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Software Development Inc.Software Development Inc. (SDI) produces and markets software for...

Software Development Inc.

Software Development Inc. (SDI) produces and markets software for personal computers, including spreadsheet, word processing, desktop publishing, and database management programs. SDI has annual sales of $800 million.

Producing software is a time-consuming, labor-intensive process. Software quality is an extremely important aspect of success in computer software markets. One aspect of quality is program reliability. Does the software perform as expected? Does it work with other software in terms of data transfers and interfaces? Does it terminate abnormally? In spite of extensive testing of the software, programs always contain some bugs. Once the software is released, SDI stands behind the product with phone-in customer service consultants who answer questions and help the customer work around problems in the software. SDI’s software maintenance group fixes bugs and sends out revised versions of the programs to customers.

SDI tracks the relation between quality costs and quality. The quality measure it uses is the number of documented bugs in a software package. These bugs are counted when a customer calls in with a complaint and the SDI customer service representative determines that this is a new problem. The software maintenance programmers then attempt to fix the program and eliminate the bug. To manage quality, SDI tracks quality costs. It has released 38 new packages or major revisions in existing packages in the last three years. The accompanying table reports the number of defects (bugs) documented in the first six months following release. Also listed in the table are total product cost and quality cost per software package release.

Product costs include all the costs incurred to produce and market the software, excluding the quality costs in the table. Quality costs consist of three components: training, prevention, and software maintenance and customer service costs. Training costs are expenditures for educating the programmers and updating their training. Better-educated programmers produce fewer bugs. Prevention costs include expenditures for testing the software before it is released. Maintenance and customer service costs include (1) the programmers charged with fixing the bugs and reissuing the revised software and (2) the customer service representatives answering phone questions. The training and prevention costs are measured over the period the software was being developed. The number of defects and maintenance and service costs are measured in the first six months following release.

SDI Defects and Quality Costs by Program Release*

Program Release

Number of Defects

Product Cost

Training Cost

Prevention Cost

Software Maintenance and Customer Service Cost

Total Costs

1

66

$3,455

$442

$ 770

$2,160

$6,827

2

86

3,959

428

447

2,658

7,492

3

14

3,609

417

1,167

687

5,880

4

73

3,948

211

655

2,334

7,148

5

17

3,104

290

1,013

544

4,951

6

48

3,179

253

547

1,556

5,535

7

80

3,112

392

508

2,633

6,645

8

41

3,529

276

577

1,563

5,945

9

50

3,796

557

634

1,666

6,653

10

67

3,444

365

947

2,140

6,896

11

42

3,922

453

869

1,444

6,688

12

64

3,846

378

1,108

1,942

7,274

13

71

3,014

555

762

2,384

6,715

14

1

3,884

301

773

423

5,381

15

18

3,183

378

1,080

857

5,498

16

85

3,475

528

1,010

2,572

7,585

17

17

3,445

357

666

631

5,099

18

50

3,203

285

427

1,546

5,461

19

22

3,839

239

1,080

891

6,049

20

73

3,060

540

1,054

2,309

6,963

21

52

3,182

329

1,079

1,867

6,457

22

75

3,075

395

832

2,697

6,999

23

35

3,456

447

969

1,518

6,390

24

53

3,987

355

651

2,042

7,035

25

25

3,836

309

1,160

1,036

6,341

26

6

3,886

234

794

252

5,166

27

78

3,846

418

833

2,800

7,897

28

82

3,106

409

1,092

2,871

7,478

29

39

3,506

448

899

1,342

6,195

30

47

3,545

450

442

1,450

5,887

31

30

3,376

456

784

1,260

5,876

32

17

3,740

542

420

607

5,309

33

67

3,479

411

821

2,018

6,729

34

51

3,773

351

1,145

1,873

7,142

35

74

3,034

497

671

2,389

6,591

36

25

3,768

268

887

1,094

6,017

37

14

3,168

356

645

837

5,006

38

77

3,561

492

1,167

2,597

7,817

Average

48

$3,509

$390

$ 826

$1,671

$6,395

*Per 100,000 lines of computer code.

All the numbers in the table have been divided by lines of computer code in the particular program release. Programs with more lines of code cost more and also have more bugs. Prior studies find that using lines of code is an acceptable way to control for program complexity. Thus, the numbers in the table are stated in terms of defects and cost per 100,000 lines of code.

The figure below plots the relation between total cost and number of defects. The vice president of quality of SDI likes to use it to emphasize that costs and quality are inversely related. She is fond of saying, “Quality pays! Our total costs fall as the number of defects declines. The more we spend on quality, the lower our costs.”

SDI total costs by defects

Required:

Critically evaluate the vice president’s analysis.

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