Figure 4

Average reported carbon reduction achievements by category. The 250 reported footprint changes were sorted into 3 categories, reflecting different underlying reasons for the reported changes as well as different granularity of the reported product footprints. Error bars show ±1 SEM around the arithmetic mean. The difference in average achieved reductions in the two samples (footprints with versus without life cycle stage information) is statistically significant (two-tailed student t-test, unequal variances; p < 0.05).