Analysis of Lighting
The following statistically significant correlations represent the influences various aspects of lighting on crop yield. Two consistent patterns appear to emerge from these preliminary correlations.
First, total lumens appears to have a stronger correlation with crop yield than total watts. This makes sense, because some light sources (e.g., HPS) are more efficient (lumens per watt) than others (e.g., fluorescent); so we would expect that total lumens would be a better predictor of crop yield than total watts.
Correlation  Significance  
Watts  .494**  .000 
** Correlation is significant at the 0.01 level 
Correlation  Significance  
Lumens  .562**  .000 
** Correlation is significant at the 0.01 level 
Secondly, HPS lighting appears to have a stronger positive impact on crop yield than either MH or fluorescent lighting. This is true whether we are comparing the three light sources in terms of total absolute watts, total absolute lumens or percent of total lumens. In fact, in all three comparisons, the HPS lighting shows a very large positive correlation with crop yield; the MH lighting actually shows a modest negative correlation; and the fluorescent lighting shows an even larger negative correlation. This indicates that crops grown under only HPS lighting will produce higher yields. It also suggests strongly that if we substitute MH lighting for HPS, then our yield will diminish. And if we rely mostly on fluorescent lighting, our yield will drop even more.
Total Watts

Correlation  Significance 
HPS

.671**  .000 
MH

.102  .211 
Fluorescent

.397**  .000 
** Correlation is significant at the 0.01 level 
Total Lumens

Correlation  Significance 
HPS

.672**  .000 
MH

.083  .308 
Fluorescent

.398**  .000 
** Correlation is significant at the 0.01 level 
Lumens Percent

Correlation  Significance 
HPS

.536**  .000 
MH

.233**  .004 
Fluorescent

.435**  .000 
** Correlation is significant at the 0.01 level 