Dr. Chakkrit (Kla) Tantithamthavorn
Lecturer, Faculty of Information Technology,

Monash University, Australia.
@klainfohttp://chakkrit.com
chakkrit.tantithamthavorn@monash.edu
AI-Driven Software
Quality Assurance 

in the Age of DevOps
Australian Taxation Office’s service outages from
software bugs lead to $4.2 billion dollars lost
2
3
Software Quality Assurance practices like 

code review and testing are still time-consuming
- Large and complex: 1 billion lines of code
- Intense quality assurance activities:
- 17K code reviews
- 100 million test cases
3
Software Quality Assurance practices like 

code review and testing are still time-consuming
- Large and complex: 1 billion lines of code
- Intense quality assurance activities:
- 17K code reviews
- 100 million test cases
It is infeasible to exhaustively review and test 

source code within the limited time and resources
4
Defect models play a significant role in
software quality management
Release
Defect

Model
Module A
Module C
Module B
Module D
Module A
Module C
Module B
Module D
4
Predict

future software 

defects
Defect models play a significant role in
software quality management
Release
Defect

Model
Module A
Module C
Module B
Module D
Module A
Module C
Module B
Module D
4
Predict

future software 

defects
Explain 

what makes software
fail
Defect models play a significant role in
software quality management
Release
Defect

Model
Module A
Module C
Module B
Module D
Module A
Module C
Module B
Module D
4
Predict

future software 

defects
Explain 

what makes software
fail
Defect models play a significant role in
software quality management
Release
Defect

Model
Module A
Module C
Module B
Module D
Module A
Module C
Module B
Module D
Develop 

empirical theories related
to software quality
5
Defect models play a significant role in
software quality management
Lewis et al., ICSE’13
Mockus et al., BLTJ’00 Ostrand et al., TSE’05 Kim et al., FSE’15
Naggappan et al., ICSE’06
Zimmermann et al., FSE’09
Caglayan et al., ICSE’15
Tan et al., ICSE’15
Shimagaki et al., ICSE’16
Defect models become widespread in many large
software organisations
Explain 

what makes software
fail
Develop 

empirical theories related
to software quality
Predict

future software 

defects
6
Today research toolkits are easily accessible
7
Statistical

Model
Training

Corpus
Classifier 

Parameters
(7) Model

Construction
Performance

Measures
Data 

Sampling
(2) Data Cleaning and Filtration
(3) Metrics Extraction and Normalization
(4) Descriptive
Analytics
(+/-) Relationship
to the Outcome
Y
X
x
Software

Repository
Software

Dataset
Clean

Dataset
Studied Dataset
Outcome Studied Metrics Control Metrics
+~
(1) Data Collection
Predictive 

Analytics
Prescriptive
Analytics
(8) Model Validation
(9) Model Analysis
and Interpretation
Importance 

Score
Testing

Corpus
PredictionsPerformance

Estimates
Patterns
In reality, defect modelling
is detailed and complex
8
A lack of practical guidelines of defect modelling have
a negative impact on software quality management
Misleading 

insights
Managers take wrong
technical decisions
Developers waste
time and resources
Wrong 

predictions
8
A lack of practical guidelines of defect modelling have
a negative impact on software quality management
Misleading 

insights
Managers take wrong
technical decisions
Developers waste
time and resources
Wrong 

predictions
Empirical investigation is needed 

to derive practical guidelines for defect modelling
9
Metric Selection
Model Construction
Model Evaluation
Control Metrics

[ICSE-SEIP’18]
Correlation

[TSE’16]
Model Statistics

[ICSE-SEIP’18]
Model Interpretation
Class Imbalance

[Under Review]
The Risks of
Unsound

Defect

Models
Data Quality
Issue Reports

[ICSE’15]
Feature Selection

[ICSME’18]
Interpretation

[Under Review]
Model Validation

[TSE’17]
Measures

[ICSE-SEIP’18]
Releases

[Under Review]
Metrics

[On-going]
Universal Models

[Under Review]
Ranking 

[On-going]
Time-Wise

[On-going]
Parameters

[ICSE’16,TSE’18]
9
Metric Selection
Model Construction
Model Evaluation
Control Metrics

[ICSE-SEIP’18]
Correlation

[TSE’16]
Model Statistics

[ICSE-SEIP’18]
Model Interpretation
Class Imbalance

[Under Review]
The Risks of
Unsound

Defect

Models
Data Quality
Issue Reports

[ICSE’15]
Feature Selection

[ICSME’18]
Interpretation

[Under Review]
Model Validation

[TSE’17]
Measures

[ICSE-SEIP’18]
Releases

[Under Review]
Metrics

[On-going]
Universal Models

[Under Review]
Ranking 

[On-going]
Time-Wise

[On-going]
Parameters

[ICSE’16,TSE’18]
10
Defect prediction models have configurable
parameters that control their characteristics
Most of the widely-used classification techniques
require at least one parameter setting
Based on the literature analysis of 

