Just, please, plot the data if you have gathered some time-to-failure data, or you have the breakdown dates for a piece of equipment. Any data really. It could be your review of your car maintenance records and notes and dates of repairs. You may have some data from field returns. You have a group of numbers and you need to make some sense of it. Just, please, plot the data.

Take the average

Finding the average seems like a great first step. Let's summarize the data in some fashion. Let's say I have the number of hours each fan motor ran before failure. I can tally up the hours, TT, and divide by the number of failures, r. This is the mean time to failure.

Or, if the data was on my car and I have the days between failures, I can also tally up the time, TT, and divide by the number of repairs, r. Same formula and we call the result the mean time between failure (MTBF).

I have a number; say it's 34,860 hours MTBF. What does that mean (no pun intended) other than on average my car operated for 34,000 hours between failures. Sometimes more, sometimes less.

 …