Query Analyzer: Execution Plan: Clustered Index Seek: I/O Cost

Can anyone explain how I/O cost is calculated?
My example:
Physical operation: Clustered Index Seek
Logical operation: Clustered Index Seek
Row count: 1
Estimated row size: 76
I/O cost: 0.00632
CPU cost: 0.000080
Number of executes: 1
Cost: 0.006408(100%)
Subtree cost: 0.00640
Estimated row count: 1
Argument: ...
If you really want to know some of the details about query costs, you should
read some of Joe Chang's articles at www.sql-server-performance.com . This
is an excellent site for performance tips, and Joe has several detailed
articles about calculating the cost of a query.
"Dave Owen" <DaveOwen@.discussions.microsoft.com> wrote in message
news:811149F2-25E0-43BA-B3A6-43B17D7014F4@.microsoft.com...
> Can anyone explain how I/O cost is calculated?
> My example:
> Physical operation: Clustered Index Seek
> Logical operation: Clustered Index Seek
> Row count: 1
> Estimated row size: 76
> I/O cost: 0.00632
> CPU cost: 0.000080
> Number of executes: 1
> Cost: 0.006408(100%)
> Subtree cost: 0.00640
> Estimated row count: 1
> Argument: ...