1. INTRODUCTION

2. DATA PRODUCTS  
2.1. The EDGE and CALIFA Surveys  
2.2. EDGE PyDB Database

3. METHODS  
3.1. Stacking of the CO Spectra  
3.2. Extracting Fluxes from Stacked Spectra  
3.3. Basic Equations and Assumptions

4. RESULTS AND DISCUSSION  
4.2. SFE and Local Parameters

5. SUMMARY AND CONCLUSIONS