When measuring employee performance, managers should make sure that measurements are all of these EXCEPT:

A) based on clear job performance criteria.
B) accurate in assessing performance.
C) providing a defensible basis for differentiating between high and low performance.
D) useful as feedback that can help future performance.
E) always positive as to not discourage employees.

The given options state that measurements should be based on clear job performance criteria, accurate in assessing performance, providing a defensible basis for differentiating between high and low performance, and useful as feedback that can help future performance. However, the option 'always positive as to not discourage employees' is not necessary as it may not reflect the actual performance of an employee and may not motivate them to improve. Constructive criticism is essential for growth and development, and feedback should be both positive and negative to help employees identify areas for improvement. Therefore, option E is not a measure that managers should consider when measuring employee performance.