Hello again and welcome back to our course on Project 2016.
In this section we’re going to look at dependencies.
And as we’re doing that we’re going to add quite a bit more detail to the plan for
the wedding.
A Dependency reflects the fact that some things happening depend on other things happening.
The way in which they depend can be quite complex but in a very simplest type of dependency
we would say that one task cannot start until another task finishes.
But we can have much complex dependencies than that.
And in particular one task may depend on many other tasks.
Now let’s take a pretty straightforward Dependency to begin with.
Let’s look at task six and seven, Select wedding dress and Order dress.
Now clearly you’re not going to order the dress until you’ve selected it.
But as soon as you’ve selected it you may want to order it.
If I want to record in my schedule that one task is dependent on another the very simplest
way of doing it, let me select the first task which is six, Select wedding dress, hold the
Control key down, press seven, Order dress, and then on the Task Tab in the Schedule Group
there is a button, a chain-link button that says Link the selected tasks.
You can link tasks so one can’t start until the other has finished.
And this establishes the very simplest kind of dependency.
If you look at the Gantt Chart on the right you can see an arrow indicating the dependency
whereby task six must finish.
You can see the arrow there starting, coming out of the finish of task six.
And you can see it going into the start of task seven, Order dress.
And if I pull the divider over here you’ll be able to see the contents of this predecessors
column.
And for task seven it now has a predecessor of task six.
Now let’s look at the durations of these tasks.
Let’s go back to Select wedding dress.
This is obviously very difficult to be absolute about but let’s suppose that the bride has
decided that in order to select a wedding dress.
It’s really quite a long and complex process.
She’s probably going to need a couple of months.
So let’s say that in terms of working days, weekday working days, I appreciate that somebody
wouldn’t be planning a wedding purely on the basis of weekday working but let’s work
on that basis for the moment.
Let’s call it eight weeks.
Let’s call it 40 days.
So if I click in the Select wedding dress task, go to the duration, I’m going to delete
what’s there already and replace it with 40 days.
That’s fine.
But in terms of ordering the dress.
That’s a very quick task.
That’s going to be a matter of perhaps going into a store and filling in a form, committing
to spending a certain amount of money.
Probably paying a deposit on the dress.
We’ll talk about things like cost later on.
And we’re really going to say that that order is going to be placed in a day.
So let’s change one day estimated to one day without estimated.
We can either just delete the question mark or as you saw earlier on we can go into the
Task Information dialogue and uncheck the estimated checkbox.
Now once the dress has been ordered the measurements and fittings can start.
There’ll be a sequence of these until the dress is finalized.
And once again let’s assume that it’s going to take a total period of 40 days for
that to all happen.
So we can select task seven and we can select task eight.
We could create a Dependency in exactly the way that we did before.
If I right click on the selection, if you look in the mini toolbar there’s a link
button there.
So I can do the link that way.
And I can do the link before I establish the second duration.
So let me double click on task eight, change its duration to not estimated and 40 days.
There we are.
And at the end of task eight we should have a wedding dress that fits.
Now let’s move on to task nine, Select and order bridesmaid dresses.
Now this is not a task which is completely independent of the wedding dress because as
I understand it in general the wedding dress would be selected first with a thought to
what the bridesmaid dresses will be like.
But you certainly wouldn’t start selecting the bridesmaid dresses till you were certain
about the wedding dress.
So let’s in this case say that the Dependency is that we’ll select the wedding dress before
we select and order the bridesmaid dresses.
Now in reality not only would Select and order bridesmaid dresses itself be broken down into
subtasks but even some of those subtasks would probably be broken down further.
So for instance measurements and fittings would probably be broken down into two or
three subtasks.
But let’s stick with the level of detail that we’ve got.
Let’s establish that link and change the duration of the Select and order bridesmaid
dresses from an estimated one day to a total of 60 days.
And as you can see our schedule now takes us towards the end of April 2016.
You can also see there that that one task, Select wedding dress has now a number of tasks
dependent on it.
And of course any task cannot only have several tasks depending on it but it can depend on
several tasks as well.
Now let’s start to look at these dependencies in a little bit more detail.
There is a Dependency from task six to task nine.
We just set that up.
If I hover over the arrow that represents that Dependency there is a Screen Tip that
comes up that gives me a summary of the Dependency.
It’s an FS, a finish to start dependency.
That means that the first task in the Dependency, that is Select wedding dress, must F, must
finish before Select and order bridesmaid dresses can S, can start.
And in fact if I double click on that line I get a Task Dependency dialogue where I could
if I wanted to change that Dependency.
