Absenteeism
Multiple instances of unauthorized absences
Excessive sick days
Frequent Monday and/or Friday absences
Repeated absences, particularly if they follow a pattern
Excessive tardiness
Frequent use of unscheduled vacation days to cover absence
Leaving work early
Peculiar and increasingly improbably excuses for absences
Higher absentee rate than other employees for colds, flu, etc.
Frequent unscheduled short-term absences (with or without medical explanation)
Identification badge frequently forgotten

On-The-Job Absenteeism
Frequent absences from post for more time than job requires
Excessive tardiness in returning from breaks, meals
Unexplained absences from work assignment

Accident rate
Accidents on job
Accidents on job due to carelessness
"Peculiar" accidents

Changes in Personal Habits
Reporting to work in other than normal condition
Returning from lunch or dinner in a noticeably different behavior mode
Declining attention to personal hygiene
Deteriorating personal appearance

Poor Job Performance
Missed deadlines
Complaints from non-employees
Improbable excuses for poor job performance
Alternate periods of high and low productivity
Difficulty in recalling instructions, details, deadlines, etc
Difficulty in recalling own mistakes
Increasing difficulty in handling complex assignments
Jobs take longer than necessary to complete
Erratic work habits
Diminished morning performance
Diminished concentration
Poor judgment
Increased mistakes
Decreased productivity (quality and quantity)
Reduced efficiency and dependability
Poor decision-making

Poor Interpersonal Relationships On-The-Job
Overreaction to real or imagined criticism
Wide swings in morale
Borrowing money from co-workers
Complaints from co-workers
Unrealistic resentments
Avoidance of associates
Increasingly argumentative with co-workers
Excessive talking with co-workers
Strained relations with co-workers

Other
Inappropriate behavior
Failure to follow organization's policy