1.
Process Performance Models:Not
Necessarily Complex
-Himanshu Pandey
Nishu Lohia
(Aricent Technologies)

2.
Process Performance Models - Not Necessary Complex
HMBP 2010
21-May-2010

3.
Who We Are
Aricent is the world’s leading independent communications
software company.
– Dedicated focus on communications software
– Unmatched depth and breadth of services
and products
– Culture of innovation, excellence and results
More than 400 customers across the world
Equipment Manufacturers
Device Manufacturers
Service Providers
7-Jun-10 3

4.
What We Offer
Wireless Data Signaling Packet networks/
Communications VoIP
GSM, GPRS/EDGE, 3G, ISDN, SS7 and SIGTRAN IMS, SIP, H.248, MGCP,
WCDMA, CDMA2000, Routers, VPN and QoS, VoWiFi, Interworking
WiMAX, UMA, Femtocell ATM, IP, MPLS, GigE,
Platform 8,000+ employees with expertise in all Communication
Engineering major communications categories Applications
Messaging, Location Based
ATCA, Network Processors
Services, Workforce
Automation, Voice Applications
Mobile Handsets Billing and OSS
User Interface, Multimedia Multi-vendor Billing,
Applications, Physical OSS Integration, Service
Layer, Middleware, Multiple Activation, OSS/BSS
OS and Platforms, DSP Business Process Re-eng
DSP Broadband and Network Transmission
Video and Voice Processing, Wireless access Management
Audio/Video Codecs, xDSL, Satellite, Cable, TL1, SNMP, CORBA and SONET/SDH, RPR, DWDM
Network Processor 802.11a/b/g/i and WiMAX CLI
Application, Microcode
Design
7-Jun-10 4

5.
Agenda
 Problem Statement
 Aricent’s way to Resolution
 Process Performance Modelling – Overview
 Models- Overview
– Rayleigh’s Defect Prediction Model
– Test End date prediction Model
– NHPP + Gompertz Model
 Combinations of Models
 Conclusion
 Q&A
7-Jun-10 5

6.
Problem Statement
• CMMI Level 5 can not be achieved without Statistical process
performance models in place.
• Models available in the market are:
• Too Costly
• Complex to understand and implement
• Limited availability
• Non-customizable
• Law of inertia is applicable to software industry as well.
• High resistance for change due to strict timelines.
• Implementation of models is an over head.
7-Jun-10 6

7.
Aricent’s Way Of Resolution
• Identify generic life cycle steps where PPM could be applied across
maximum projects
• Identify in-house developed statistical tools which are being used most
frequently across the organization.
• Identify the tools those can be used in collaborative mode effectively to:
• Perform What if Analysis
• Implement PDCA cycle
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8.
Process Performance Modeling
• The CMMI definition of PPM -> description of the relationships among
process attributes and its work products that are developed from
historical process-performance data and calibrated using collected
process and product measures from the project which are used to
predict results to be achieved by following a process
• Makes quantitative predictions about a particular process
• May estimate resource consumption, effectiveness, efficiency
depending upon organization goals
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9.
In-house Statistical Tools
 Rayleigh’s Defect Prediction Model
 Test End Date Prediction Model
 NHPP + Gompertz Model
7-Jun-10 9

10.
In-house developed Models Overview
• The 3 models developed in-house are:
Rayleigh’s Defect Prediction Model
Test End Date Prediction Model
NHPP + Gompertz Model
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11.
Rayleigh’s Defect Prediction Model
• Input to the Tool:
• Total number of detected/injected defects in past phases
• Duration of the past and upcoming phases
• Output from the tool:
• Phase wise Estimated vs Actual Defect Distribution
• Estimation of Defects passed to customer
Phase wise & Cumulative Defect Distribution
90 160
80
Phase wise Defects
140
70
• Benefits:
120
Cum_Defects
60
100
50
80
40
60
• Forecast on Defect Passed to Customer
30
20 40
10 20
• Comparison of estimated vs actual defects in phases 0
SRS Design CUT RT PQT
0
Actual Defects (Phase wise) Estimated Defects(Phase wise)
Estimated Defects (Cumulative) Actual Defects (Cumulative)
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12.
In-house developed Models Overview
• The 3 models developed in-house are:
Rayleigh’s Defect Prediction Model
Test End Date Prediction Model
NHPP + Gompertz Model
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13.
Test End Date Prediction Model – Overview
• Performs simulation to forecast:
• Testing End date
• Using EWMA control charts which helps in
• Observing/monitoring the variations in current test execution rate
• Generating results to predict number of days to finish testing
Test Case Executed Per Day
40.00
35.00
30.00
25.00
20.00
15.00
10.00
5.00
0.00
1 2 3 4 5 6
Exp. Mov. Average UCL LCL
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14.
Test End Date Prediction Model cont..
• Input to the Tool:
• Total number of cases planned for execution and actual test case execution data
• Revised test execution data included failed test cases
• Output from the Tool:
• Predicts the number of days pending to finish the remaining planned number of test cases
• Benefits
• Strategizing remaining number of days in order to finish testing on time
Distribution of Possible Days to End Testing Date at 90%
Replicate1
350 100%
Replicate2
X Axis - Days to finish testing
Y Axis - Frequency
Replicate3
90%
Replicate4
300
Replicate5
80%
Replicate6
250 70% Replicate7
Replicate8
200
60% Replicate9
Number of
days
Replicate10
50% Replicate11
150 Replicate12
40%
Replicate13
Replicate14
100 30%
Replicate15
Replicate16
20%
Replicate17
50
10% Replicate18
Replicate19
0 0% Replicate20
14.7 to 14.75
14.8 to 14.85
14.9 to 14.95
15 to 15.04
15.09 to 15.14
15.19 to 15.24
15.29 to 15.34
15.39 to 15.44
15.49 to 15.54
15.59 to 15.64
15.69 to 15.74
15.79 to 15.83
15.88 to 15.93
15.98 to 16.03
16.08 to 16.13
16.18 to 16.23
16.28 to 16.33
16.38 to 16.43
16.48 to 16.53
16.58 to 16.62
16.67 to 16.72
16.77 to 16.82
16.87 to 16.92
16.97 to 17.02
17.07 to 17.12
17.17 to 17.22
17.27 to 17.32
17.37 to 17.41
17.46 to 17.51
17.56 to 17.61
% Distribution of
Replicate1
90%_Line
7-Jun-10 14

