A common problem that requires a data mining solution is anomaly detection — that is, finding those values that "do not fit" based on the patterns present in the rest of the data. You'll see how to solve this problem using SQL Server 2005 Data Mining for an Excel worksheet.
This solution doesn't require any separate treatment of the data; it works directly in your workbook after a few mouse clicks. The code that accompanies this article is an Excel addin
you can install in Microsoft Excel and use for detecting anomalies in any Excel worksheet.