3 Project Management Scheduling by b8REurq

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									Project Scheduling

   Project Management 517
                    Chapter 8


                  Prof. M. Anvari
     http://www.anvari.net/project_management.htm
Scheduling
   Scheduling Defined
   Gantt Charts
   Network Techniques: PERT and CPM
   Determining Task Durations
       Probability and Simulation
   Some Examples


                     PM-517 Anvari   8-2
Scheduling Defined
   The conversion of a project action plan
    into an operating timetable
       Serves as the basis for monitoring and
        controlling the project
       A major tool for the management of
        projects




                     PM-517 Anvari               8-3
    Scheduling
   A schedule is the conversion of a project
    action plan into an operating timetable
   It serves as the basis for monitoring and
    controlling project activity
   Taken together with the plan and budget, it
    is probably the major tool for the
    management of projects



                     PM-517 Anvari            8-4
Some Benefits of Successful
Scheduling
   Illustrates interdependence of all tasks
   Identifies times when resources must be
    available
   Facilitates communication throughout the
    project
   Determines critical activities/critical path
   Affects client expectations through
    establishment of activities, milestones, and
    completion dates

                    PM-517 Anvari             8-10
A Process for Scheduling
   1. Think
   2. List activities
   3. Arrange activities considering precedence
    and relationships
   4. Develop Gantt charts and PERT/CPM
    networks
   5. Determine critical activities/critical path
   6. Crash and adjust as necessary

                    PM-517 Anvari             8-11
      Gantt Charts

   The Gantt chart shows planned and actual progress
    for a number of tasks displayed against a horizontal
    time scale
   It is an effective and easy-to-read method of
    indicating the actual current status for each set of
    tasks compared to the planned progress for each
    item of the set
   It can be helpful in expediting, sequencing, and
    reallocating resources among tasks
   Gantt charts usually do not show technical
    dependencies

                          PM-517 Anvari                8-12
                                       JAN            FEB        MAR



Gantt Charts
                                       1   8 15 22 29 5 12 19 26 5 12 19 26




   Advantages
       Easy to understand
       Easy to show progress and status
       Easy to maintain
       Most popular view to communicate project status
        to client and/or senior management
   Disadvantages
       Can be superficial
       Not always easy to see precedence, relationships
                       PM-517 Anvari                              8-14
    Network Techniques: PERT and CPM

   With the exception of Gantt charts, the most
    common approach to scheduling is the use of
    network techniques such as PERT and CPM
   The Program Evaluation and Review Technique
    (PERT) was developed by the U.S. Navy in 1958
   The Critical Path Method (CPM) was developed by
    DuPont, Inc during the same time period




                         PM-517 Anvari                8-15
    Scheduling Terminology

   Activity - A specific task or set of tasks that are
    required by the project, use up resources, and take
    time to complete
   Event - The result of completing one or more
    activities. An identifiable end state occurring at a
    particular time. Events use no resources.
   Network - The combination of all activities and events
    define the project and the activity precedence
    relationships


                           PM-517 Anvari                  8-17
     Scheduling Terminology

   Path - The series of connected activities (or
    intermediate events) between any two events in
    a network
   Critical - Activities, events, or paths which, if
    delayed, will delay the completion of the
    project. A project’s critical path is understood
    to mean that sequence of critical activities that
    connect the project’s start event to its finish
    event

                         PM-517 Anvari              8-18
        Scheduling Terminology

   An activity can be in any of these conditions:
       It may have a successor(s) but no predecessor(s) -
        starts a network
       It may have a predecessor(s) but no successor(s) - ends
        a network
       It may have both predecessor(s) and successor(s) - in
        the middle of a network
   Interconnections from horizontal links in vertical
    WBS

                             PM-517 Anvari                8-19
    PERT/CPM Network Charts

   Advantages
       Allows visualization of task relationships
       Facilitates calculation of critical path
       Clarifies impact of decisions on downstream
        activities
   Disadvantages
       Complex, not easy to comprehend at a glance
       Charts don’t readily depict durations, dates,
        progress
                           PM-517 Anvari                8-20
Look at a Simple Network, for
a Simple Project
                    Duration
    Activity                         Predecessor
                    (weeks)
A              14                   Start