So it says from Select wedding dress to Select and order bridesmaid dresses there is a finish
to start dependency with a lag of zero days.
Now if I had decided in this particular case that after the wedding dress was selected
and at the point that we were going to order it we could certainly start looking at selecting
and ordering bridesmaid dresses but we needed to leave a gap of say five days for some reason
that would represent a lag of five days.
And if I then click on that as my dependency what you’ll see is a five day gap.
Effectively we finish Select wedding dress, then there’s a five day gap and then we
Select and order bridesmaid dresses.
So that’s a lag.
And I could also have said let’s have a lag of minus five days.
Now what that is, a negative lag we often refer to as a lead.
We still have a finish to start relationship but what the relationship now says is that
the second task can start five days before the first task finishes.
So we can actually get started on selecting and ordering the bridesmaid dresses five days
before we finish selecting the wedding dress.
Now I’m going to restore that to being a lag of zero days in a moment but first of
all I’d like you to look at the predecessors column.
If you look at task seven, Order dress, its predecessor was six.
Look at task eight.
Its predecessor was seven.
Where all you see in the predecessor column is a number, that indicates a default finish
to start relationship with zero lag.
If there’s more complexity to the Dependency then you’ll see something such as you can
see for task nine.
The Dependency is on task six so it begins with a six.
The FS basically says this is a finish to start dependency, which is the default.
But the reason it says that is because it then says minus five days.
So that code tells you that task nine has a finish to start relationship with task six
which means that six must finish before nine starts but there is a five day lead.
So in effect task nine can start five days before task six finishes.
And whenever there is anything other than a standard default finish to start relationship,
so if it’s any other type of relationship or if there is lag or lead you’ll see that
coded in the predecessors column.
So let me once again open up that dialogue and change that back to being a zero lag.
And just before I change this back the way it was let’s look at those other types of
Dependency.
There are four types in total.
It’s finish to start, the default.
There is start to start which means that the second task can start when the first one does.
Of course you can apply lag or lead to any of these.
Finish to finish which means that the second task can only finish when the first task finishes.
And there is a start to finish which means that the second task can’t finish until
the first task starts.
Now by far the most common Dependency is the finish to start but you are very likely to
come across the others.
And in the next section or two I’m going to show you one or two examples of these other
types of Dependency.
The next task that I want to look at is the task of Making the guest list.
Now Making the guest list can be quite a long and controversial subject.
I’m going to assume for the moment that it’s going to take maybe three to four weeks
to try to make sure that everybody that should be invited is invited.
So let’s change that eight days to fifteen.
But let’s also say that once we’ve got some guests on the guest list who are definitely
going to be invited we might start sending out the invitations pretty much straightaway.
So sending out the invitations would be a task that would pretty much run throughout
the period of Making the guest list.
We may even wait and see what responses we get to some of the invitations until we decide
if you like close the guest list.
So let’s extend Send out invitation to be say a 20 day task.
And let’s say that it’s going to start five days after Making the guest list starts.
So once we’ve been working on the guest list for a week we’re going to start sending
out the first batch of invitations and see what sort of responses we get.
So we’ll link those two.
And then what we’re going to do is change that Dependency from finish to start to start
to start and put in a five day lag, start to start.
We need to allow time for people to respond to invitations.
As usual quite a controversial subject, how long you would give people to respond to an
invitation.
But probably a figure of something like two or three weeks.
So you’re going to start sending out invitations on a particular date and then over a period
of time you’ll send out some more and you’ll start to get replies back.
But in reality you can’t really finalize the guest list until you’ve received all
of the responses to the invitations.
So what I’m going to do is to create a link between Send out invitations and Finalize
guest list that works on the principle that you need to allow say three weeks from the
end of sending out the invitations before you can actually finalize the guest list.
So I’m going to create a link between those two and I’m going to put a lag of fifteen
days in.
And then instead of saying that it’s a finish to start link I’m going to say it’s a
finish to finish link.
And I’m going to say that Finalize guest list is just say a five day task.
And what you can see there is a situation where at some point before our deadline we’re
going to start to finalize the guest list but we’re not actually going to be able
to finish it until fifteen days after we’ve sent out the last invitation.
Now of course the way that I’ve done that was partly just to demonstrate these type
of dependency.
But you’ll see from that also that when you’re setting up dependencies there are
often a number of options to consider.
And coming up with the right sort of dependency can sometimes involve quite a bit of thought
and discussion.
So we’ve put in quite a bit more detail into our plan now for the wedding.
In the next section we’re going to look at Constraints and Deadlines and we’re also
going to do a little bit more on dependencies as well.
So please join me for that.