Critical path Analysis Flashcards
What is the precedence table
How to make the precedence tables
This a table to show each activity and what they depend on (what must be com0leted first) for that activity ti continue )
Make a chart with activities on left and dependence on right
How to SIMPLIFY precedence tables
Basically if it says something like G depends on all, think of activities that if you included means you don’t have to include another, because one DEPENDS on another
Basically if it says all, add all activities that ARENT present in the precedence’s before
How to convert the precedence table into an ACTIVITY NETWORK
Label each new node , starting from 0 of the sink
1) MUST have a source and sink node.
2) things that don’t depend on anything come out of sink
3) try make as straight and not overlap as possible, but if can’t it’s okay
What does a dummy activity hold value waive and what does it do
It holds 0
It just connects nodes together which would otherwise be impossible to connect
When making an activity network, what should you aim to do FIRST to avoid mistakes?
Always try do the activities that depend on ONE THING ONLY first, otherwise it might be impossible to do
Then try do those depend on 2 ONLY
You’ll find this way you won’t make mistake with dummy variables
What does an activity network allow you to model
Basically tasks, and their durations , what depends on each other
You can see which tasks must be done on time to avoid the overall project form running late etc, snd which tasks have more freedom when to be completed
How to do FORWARD PASS to find Early times
whatever the number is, add the arc weight to it
2; next compare all options, and when a decision must be made PICK THE BIGGEST SIZE CHOICE
(This because for that event to pass, all other activities must at least pass, so you know to pick the biggest earliest time to accommodate for everyone Else)
How to do BACKWARD PASS to find all the late START times
First the LAST BOX IS DUPLICATED
- subtract this time when going back in weights
- only make a choice if you have all backward pass OPTIONS AVAILABLE TO YOU
- when making a choice, pick the EARLIEST TIME
(This because if you pick a bigger time, then an activity will be missed as you went past it’s deadline)
When done the forward and backward pass, what should look like and how to find CRITICAL ACTIVITIES AND PATHS
What is a critical path even show
First should be 00 and last same same
- critical activities are those with the same early and late start
- critical path is where two critical activities are connected EXACTLY by the weight in between
This means this activity must start at this and end at that time, else whole project overload
How ti find overall critical path
critical vs non critical?
Just connect all other critical paths up
2) Remember critical paths are activities that must start and finish at certain times else project is late
Whereas non critical paths have some room to FLOAT
3 types of float
Total
Independent
Interfering
How to work out total float
Late finish - early start - duration
Or OUTER - outer - duration
(This bevause the total length is subtraction of outer, but actual wriggle room in thr slider is given by subtracting from the weight too)
What is the INDEPENDENT FLOAT
How to work out
What happens if answer is less than 0?
1) independent float is the amount of float activity can do without causing any other activities to start late or finish earlier
(For example if I finish late, then the next activity can’t start earlier )
2) INNER - INNER - DURATION
if less than 0, then = to 0
What is the interfering float and how to calculate
This is the float that WILL cause neighbouring activities to be forced to start and finish differently
Would = total float - independent float
What is the total independent and interfering float for critical activities
00 and 0