300+ defect studies
10
Defect prediction models have configurable
parameters that control their characteristics
Most of the widely-used classification techniques
require at least one parameter setting
Based on the literature analysis of 

300+ defect studies
#trees for 

random forest
#clusters for 

k-nearest neighbors
10
Defect prediction models have configurable
parameters that control their characteristics
Most of the widely-used classification techniques
require at least one parameter setting
Based on the literature analysis of 

300+ defect studies
#trees for 

random forest
#clusters for 

k-nearest neighbors
80% of top-50 highly-cited defect studies
rely on a default setting [IST’16]
10
Defect prediction models have configurable
parameters that control their characteristics
Most of the widely-used classification techniques
require at least one parameter setting
Based on the literature analysis of 

300+ defect studies
#trees for 

random forest
#clusters for 

k-nearest neighbors
80% of top-50 highly-cited defect studies
rely on a default setting [IST’16]
Even within the R toolkit, 2 random forest
packages have different default settings
What is the impact of optimization
techniques on defect models?
11
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
What is the impact of optimization
techniques on defect models?
11
(RQ1) What is the impact of automated parameter optimization
on the accuracy of defect models?
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
What is the impact of optimization
techniques on defect models?
11
(RQ1) What is the impact of automated parameter optimization
on the accuracy of defect models?
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
What is the impact of optimization
techniques on defect models?
11
(RQ1) What is the impact of automated parameter optimization
on the accuracy of defect models?
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
(RQ3) What are the best classification techniques for defect
models when automated parameter optimization is applied?
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
12
A comprehensive framework to extensively evaluate the
impact of optimization techniques on defect models
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
Defect 

Dataset
12
A comprehensive framework to extensively evaluate the
impact of optimization techniques on defect models
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
Defect 

Dataset
Default 

Setting
Construct 

Defect

Models
Optimized 

Setting
12
A comprehensive framework to extensively evaluate the
impact of optimization techniques on defect models
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
Defect 

Dataset
Default 

Setting
Construct 

Defect

Models
Optimized 

Setting
Optimized

Model
Default-setting

Model
12
A comprehensive framework to extensively evaluate the
impact of optimization techniques on defect models
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
Defect 

Dataset
Default 

Setting
Construct 

Defect

Models
Optimized 

Setting
Optimized

Model
Default-setting

Model
Calculate

accuracy
The accuracy of

optimized model
The accuracy of

default model
12
A comprehensive framework to extensively evaluate the
impact of optimization techniques on defect models
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
Defect 

Dataset
Default 

Setting
Construct 

Defect

Models
Optimized 

Setting
Optimized

Model
Default-setting

Model
Calculate

accuracy
The accuracy of

optimized model
The accuracy of

default model
Rank metrics
by importance
score
The ranking of

metrics in 

optimized model
The ranking of

metrics in 

default model
12
A comprehensive framework to extensively evaluate the
impact of optimization techniques on defect models
26 classification techniques 

(e.g., C5.0, Random Forest)
12 performance measures 

(e.g., AUC, F-measure)
4 optimization algorithms 

(e.g., genetic algorithm, and
differential evolution)
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
Defect 

Dataset
Default 

Setting
Construct 

Defect

Models
Optimized 

Setting
Optimized

Model
Default-setting

Model
Calculate

accuracy
The accuracy of

optimized model
The accuracy of

default model
Rank metrics
by importance
score
The ranking of

metrics in 

optimized model
The ranking of

metrics in 

default model
13
Case Study Setup
Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter
Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
Code Metrics

