Phalp, Keith T.

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Bournemouth University Research Online

Invited talk given to the Software Reliability and Metrics Club Brighton, November 1994Keith PhalpK.Phalp@ecs.soton.ac.ukExperiences of Software Process ModellingKTP 2Modelling - An Agenda* A  multitude of representation schemesbut little to guide the practitioner.* Need to consider environment and organizational goals. * Need to incorporate measurement.* Need for reported experience (case studies) within 'real' organizations.KTP 3Pilot  Study AIMS* Produce preliminary models of the launch procedures and process.* Identify discrepancies between the documented and the actual process.* Discover, problems with current process (procedures).METHOD1)Goal-based strategy.  2) Low cost, low impact approach.3) Phased ModelsLater developed to form the GUIDE  method.KTP 4Instance Models1) Pilot study models of actual process were based on a mishmash of several projects. 2) Interesting questions centred on how specific projects deviated from process descriptions.3) A model based on many projects is in danger of only ever modelling the 'lowest common denominator'.KTP 5Extended DFD Notation* Used to describe software projects.This shows one activity from project X.This activity took 32 days. The effort expended was 32 * 0.125  =  4 man days 0.12532Develop Project Plan revision AKTP 6Project XHorizontal : Each unit  = 1 day (actual time axis). Vertical : Each unit = 0.01 people per day (only a scale).5 days or 1 week For 100% ie 1:1 Print 1 unit = 2mm For 50% 1 unit (eg 1 day) = 1mm  For 25% 2 units (eg 2 days) = 1mmDay   0 10          20          30          40           50          60          70           80          90         100        110        120       130         140        150        160        170        180Official project start  -30        -20        -10Raise Phase Plan6/9/922290.3630Develop Product  Proposal  Revision A5/8/92 17/9/92Develop pdp  Rev B110.39pdp revA0.645Develop   pdp   rev   Cpdp revBDevelop pdp  Rev D10pdp revDpdp revC180.06 Develop pdp  rev E12Phase   One   Review  Product  Proposal   Rev  E  and   Project   Plan  Rev   CDevelop pdp Rev F100.24pdp revEpdp revE18/12/9214.13Review of  Product  Proposal  Rev  F   and                Project   Plan  Rev  DFollow on  Reviews1 11.520/1/93Develop pdp Rev 1pdp rev1pdp revFpdp revFpdp rev10.1232Develop Project Plan revision A0.0522Dev pjp rev Bpjp revA230.02 Dev pjp rev Cpjp revB100.08Develop pjp revDpjp revCpjp revCpjp revDDev pjp rev1pdp rev1Phase 1 Implementation29?Implementation Phase 2 -> --->  ----> ---->-----> ------>Project XKTP 7Project Y -110      -100       -90         -80        -70        -60         -50        -40        -30         -20         -10           0 10          20          30          40           50          60          70           80          90         100        110        120       130         140        150        160        170        180         190       200         210        220        23 0         240        250        260      -110      -100       -90         -80        -70        -60         -50        -40        -30         -20         -10           0 10          20          30          40           50          60          70           80          90         100        110        120       130         140        150        160        170        180         190       200         210        220        23 0         240        250        260     70.29 Write high level proposalCommitment from high level meeting with BAeDevelop  Protptype  for  Meeting  with  BAe  (Impl'n Phase One)160.75BAE visit. Demonstrate Prototype and meetings to finalize requirements?1Write  spec150.75ExtendPrototype110.5Project number allocatedStart Blue  BookPhase Plan Approved0.01 34Develop pdp rev AProposalSpecReview High  level  Spec   -RevA   of   pdp -Spec11  proj_numDevelop  pdp  rev  B0.65pdp revA7Dev pdp rev10.14pdp revBDevelop pjp rev A0.01SpecDev pjp  rev10.05pjp revABlue  Book  Reviewpdp rev1pjp rev1(Impl'n Phase One)Priority to other projects70160.53 Alpha testing phase one  and bug  fixing0.796Alpha  test  phase  two0.71 Alpha testing phase three  and bug  fixing21Further bugs and testing effort0.18Release Review  Decide to  go for Beta Release1?Collecting this dataPROJECT YKTP 8Project SuccessCharacteristic V W X Y Z MedianResponseBudget 5 8 8 1 8 8Customer satisfaction 7 6 7 2 8 7Forced changes to design 2 5 7 2 6 5Keeping to specification 4 10 8 9 10 9Management of Risks 6 5 6 4 7 6Panics 8 7 7 7 5 7Post-integration bugs 3 9 7 1 9 7Re-work 3 7 7 1 8 7Requirements problems 5 10 9 9 5 9Within schedule 5 2 7 7 8 7Unexpected problems 3 7 7 2 7 7Unplanned over-time 3 10 5 5 3 5Median Score 4.5 7 7 3 7.5 7KTP 9AnalysisProject Factors Overall