LESSON 3-4: Assigning Relationships

This tutorial describes:
•    Relationships
•    Relationship Types 
•    Relationships with Lag
•    How to create Relationships

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1. Relationships.
Relationships define the start or finish of an activity based on its dependencies, its predecessor and successor activities. 

2. Relationship Types.
In this tutorial, we will review the four types of relationships. The first and most common relationship type is Finish to Start (FS), which states that when activity A finishes, activity B can start. 
Start to Start (SS) states that activity B can start when activity A starts. Finish to Finish (FF)  indicates that activity B can finish only when activity A finishes. Start to Finish (SF) is the least used activity type. It states that activity B can finish after activity A starts. Assign relationships before you schedule. After scheduling, these relationships, in combination with activity duration, will establish starts and finish dates throughout the project plan.

3. Relationships with Lag.
You can further modify relationships using lag. Lag can be assigned to a relationship to accelerate or delay the start or finish date of a dependent activity.
For example, if you assign a seven-day lag to a finish to start a relationship, the successor activity cannot start until seven days after its predecessor has finished. You can also assign negative lag to creates lead time between activities. 

4. Create Relationships.
As you can see in the Gantt chart, this project already contains activities, each with its own duration. However, without relationship logic, all of the activities are scheduled to start on the same day. We will create relationships between activities to prepare the project for scheduling. First, on the activities page, select an activity on the grid. Then use the relationships detail window to assign relationships. The detailed window is divided into two sections.
Use predecessors to specify relationships for activities that occur before the selected activity. Use successors to specify relationships for activities that occur after the selected activity. Click assign to open the assign relationships panel. Use the panel to assign predecessors and successors for the selected activity. Leave the panel open, and select another activity to assign its predecessors and successors.
Relationships are added with the default type. For example, two Activity Dependent activities will be linked with a finish to start relationship. Close the panel. Then use the relationships detail window to set the relationship types and lag.
After the project is scheduled, activities are positioned on the Gantt chart accordingly by their durations and relationships.