(e.g., lines of code

code complexity)
Process Metrics

(e.g., #commits

#added_lines)
Human Factor

(e.g., #dev,

ownership)
600 - 10,000 modules

11-48% defective ratios
18 software releases 15-38 software metrics
Large Medium Small
●
●
●
●
●
● ●
●
0.0
0.1
0.2
0.3
0.4
C
5.0
AdaBoost
AVN
N
etC
ART
PC
AN
N
etN
N
etFDA
M
LPW
eightD
ecayM
LP
LM
TG
PLS
LogitBoostKN
N
xG
BTreeG
BM
N
B
R
BF
SVM
R
adial
G
AM
Boos
AUCPerformanceImprovement
14
(RQ1) What is the impact of automated parameter
optimization on the accuracy of defect models?
Approach: Compute the accuracy difference between optimized
models and default-setting models
AUCDifference(Optimized-Default)
Large Medium Small
●
●
●
●
●
● ●
●
0.0
0.1
0.2
0.3
0.4
C
5.0
AdaBoost
AVN
N
etC
ART
PC
AN
N
etN
N
etFDA
M
LPW
eightD
ecayM
LP
LM
TG
PLS
LogitBoostKN
N
xG
BTreeG
BM
N
B
R
BF
SVM
R
adial
G
AM
Boos
AUCPerformanceImprovement
14
(RQ1) What is the impact of automated parameter
optimization on the accuracy of defect models?
9 of the 26 studied
classification techniques
have a large accuracy
improvement
Approach: Compute the accuracy difference between optimized
models and default-setting models
AUCDifference(Optimized-Default)
Large Medium Small
●
●
●
●
●
● ●
●
0.0
0.1
0.2
0.3
0.4
C
5.0
AdaBoost
AVN
N
etC
ART
PC
AN
N
etN
N
etFDA
M
LPW
eightD
ecayM
LP
LM
TG
PLS
LogitBoostKN
N
xG
BTreeG
BM
N
B
R
BF
SVM
R
adial
G
AM
Boos
AUCPerformanceImprovement
14
(RQ1) What is the impact of automated parameter
optimization on the accuracy of defect models?
9 of the 26 studied
classification techniques
have a large accuracy
improvement
Approach: Compute the accuracy difference between optimized
models and default-setting models
AUCDifference(Optimized-Default)
Large Medium Small
●
●
●
●
●
● ●
●
0.0
0.1
0.2
0.3
0.4
C
5.0
AdaBoost
AVN
N
etC
ART
PC
AN
N
etN
N
etFDA
M
LPW
eightD
ecayM
LP
LM
TG
PLS
LogitBoostKN
N
xG
BTreeG
BM
N
B
R
BF
SVM
R
adial
G
AM
Boos
AUCPerformanceImprovement
14
(RQ1) What is the impact of automated parameter
optimization on the accuracy of defect models?
9 of the 26 studied
classification techniques
have a large accuracy
improvement
Approach: Compute the accuracy difference between optimized
models and default-setting models
Optimization substantially improves the accuracy of defect
prediction models
AUCDifference(Optimized-Default)
15
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Optimized

Model
Default

Model
Approach: Compute the percentage of the top-rank metrics in
optimized models that appears at the top-rank in default models
15
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Optimized

Model
Default

Model
Calculate an
importance
score for each
metric
Approach: Compute the percentage of the top-rank metrics in
optimized models that appears at the top-rank in default models
15
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Optimized

Model
Default

Model
Calculate an
importance
score for each
metric
Ranking of metrics

in optimized models
Ranking of metrics

in default models
Approach: Compute the percentage of the top-rank metrics in
optimized models that appears at the top-rank in default models
15
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Optimized

Model
Default

Model
Calculate an
importance
score for each
metric
Ranking of metrics

in optimized models
Ranking of metrics

in default models
Calculate the
rank difference
for each metric
Diff %metrics
0 60%
-1 20%
Approach: Compute the percentage of the top-rank metrics in
optimized models that appears at the top-rank in default models
16
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Approach: Compute the percentage of the top-rank metrics in
optimized models that appears at the top-rank for default models
0%
20%
40%
60%
80%
100%
0 -1 -2 -3 -4
Percentageofmetrics
Rank difference
16
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Approach: Compute the percentage of the top-rank metrics in
optimized models that appears at the top-rank for default models
36% of the top-rank metrics in
optimized models 

do not appear at the top-rank for
default models
0%
20%
40%
60%
80%
100%
0 -1 -2 -3 -4
Percentageofmetrics
Rank difference
16
(RQ2) How much does the interpretation of defect models
change when automated parameter optimization is applied?
Approach: Compute the percentage of the top-rank metrics in
optimized models that appears at the top-rank for default models
36% of the top-rank metrics in
optimized models 

do not appear at the top-rank for
default models
0%
20%
40%
60%
80%
100%
0 -1 -2 -3 -4
Percentageofmetrics
One-third of the most important metrics are missing 