Project Success% Project Effort spent on  0.9747first version of product proposal sig  .142% Project Effort on 0.6669Project Planning sig .109% Effort prior to official -0.513project start sig .467Significant positive relationship between  percentage of time on first revision  of product proposal and:* Remaining within budget* Minimizing post integration defects* Minimizing unplanned changes* Management  of risks* User Satisfaction* Minimizing project reworkKTP 10Implications1) Software development still not well understood.2) Huge variety in processes carried out by software projects (even with a defined process)–a) Suggests different types of projects even in one organization, and implies much greater variety across different sites or different organizations. –b) Suggests that enaction will be difficult to achieve.3) Need for process guidance.4) Variety in software projects makes (quantitative) data analysis very difficult.5) Process modelling and software measurement have complementary roles.KTP 11More Implications6) Having  generic process can aid data collection.7) Need for pragmatic approaches to process modelling.8) Need for goal-based approaches to process modelling.9) Greater Emphasis needed on Industrial and Empirical Process Modelling Work.10) Industrial Needs Inevitably Compromise Experimental Ideals.  KTP 12Lessons Learned 1* Concentrate on the goals and characteristics of the organization.Start by letting the organization suggest the problem or opportunity.  Choose a feasible goal. * Have a champion of your cause within the organization. * Don't criticize any individuals: simply assess the process.* It is a huge benefit to be seen as independent. * Explain what you are doing and why. * Be honest.  Confess your ignorance.* Make the organization take decisions.* Get process users involved in discussion about the process. * Be prepared to be flexible. Many people have tremendous demands on their time.  You may not always be the highest priority.KTP 13Lessons Learned 2* Decide what measures need to be collected, what this will tell you, and how it will be used, and then and only then try to find out how this data can be made available.* Try to avoid the time-period between interviews being compressed through problems with staff availability or time-pressure. * If the process model is a collection framework, then you must know how well projects conform to that model before it can be used in this way.* Be consistently available or on-site so that people know how and where to contact you.* Don't be afraid to abandon a strategy, and admit to its failings.* Be persistent.KTP 14GUIDEGoal: To understand (passive purpose) the launch process (object) at site X (environment) from the view point (perspective) of the actors in that process.Use: Senior managers and other actors in the process (audience) will use the models in order to enhance their understanding (use1) of the existing process, to aid discussion of it (use2) , and to suggest and communicate (use3) improvements. The model will be used by a guide for enaction by people. There is no need for an enactable model (enaction).Investment: The initial modelling pilot is allowed only five person days (effort). There will be no additional funding for automated support (other resource) . Deliverables: Model of procedures(d1). Models of actual process(d2). Report(d3) and presentation(d4) on discrepancies between procedures and reality. Experience/Environment : Existing procedures focus on activities and products. The engineers and managers are comfortable with procedural notations. KTP 15Further Observations1) Its not using models or describing processes that's the hard bit, it's figuring out what the process is in the first place.2) Easy to get drawn into organizational rather than research goals.3) Practical and people problems are as important and time-consuming as technical ones (if not more-so).KTP 16Project VHorizontal : Each unit  = 1 day (actual time axis). Vertical : Each unit = 0.01 people per day (only a scale).5 days or 1 week For 100% ie 1:1 Print 1 unit = 2mm For 50% 1 unit (eg 1 day) = 1mm  For 25% 2 units (eg 2 days) = 1mmDev  pdp  rev  A12/4/935230.4.09Develop pdp rev B0.229Dev  pdp  rev CDevelop  pdp  rev  DDevelop  pdp  rev   E40.540.5Dev  pdp  rev   F70.29Dev  pdp  rev   G70.290.15Dev pdp rev1Review pdp   rev112Develop PSO Plan  Version One100.25Dev pjp rev A50.1Release   Review1pdp revApdp revBpdp revCpdp revDpdp revEpdp revFpdp revGpdp rev1pjp revA  -20        -10Working daysDay   0 10          20          30          40           50          60          70           80          90   Official project startProject VKTP 17Project W5 days or 1 week For 100% ie 1:1 Print 1 unit = 2mm For 50% 1 unit (eg 1 day) = 1mm  For 25% 2 units (eg 2 days) = 1mmDay   0 Official