An example of the use of ISO 9126

Tor StålhaneIDI / NTNU

The customers’ quality viewThe PROFF project did a survey of quality factors’importance for Norwegian companies that buy software.• Rank ISO 9126’s factors on a three point scale – 1 to 3• Indicate the cost of the last software acquisition using

three categories:– Category 1: les than NOK 10 001– Category 2: NOK 10 001 to 50 000– Category 3: more than NOK 50 001

• Indicate type of software in last acquisition:– COTS– Standardized software package– Tailor made software

ISO 9126 – Software quality

ISO 9004 – Service quality

Scores for all products pooled

Factor ScoreService responsiveness 2.81Service capacity 2.74Product reliability 2.71Service efficiency 2.65Product functionality 2.60Service confidence 2.60Product usability 2.57Product efficiency 2.46Product portability 2.05Product maintainability 1.89

Top productcharacteristic

Scores according to product categoryFactor COTS (36) Standardized

soft ware packages (27)

Customized and tailored software (19)

Product functionality 2.55 2.65 2.62

Product reliability 2.65 2.77 2.74

Product usability 2.67 2.47 2.54Product efficiency 2.47 2.35 2.58

Product maintainability 1.68 1.94 2.32Product portability 2.01 2.04 2.09

Service confidence 2.55 2.59 2.67Service efficiency 2.64 2.67 2.61

Service capacity 2.69 2.74 2.84Service responsiveness 2.82 2.83 2.76

1

11 2

2

2

3

3

3

Ranking for each software category

Factor importance vs. price category

Factor Price category 1 (20)

Price category 2 (22)

Price category 3 (42)

Product functionality 0.62 5 0.79 2 0.73 5Product reliability 0.60 6 0.82 1 0.77 2Product usability 0.70 2 0.60 7 0.64 8Product efficiency 0.43 8 0.57 8 0.51 9Product maintainability 0.33 9 0.38 9 0.07 10Product portability 0.33 9 0.38 9 0.76 3Service confidence 0.65 3 0.67 6 0.76 3Service efficiency 0.59 7 0.72 4 0.73 5Service capacity 0.75 1 0.77 2 0.81 1Service responsiveness 0.64 4 0.71 5 0.69 7

Ranking for each price category

Changes over categories – 1 Score differences

Factor Product categories Price categories

Product functionality - 0.17 + 0.11Product reliability + 0.14 + 0.17Product usability - 0.11 - 0.06Product efficiency + 0.09 + 0.08Product maintainability + 0.23 - 0.26Product portability + 0.01 + 0.43Service confidence + 0.33 + 0.11Service efficiency + 0.05 + 0.14Service capacity + 0.18 + 0.06Service responsiveness - 0.20 + 0.05

Product category: COTS => standardized software => tailor made software Product price: < 10 001 => 10 001 – 50 000 => > 50 000

Changes over categories – 2 Move from COTS products to tailor-made products• Product maintainability, service confidence and service capacity get

more importance• Customers who buy tailored software do not expect the producer

to put new, improved product versions on the market, except if they have a maintenance contract.

• Maintenance is a long term commitment, the requirements on service responsiveness decreases.

Price increases• Customers increase requirements on reliability and portability. • The customers’ need to protect their investment in expensive

software systems. • They need to be able to port expensive software so that they do not

have to buy new versions when the environments are changed.

Nordic Telecom company survey – 1 They asked their customers: • Would you buy from this company again?• Would you recommend others to buy from this company?

Nordic Telecom company survey – 2

The only case where we get a 100% “Yes” on the question “Would you recommend others to buy from this company?” is if the customer

• Complained• Got a satisfactory response.

If no complaints, the same question only got 87% yes.

For the customers it is more important with a satisfactory service response to his problems than having no problems at all.

Conclusions – 1 • Software products are considered to be complex with a

large potential to cause problems that the average user cannot handle. This lead to a focus on service quality.

• Maintainability and portability are – not important for the average software customer. It is the

producer’s responsibility to provide updated and enhanced versions of the software on the platform that they need.

– important for the producer. They must provide the services that the customer requires.

• Software customers behave in an economically rational way when they set priorities on quality requirements.

– Their preferences can be deduced from simple economic relations.

– If the pricing policy or market mechanisms change, so will the importance of each quality factor.

Conclusions – 2

The customers’ focus on service quality is an opportunity , not a problem.

The advice is: • Do not sell just a product; sell a product plus

service, provided through personal contacts. • The personnel used to provide services must

– know the customer’s applications– know his problems and needs.– show a genuine interest in that the customer reaps

the benefits he expected from the product he bought.