if we do not apply parameter optimization
Rank difference
17
(RQ3) What is the best classification techniques for defect
models when automated parameter optimization is applied?
Approach: Compute the average rank of classification techniques
across the studied datasets
A JMLR’14 paper finds that random
forest is top-performing classifiers for
machine learning datasets
17
(RQ3) What is the best classification techniques for defect
models when automated parameter optimization is applied?
Approach: Compute the average rank of classification techniques
across the studied datasets
A JMLR’14 paper finds that random
forest is top-performing classifiers for
machine learning datasets
Optimized xGBTree
Optimized C5.0
Optimized RF
Surprisingly, the best technique like
Random Forest in ML domains is not
always be the best in SE domains
17
(RQ3) What is the best classification techniques for defect
models when automated parameter optimization is applied?
Approach: Compute the average rank of classification techniques
across the studied datasets
A JMLR’14 paper finds that random
forest is top-performing classifiers for
machine learning datasets
Optimized xGBTree
Optimized C5.0
Optimized RF
Surprisingly, the best technique like
Random Forest in ML domains is not
always be the best in SE domains
Domain-specific modelling guidelines are critically needed
What is the impact of optimization
techniques on defect models?
18
Optimization substantially improves the accuracy of defect
prediction models
One-third of the most important metrics are missing if we do
not apply parameter optimization
The best technique (RF) in ML domain might not always be the
best in SE domain when parameter optimization is applied
Automated parameter optimization should be applied for
defect prediction models
19
“This is a much needed
contribution both for researchers
and for practitioners: 



Researchers will find a checklist for
the quality assurance of their defect
modelling methods. 



Practitioners, that is software quality
experts in companies, will avoid a
false interpretation of their data.” 



- An Anonymous Reviewer -
20
Open Challenges: 

Faster dev. speed, but Slower QA activities
Software companies are shifting 

from long to rapid release cycles
20
Open Challenges: 

Faster dev. speed, but Slower QA activities
Software companies are shifting 

from long to rapid release cycles
Large volume of code changes
20
Open Challenges: 

Faster dev. speed, but Slower QA activities
Software companies are shifting 

from long to rapid release cycles
Large volume of code changes
Slow CI builds and tests
20
Open Challenges: 

Faster dev. speed, but Slower QA activities
How to develop an AI agent to accurately and intelligently
remove software defects prior to CI build runs?
Software companies are shifting 

from long to rapid release cycles
Large volume of code changes
Slow CI builds and tests
21
Future Research Agenda: 

AI-Driven Software Quality Assurance in the Age of DevOps
21
Future Research Agenda: 

AI-Driven Software Quality Assurance in the Age of DevOps
Accurate Predictions

of Future Defects
21
Future Research Agenda: 

AI-Driven Software Quality Assurance in the Age of DevOps
Accurate Predictions

of Future Defects
Explain the Nature

of Software Defects
21
Future Research Agenda: 

AI-Driven Software Quality Assurance in the Age of DevOps
Accurate Predictions

of Future Defects
Explain the Nature

of Software Defects
Generate Actionable 

Guidelines
21
Future Research Agenda: 

AI-Driven Software Quality Assurance in the Age of DevOps
Accurate Predictions

of Future Defects
Explain the Nature

of Software Defects
Generate Actionable 

Guidelines
Bug Hunter
21
Future Research Agenda: 

AI-Driven Software Quality Assurance in the Age of DevOps
Accurate Predictions

of Future Defects
Explain the Nature

of Software Defects
Generate Actionable 

Guidelines
Bug Hunter
This research project is expected to reduce software defects and operating costs,
while accelerating development productivity for Australian software industry
22
I'm actively recruiting Ph.D. students
Jirayus Jiarpakdee
Nov 2017 - current

Publications: ICSME’18, ICSE’19,

TSE’19, more to come …
Benefits
- Tuition Fees Scholarships
- Full stipends ($27,353 per annum in 2018, indexed annually)
- International Travel Funding
- Work with Experts in AI/ML/DataMining/SE
- Access to Monash HPC clusters
- Possible Domestic and International Internships
Current Ph.D. student:
23
23
23
23
23
Dr. Chakkrit (Kla) Tantithamthavorn
@klainfohttp://chakkrit.com
chakkrit.tantithamthavorn@monash.edu