B              3                    Start

C              3                    A,B

D              7                    B

E              4                    C,D

F              10                   E


                    PM-517 Anvari              8-21
    Drawing Networks

   Activity-on-Arrow (AOA) networks use arrows to
    represent activities while nodes stand for events
   Activity-on-Node (AON) networks use nodes to
    represent activities with arrows to show precedence
    relationships
   The choice between AOA and AON representation is
    largely a matter of personal preference




                         PM-517 Anvari                8-22
AOA Network Building Blocks

       Activity                     Event




            Install software
  79                                 80




                    PM-517 Anvari           8-23
Activity-on-Node Network Fundamentals

                                                                J, K, & L can all begin at
                                                    J           the same time, if you wish
                                                                (they need not occur
    A         B          C
                                                                simultaneously)
        A is preceded by nothing                    K      M    but
        B is preceded by A
        C is preceded by B                                      All (J, K, L) must be
                                                    L           completed before M can
              (A)                                         (C)   begin


          Y    Y and Z are preceded by X        X          Z    Z is preceded by X and Y

X

          Z    Y and Z can begin at the
                                                Y          AA AA is preceded by X and Y
               same time, if you wish

              (B)                                         (D)

                                          PM-517 Anvari                            8-24
A Simple Network (AON)
(cont’d)
        A   14        C     3

Start                            E   4   F   10

        B    3        D      7           Finish


        Calculate:

            Critical Path

            Project Duration
                     PM-517 Anvari                8-25
 The Critical Path
        ES = 0      ES = 14
        EF = 14     EF = 17

                                 ES = 17    ES = 21
        A   14      C      3     EF = 21    EF = 31

Start                           E       4   F     10

        B    3      D       7               Finish
        ES = 0      ES = 3
        EF = 3      EF = 10
                                             ES = Early Start
                                             EF = Early Finish
  = Critical Path
                        PM-517 Anvari                            8-26
Determining Slack
   How much slack is there
   Where is it?
   How do you know?
   Why might you care?



               PM-517 Anvari   8-27
        Determining Slack (cont’d)
        ES = 0     ES = 14
        EF = 14    EF = 17
        LS = 0     LS = 14    ES = 17     ES = 21
        LF = 14    LF = 17    EF = 21     EF = 31
                              LS = 17     LS = 21
         A   14     C   3     LF = 21     LF = 31
                                                    Work Back . . .
Start                         E   4       F   10

         B    3     D    7               Finish
         ES = 0     ES = 3                             ES = Early Start
         EF = 3     EF = 10                            EF = Early Finish
                                                       LS = Late Start
         LS = 7     LS = 10
                                                       LF = Late Finish
         LF = 10    LF = 17


                                  PM-517 Anvari                            8-28
     Determining Slack (cont’d)
           ES = 0        ES = 14
           EF = 14       EF = 17
           LS = 0        LS = 14       ES = 17       ES = 21
           LF = 14       LF = 17       EF = 21       EF = 31
                                       LS = 17       LS = 21
           A    14        C    3
                                       LF = 21       LF = 31
   Start                               E   4         F    10

            B        3    D        7                 Finish
            ES = 0        ES = 3
            EF = 3        EF = 10
            LS = 7        LS = 10
                                           Slack = LS - ES
            LF = 10       LF = 17
                                           CP = 0 Slack, where ES = LS


What does all this mean?
                                   PM-517 Anvari                         8-29
Three Sequential Activities,
AON Format




            PM-517 Anvari      8-30
Activity Network, AON Format




           PM-517 Anvari   8-31
Activity Network, AOA Format




           PM-517 Anvari   8-32
Sample of Network
Construction, Figure 8-5
   AON                     AOA




           PM-517 Anvari         8-33
Sample of Network
Construction, Figure 8-6
   AON                     AOA




           PM-517 Anvari         8-34
Sample of Network
Construction, Figure 8-7
   AON                     AOA




           PM-517 Anvari         8-35
Networking Concurrent
Activities, Figure 8-8




           PM-517 Anvari   8-36
Activity c Not Required for e,
Figure 8-9




             PM-517 Anvari   8-37
Showing Precedents,       Figure 8-10




          PM-517 Anvari           8-38
MSP Gantt Chart, Figure 8-11




           PM-517 Anvari   8-39
MSP AON Network, Figure
8-12




          PM-517 Anvari   8-40
An AON Network for a 10-
Activity Project, Figure 8-13




            PM-517 Anvari       8-41
Distribution of Possible Activity
Times, Figure 8-14




            PM-517 Anvari    8-42
AON Network with Durations
and Variances, Figure 8-15




          PM-517 Anvari   8-43
AON Network with Earliest/Latest
Start/Finish Times, Figure 8-16




