The performance review should be a summary of all of the conversations that you had during the previous year with the employee.
You of course had those conversations, right?
If not, go back to the SMART goals that you wrote for the employee a year ago. SMART goals are:
Specific, Measurable, Attainable, Realistic and Timely.
Given that the SMART goals have been completed, I always ask the employee to submit their assessment a week in advance of the sit down review. Ask the employee to provide specific examples or metrics to demonstrate how they performed on a particular goal.
It is your turn to do the exact same thing.
Then when the employee completes their assessment, you can compare it to yours. Is there a big difference?
If so, I am sorry to say that the manager did not do a good job this past year!
The employee should never be surprised about what they are receiving on their performance review. The review should simply be the process of formally documenting everything that has been talked about during the entire year.