PMP Exam Prep - Chapter 6

Time Management

There are many parts to time management and they all fit into the project management process in one group or another. Defining activities, sequencing activities, estimating activity resources, estimating activity durations, and developing the schedule are all done during the planning process group. Controlling the schedule is done during the monitoring and controlling process group. When reading about sequence activities I thought about Microsoft Project 2010 because it sequences the activities in the project, just like in the book.

Once you are done with sequencing activities, you move on to estimating activity resources. Estimating activity resources is pretty clear to me. You look at each activity and estimate the resources involved. Simple enough, right? When estimating the activity resources be sure to remember that not only are equipment and materials resources, but people are too. The next step in time management would be to estimate activity durations. Simply guessing a time frame and designating it to an activity will not work. Like all other time management processes, research and information gathering must be involved to properly estimate an activity duration. A few estimating techniques the book mentions include, one-point estimating, analogous estimating, parametric estimating, and three-point estimating.

One-point estimating involves submitting one time estimate per activity. PMP Exam Prep suggests, "One-point estimates should only be used for projects that do not require a detailed, highly reliable schedule." On the other hand, analogous estimating can be used on a project or a separate activity. This style of estimating relies solely on historical information and judgement. You look at other similar projects or activities durations and estimate the current project's time based off your findings. Parametric estimating calculates estimates based on the relationship between variables on an activity. Two ways an estimator may create parametric estimates are regression analysis (scatter diagram) or learning curve.

Three-point estimators give an optimistic (O), pessimistic (P), and most likely (M) estimate for each activity. This type of estimating is helpful because it provides a risk-based duration by taking the average of the three estimates. The formulas are as follows:

• Expected Activity Duration(EAD) = (P+4M+O)/6
• Activity Standard Deviation(SD) = P-O/6
• Activity Variance = (P-O/6)^2

For example, if P=47, M=27, and O=14. Calculating EAD would look like this: (47+4(27)+14)/6 = 169/6 = 28.167. So the Expected Activity Duration would be 28.167. Once you generate an answer for all three of the formulas, you can then calculate a range of the estimate. Brace yourself for more of my fancy calculation skills. To calculate the range you must know the EAD and SD. The range is calculated using EAD +/- SD. If we keep the variables the same as above, the start of the range would be 28.167-5.500 = 22.667, and the end of the range would be 28.167+5.500 = 33.667. So the range of the estimates would be 22.667 to 33.667, or 28.167 +/- 5.500. These formulas do not relate to the overall project, but rather to activities within the project.

To calculate the duration estimate of the overall project you need to find the expected project duration, the project standard deviation, and the project variance. To calculate the expected project duration you add the EADs for all activities on the critical path. If I use the numbers from the last example, our expected project duration is 170.167. Project standard deviation is calculated by adding the variances of each critical path activity, and then taking the square root of the sum. The project standard deviation for this project is 10.060. Project variance is calculated by adding each of the activity variances. 101.196 is the project variance for the project in this case.

Creating a reserve is different from padding because the project manager has the necessary information to calculate additional time or funds the project may need. Padding is determined using little, to no information and is basically an uneducated guess. Some project managers use a pad on their estimates and this is not recommended due to the uncertainties of the estimate, which can be detrimental to the project.

The next thing to do, once you have created a network diagram and completed activity duration estimates, is to develop a schedule. A schedule differs from an estimate because it is calendar-based. PMP Exam Prep explains, "Once you have an initial schedule, you begin schedule network analysis to create the final schedule. This analysis may take the form of one or more of the following techniques:

• Critical path method: involves determining the longest path through network diagram, earliest and latest activity can start, and the earliest and latest it can be completed.
• Schedule compression: helps determine if desired completion date can be met, and, if not, what can be changed to meet requested date.
• What-if scenario analysis: used to help create a finalized, realistic schedule by asking "What if?".
• Resource leveling: used to produce a resource-limited schedule.
• Critical chain method: uses network diagram and develops schedule by assigning each activity to occur as late as possible to still meet end date."

You would think I was getting close to my rant on chapter six! The joke is on you because I have much more ranting to rant on. :)

Going back to the critical path method, there are basic concepts that need to be understood in order to use this method. Those methods include critical path, near-critical path, and float (Slack). A helpful trick PMP

There are three types of floats that need to be remembered, and calculated, for the exam. Total float is the first and can be recognized as the primary type of float. It is the amount of time an activity can be delayed without delaying the project end date. The second float is free float. Free float calculates the amount of time an activity can be delayed without delaying the early start date of its successor(s). Project float is the final float and it is the amount of time a project can be delayed without delaying the imposed project end date required by the customer, manager, or project manager. We have total float, which relates to activity versus project, free float, which is activity versus successor, and project float, which is project versus project. Although this may not make complete sense to you, this is how I remember the floats, or slacks, for the exam.