             PM-517 Anvari         8-44
Gantt Chart of Table 8-4,
Figure 8-17




              PM-517 Anvari   8-45
AON Network of Table 8-4,
Figure 8-18




              PM-517 Anvari   8-46
MSP Gantt Chart of Table 8-4,
Figure 8-19




              PM-517 Anvari   8-47
MSP Gantt Chart, Video Project,
Figure 8-20




              PM-517 Anvari   8-48
MSP AON Network, Video Project,
Figure 8-21




              PM-517 Anvari   8-49
MSP Calendar, Video Project,
Figure 8-22




              PM-517 Anvari   8-50
MSP Calendar, Video Project,
Figure 8-22 (continued)




              PM-517 Anvari   8-51
MSP Gantt Chart, Video Project,
Figure 8-23




              PM-517 Anvari   8-52
Probability Distribution,
Figure 8-24




              PM-517 Anvari   8-53
a, m, and b Estimates,
Figure 8-25




              PM-517 Anvari   8-54
Crystal Ball® Spreadsheet,
Figure 8-26




              PM-517 Anvari   8-55
CB Frequency Chart,
Figure 8-27




              PM-517 Anvari   8-56
CB Summary Statistics,
Figure 8-28




              PM-517 Anvari   8-57
CB Percentile Probabilities,
Figure 8-29




              PM-517 Anvari    8-58
CB Cumulative Probability Chart,
Figure 8-30




              PM-517 Anvari   8-59
Precedence Diagramming
Conventions, Figure 8-31




           PM-517 Anvari   8-60
Sample GERT Network,
Figure 8-33




              PM-517 Anvari   8-61
Apartment Complex Network,
Figure 8-35




              PM-517 Anvari   8-62
   Hypothetical Network
                              3
                    13                16

           30                              5
     1             2                  5         6
                         20       6            TE=64

                              4

Calculate t(e) and Z for this network……


                         PM-517 Anvari                 8-63
Activity and Project Frequency Distributions


    ACTIVITY                         PROJECT




a      m                   b           TE
               (A)                     (B)




                     PM-517 Anvari             8-64
     PERT Activity Calculation


t(e) = a + 4m + b          a = Most Optimistic (MO)
            6              m = Most Likely (ML)
                           b = Most Pessimistic (MP)
                           t(e) = Activity Duration


When a single estimate for activity time is not sufficient!




                         PM-517 Anvari                  8-65
   PERT Schedule Probability

Z = T(S) – T(E)            Z = Probability of
       SSD(T[E])2              Meeting Schedule

                           T(S) = Scheduled Duration

                           T(E) = Critical Path Duration


 Z is derived from a table of predetermined probabilities


                        PM-517 Anvari                 8-66
  PERT Activity Times & Variances

Activity   a         m          b    t(e)
  1-2      17       29          47
  2-3      6        12          24
  2-4      16       19          28
  3-5      13       16          19
  4-5      2         5          14
  5-6      2         5          8

                PM-517 Anvari
    Variance of Activity Estimates

Activity   a    m                b    t(e)   [(b-a)/6]2
                                                Var


  1-2      17   29               47   30
  2-3      6    12               24   13
  2-4      16   19               28   20
  3-5      13   16               19   16
  4-5      2    5                14    6
  5-6      2    5                8     6
                 PM-517 Anvari
Possible Project Durations




                TS=67

           TE=64




           PM-517 Anvari     8-69
Z Table

Z Value   Probability               Z Value   Probability
  -2.0       0.02                    +2.0        0.98

  -1.5       0.07                    +1.5        0.93

  -1.0       0.16                    +1.0        0.84

  -0.7       0.24                    +0.7        0.76

  -0.5       0.31                    +0.5        0.69

  -0.3       0.38                    +0.3        0.62

  -0.1       0.36                    +0.1        0.54
                    PM-517 Anvari

								
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