Item O2 Item O3 … Item C1 … Item E1 … Item A1 … Item N1 Item N2 Item N3 Based on theory: Openness Conscientiousness Extraversion Agreeableness Neuroticism ETC… To be tested

  9. CONFIRMATORY OR EXPLORATORY? Item O1 Item O2 Item O3 … Item C1 … Item E1 … Item A1 … Item N1 Item N2 Item N3 Number and meaning of factors unknown, to be ‘found’ in the data. Items based on the idea of “having a personality” ETC…

  10. FACTOR MATRIX Factor loadings Squared and summed = ‘Explained variance’ by a factor divided by the number of items = “Eigenvalue”

  11. SCREE PLOT Eigenvalue Elbow criterion: selecting factors on the steep part of the scree plot Kaiser’s criterion: select factors based on Eigenvalue > 1 1 Factor 3 4 2 Etc… 1

  12. SELECTING # FACTORS IN EXPLORATORY FACTOR ANALYSIS • Does the scree plot show an ‘elbow’? Yes? Select factors in the steep part of the scree plot, before the plot levels of • How many factors have an Eigenvalue over 1? • Can they be ‘interpreted’ (after ‘rotation’)?

  13. FACTOR MATRIX Factor loadings Rotation is a way to facilitate interpretation of the relationship between items and factors

  14. THIS MICROLECTURE Selectingtheappropriatenumber of factors/dimensions in exploratory factor analysis. Three criteria forselectingthenumber of factors: • Eigenvalues and Kaiserscriterion • Scree plot and elbowcriterion • (very short: rotation and interpreting factor loadings)

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