Accurate calculations of First Time Quality / First Time Yield

#1
Currently working in the food industry and our unit of measure for production is LBS Produced.

I have been asked to calculate FTQ for the past few weeks. Occassionally we will put LBS on "hold" that were produced earlier in the week and/or month. When I am performing my calculation for FTQ, should I only be focusing on the production runs within the specific timeframe or any lbs that we held during that timeframe, regardless of of it's production date.

i.e. should my FTQ be based on date that a production run was held, regardless of when that production run was produced.

Thanks in advance
 
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Miner

Forum Moderator
Staff member
Admin
#2
It depends. The intent of a good metric is to drive the correct behavior, and to not drive bad behavior. A metric also needs to be real time and easy to calculate. The question that you raise will make it harder to calculate, and may impact the real time aspect, so the next question would be: What will be the difference in impact on behavior of one approach versus the other? If there is no difference, opt for the easier approach. If one will drive better behavior, take that approach. Don't get caught up chasing a "purist" approach.
 

somashekar

Staff member
Super Moderator
#3
Currently working in the food industry and our unit of measure for production is LBS Produced.

I have been asked to calculate FTQ for the past few weeks. Occassionally we will put LBS on "hold" that were produced earlier in the week and/or month. When I am performing my calculation for FTQ, should I only be focusing on the production runs within the specific timeframe or any lbs that we held during that timeframe, regardless of of it's production date.

i.e. should my FTQ be based on date that a production run was held, regardless of when that production run was produced.

Thanks in advance
If you are going about the FTQ on a weekly basis and if any LBS is on hold for matters other than quality in that week., then you have to consider this held quantity too.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#4
In my experience, FTY is a trailing metric that doesn't need - and really can't support - immediate action. daily failure rates will do that for you. It is also a dynamic metric as you have described. lots or products that all start in one week do not finish together. in general it is the start week that better represents the changing factors for yield; it's not perfect but it's way cleaner than lumping multiple start weeks into the same finish week. In my organization we subgroup FTY by week of product start. We take the products that have been scrapped or released/shipped in any given week and enter them into the proportion for their week of start. the marker is white with a black circle outline when the data are still incomplete. (in other words, not products started that week have been released or scrapped - final disposition). once the subgroup is complete we change the marker to a solid black circle. Everyone understands that a white marker is incomplete data. it takes about 4-6 weeks for a subgroup to complete. if it takes longer than that we know something bad happened - too many lots or products circling in rework.

Of course, this works for us. your situation may be somewhat different and using just the completion week may be sufficient. as Miner said.
 
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