How To Read OC Curves for Individual sampling plans in Z1.4 2003

Can anyone explain how to read the OC curves for Individual sampling plans?

Example: I'm using sample size J and looking at the chart J at the top. I based my sample on a .15 AQL using level III (new supplier of a critical component). Let's say I just inspected 80 pieces in a 500 piece lot. I found 0 nonconforming. Does this mean if I follow the curve for a .15 AQL that 99.9...% of the lots would expect to be accepted? Similarly, if I found 5 nonconforming with same sample size and AQL (1% nonconforming), the curve shows me 45% of the lots would be accepted.

Just want to do a reality check..................

I just took a look at the chart and I'd make two suggestions...

1) If you find 5 nonconforming in the sample of 80, that would be 5/80 = 6.25%. You don't want to use the size of the whole lot to get 5/500 = 1%. It looks like the 45% number you used corresponds to 1% nonconforming on the OC curve. (I expect that you knew that but you just got typing a little faster than you were thinking )

2) Your interpretation of the table is slightly turned around. The table say that if the actual quality of the lot is 1% then 45% of the lots will be rejected using this sampling scheme. That is slightly different than saying that if you found 1% nonconforming in your sample, then the actual quality is 1% nonconforming. 1% would of course be a good estimate of the true nonconformance rate, but from that single sample there would be considerable uncertainty. That means that there would be considerable uncertainty in the 45% lot rejection rate.

Does that make sense?

Tim F