Planning Tools and Techniques Part 2

Transcription

1 Planning Tools and Techniques Part 2 1

2 Planning Tools and Techniques Planning tools Network diagrams Critical path method PERT analysis Gantt charts Resource histogram Containment of risk 2

3 PERT analysis PERT stands for: Program Evaluation & Review Technique A way of modelling uncertainty when scheduling If used properly will lead to more stable schedules 3

4 PERT analysis Expected time calculated from 3 estimates for the duration of each activity optimistic time (o) if things go well most likely time (m) this is usually the original estimate pessimistic time (p) if it can go wrong, it will... 4

5 PERT analysis Based on distribution, the expected time t e is calculated as: t e = [o + 4m + p] / 6 Our activity B has estimate of 4. Let us say: o = 3, m = 4, p = 11 t e = [ ] / 6 Expected time t e is 5, longer than the most likely time This could change the critical path in the network diagram 5

6 PERT analysis try out the tasks past exam questions 6

7 Gantt charts Devised by Henry Gantt (early 1900 s) Block representation of tasks Length of task bar proportional to duration Each start/end time represented by task bar Graphical representation of project Can translate network diagram into Gantt chart Easy to read 7

8 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Can set questions while requesting and reviewing papers Might not need two full weeks 8

9 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Might be able to start this task early...and finish early 9

10 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Might not have to start this task straight away Might want to delay while doing other things 10

11 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Might be able to set questions in the middle of the time slot 11

12 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Questionnaire must be prepared before it can be issued 12

13 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Questionnaire must be issued & returned before results can be analysed 13

14 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Analyse data before interviewing subjects 14

15 week 1 week 2 week 3 week 4 week 5 week 6 week 7 week 8 week 9 week 10 Gantt charts Time line: Activities: Request Jones paper Request Smith paper Review Jones paper review Smith paper Interview subjects set q's for questionnaire issue questionnaire Analyse data from q'naire have report proof read Write report Submit report Interview subjects before writing report 15

16 Gantt charts in MS Project ID Task Name Duration 1 Task 1 3 days 12 Mar '00 19 Mar '00 T F S S M T W T F S S M T W T F 2 Task 2 2 days 3 Task 3 5 days 4 Task 4 3 days 5 Task 5 6 days 6 Task 6 3 days 7 Task 7 4 days 8 Task 8 1 day 16

17 Gantt charts In their basic form Gantt charts: Do not explicitly show logical dependencies Do not optimise resources and costs Do not display current progress But... They are simple to read 17

18 Gantt charts in MS Project ID Task Name 1 Activity 1 2 task task task Mar '00 19 Mar '00 W T F S S M T W T F S S M T W T F AB AB[50%],CD[50%] EF 5 Activity 2 6 task 2.1 AB 7 task 2.2 CD 8 task 2.3 AB,CD 9 task 2.4 EF 10 deliver 20/

19 Gantt charts In more advanced forms Gantt charts: Soon become cluttered Become more difficult to read Become more difficult to update Still cannot easily show all task dependencies Require computer software to keep up to date 19

20 Gantt charts try out the tasks including past exam papers 20

21 Resource histogram Identifies resource requirements over time Helps to identify peak resource requirements Helps to identify unnecessary peaks and troughs (resource smoothing: keep within limits) Commonly used to analyse staff resource levels 21

22 Resource histogram Week number Staff required 22

23 Resource histogram upper limit of staff resources 23

24 Resource histogram upper limit of staff resources 24

25 Staff resources try out the tasks including past exam papers 25

26 Risk: Isolate the Baseline Plan Risks must be associated with a plan before they can be handled As risks could prevent the achievement of objectives, plans for achieving objectives must be in place before risks can be considered 26

27 Risk revisited Identify: What are the potential risks? Assess: What is the impact of each risk? What is the likelihood of the risk occurring? How can the risk be prevented or identified early? What needs to be done if the risk does occur? Allocate: To whom can I assign the risk? 27

28 Containment A new MS Access/Visual Basic system for a retail company Duration: requirements capture: 2 weeks development: 8 weeks acceptance testing: 2 weeks 28

29 Sequence of Activities Requirements Capture Development Acceptance 2 Weeks 8 Weeks 2 Weeks Project will last 12 weeks (i.e ) 29

30 What is the risk? There is an 90% chance that this length of time is insufficient because the MS Access specialist may be required to support a project of higher priority. If this were to happen, the 8 weeks scheduled for development would then extend to 10 weeks i.e. a 2 week delay with 7 person-weeks further effort Consider a containment action investigate whether this is a cost-effective solution 30

31 Including the element of risk 2 Weeks 7 Person Weeks Risk: 2 week over-run 90% RC Development Acceptance 10% 2 Weeks 8 Weeks (10%) 2 Weeks 10 Weeks (90%) Project will last 12 weeks (10%) or 14 weeks (90%) 31

32 Containment Calculation Expected value of additional duration = 0.9 * 2 = 1.8 weeks This evaluates the 90% chance of a 2 week delay Expected value of additional effort = 0.9 * 7 = 6.3 person-weeks This evaluates the 90% chance of a further 7 person-weeks This calculation is without a containment action 32

33 Containment A 3-week training course in parallel (i.e. 1 extra week) with the requirements capture would reduce the risk to 25% with an additional 2 person-weeks effort Draw a diagram to show the containment action and recalculate the revised impact on effort and duration 33

34 Containing the risk 3 Week course 1 extra Week 2 Person-weeks Course 2 Weeks 7 Person-weeks Risk: 2 week over-run Using a training course as a containment action 25% RC Development Acceptance 75% 2 Weeks 8 Weeks (75%) 2 Weeks 10 Weeks (25%) Project will last 13 weeks (75%) or 15 weeks (25%) 34

35 Containment Calculation Expected value of additional duration = 1 + (0.25 * 2) = 1.5 weeks This evaluates the extra week on the course, plus the reduced risk of 25% of a 2 week delay Expected value of additional effort = 2 + (0.25 * 7) = 3.75 person-weeks This evaluates extra 2 person-weeks on the course, plus the reduced risk of 25% of a further 7 person-weeks This calculation includes a containment action 35 35

36 Dealing with risk Would you book the course? What other factors need to be considered? How would the diagram look if the course is before Requirements Capture? is between Requirements Capture and Development? 36 36

37 Risk analysis try out the tasks - including past exam papers 37 37

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39 Further reading Bentley C (1997) PRINCE 2: A Practical Handbook Oxford: Butterworth-Heinemann Brooks F. (1995) The Mythical Man-Month (Anniversary Edition), Harlow: Addison-Wesley Burke R (1999). Project Management: Planning and Control Techniques, Chichester: Wiley Central Computer & Telecommunications Agency (1997) PRINCE 2: An Outline, London: The Stationery Office Field M & Keller L (1998) Project Management, Oxford: International Thomson Business Press 39