1. INTRODUCTION  
2. DATA AND DATA PREPARATION  
2.1. BOSS Spectra  
2.2. Continuum Fits and Normalization  
2.3. Principal Component Analysis Fits  
2.4. Photometric Observations  
3. VARIABILITY MEASUREMENTS  
3.1. Searching for Variability  
3.2. Measurements  
4. DISCUSSION  
4.1. Observed Variability in Context  
4.2. Possible Causes of Variability  
4.3. Physical Constraints from the Lack of Trough-Profile Variability  
4.4. Physical Constraints from Ionization State Variability  
5. SUMMARY AND FUTURE WORK