AI-Driven Software Quality Assurance in the Age of DevOps

  • 1.
    Dr. Chakkrit (Kla)Tantithamthavorn Lecturer, Faculty of Information Technology,
 Monash University, Australia. @klainfohttp://chakkrit.com chakkrit.tantithamthavorn@monash.edu AI-Driven Software Quality Assurance 
 in the Age of DevOps
  • 2.
    Australian Taxation Office’sservice outages from software bugs lead to $4.2 billion dollars lost 2
  • 3.
    3 Software Quality Assurancepractices like 
 code review and testing are still time-consuming - Large and complex: 1 billion lines of code - Intense quality assurance activities: - 17K code reviews - 100 million test cases
  • 4.
    3 Software Quality Assurancepractices like 
 code review and testing are still time-consuming - Large and complex: 1 billion lines of code - Intense quality assurance activities: - 17K code reviews - 100 million test cases It is infeasible to exhaustively review and test 
 source code within the limited time and resources
  • 5.
    4 Defect models playa significant role in software quality management Release Defect
 Model Module A Module C Module B Module D Module A Module C Module B Module D
  • 6.
    4 Predict
 future software 
 defects Defectmodels play a significant role in software quality management Release Defect
 Model Module A Module C Module B Module D Module A Module C Module B Module D
  • 7.
    4 Predict
 future software 
 defects Explain
 what makes software fail Defect models play a significant role in software quality management Release Defect
 Model Module A Module C Module B Module D Module A Module C Module B Module D
  • 8.
    4 Predict
 future software 
 defects Explain
 what makes software fail Defect models play a significant role in software quality management Release Defect
 Model Module A Module C Module B Module D Module A Module C Module B Module D Develop 
 empirical theories related to software quality
  • 9.
    5 Defect models playa significant role in software quality management Lewis et al., ICSE’13 Mockus et al., BLTJ’00 Ostrand et al., TSE’05 Kim et al., FSE’15 Naggappan et al., ICSE’06 Zimmermann et al., FSE’09 Caglayan et al., ICSE’15 Tan et al., ICSE’15 Shimagaki et al., ICSE’16 Defect models become widespread in many large software organisations Explain 
 what makes software fail Develop 
 empirical theories related to software quality Predict
 future software 
 defects
  • 10.
    6 Today research toolkitsare easily accessible
  • 11.
    7 Statistical
 Model Training
 Corpus Classifier 
 Parameters (7) Model
 Construction Performance
 Measures Data
 Sampling (2) Data Cleaning and Filtration (3) Metrics Extraction and Normalization (4) Descriptive Analytics (+/-) Relationship to the Outcome Y X x Software
 Repository Software
 Dataset Clean
 Dataset Studied Dataset Outcome Studied Metrics Control Metrics +~ (1) Data Collection Predictive 
 Analytics Prescriptive Analytics (8) Model Validation (9) Model Analysis and Interpretation Importance 
 Score Testing
 Corpus PredictionsPerformance
 Estimates Patterns In reality, defect modelling is detailed and complex
  • 12.
    8 A lack ofpractical guidelines of defect modelling have a negative impact on software quality management Misleading 
 insights Managers take wrong technical decisions Developers waste time and resources Wrong 
 predictions
  • 13.
    8 A lack ofpractical guidelines of defect modelling have a negative impact on software quality management Misleading 
 insights Managers take wrong technical decisions Developers waste time and resources Wrong 
 predictions Empirical investigation is needed 
 to derive practical guidelines for defect modelling
  • 14.
    9 Metric Selection Model Construction ModelEvaluation Control Metrics
 [ICSE-SEIP’18] Correlation
 [TSE’16] Model Statistics
 [ICSE-SEIP’18] Model Interpretation Class Imbalance
 [Under Review] The Risks of Unsound
 Defect
 Models Data Quality Issue Reports
 [ICSE’15] Feature Selection
 [ICSME’18] Interpretation
 [Under Review] Model Validation
 [TSE’17] Measures
 [ICSE-SEIP’18] Releases
 [Under Review] Metrics
 [On-going] Universal Models
 [Under Review] Ranking 
 [On-going] Time-Wise
 [On-going] Parameters
 [ICSE’16,TSE’18]
  • 15.
    9 Metric Selection Model Construction ModelEvaluation Control Metrics
 [ICSE-SEIP’18] Correlation
 [TSE’16] Model Statistics
 [ICSE-SEIP’18] Model Interpretation Class Imbalance
 [Under Review] The Risks of Unsound
 Defect
 Models Data Quality Issue Reports
 [ICSE’15] Feature Selection
 [ICSME’18] Interpretation
 [Under Review] Model Validation
 [TSE’17] Measures
 [ICSE-SEIP’18] Releases
 [Under Review] Metrics
 [On-going] Universal Models
 [Under Review] Ranking 
 [On-going] Time-Wise
 [On-going] Parameters
 [ICSE’16,TSE’18]
  • 16.
    10 Defect prediction modelshave configurable parameters that control their characteristics Most of the widely-used classification techniques require at least one parameter setting Based on the literature analysis of 
 300+ defect studies
  • 17.
    10 Defect prediction modelshave configurable parameters that control their characteristics Most of the widely-used classification techniques require at least one parameter setting Based on the literature analysis of 
 300+ defect studies #trees for 
 random forest #clusters for 
 k-nearest neighbors
  • 18.
    10 Defect prediction modelshave configurable parameters that control their characteristics Most of the widely-used classification techniques require at least one parameter setting Based on the literature analysis of 
 300+ defect studies #trees for 
 random forest #clusters for 
