> Product have an expected lifespan longer than the warranty period. This is malicious if given as a target.
Also it is mathematically stupid, because products do not fail at consistent rates, nor are they used by customers are equal rates. If you want to minimize warranty costs, you do need to target some mean lifetime well beyond the warranty period.
MTBF (or MTTF) might be useful number if you buy 100 light bulbs, but is not really a useful number for you buying one appliance. Product failures don't follow a normal distribution. The stuff that ticks people off about shitty products is the infancy-failure part of the bathtub curve -- It's when you get 13 months out of a $200 blender that fails in infancy that you're pissed. Not when you get 24 months out of a $20 blender that fails from end-of-life.
Also it is mathematically stupid, because products do not fail at consistent rates, nor are they used by customers are equal rates. If you want to minimize warranty costs, you do need to target some mean lifetime well beyond the warranty period.
MTBF (or MTTF) might be useful number if you buy 100 light bulbs, but is not really a useful number for you buying one appliance. Product failures don't follow a normal distribution. The stuff that ticks people off about shitty products is the infancy-failure part of the bathtub curve -- It's when you get 13 months out of a $200 blender that fails in infancy that you're pissed. Not when you get 24 months out of a $20 blender that fails from end-of-life.