Circulation Obsolescence
Circulation Obsolescence is an idea put forth by David "NickelSearcher" Knipfer in a post on the Coin Community Forums. The following is his original post.
"Fair warning ...... this is a mathematical post. 
One of the more interesting (to me at least) measures is what I call "Circulation Obsolescence
Simply put ....... what percentage of the original mintage has disappeared from circulation for any reason. The reasons are many .... hoarding, collected, melted, lost on the beach, whatever.
When I speak to people live about this I use the following analogy ..... In the year 1937 you could walk into any bank and purchase any roll of nickels and be GUARANTEED it will be fully 100% Buffalo's with a few V's thrown in. The reason you can not do that today is Circulation Obsolescence.
It is not difficult to measure if you have a large enough data base. I've just passed through 140,000 nickels searched ..... a reasonable data base size ..... and the accuracy of my estimates will improve with more evidence.
Sooooo ... all that said ...... consider the following ...
The total mintage of the entire Jefferson series (1938 through 2009) is 52,269.7 million coins.
The total mintage of the coins I search for (Jefferson's 1938 through 1959) is 3,524.4 million.
Do a simple division of 3524.4/52,269.7 and you can see that 'early pre-1960 Jefferson's account for 6.743% of the total Jefferson's ever minted.
Sooooooo .... if they were all still in circulation (no obsolescence) I should be finding them at that rate during my roll searches.
However ..... I find them at a rate of 1.255% instead ...... which means that there is an overall 81.4% Circulation Obsolescence Loss.
If that makes sense the rest is easy .....
In addition to looking at the overall 'big picture', I sub-divide the years 1938 through 1959 into smaller groupings and follow the same logic as stated above ........ the ratio of total mintage for that period divided by overall mintage gives the 'expected no-loss find rate' ...... compare this to my actual find rates and ... voila ..... Circulation Obsolescence for that period.
To that end ..... here are my calculated Jefferson Nickel Circulation Obsolescence rates for the various time periods I chose:
1930's @ 83.0%
Pre-War 1940's @ 82.2%
War Silver @ 98.2%
Post-War 1940's @ 77.8%
Early 1950's @ 73.6%
Late 1950's @ 68.9%
Once you have these figures in hand ..... then you can play games with 'what if' type of questions. For example:
What is the estimate of the number of War Silver Jefferson's still in circulation today?
Well .... we can answer that (it might surprise you) ....
Obsolesence data says that 98.2% have been 'lost' ...... which means that 1.8% still exist in circulation.
The total mintage of War Silver Jefferson's was a staggering 870 million (they alone account for nearly 25% of the total mintage 1938 through 1959) ...
Soooo .... 1.8% of 870 million is .... 15,660,000 War Silvers still out there to be found!
Keep that in mind the next time you get discouraged about not finding any for awhile.
Enjoy"
Through a series of emails between myself and David he has given me permission to research Circulation Obsolescence. I WANT TO MAKE SOMETHING PERFECTLY CLEAR: THE ORIGINAL IDEA FOR CIRCULATION OBSOLESCENCE WAS DAVID'S. I AM SIMPLY EXPANDING THE RESEARCH.