project start  -50        -40       -30        -20         -10Working daysDay   0 10          20          30          40           50          60          70           80          90         100        110        120       130         140        150        160        170        180         190       200         210        220        23 0         240        250        260        270        280         290         300      310        320         330        340        350        360        370         380        390        400 Official project start  -50        -40       -30        -20         -10Approve Phase Plan30.336/3/92Develop Product Proposal Revision A410.10Raise Phase Plan6/1/926/1/92Develop pdp Rev 1190.08Review Product   Proposal  Rev  1  - Phase  Review-Develop PSO Plan  (imp 1)100.331/5/92Implementation run 1 ?3030/4/9212/6/92166 1/2/93Develop pdp Rev 2130.15Develop PSO Plan  (imp 2)100.2Phase Planpdp rev Apdp rev1PSO Plan10          20          30          40           50          60          70           80          90         100        110        120       130         140        150        160        170        180         190       200         210        220        23 0         240        250        260        270       280        290         300          310        320         330        340        350        360        370         380        390        400         Develop  Project  Plan  Revison  A50.9Dev pjp rev150.13pjp RevApjp Rev1pdp rev11/6/93PSO PlanProject Stopped Project Stopped0KTP 18Project Z -110      -100       -90         -80        -70        -60         -50        -40        -30         -20         -10           0 10          20          30          40           50          60          70           80          90         100        110        1 -110      -100       -90         -80        -70        -60         -50        -40        -30         -20         -10           0 10          20          30          40           50          60          70           80          90         100        110        1PROJECT ZRaisePhasePlanProblemsnoted withTASCOAct on AT&T RFQAT&T Business coming inGetProjectNumberApprovePhasePlanDevelop Product Proposal Revision ADevelop Revsions B and Cof Product ProposalEffort taken by reviews and getting documents signed up  ?????0.343990.330.09Implementation Starts? DevelopPSOPlan??FinishKTP 19Collection MechanismActivity Name Start Finish Duration Effort UsageDevelop pdp rev A 5/8/92 17/9/92 31 11.25 0.36Develop pdp rev B 17/9/92 2/10/92 11 4.25 0.39Develop pdp rev C 2/10/92 9/10/92 5 3.19 0.64Phase One Review 4/12/92 4/12/92 1 2.00 2.00Follow on reviews 20/1/93 20/1/93 1 1.50 1.50Develop pdp rev 1 20/1/93 8/2/93 13 1.50 0.12Develop PSO plan 17/9/93 18/12/93 66 0.50 0.01Develop pjp rev A 5/8/92 18/9/92 32 3.75 0.12Develop pjp rev 1 8/1/93 27/1/93 13 0.50 0.04See template for all 155 activities & codesSelection of activities from project XKTP 20Correlations with MeansMeasures ProjectsV W X Y Z1 % effort on product proposal A 7.39 18.18 25.16 0.20 30.09 Percent2 % effort on project plan 1.85 20.45 8.39 0.20 6.02 Percent3 Implementation start - Product Proposal A finish 45.00 23.00 -110.00 -11.00 Days4 Raw launch activity effort before day 0 3.49 5.30 10.70 28.00 22.71 Days5 All effort expended before day 0 114.50 DaysTotal launch activity effort 27.06 22.00 44.72 33.63 108.006 % of launch activities effort expended before day 0. 12.90 24.09 23.93 83.27 21.02 Percent Total of all launch period effort 127.38 Percent7 % of launch period effort expended before day 0. 89.89 PercentSELECTED SCORES FROM SUCCESS FACTORS V W X Y Z1 Mean Success score 4.50 7.17 7.08 4.08 7.082 Customer Satisfaction 7.00 6.00 7.00 2.00 8.003 Budget 5.00 8.00 8.00 1.00 9.004 Rework 3.00 7.00 7.00 1.00 7.005 Schedule 5.00 2.00 7.00 7.00 8.00EXAMPLE CORRELATIONS Correl% effort on pdp (M1) with Mean Success 0.92457 Significant at 5% level% effort on pdp (M1) with Satisfaction 0.79307% effort on pdp (M1) with Budget 0.94234 Significant at 5% level% effort on pdp (M1) with Rework 0.93906 Significant at 5% level% effort on pdp (M1) with Schedule 0.18333% effort on project plan (M2) with Mean Success 0.74509% effort on project plan (M2) with Satisfaction 0.28632% effort on project plan (M2) with Budget 0.62603% effort on project plan (M2) with Rework 0.72083% effort on project plan (M2) with Schedule -0.7285 % launch activity before day 0 (M6) with Mean Success -0.56353% launch activity before day 0 (M6) with Satisfaction -0.95269 Significant at 5% level% launch activity before day 0 (M6) with Budget -0.81462% launch activity before day 0 (M6) with Rework -0.68609% launch activity before day 0 (M6) with Schedule 0.26883

Experiences of Software Process Modelling

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