What are some causes of the number of bytes on the wire exceeding the number of bytes being captured?

Some causes of the number of bytes on the wire exceeding the number of bytes being captured is that not everything is being captured or that partial packets may be captured which could lead to incorrect analysis. If there are regularly more bytes on the wire than captured, then, it is possible that the computer on which Wireshark is running is not able to keep up with the interface.