SDPM - Lecture 4 - Activity planning and resource allocation

Leiden Institute of Advanced Computer Science

System s Development and Project
Management –
Activity planning and resource
allocation

Prof. Dr. Thomas Bäck

1

Leiden Institute of Advanced Computer Science Dates

Feb. 1 14:45 – 17:30 Introduction, Project Description
Feb. 2 13:45 – 16:30 STEP WISE Approach to Project Planning
Feb. 9 13:10 – 15:45 Selecting an Appropriate Software Dev.
Approach
Feb. 15 14:45 – 17:30 Activity Planning and Resource Allocation
Feb. 16 15:15 – 18:00 Software Effort Estimation
Feb. 22 14:45 – 17:30 Risk management, project escalation
Feb. 23 13:45 – 16:30 Project monitoring and control
Mar. 1 14:45 – 17:00 Exam
Mar. 2 13:45 – 16:30 Software Quality Assurance
Mar. 8 14:45 – 17:30 Managing People; Contract Management
Mar. 9 13:45 – 16:30 Various
Mar. 15 14:45 – 17:30 Trade Fair

2


STEP WISE overview
1. Identify project objectives 0. Select Project 2. Identify project infrastructure

3. Analyze pr. characteristics

4. Identify products and activities
Review lower
level detail
5. Estimate effort for activity
For each activity

6. Identify activity risks

10. Lower level planning 7. Allocate resources

9. Execute plan 8. Review / publicize plan

System‘s Development and Project Management - Prof. Dr. Thomas Bäck 3


Sequencing and scheduling objectives

!   Time is nature s way of stopping everything
happening at once
!   Recall…
!  The difference between elapsed time and effort
!  Examples: baking bread, brewing beer

4


Sequencing and scheduling objectives
(cont d)
!   Feasibility assessment
!  Is the project possible within time and resource constraints?
!   Resource allocation
!  What are the most effective ways of allocating resources to
the project?
!   Detailed costing
!  When are expenditures likely to take place?
!   Motivation
!   Co-ordination
!  When does staff has to be transferred between projects?

5


Main stages for sequencing and
scheduling
1.  Ideal activity plan: what activities need to be
carried out in which order?
2.  Activity risk analysis: aimed at identifying
potential (resource) problems
3.  Resource allocation
4.  Schedule production: indicates planned start
and completion dates and resources for
each activity

6


Identifying activities
!   Activity-based approach
!  Ad-hoc vs. Work Breakdown Structure (WBS)
•  WBS may be based on project s products, in turn based
on a simple list of final deliverables, and a set of activities
required to produce that product.
!  May be redefined as project proceeds
!   Product-based approach
!  Product Breakdown Structure (PBS)
!  Product Flow Diagram (PFD)
•  Can easily be transformed into ordered list of activities
!   Hybrid approach
7


Graphical representation
Do B
Activity-on-node

Do A Do D
Do C
Activity-on-arrow
Do A Do B

Do D
Do C

8


Techniques History
!   Originally developed in the 50s
!   Critical Path Method (CPM)
!   Program Evaluation Review Technique (PERT)
!   CPM using Activity-on-Node
!   PERT using Activity-on-Arrow
!   Alternative: Precedence Networks
!  Activity-on-Node
!  Links represent precedence or sequencing
requirements.

9


Events vs. activities
events
Prepare breakfast Eat breakfast

activities

!   Event = a point in time (used in activity-on-arrow
networks)
!  Has no duration
!  E.g the start or end of an activity
!   Activity = a task or an action with a recognizable start
and finish and a duration

10


Remarks
!   No loops in a network!
!  Iterations may occur in practice, but cannot be
represented
!  Solution: Repeat set of activities
!   No dangles
!  Dangling activities indicate logical errors
!  Add a final completion activity as a remedy

11


Next Step after creation of the Logical Network
!   Think about the when …
!   CPM primary objectives:
!  Planning such that project is completed as early as
possible
!  Identifying activities likely to affect overall end date
!  Dummy activities (dotted lines on a network diagram)
•  Zero duration, no resources
•  Aid the layout

12


Start and finish times Latest
Earliest start finish
activity

Latest start Earliest finish

! Activity write report software
 
! Earliest start (ES)
 
! Earliest finish (EF) = ES + duration
 
! Latest finish (LF) = latest task can be completed without
 
affecting project end; latest start = LF – duration
!   Activity span = LF – ES
(maximum time allowable for activity)
13


Example

!   Earliest start = day 5 !   Earliest finish = ?
!   Latest finish = day 30 !   Latest start = ?
!   Duration = 10 days

Float = LF - ES - duration
What is it in this case?