 k-nearest neighbors 80% of top-50 highly-cited defect studies rely on a default setting [IST’16]
  • 19.
    10 Defect prediction modelshave configurable parameters that control their characteristics Most of the widely-used classification techniques require at least one parameter setting Based on the literature analysis of 
 300+ defect studies #trees for 
 random forest #clusters for 
 k-nearest neighbors 80% of top-50 highly-cited defect studies rely on a default setting [IST’16] Even within the R toolkit, 2 random forest packages have different default settings
  • 20.
    What is theimpact of optimization techniques on defect models? 11 Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
  • 21.
    What is theimpact of optimization techniques on defect models? 11 (RQ1) What is the impact of automated parameter optimization on the accuracy of defect models? Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
  • 22.
    What is theimpact of optimization techniques on defect models? 11 (RQ1) What is the impact of automated parameter optimization on the accuracy of defect models? (RQ2) How much does the interpretation of defect models change when automated parameter optimization is applied? Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
  • 23.
    What is theimpact of optimization techniques on defect models? 11 (RQ1) What is the impact of automated parameter optimization on the accuracy of defect models? (RQ2) How much does the interpretation of defect models change when automated parameter optimization is applied? (RQ3) What are the best classification techniques for defect models when automated parameter optimization is applied? Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32.
  • 24.
    12 A comprehensive frameworkto extensively evaluate the impact of optimization techniques on defect models Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32. Defect 
 Dataset
  • 25.
    12 A comprehensive frameworkto extensively evaluate the impact of optimization techniques on defect models Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32. Defect 
 Dataset Default 
 Setting Construct 
 Defect
 Models Optimized 
 Setting
  • 26.
    12 A comprehensive frameworkto extensively evaluate the impact of optimization techniques on defect models Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32. Defect 
 Dataset Default 
 Setting Construct 
 Defect
 Models Optimized 
 Setting Optimized
 Model Default-setting
 Model
  • 27.
    12 A comprehensive frameworkto extensively evaluate the impact of optimization techniques on defect models Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32. Defect 
 Dataset Default 
 Setting Construct 
 Defect
 Models Optimized 
 Setting Optimized
 Model Default-setting
 Model Calculate
 accuracy The accuracy of
 optimized model The accuracy of
 default model
  • 28.
    12 A comprehensive frameworkto extensively evaluate the impact of optimization techniques on defect models Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32. Defect 
 Dataset Default 
 Setting Construct 
 Defect
 Models Optimized 
 Setting Optimized
 Model Default-setting
 Model Calculate
 accuracy The accuracy of
 optimized model The accuracy of
 default model Rank metrics by importance score The ranking of
 metrics in 
 optimized model The ranking of
 metrics in 
 default model
  • 29.
    12 A comprehensive frameworkto extensively evaluate the impact of optimization techniques on defect models 26 classification techniques 
 (e.g., C5.0, Random Forest) 12 performance measures 
 (e.g., AUC, F-measure) 4 optimization algorithms 
 (e.g., genetic algorithm, and differential evolution) Chakkrit Tantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32. Defect 
 Dataset Default 
 Setting Construct 
 Defect
 Models Optimized 
 Setting Optimized
 Model Default-setting
 Model Calculate
 accuracy The accuracy of
 optimized model The accuracy of
 default model Rank metrics by importance score The ranking of
 metrics in 
 optimized model The ranking of
 metrics in 
 default model
  • 30.
    13 Case Study Setup ChakkritTantithamthavorn, Shane McIntosh, Ahmed E. Hassan, and Kenichi Matsumoto. 2018. The Impact of Automated Parameter Optimization on Defect Prediction Models. IEEE Transactions on Software Engineering (TSE) (2018), pp. 1-32. Code Metrics
 (e.g., lines of code
 code complexity) Process Metrics
 (e.g., #commits
 #added_lines) Human Factor
 (e.g., #dev,
 ownership) 600 - 10,000 modules
 11-48% defective ratios 18 software releases 15-38 software metrics
  • 31.
    Large Medium Small ● ● ● ● ● ●● ● 0.0 0.1 0.2 0.3 0.4 C 5.0 AdaBoost AVN N etC ART PC AN N etN N etFDA M LPW eightD ecayM LP LM TG PLS LogitBoostKN N xG BTreeG BM N B R BF SVM R adial G AM Boos AUCPerformanceImprovement 14 (RQ1) What is the impact of automated parameter optimization on the accuracy of defect models? Approach: Compute the accuracy difference between optimized models and default-setting models AUCDifference(Optimized-Default)
  • 32.
    Large Medium Small ● ● ● ● ● ●● ● 0.0 0.1 0.2 0.3 0.4 C 5.0 AdaBoost AVN N etC ART PC AN N etN N etFDA M LPW eightD ecayM LP LM TG PLS LogitBoostKN N xG BTreeG BM N B R BF SVM R adial G AM Boos AUCPerformanceImprovement 14 (RQ1) What is the impact of automated parameter optimization on the accuracy of defect models? 9 of the 26 studied classification techniques have a large accuracy improvement Approach: Compute the accuracy difference between optimized models and default-setting models AUCDifference(Optimized-Default)
  • 33.
