I have compared the data (amount total) on the pipeline against the database and it comes out different.

For example if I run the following SQL against the databse:
SELECT SUM(amount) AS Expr1
FROM opportunities
WHERE (sales_stage = 'Suspect')
The value I get out is some £97,000 different to the value in the pipeline!
Its not the filtering because I get the same result as the pipeline if I create a custom report that does not have any filtering.
For some sales stages the result is accurate (i.e. the pipeline value matches the database).

Has anyone seem this before and/or have an explanation?