Activities make up work packages; activities are the line items inside of work packages that need to be completed to close a work package. some activities need to be completed before others, these are referred to as "predecessors". predecessor activities have to be completed before its "successor" activity. The "predecessor" to "successor" relationship is referred to as a "Finish to start" relationship.
By laying out all our activities with a predecessor successor relationship we can layout the timeline for our entire project. activities with no predecessor can be started on day one of the project, otherwise they need to be completed sequentially.
Predecessor relationships are only defined at the activity level and not the work package or deliverable levels.
Activity Resourcing
Once we've planned our activities we need to assign resources to them, these could be people, assets, commodities, services, supplies, materials, or money, basically anything that is required to complete the activity.
Activity Duration & Effort
After the resources are assigned to each activity it's time to estimate
- Duration: The number of business days required for an activity; used to estimate schedule
- Effort: The total number of hours required for an activity; used to determine the budget.
For example 3 employees could be working on a activity at the same time, so it would be 1 workday of duration but 24 hours of effort; or you could have 2 employees working 50% of an 8 hour work day on an activity that requires 12 hours of effort, two employees working half their time would have an 1.5 days of duration.
as always you're values are only as good as your estimates, ideally you would want the people who will be doing the work estimating or someone who has a good understanding for the activities and their complexity
