SOFTWARE FAILURE MODE AND EFFECT ANALYSIS (SFMEA) - Software Design for Six-Sigma: A Roadmap for Excellence - page 430

TABLE 16.6 The Software FMEA Ratings

Likelihood of
Occurrence Rating Severity of Effect Detection

1 Cosmetic Error: No loss in product

functionality. Includes incorrect
documentation

1 per 100
unit-years
(1/50m)

Requirements/
design
reviews

2 Cosmetic Error: No loss in product

functionality. Includes incorrect
documentation

1per10
unit-years
(1/5m)

Requirements/
design
reviews

3 Product Performance Reduction:

Temporary through time-out or system
load the problem will “go away” after a
period of time

1 perl unit-year
(1/525k)

Code walk-
throughs/unit
testing

4 Product Performance Reduction:

Temporary Through time-out or system
load the problem will “go away” after a
period of time

1per1
unit-month
(1/43k)

Code walk-
throughs/unit
testing

5 Functional Impairment/Loss: The

problem will not resolve itself, but a
“work around” temporarily can bypass
the problem area until fixed without
losing operation

1 perweek
(1/10k)

System
integration
and test

6 Functional Impairment/Loss: The

problem will not resolve itself, but a
“work around” temporarily can bypass
the problem area until fixed without
losing operation

1perday
(1/1440)

System
integration
and test

7 Functional Impairment/Loss: The

problem will not resolve itself, and no
“work around” can bypass the problem.
Functionality either has been impaired
or lost, but the product still can be used
to some extent

1 per shift
(1/480)

Installation and
start-up

8 Functional Impairment/Loss: The

problem will not resolve itself, and no
“work around” can bypass the problem.
Functionality either has been impaired
or lost, but the product still can be used
to some extent

1 per hour
(1/60)

Installation and
start-up

9 Product Halts/Process Taken

Down/Reboot Required: The product is
completely hung up, all functionality
has been lost, and system reboot is
required

1 per 10 min
(1/10)

Detectable only
once “online”

10 Product Halts/Process Taken

Down/Reboot Required: The product is
completely hung up, all functionality
has been lost, and system reboot is
required

1 + permin
(1/1)

Detectable only
once “online”