In the past, SCDigest editor Dan Gilmore has authored very popular columns on what he calls “The 50 Percent Problem,” or the tendency of most of us to rate our own or our company’s performance as in the top of the performance curve, while in reality, by definition, half must be in the bottom half of the class. (See The 50 Percent Problem Revisited.)

That issue was well-manifested in a recent supply chain survey from Computer Sciences Corp. and Michigan State.  (See Dimensions of Supply Chain Competence.) For example, 60.7 percent of firms rated themselves in the top one-third of the industry in terms of product reliability and product conformance. Half of them are wrong.

Similarly, a full 78% of respondents rated themselves as 3 (average) or above on a scale of 1-5 in terms of supply chain competence. Based on the math, that’s 38% too high.

In fairness, it could be companies with better than average supply chains are more likely to complete a survey like this, which would skew the percentages in a way that looks like over-rating.

It also can be that as you get nearer to the middle of the performance curve, the differences between say the second quartile of performers and the third are very small, making it much easier for companies to overrate themselves in terms of how they stack up.

But we think this probably only partially explains the results, and that the 50 Percent Problem is at work as usual.