Statistical Analysis Of Key And Semi-Key Indian Head Cents

For background information, I posted a similar thread on Lincoln Cents:

https://goccf.com/t/88992#735292

Now for the Indian Head cents. I thought I would treat these as a single group, and also compare my findings with the current price (as found on numismedia.com for G4.)

For the Indian Head cents, there has been 3 key dates: 1877, 1909-S, and 1908-S. I get good comparable values with the LWC study: key date z-values of -2.2 and less; semi-keys between -2.2 and -1.5.

To get a z-value, I determine the relative standard deviation from the mean (log mintage) values. The results for the "top 10" IHC are as follows:

1909-S -3.49 key
1877 -2.66 key
1908-S -2.44 key
1871 -1.40
1872 -1.38
1870 -1.16
1878 -1.08
1869 -0.99
1876 -0.82
1866 -0.69

Notice there is a large gap between the 3 key dates and the nearest others. I think most people would consider the 1871 and 1872 as semi-key dates, however.

Since the IHC have LONG been out of circulation, I thought it would be interesting to compare these z-values with a current price. Since I am looking strictly at mintage values, I thought that the price for a G4 would be most indicative for comparison purposes. That way, we don't get into other issues like which are more difficult to find in higher grades. The graph below shows the x-axis as the z-values above, while the y-axis shows the log of the price (from numismedia.com).



You can clearly see the 3 key dates as being the higher priced ones with large negative z-values. There is definitely a trend with current prices and you can also see the more common dates (positive z-values) having low prices. It also seems that you need a z-value of less than about -0.5 to see any appreciable premium.

Comments? Thanks for reading...