Exploratory factor analysis/Data analysis tutorial/SPSS

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Tutorial - Exploratory Factor Analysis

  1. This tutorial provides practical experience in conducting exploratory factor analyses (EFAs) with several introductory data sets using SPSS.
  2. Save your data, syntax and output for each analysis.

Contents

[edit] Steps

Recommended steps are to:

  1. Test assumptions
  2. Choose type of:
  3. Determine the number of factors
  4. Identify which items belong to each factor, drop items as necessary, and repeat analysis
  5. Name and define each factor
  6. Examine correlations amongst the factors
  7. Examine internal reliability for each factor
  8. Compute composite scores (if needed)

[edit] SPSS

[edit] Exploratory factor analysis

How to do an exploratory factor analysis with SPSS:

  1. Analyze - Data Reduction - Factor Analysis - Put target variables into the Variables box (order doesn't matter, but the output will be neater to read if the variables are sequentially ordered from 1 to X)
  2. Descriptives
    1. Initial solution
    2. Correlation matrix
      1. Coefficients
      2. KMO and Bartlett's
      3. Anti-image
  3. Extraction
    1. Analyze - Correlation matrix
    2. Display - Screen plot
    3. Extract - Eigenvalues over 1 - or usually better is to specify the number of factors
    4. Rotation - Varimax (uncorrelated factors) or Direct Oblimin (correlated factors)
    5. Options - Sort by size and Suppress values less than .20

[edit] Correlations between factors

After checking internal consistency and creating composite scores, also work out the correlations between the factors:

  1. Create composite scores for each of the factors
  2. Obtain the bivariate correlations between these factors. In SPSS - Analyze - Correlate - Bivariate - and put all your composite factor scores in.
  3. Report these correlations as part of your EFA results.

[edit] Exercises

Smoking attitudes
  • Allen & Bennett Ch 14 (pp. 193-204) [1] | .sav | .sps | .spo
  • Solution: PAF varimax (5 items; N = 107):
    1. Smoking acceptance
    2. Smoking in food/restaurants
Rating scale
On a scale from 1 to 100, where 1 represents "strongly disagree" and 100 represents "strongly agree"; please indicate the extent with which you agree with each of the following statements.
Items
1 I think smoking is acceptable.
2 I don't care if people smoke around me.
3 I don't think people should smoke in restaurants
4 I think people should have the right to smoke.
5 I don't think people should smoke around fod.
Classroom behaviour
  • Francis 5.6 (pp. 157-166) [2] | .sav | .sps | .spo
  • Solution: 3-factor PAF Oblimin (11 items; N = 1500), Drop items 6 and 7
    1. Sociability
    2. Task orientation
    3. Settledness
  • See also: Lecture slides: 28-31, 52, 55, 68, 75
Rating scale
Teachers, for each of the following paired behavioral statements, please mark a cross over the dot which is nearest the statement that best describes the TYPICAL behavior of THIS student at school
Items
1 CONCENTRATES Cannot concentrate on any particular task; easily distracted <-> Can concentrate on any task; not easily distracted
2 CURIOUS Eager to learn; curious and enquiring <-> Shows little curiousity or motivation
3 PERSEVERES Perserveres in the face of difficult or challenging work <-> Lacks perseverance; is impatient with difficult or challenging work
4 EVEN-TEMPERED Irritable,'touchy', 'cranky' <-> Even-tempered
5 PLACID Easily excited; gets 'high' <-> Not easily excited; placid
6 COMPLIANT Patient and compliant <-> Demanding and argumentative
7 SELF-CONTROLLED Is able to control own behaviour <-> Has difficulty controlling own behaviour
8 RELATES-WARMLY Relates warmly to others <-> Provocative; disruptive; short attention span
9 SUSTAINED ATTENTION Persistent, sustained attention span <-> Easily frustrated; short attention span
10 COMMUNICATIVE Difficult to reason and communicate with <-> Easy to reason and communicate with
11 RELAXED Restless; fidgety; can't sit still <-> Relaxed; can sit still
12 CALM On the go; lively; always moving <-> Settled, calm
13 PURPOSEFUL ACTIVITY Purposeful activity <-> Aimless activity
14 COOPERATIVE Co-operative; shared with others <-> Disputes, fights over sharing
15 CONTENTED Is easily upset; unhappy <-> Contented; happy
Managerial skills
  • Francis 5.12 (pp. 166, 258) [3] | .sav | .sps | .spo
  • Solution: 3 factor PAF Oblimin (13 items; N = 114):
    1. Feedback
    2. Time Management
    3. Problem Solving


Rating scale
Try to assess the extent to which you possess these skills (Scores ranged from 1 = very little extent to 7 = to a very great extent.)
Items
1 I show confidence in my staff
2 I let my staff know they are doing well
3 I give feedback to staff on how well they are working
4 I would personally compliment staff if they did outstanding work
5 I believe in setting goals and achieving them
6 I achieve the things I want to get done in a day
7 I never try to put off until tomorrow what I can finish today
8 I plan the use of my time well
9 I remain clear headed when too many demands are made upon me
10 I rarely overlook important factors when plans are made
11 I handle complex problems efficiently

[edit] See also

This tutorial
Next steps

[edit] References

  1. ↑ Allen, P. & Bennett, K. (2008). SPSS for the health and behavioural sciences. South Melbourne, Victoria, Australia: Thomson. | Companion site
  2. ↑ Francis, G. (2007). Introduction to SPSS for Windows: v. 15.0 and 14.0 with Notes for Studentware (5th ed.). Sydney: Pearson Education. | Support site
  3. ↑ Francis, G. (2007). Introduction to SPSS for Windows: v. 15.0 and 14.0 with Notes for Studentware (5th ed.). Sydney: Pearson Education. | Support site

[edit] External links

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