    Large Medium Small ● ● ● ● ● ●● ● 0.0 0.1 0.2 0.3 0.4 C 5.0 AdaBoost AVN N etC ART PC AN N etN N etFDA M LPW eightD ecayM LP LM TG PLS LogitBoostKN N xG BTreeG BM N B R BF SVM R adial G AM Boos AUCPerformanceImprovement 14 (RQ1) What is the impact of automated parameter optimization on the accuracy of defect models? 9 of the 26 studied classification techniques have a large accuracy improvement Approach: Compute the accuracy difference between optimized models and default-setting models AUCDifference(Optimized-Default)
  • 34.
    Large Medium Small ● ● ● ● ● ●● ● 0.0 0.1 0.2 0.3 0.4 C 5.0 AdaBoost AVN N etC ART PC AN N etN N etFDA M LPW eightD ecayM LP LM TG PLS LogitBoostKN N xG BTreeG BM N B R BF SVM R adial G AM Boos AUCPerformanceImprovement 14 (RQ1) What is the impact of automated parameter optimization on the accuracy of defect models? 9 of the 26 studied classification techniques have a large accuracy improvement Approach: Compute the accuracy difference between optimized models and default-setting models Optimization substantially improves the accuracy of defect prediction models AUCDifference(Optimized-Default)
  • 35.
    15 (RQ2) How muchdoes the interpretation of defect models change when automated parameter optimization is applied? Optimized
 Model Default
 Model Approach: Compute the percentage of the top-rank metrics in optimized models that appears at the top-rank in default models
  • 36.
    15 (RQ2) How muchdoes the interpretation of defect models change when automated parameter optimization is applied? Optimized
 Model Default
 Model Calculate an importance score for each metric Approach: Compute the percentage of the top-rank metrics in optimized models that appears at the top-rank in default models
  • 37.
    15 (RQ2) How muchdoes the interpretation of defect models change when automated parameter optimization is applied? Optimized
 Model Default
 Model Calculate an importance score for each metric Ranking of metrics
 in optimized models Ranking of metrics
 in default models Approach: Compute the percentage of the top-rank metrics in optimized models that appears at the top-rank in default models
  • 38.
    15 (RQ2) How muchdoes the interpretation of defect models change when automated parameter optimization is applied? Optimized
 Model Default
 Model Calculate an importance score for each metric Ranking of metrics
 in optimized models Ranking of metrics
 in default models Calculate the rank difference for each metric Diff %metrics 0 60% -1 20% Approach: Compute the percentage of the top-rank metrics in optimized models that appears at the top-rank in default models
  • 39.
    16 (RQ2) How muchdoes the interpretation of defect models change when automated parameter optimization is applied? Approach: Compute the percentage of the top-rank metrics in optimized models that appears at the top-rank for default models 0% 20% 40% 60% 80% 100% 0 -1 -2 -3 -4 Percentageofmetrics Rank difference
  • 40.
    16 (RQ2) How muchdoes the interpretation of defect models change when automated parameter optimization is applied? Approach: Compute the percentage of the top-rank metrics in optimized models that appears at the top-rank for default models 36% of the top-rank metrics in optimized models 
 do not appear at the top-rank for default models 0% 20% 40% 60% 80% 100% 0 -1 -2 -3 -4 Percentageofmetrics Rank difference
  • 41.
    16 (RQ2) How muchdoes the interpretation of defect models change when automated parameter optimization is applied? Approach: Compute the percentage of the top-rank metrics in optimized models that appears at the top-rank for default models 36% of the top-rank metrics in optimized models 
 do not appear at the top-rank for default models 0% 20% 40% 60% 80% 100% 0 -1 -2 -3 -4 Percentageofmetrics One-third of the most important metrics are missing 
 if we do not apply parameter optimization Rank difference
  • 42.
    17 (RQ3) What isthe best classification techniques for defect models when automated parameter optimization is applied? Approach: Compute the average rank of classification techniques across the studied datasets A JMLR’14 paper finds that random forest is top-performing classifiers for machine learning datasets
  • 43.
    17 (RQ3) What isthe best classification techniques for defect models when automated parameter optimization is applied? Approach: Compute the average rank of classification techniques across the studied datasets A JMLR’14 paper finds that random forest is top-performing classifiers for machine learning datasets Optimized xGBTree Optimized C5.0 Optimized RF Surprisingly, the best technique like Random Forest in ML domains is not always be the best in SE domains
  • 44.
    17 (RQ3) What isthe best classification techniques for defect models when automated parameter optimization is applied? Approach: Compute the average rank of classification techniques across the studied datasets A JMLR’14 paper finds that random forest is top-performing classifiers for machine learning datasets Optimized xGBTree Optimized C5.0 Optimized RF Surprisingly, the best technique like Random Forest in ML domains is not always be the best in SE domains Domain-specific modelling guidelines are critically needed
  • 45.
    What is theimpact of optimization techniques on defect models? 18 Optimization substantially improves the accuracy of defect prediction models One-third of the most important metrics are missing if we do not apply parameter optimization The best technique (RF) in ML domain might not always be the best in SE domain when parameter optimization is applied Automated parameter optimization should be applied for defect prediction models
  • 46.
    19 “This is amuch needed contribution both for researchers and for practitioners: 
 
