Decision 8: Critical Path Analysis

Question 1

What is a precedence/dependence table?

Answer 1

A table that shows which activities must be completed before others are started

Question 2

What is an activity network? (3)

Answer 2

A network where activities are represented by arcs and the completion (events) are represented by nodes
The source node is the first node (represented by 0 or 1)
The sink node is the final node

Question 3

What is a dummy activity?

Answer 3

An activity with no time or cost, used to show dependencies between activities

Question 4

Why is it important that there is only one activity between any two events?

Answer 4

Every activity must be uniquely represented in terms of its events

Question 5

What is duration?

Answer 5

The length of time an activity takes to complete

Question 6

What is early event time?

Answer 6

The earliest time of arrival at the event, allowing for the completion of all preceding activities

Question 7

What is late event time?

Answer 7

The latest time an event can be left without extending the overall duration of the project

Question 8

What is the forward pass? (3)

Answer 8

Calculates early event times
Starts from source node
Choose highest numbers

Question 9

What is the backward pass? (3)

Answer 9

Calculates late event times
Starts from sink node
Choose lowest numbers

Question 10

What is a critical activity?

Answer 10

An activity where any increase in its duration results in a corresponding increase in the overall duration of the project

Question 11

What is a critical path? (2)

Answer 11

A path from the source node to the sink node, using only critical activities
The longest path in a network

Question 12

What does every network have?

Answer 12

At least one critical path

Question 13

What is the total float of an activity? (2)

Answer 13

The amount of time that its start may be delayed without affecting the duration of the project
Total float = latest finish time - duration - earliest start time

Question 14

What is the float of a critical activity?

Answer 14

Zero

Question 15

What is a Gantt chart?

Answer 15

A graphical way to represent the range of possible start and finish times for all activities in a project

Question 16

How does scheduling work? (4)

Answer 16

The first available worker should always be chosen
One worker completes the critical path
If there is a choice of activities, always choose the one that ends first
The order cannot break any previously established dependencies

Question 17

What is the lower bound of workers? (3)

Answer 17

The fewest workers needed to complete an activity in the given time
Lower bound = sum of activity times / critical time (rounded up)
If there is a higher number of activities that MUST be happening simultaneously, then this is the lower bound

Question 18

How do you set up a resource histogram? (2)

Answer 18

Workers on y-axis

Length of time on x-axis

Question 19

What is resource levelling?

Answer 19

The process of adjusting start and finish times of activities in order to minimise the number of workers needed simultaneously