כ"ז/שבט/תשע"ח An Overview of Software Development Effort and Cost Estimation Techniques Professor Ron Kenett Tel Aviv University School of Engineering

Software Cost Estimation Models כ"ז/שבט/תשע"ח Software Cost Estimation Models TRW Doty Boeing IBM-FSD Rayleigh SLIM RCA Price/S COCOMO 81 JPL

Software Cost Estimation Models כ"ז/שבט/תשע"ח Software Cost Estimation Models Doty - 14 factors IBM-FSD - 29 factors COCOMO 81 - 15 factors JPL - 40 factors

Cost Adjustment Factors כ"ז/שבט/תשע"ח Cost Adjustment Factors TRW Easy 0.8 Medium 1.0 Hard 1.2 New module 1.0 Old module 0.7

Development Efforts (MM) כ"ז/שבט/תשע"ח Development Efforts (MM) IBM-FSD W = 5.2 L^0.91 RADC W = 4.86 L^0.976 Doty W = 5.25 L^1.057 JPL W = 2.43 L^0.962

Staffing Size (Persons) כ"ז/שבט/תשע"ח Staffing Size (Persons) IBM-FSD S = 0.409 W^0.65 RADC S = 0.388 W^0.641

Project Duration (Months) כ"ז/שבט/תשע"ח Project Duration (Months) IBM-FSD T = 2.47 W^0.35 RADC T = 3.59 W^0.358 T = 4.55 L^0.349

COnstructive COst Model כ"ז/שבט/תשע"ח COnstructive COst Model Barry Boehm Software Engineering Economics Prentice Hall, 1981

Basic COCOMO 81 Organic MM = 2.4 (KDSI)^1.05 TDEV = 2.5 (MM)^0.38 כ"ז/שבט/תשע"ח Basic COCOMO 81 Organic MM = 2.4 (KDSI)^1.05 TDEV = 2.5 (MM)^0.38 Semidetached MM = 3.0 (KDSI)^1.12 TDEV = 2.5 (MM)^0.35 Embedded MM = 3.6 (KDSI)^1.20 TDEV = 2.5 (MM)^0.32

Intermediate COCOMO 81 Organic (MM)nom = 3.2 (KDSI)^1.05 כ"ז/שבט/תשע"ח Intermediate COCOMO 81 Organic (MM)nom = 3.2 (KDSI)^1.05 TDEV = 2.5 (MM)^0.38 Semidetached (MM)nom = 3.0 (KDSI)^1.12 TDEV = 2.5 (MM)^0.35 Embedded (MM)nom = 2.8 (KDSI)^1.20 TDEV = 2.5 (MM)^0.32

COCOMO 81

COCOMO 81

COCOMO 81

COCOMO II, 1997 Challenges faced in calibrating COCOMO II כ"ז/שבט/תשע"ח COCOMO II, 1997 Challenges faced in calibrating COCOMO II GUI builders, COTS, 4GL’s, reuse – Need to rethink size metrics Distributed interactive applications – Web- based, object- oriented, event- based – Middleware effects New process models (evolutionary, incremental, spiral) – Phases overlap – Where are cost measurement endpoints? Lack of good data – not enough data (i. e. very little degrees of freedom) – lack of dispersion – heteroskedasticity

כ"ז/שבט/תשע"ח COCOMO II The 1997 version – Multivariate Linear Regression with 10%weighted average of expert- determined and data-determined The 1998 version – Bayesian Regression Analysis – Model more Data- Determined The 19??/ 20?? version – 100% Data- Determined

כ"ז/שבט/תשע"ח COCOMO II COCOMO II. 1997 Calibration Process Began with expert- determined a- priori model parameters – Iterated with Affiliates (Result => Original Post Architecture Model) - Collected Data - Identified and consolidated highly correlated model parameters - Statistically determined estimates of consolidated model parameters from data – Using logarithms to linearize regression - Used data determined model parameters to adjust a- priori model parameters – Experimented with weighting factors

כ"ז/שבט/תשע"ח COCOMO II

כ"ז/שבט/תשע"ח COCOMO II

COCOMO II Consolidated Highly Correlated Parameters כ"ז/שבט/תשע"ח COCOMO II Consolidated Highly Correlated Parameters TIME 1.0000 0.6860 -0.2855 -0.2015 STOR 0.6860 1.0000 -0.0769 -0.0027 ACAP -0.2855 -0.0769 1.0000 0.7339 PCAP -0.2015 -0.0027 0.7339 1.0000 TIME STOR ACAP PCAP • What do we do? Þ Combine : TIME & STOR to give RCON (Resource Constraints) ACAP & PCAP to give PERS (Personnel Factors) Thus, 15 effort multipliers instead of 17 for calibration

כ"ז/שבט/תשע"ח COCOMO II Process Maturity does effect effort. A one increment change in PMAT (Level 1 Upper to Level 2, Level 2 to Level 3, etc.) results in a 7% to 21% reduction in effort for a 30 KDSI project. Effect is larger for larger products Using it as a scale factor appears to provide a stronger influence on effort than as a multiplicative factor. Its influence is less than the personnel capability of the team, about the same as product complexity (CPLX), and higher than other COCOMO cost drivers. Process Maturity should be in all Software Cost Estimation Models; it is well defined and measurable. Some Observations on Effects of Process Maturity on Effort

כ"ז/שבט/תשע"ח COCOMO II

כ"ז/שבט/תשע"ח COCOMO II

כ"ז/שבט/תשע"ח COCOMO II