Hard Drive Reliability Update – Sep 2014
Since annual failure rate is a function mostly of age, it would be interesting to see a line chart of cumulative failure rate vs age. But since new drives are continually being added to the population, there would be fewer drives in the data set as you moved up each curve.I guess you could calculate confidence intervals at quarterly intervals, and so the error bars would get larger as age increases and 'n' decreases.How would you calculate the CI for failure rate? It's not binomial or poisson, since failure rate goes to 1 over time...A little searching turns up http://rmod.ee.duke.edu/statistics.htm which I'm sure completely explains how to do this... (rolls eyes). I hate that this is how statistics is commonly taught. Knowing which distribution to use and applying it correctly can actually be intuitive if taught properly. It doesn't always need to be an exercise in alphabet soup / deriving from base principles.