15.
In-house developed Models Overview
• The 3 models developed in-house are:
Rayleigh’s Defect Prediction Model
Test End Date Prediction Model
NHPP + Gompertz Model
7-Jun-10 15

16.
NHPP + Gompertz Model – Overview
CURRENT STATUS OF
• Performs forecast on SOFTWARE RELIABILITY
DATE FOR WHICH S/W RELIABILITY
• Reliability of the software under testing
23-Mar-10
STATUS IS GIVEN
SOFTWARE RELIABILITY ON ABOVE
79.72%
MENTIONED DATE
• based on MTBF UPPER LIMIT OF 95% CONFIDENCE
INTERVAL
Almost 100%
LOWER LIMIT OF 95% CONFIDENCE
50.94%
• based on Gompertz reliability growth model INTERVAL
• Expected number of failures in remaining number of testing days
• Based on NHPP equation
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17.
NHPP + Gompertz Model Cont..
• Input to the Tool:
• Actual test case execution data; each case run failed or passed.
• Number of days of testing and average testers per day
• Output from the Tool:
• Reliability Growth Pattern
• Current reliability of software
• Failure Forecast
• Benefits:
• Strategizing remaining number of testing days in order to improve reliability and minimize
failures passing to customer
7-Jun-10 17

18.
Process Performance Models
 NHPP- Gompertz + Test End Date Prediction
 Rayleigh’s Model + Test End Date Prediction
 NHPP-Gompertz Model + Test End Date
Prediction Model+ Rayleigh’s Model
7-Jun-10 18

19.
NHPP- Gompertz + Test End Date Prediction
• Test End Date Prediction Tool takes test execution data as input and provides the number of days
pending to finish the testing
• NHPP Model, along with execution data, require to know how many more days testing will
continue in order to predict the failures
• Number of failed test cases predicted by NHPP then in turn act as revised input for Test End Date
Prediction to re-calibrate the testing end date
• Perform multiple calibrations in order to arrive at best suitable situation to strategize where
highest software reliability can be achieved within lesser time and lesser failures
7-Jun-10 19

20.
Rayleigh’s Model + Test End Date Prediction
• Test End Date Prediction Tool takes test execution data as input and provides the number of days
pending to finish the testing
• Rayleigh’s Model, require to know for how many days testing will continue in order to predict the
defects
• Derive number of test case failures from number of defects predicted by Rayleigh’s model using
baseline defects/failure rate and use this as input in Test End Date prediction for revised number
of days.
• Perform multiple calibrations in order to know estimated defect leakage to customer and
strategize for the prevention.
7-Jun-10 20

21.
NHPP-Gompertz + Test End Date Prediction + Rayleigh’s Model
• Test End Date Prediction Tool usage along with NHPP and Rayleigh models separately has been
discussed
• Now, comparing the results of two, brings down to an interesting analysis in order to verify the
defects/TC failure rate with baseline figures.
• Hence, knowing your current project’s performance in comparison to past project’s performance
justifies our subjective confidence on how far/close we are w.r.t. to achieving our targets.
• Re-calibration and verification analysis based PCDA format, helps in strengthening our prevention
strategies and hence achieving great results.
7-Jun-10 21

22.
NHPP-Gompertz + Test End Date Prediction + Rayleigh’s Model
• Special scenario:
• When Rayleigh’s and NHPP’s forecasts are not in synch:
• Study the phase wise defect distribution curve
• Study Actual value curve vs Estimated value curve
• Identify and Analyze the phases outside our control
• Study the co-efficient of determination
• Correctness of available data
• Availability of support data used for forecasts
• Decision
• Choose the model for which most of the above parameters are satisfied
7-Jun-10 22

23.
Conclusion
• Yes! We applied these in-house developed PPMs and achieved CMMI level 5 (v1.2) successfully.
• Applied on wide range of Projects.
• The models applied ,undoubtedly:
• Has almost no Cost
• Are easy to understand and implement
• Are Easily Customizable
• Are not Overhead to Implement
• Implies no resistance to use
• Has no constraints of availability
• Satisfies CMMI practices completely
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24.
Thank You!
7-Jun-10 24

25.
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