Anyone who has followed coin collecting closely
no doubt has encountered the "Green Sticker", slang for a CAC label
attached to a slabbed coin.
Step 1: For a given recent sale, pulled out all the CAC coins. In a sale of a three thousand coin lots, typically a few hundred of them carry the CAC green sticker.
Step 2: For the CAC coins, pull out matching coins from remainder of the sold coins from the sale. Definition of a match: same coin type, date, denomination, variety, grade, and grading service.
Step 3: If one of the coins in a matched pair had some other degree of separation, such as color (if applicable -- for example, Red or Red-Brown), a "Plus", "Secure" or some other type of additional quality indicator, or anything else, it was removed from the study. The objective of Steps 2 and 3 was to get the best "apples to apples" comparison possible.
Step 4: Go to another set of auction sale results and repeat Steps 1 through 3. Please note this methodology only isolated matches within the same sale. In other words, both coins in a matched pair were sold at essentially the same time. One could argue it would've been acceptable to match pairs sold a few months apart, but there was no trouble gathering data points for the study with this approach. Thus, all matched pairs were sold literally within hours of one another. Four sets of auction results were analyzed, covering 10,000 lot sales, from which 90 fully matched pairs were distilled.
Step 5: Compute the percent difference selling price of the matched pairs accordingly: CAC coin/Non-CAC coin, and sort from lowest to highest.
Step 6: Discard outliers. There were only two outliers, one the high side and one on the low side, leaving 88 pairs in the study.
Step 7: Create a chart to represent results of the study and perform other statistical analyses.
Forgive me for boring you to death, but it
really is necessary to reveal the methodology underlying the study. The
chart below captures
The key points gleaned from the chart above are:
Bottom Line: Yes, the vaunted CAC Green Sticker DOES INDEED tend to improve the selling price of a given coin when compared to its non-CAC counterpart. On average, this premium is about 25%, but this should never be viewed as an absolute rule. Your CAC coin may or it may not sell at a premium, but the odds are good that it will, although the size of the premium (if any at all) could be small or very large.