Project Scheduling Project Management 517 Chapter 8 Prof

Project Scheduling Project Management 517 Chapter 8 Prof. M. Anvari http: //www. anvari. net/project_management. htm

Scheduling n n Scheduling Defined Gantt Charts Network Techniques: PERT and CPM Determining Task Durations n n Probability and Simulation Some Examples PM-517 Anvari 8 -2

Scheduling Defined n The conversion of a project action plan into an operating timetable n n Serves as the basis for monitoring and controlling the project A major tool for the management of projects PM-517 Anvari 8 -3

Scheduling n n n 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 n n n 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 n n n 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 n n 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 Gantt Charts n MAR 8 15 22 29 5 12 19 26 Advantages n n n 1 FEB 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 n n Can be superficial Not always easy to see precedence, relationships PM-517 Anvari 8 -14

Network Techniques: PERT and CPM n n n 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 Du. Pont, Inc during the same time period PM-517 Anvari 8 -15

Scheduling Terminology n n n 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 n n 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 n An activity can be in any of these conditions: n n 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 n Advantages n n Allows visualization of task relationships Facilitates calculation of critical path Clarifies impact of decisions on downstream activities Disadvantages n n 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 (weeks) Activity Predecessor 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 n n n 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 79 Event Install software PM-517 Anvari 80 8 -23

Activity-on-Node Network Fundamentals J A B C K A is preceded by nothing B is preceded by A C is preceded by B L (A) M (C) J, K, & L can all begin at the same time, if you wish (they need not occur simultaneously) but All (J, K, L) must be completed before M can begin Y Y and Z are preceded by X X Z Z Y and Z can begin at the same time, if you wish Y AA AA is preceded by X and Y Z is preceded by X and Y X (B) (D) PM-517 Anvari 8 -24

A Simple Network (AON) (cont’d) A 14 C 3 Start E B 3 D 7 4 F 10 Finish Calculate: Critical Path Project Duration PM-517 Anvari 8 -25

The Critical Path ES = 0 EF = 14 ES = 14 EF = 17 A C 14 3 Start ES = 17 EF = 21 E B 3 ES = 0 EF = 3 D 7 ES = 3 EF = 10 = Critical Path PM-517 Anvari 4 ES = 21 EF = 31 F 10 Finish ES = Early Start EF = Early Finish 8 -26

Determining Slack How much slack is there n Where is it? n How do you know? n Why might you care? n PM-517 Anvari 8 -27

Determining Slack (cont’d) ES = 0 EF = 14 LS = 0 LF = 14 A 14 ES = 14 EF = 17 LS = 14 LF = 17 C 3 Start ES = 17 EF = 21 LS = 17 LF = 21 E B 3 ES = 0 EF = 3 LS = 7 LF = 10 D 7 4 ES = 21 EF = 31 LS = 21 LF = 31 F Work Back. . . 10 Finish ES = Early Start EF = Early Finish LS = Late Start LF = Late Finish ES = 3 EF = 10 LS = 10 LF = 17 PM-517 Anvari 8 -28

Determining Slack (cont’d) ES = 0 EF = 14 LS = 0 LF = 14 A ES = 14 EF = 17 LS = 14 LF = 17 14 C ES = 17 EF = 21 LS = 17 LF = 21 3 Start E B 3 ES = 0 EF = 3 LS = 7 LF = 10 D 7 ES = 3 EF = 10 LS = 10 LF = 17 What does all this mean? 4 ES = 21 EF = 31 LS = 21 LF = 31 F 10 Finish Slack = LS - ES CP = 0 Slack, where ES = LS 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, PM-517 Anvari Figure 8 -10 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 1 30 16 2 5 20 5 6 6 TE=64 4 Calculate t(e) and Z for this network…… PM-517 Anvari 8 -63

Activity and Project Frequency Distributions ACTIVITY a PROJECT m b (A) TE (B) PM-517 Anvari 8 -64

PERT Activity Calculation t(e) = a + 4 m + b 6 a = Most Optimistic (MO) 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) SSD(T[E])2 Z = Probability of 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 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 t(e)

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

Possible Project Durations TS=67 TE=64 PM-517 Anvari 8 -69

Z Table 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. 76 -0. 5 0. 31 +0. 5 0. 69 -0. 38 +0. 3 0. 62 -0. 1 0. 36 +0. 1 0. 54 PM-517 Anvari