Help With Cycle Time Problem

Hi Roger,

It sounds like you were given a set of individual cycle time measurements…and they want you to estimate the cycle time 80% of the time…Which is a rather vague request.
If they wanted you to tell them a value that 80% of the cycle time values are less than, then you would want to sort the data, and find the value that 80% are less than.
If they wanted you to assume that cycle times follow a normal distribution, you would use this sample of cycle times to come up with a sample mean and sample standard deviation, and use the normal distribution to estimate the value that 80% of the cycle times are less than.

If you want the maximum cycle time you’d expect 80% of the time, you can add 0.84 times the standard deviation and add to the mean cycle time–if you are comfortable with assuming a normal distribution.