14


Notation
Activity label Duration

ES Activity EF
description
LS LF
Activity span: LF-ES Float: LF-ES-Duration

15


Complete for previous example

A 10

5 Write report 15

20 software 30

25 15

16


Earliest start date
EF = day 7
ES = day10

EF = day10

!   Earliest start date for the current activity = earliest
finish date for the previous
!   When there is more than one previous activity, take
the latest earliest finish
!   Note ‘day 7’ = end of work on day 7

17


Example: ES for activity G?
B
E
Duration 6

Duration 8
A C G

Duration 5
Duration 10 F Duration 4

D Duration 3

ES = day 0
Duration 9
18


Complete the table
Activity
ES
D uration
EF

A

0
5
5
B

5 6 11
C

5
10
15
D

5
9
14
E

15 8 23
F

14
3
17
G

23 4 27
19


Latest start dates

!   Start from the last activity
!   Latest finish (LF) for last activity = earliest
finish (EF)
!   Work backwards
!   Latest finish for current activity = latest start
for the following
!   More than one following activity - take the
earliest LS
!   Latest start (LS) = LF for activity - duration
20


Example: LS for all activities?
B
E
Duration 6

Duration 8
A C G

Duration 5
Duration 10 F Duration 4

D Duration 3

ES = day 0
Duration 9
21


Complete the table
Activity
ES
Dur
EF
L S
L F

A

0
5
5
0
5
B

5
6
11
9
15
C

5
10
15
5
15
D

5
9
14
11
20
E

15
8
23

15 23
F

14
3
17
20
23
G

23
4
27
23
27

22


Float

Float = Latest finish -
earliest start -
Image Source: Wikimedia duration
FLOAT
ES LF
activity

Latest start
23


Complete the table LF-ES-Dur

Activ.
ES
Dur
EF
L S
L F
Float

A

0
5
5
0
5
0
B

5 6 11 9 15 4
C

5
10
15
5
15
0
D

5
9
14
11
20
6
E

15
8
23

15 23 0
F

14
3
17

6
20 23
G

23
4
27
23
27
0

24


Critical path: Defines project duration

!   Note the path through network with zero
floats
!   Critical path: any delay in an activity on this
path will delay whole project
!   Can there be more than one critical path?
!   Can there be no critical path?
!   Sub-critical paths

25


Types of schedules

!   Activity schedule - indicating start and
completion dates for each activity
!   Resource schedule - indicating dates when
resources needed + level of resources
!   Cost schedule showing accumulative
expenditure

26


Resources

!   These include
!  Labor
!  Equipment (e.g. workstations)
!  Materials
!  Space
!  Services
!   Time - elapsed time can often be reduced by
adding more staff
!   Money - used to buy the other resources

27


Resource allocation

!   Identify the resources needed for each
activity
!   Identify resource types - individuals are
interchangeable within the group (e.g. VB
programmers as opposed to software
developers )
!   Allocate resource types to activities and
examine the resource histogram

28


Resource histogram: systems analysts
5
Staff required

4

3

2

1

Week 1 2 3 4 5 6 7

29


Resource clashes

!   Can be resolved by:
!  Delaying one of the activities
•  Taking advantage of float to change start date
•  Delaying start of one activity until finish of the other
activity that resource is being used on - puts back project
completion
!  Moving resource from a non-critical activity
!  Bringing in additional resource - increases costs

30


Priorities

!   Critical path activities
!   Other activities with little float
!   When a short activity would allow a number of larger
activities to start

30 days
resource 10 days
clash

4 days 15 days

15 days
31


Burman s priority list: Activities that can
proceed at same time
1.  Shortest critical activity
2.  Critical activities
3.  Shortest non-critical activity
4.  Non-critical activities with least float
5.  Non-critical activities

32


Resource usage

!   Need to maximize percentage usage of
resources i.e. reduce idle periods between
tasks
!   Need to balance costs against early
completion date
!   Need to allow for contingency
!  Scheduling can create new critical paths

33


Cost schedules

!   Staff costs: salaries as well as other direct costs of
employment
!   Overheads: expenditure that organization incurs
which cannot be directly related to individual projects
!   Usage charge: e.g. processing time

Schedule is usually presented on a weekly
or cumulative basis

34

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