the Quest for the Magic Number

[declanwmagee]

Hello there. You all seem like wise people - I'd be very interested in your thoughts...

I am trying to come up with a scoring mechanism - a Magic Number that tells me how good a coin that is, so I can identify the worst coin I have in stock, and make sure I sell that one before a better one. We run a little eBay Shop, and, like most collectors, I imagine, fund purchases for our collection by selling duplicates.

It's easy to decide which is the better coin when you're only comparing a few at a time, but when you're trying to choose from hundreds, you need a system.

That system has to be able to compare apples with pears, as it were. Is this UNC G-VI halfpenny better or worse than this Fine George V halfcrown? Which would I rather keep? I think I'd keep the UNC, but what if it was a 1925 Halfcrown? Oh, well that might be different - I might keep that and sell the common UNC.

Do you see what I mean?

What I do at the moment is take the following factors:

1) Grade, converted to a number (I use a home-made 50 point grading system)

2) Rarity Rating (according to ESC or Peck), converted to a number

3) Metal composition combined with weight, so a halfcrown gets more than a sixpence on this measure, for example, and a silver coin always beats Cupro-Nickel, Copper, or Bronze

4) How much we've been able to sell examples of that coin for in the last 12 months, adjusted for grade. (For each coin we sell, I calculate an UNC equivalent figure, i.e. how much we could have got if that coin had been UNC. Then for the coin that's being evaluated, I take that UNC equivalent figure and factor it down from UNC to the grade it's at.)

5) then I bung in a tie-breaker of Age, so two coins that score the same thus far will be separated by 1 point per year of Age difference.

Each of these inputs is subject to a fiddle-factor that I change whenever it throws up something I don't like, so I might reduce the importance of grade if it's throwing out low grade Scarce G-V silver and keeping all the 1967 UNCs, for example.

This is all great, at the risk of turning Coin Collecting into adventures with Excel, but it has never really settled down - I seem to always be changing the fiddle factors....

How do you good people decide what to sell and what to keep?

thanks for listening...

Declan & Suze

the Pwincess and the Coin Collector

[Chris Perkins]

Bloody hell that all sounds far more complicated than it should be!

I usually just put coins on a tray, scan them and then list them on the website. If you make it too complicated you'd probably spend more time manipulating lists than selling coins.

Can't you just go through them all and use instict and feeling to tell you which ones you should sell? Or, even better, send them all to me and I'll make a fair offer for the lot and that could save you weeks!

[declanwmagee]

thanks for answering Chris. Believe it or not, this is designed as a timesaver! We tend to put a few out each day just to maintain a presence, so this tells me instantly which few it's going to be. The arithmetic behind it is complex, but the daily operation is very quick.

I suppose the question behind the question was about systems and methodology - stock control even...

[Guest Panterex]

Jeez!!!

Confused.com!!!

Chris, I'd say, gave you The Best solution to your problem... Don't make your life harder then it is...

[Geoff T]

The danger of trying to be over-precise is that you end up believing you own grading to be definitive and don't allow any room for difference of opinion. That's the mindset that's led to the dreadful practice of slabbing. The grading system we all use is uncomplicated and it does leave some room for dissent, but to me that's a plus factor, not a minus.

Geoff

[declanwmagee]

that's a really good point Geoff. Do you know I've never had anyone do a sanity check on my grading? I use the guidelines from a Coin Yearbook from the 1980s sometime (I don't have the book anymore, but I do have the information, and still use it on a daily basis). You probably all know them - "Edge of beard just visible" for a George V VF, for instance. The customers seem happy with the grades I give the coins they buy but would they really tell me if they disagreed?

I suppose, because I'm a chap who likes to have a system, I've fallen into the trap of thinking all coinies are systems people too. Having a system just saves me having to make too many decisions after a hard day at work - I can just flump myself down, run the thing - it'll throw up the coins to sell tonight, and it's done and dusted.

Beyond the basic principle of "buy better than your best" and "sell your worst", I'd still be fascinated to know how other people manage their collections though...I'm keen to learn and keen to streamline!

thanks

Declan