BV41840 Schedule Risk Analysis of Software Development By: Dr. Joe H. Dean Engineering Chief Risk & System Analysis LFWC And: Mr. David W. Benson, Jr. Engineering Specialist Avionic Software Engineering LFWC

Why Integrated Schedule Risk Analysis? BV41841 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Current Practice – Schedule Risk Analyses for Software Projects Are Typically Performed for Individual Software Tapes –However, No Quantification of Integrated Schedule Risk Is Made Short Coming – If a Tape Is High Risk (or Moderate or Low) What Does That Mean Regarding the Probability of Timely Completion –Of That Tape? –Of Effected Programs? Needed – Cumulative Analysis to Show Sensitivity of Integrated Program Schedules to Tasks on Individual Software Tapes

BV41842 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Schedule Risk Model Basis & Capability Risk Issues Program Schedules Task Relationships Schedule Risk Analysis SS SF FF FS FF FS SS Task Relationships: SS Start-to-start SF Start-to-finish FS Finish-to-start SS Finish-to-Finish Program Schedule Risk Alternative Critical Paths Abatement Analysis Task Duration Consequences Abatement Options Robustness Sensitivities Delivery Dates Prob Time Min.MostMax Likely

Task Connectivity Within & Between Tapes Is Modeled BV41843 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design FS Preliminary Design CSC Test... System Design Software Start FS FS: Finish-to-Start Detailed Design Code/Unit Test TAPE 1

Task Connectivity Within & Between Tapes Is Modeled (Cont’d) BV41844 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design FS Preliminary Design CSC Test... Preliminary Design Detailed Design Code/Unit Test System Design System Design... Software SW Start FS FS: Finish-to-Start Detailed Design Code/Unit Test FS TAPE 1 TAPE 2

BV41845 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Task Connectivity Within & Between Tapes Is Modeled (Cont’d) Software Start Preliminary Design CSC Test FS System Design Preliminary Design FS Detailed Design FS Code/Unit Test FS FF FS Code/Unit Test Detailed Design FS Detailed Design Preliminary Design FF System Design FS Detailed Design FS Preliminary Design FS Preliminary Design Preliminary Design FS LOA System Design FS Preliminary Design Flight Test FS System Design Tape 1 (Prog. 1) Tape 2 (Prog. 1) Tape 3 (Prog. 1) Tape 4 (Prog. 1) Tape 1 (Prog. 2) Tape 2 (Prog. 2) Tape 1 (Prog. 3) Tape 2 (Prog. 3) Task Relationships FF: Finish-to-Finish SF: Start-to-Finish Detailed Design Preliminary Design System Design

75% OF NOMINAL NOMINAL RISK BV41846 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design REVIC Basics COCOMO (Constructive Cost Model) Developed by Dr. Barry Boehm Based on Curve Fit of Approx. 70 Projects Across Industry –Model Calibration via 15 Factors Covering Product, Computer, Personnel, and Project Attributes –Model Covers Tasks from Availability of Firm Software Requirements (Assumed Reasonably Stable) through Completion of Software Test –Schedule Compression Adds Cost and Risk and Cannot Be Compressed to Less than 75% of Nominal REVIC (Revised Version Intermediate COCOMO) Based on USAF Specific Projects The F-16 SPO and LFWC Have Used COCOMO/REVIC Since the Mid 1980’s Software Task (e.g. DSI) Time

BV41847 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Task Completion Variations Are Assigned Based on REVIC Analysis Time High Risk Schedule Less than 80% of Nominal 90%100%140% Moderate Risk Schedule % of Nominal 90%100%120% Nominal Risk Schedule Within 92.5% of Nominal 90%100%110% 75% OF NOMINAL NOMINAL RISK Task Size (DSI)

BV41848 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Monte Carlo Process In Schedule- Risk Model Is Straightforward 1 Enter Task Completion Variability and Connectivity Between Tasks 2 Random Draw Determines Completion Time for Each Task 3 For Each Trial (Total Network), Construct Critical Path & Project Completion Date. 4 At Any Given Time (Date), Probability of Success # of Trials Complete Total # Trials Random Number Completion Time 1 0 MinMost LikelyMax 1 0 t = Time P (t) S [Repeat N Trials] FS FF SSFS MINMAX 0 Time (Completion Dates) Trial Results =

BV41849 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Probability of Completion vs. Planned Finish Time Number of Days from Planned Finish PLANNED TIME (BASELINE) Probability of Completion

BV41850 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Assessing Schedule Changes Resulting from Risk Abatement Plan Number of Days from Planned Finish Probability of Completion Change In Probability Completion RISK ABATEMENT ALTERNATIVE BASELINE PLAN Change In Planned Finish

Summary BV41851 Verification Product Data Customer Needs Requirements Analysis & Control Allocations Design Results Corresponded Well with Expert Opinion Software Task/Tape Completion Times Were “Reasonably” Bounded in Regard to Program Schedule Impact This Process Is a Promising Method to Quantify Schedule Uncertainty, Especially in Highly Interrelated Task Networks This Process Allow Potential Schedule “Savings” from Risk Abatement Alternatives to Be Considered as an Aid in Decision Making Preliminary Findings Appraisal