Exercise 4: Measurement — reliability, PCA, EFA, and CFA

Use data/employee_survey.csv.

1. Reverse-code leadership_4_reverse and engagement_4_reverse.
2. Estimate Cronbach’s alpha for the four leadership items.
3. In one sentence, explain what alpha can and cannot establish.
4. Select the 12 leadership, engagement, and role-clarity items and remove rows with missing item responses for this exercise.
5. Split the complete cases into an exploratory half and a confirmatory half using set.seed(2026).
6. Run PCA on the exploratory half and inspect the first three components.
7. Run parallel analysis and a three-factor oblimin EFA.
8. Identify the strongest item loading for each factor.
9. Specify a three-factor CFA model in lavaan.
10. Fit it in the confirmatory half using ordered indicators and WLSMV.
11. Report CFI, TLI, RMSEA, and SRMR.
12. Explain the difference among PCA, EFA, and CFA in three concise sentences.