4 (True story) The light bulb in the men’s lavatories of a factory finally burnt out after 70 years of operation.

The manager at the firm said, ‘It is actually a little bit sad. I joined the firm when I was fifteen (he is now sixty three) and it was there then.’ In fact, the bulb had survived bombs dropped in the Second World War that had devastated neighbouring buildings, the army firing its guns in the next-door park and punk band ‘the Clash’ playing at a neighbouring venue, which caused residents to complain that their windows were being shaken by the noise. When it did eventually fail, the firm had it mounted on a stand and gave it a place of honour. More remarkable, they tracked down the original supplier of the bulb. He had also survived. He was 99 years old and still remembered selling them. Does this incident invalidate the use of failure data in estimating component life?