 Researchers will find a checklist for the quality assurance of their defect modelling methods. 
 
 Practitioners, that is software quality experts in companies, will avoid a false interpretation of their data.” 
 
 - An Anonymous Reviewer -
  • 47.
    20 Open Challenges: 
 Fasterdev. speed, but Slower QA activities Software companies are shifting 
 from long to rapid release cycles
  • 48.
    20 Open Challenges: 
 Fasterdev. speed, but Slower QA activities Software companies are shifting 
 from long to rapid release cycles Large volume of code changes
  • 49.
    20 Open Challenges: 
 Fasterdev. speed, but Slower QA activities Software companies are shifting 
 from long to rapid release cycles Large volume of code changes Slow CI builds and tests
  • 50.
    20 Open Challenges: 
 Fasterdev. speed, but Slower QA activities How to develop an AI agent to accurately and intelligently remove software defects prior to CI build runs? Software companies are shifting 
 from long to rapid release cycles Large volume of code changes Slow CI builds and tests
  • 51.
    21 Future Research Agenda: AI-Driven Software Quality Assurance in the Age of DevOps
  • 52.
    21 Future Research Agenda: AI-Driven Software Quality Assurance in the Age of DevOps Accurate Predictions
 of Future Defects
  • 53.
    21 Future Research Agenda: AI-Driven Software Quality Assurance in the Age of DevOps Accurate Predictions
 of Future Defects Explain the Nature
 of Software Defects
  • 54.
    21 Future Research Agenda: AI-Driven Software Quality Assurance in the Age of DevOps Accurate Predictions
 of Future Defects Explain the Nature
 of Software Defects Generate Actionable 
 Guidelines
  • 55.
    21 Future Research Agenda: AI-Driven Software Quality Assurance in the Age of DevOps Accurate Predictions
 of Future Defects Explain the Nature
 of Software Defects Generate Actionable 
 Guidelines Bug Hunter
  • 56.
    21 Future Research Agenda: AI-Driven Software Quality Assurance in the Age of DevOps Accurate Predictions
 of Future Defects Explain the Nature
 of Software Defects Generate Actionable 
 Guidelines Bug Hunter This research project is expected to reduce software defects and operating costs, while accelerating development productivity for Australian software industry
  • 57.
    22 I'm actively recruitingPh.D. students Jirayus Jiarpakdee Nov 2017 - current
 Publications: ICSME’18, ICSE’19,
 TSE’19, more to come … Benefits - Tuition Fees Scholarships - Full stipends ($27,353 per annum in 2018, indexed annually) - International Travel Funding - Work with Experts in AI/ML/DataMining/SE - Access to Monash HPC clusters - Possible Domestic and International Internships Current Ph.D. student:
  • 58.
  • 59.
  • 60.
  • 61.
  • 62.
    23 Dr. Chakkrit (Kla)Tantithamthavorn @klainfohttp://chakkrit.com chakkrit.tantithamthavorn@monash.edu