Since the bulbs last so long, and it would be prohibitive to wait until a death rate of 50%, they use 6000 hours as the laboratory test time which has good corr

Since the bulbs last so long, and it would be prohibitive to wait until a death rate of 50%, they use 6000 hours as the laboratory test time which has good correlation with information known so far from LED manufacturers. By that age they tend to be in a main sequence of life.