Now that we have the definitions of the floats, we can talk about calculation. Float is calculated by using one of the following equations:
Float = Late Start (LS) - Early Start (ES), or Float = Late Finish (LF) - Early Finish (EF). PMP Exam Prep. suggests remembering the first formula as the stat formula, and the second as the finish formula. How do you determine which formula to use? You use the information the exam gives you. PMP Exam Prep. uses the following example:
"You have a late start date of 30, an early start of 18, and a late finish of 34, how do you find the float?" You need to either subtract the two starts or the two finishes, and since you have to starts and only one finish you, you subtract 30(LS) - 18(ES) and get 12. 12 would the answer and would be your float for this question.

One the critical path, and all of it's connecting terms are defined, chapter six moves into using the critical path method. The network diagram below is similar to the one Rita Mulcahy uses in her book as an example to explain how the critical path method works. "To determine the earliest and latest each activity can start and the earliest and latest each activity can be completed, you need to perform a forward and backward pass through the network diagram." explains PMP Exam Prep. To calculate the "early" figures you must do a forward pass through the network diagram. To find the "late" figures you must start at the end of the project and follow the dependencies to the beginning of the project. You would need to do, what Rita Mulcahy calls, a "backward" pass.

The diagram below is very similar to the diagram above, the only difference is that it has different shapes and includes boxes to enter your early start (ES), early finish (EF), late start (LS), and late finish (LF). You can choose to either do the forward or backward pass first. Just remember that the top boxes (ES and EF) are for the forward pass, and the backward pass should fill the bottom boxes (LS and LF).

The key for the previous diagram is as follows:

To begin the forward pass, you must begin with the first two boxes at "Start. If the network diagram converges at any point, you must do the forward pass on both paths that lead to the path convergence. You would then select the later early finish to use as the early start date for the box of convergence, since the next activity cannot start until the previous activities are completed. You should use the same process to calculate the early finish of each activity, before moving to the next path convergence. Once you have completed the forward pass through the critical path, you can move on to the backward pass. To begin calculating the late start and late finish for each activity, you use the duration of the critical path (Early Finish), as the early finish of the last activity in the network.

After you have completed the backward pass, and have calculated all of the starts and finishes, you may then calculate float. This is the time where you go back to the Start and Finish formulas. The bold arrows in the diagram I posted above represent the critical path. Use the Start and Finish formulas to calculate the float of each activity and record this number in your network diagram.

The goal of schedule compression for a project manager should be to compress the schedule, while keeping the same project scope. Fast tracking and crashing are both schedule compression techniques. Fast tracking involves paralleling activities on the critical path. Crashing is all about trading. It involves asking yourself, "Which option will cause the least impact on cost, if time MUST change?". Fast tracking always adds risk, while crashing always adds cost. So as a project manager you must review which option would have the least risk, and be the most efficient.

The Monte Carlo Analysis is a technique used in "what-if" scenarios. It uses computer software that is based on the three-point estimates of each activity, plus the network diagram. According to PMP Exam Prep., the simulation used in the Monte Carlo analysis can tell you:

• The probability of completing the project on any specific day.
• The probability of completing the project for any specific amount of cost.
• The probability of any activity actually being done on the critical path.
• The overall project risk.

The project schedule can be shown with or without dependencies, and can be formatted in a network diagram, milestone chart, or bar chart. You should choose the correct format based on the needs of the project. Milestone charts show major events and represent the completion of activities, but they do not include duration. According to PMP Exam Prep, bar charts are not project management plans, but are effective tools for progress reporting and control. Bar charts are also known as Gantt charts.

The schedule baseline is the almighty project manager. Not only is the project managed using the schedule baseline, but the team's performance is measured against it. The baseline cannot be changed until it is formally approved. Control schedule involves protecting the schedule, and looking out for anything that could affect the schedule. A list of additional activities involved in controlling the schedule that are provided in PMP Exam Prep are as follows:

• Reestimating remaining components of the project partway through the project
• Conducting performance reviews by formally analyzing how the project is progressing
• Adjusting future parts of the project to delay with delays
• Measuring variances against the planned schedule, determining if the variances warrant attention
• Considering leveling resources to distribute work more evenly among resources
• Continuing to play "What if...?" with the project schedule to better optimize it
• Adjusting metrics that are not giving the project manager the information needed to properly manage the project
• Adjusting progress reports and reporting as needed to capture the information necessary to control and manage the project
• Identifying the need for changes
• Following the change control process

Reestimating is the final topic discussed in chapter six. What!? I know, I can't believe it either! Reestimating involves looking at the remaining pieces of the project and reestimating them to meet the end date, and other project objectives if they do not already adhere to the originally estimated objectives.