These are the results of a confidential questionnaire, which asked how medical errors occur. The questionnaire was given to 254 medical residents. These same residents were asked how they changed their approach after medical errors occurred.

Perceived Causes	%
Inexperience
Lack of Knowledge	54
Not enough experience	42
Did not ask for advice	33

Job Overload
To many other responsibilities	51
Fatigue	41

Faulty Judgment
Missed warning signs	50
Unusual case	39
Very complex case	38
Hesitating too long	32

Changes in Practice
Pay more attention to detail	82
Personally confirm data	72
Seek more advice	62
Ask peers	60
Ask supervisors	56
Read	54
Change organization of data	52
Trust other�s judgment less	49
Ask for references	26

Defensive Changes
Keep mistakes to self	13
Avoid similar patients	6