Time Management

A project manager is responsible for building a realistic schedule. Before execution starts, check whether the planned finish date is achievable.

Schedule Management Plan

Decide in advance how to plan and control the schedule. Identify who will take part in scheduling, how to build the schedule, which organizational processes and procedures to follow, which tools to use, and how to manage the work against the schedule baseline and address deviations.

Create the schedule management plan as part of Develop Project Management Plan in Integration Management. The plan is required, and most project managers overlook it in practice. The plan can be formal or informal.

• Describe the scheduling method and how the team will use scheduling software.
• Specify how to express estimates and measure progress, such as in hours, days, weeks, months, or quarters. Record the expected duration and effort for each activity to help establish the schedule baseline.
• Plan performance measures in advance. Capture and report them during the project.
• Use the baseline to monitor and control the project through its phases. Define how to analyze and address variances.
• Establish change control procedures for schedule changes and define reporting requirements.

Agreed guidelines for expressing estimates speed up schedule estimation. During monitoring and controlling, the team can compare actual progress with the schedule baseline and act on deviations. The plan also determines how to report project progress.

Define Activities

In Scope Management, the work breakdown structure (WBS) divided the project into work packages. Define Activities uses those packages as inputs and breaks them into activities needed to deliver the work. Keep each activity small enough to estimate, schedule, monitor, and manage. Sequence the activities next.

In practice, some project managers define activities while creating work packages, and some build network diagrams at the work-package level instead of the activity level.

Two things are critical for defining activities:

1. The scope baseline, which includes the scope statement, WBS, and WBS dictionary.
2. An available project team.

Defining activities involves estimating. Involve the team early to improve estimate accuracy.

When there are too many components to break down and schedule in detail at the outset, use rolling wave planning. Plan activities in enough detail to manage the work as each phase of the project life cycle begins. Use the technique to time detailed planning appropriately and keep up with the planning the project requires.

Define Activities produces an activity list and activity attributes, which document each activity’s details. The process also identifies milestones.

Milestones

The time allotted to an activity is distinct from a milestone. In this chapter, milestones mark interim deliverables in the schedule. The project charter includes a milestone summary.

Like a sponsor, the project manager can impose milestones during Sequence Activities or Develop Schedule to help control the project. When a milestone date arrives and the required work is unfinished, it reveals a deviation from the plan. Create the milestone list during Define Activities. Add it to the project management plan and, as planning evolves, to the project scope statement and the WBS dictionary.

Sequence Activities

Sequence Activities takes the activities and milestones from Define Activities and arranges them in the order in which the work will be performed.

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Methods for Drawing Network Diagrams

• Precedence Diagramming Method (PDM).
• Arrow Diagramming Method (ADM).
• Graphical Evaluation and Review Technique (GERT).

Project managers generally use PDM.

Precedence Diagramming Method (PDM) or Activity-on-Node (AON)

• Finish-to-start (FS). The successor can start only after its predecessor finishes. This is the most common relationship. For example, open a can of soda before you start drinking it.
• Start-to-start (SS). The successor can start only after its predecessor starts. For example, start building a presentation and allow a one-week lag to complete enough slides before voice-over recording starts.
• Finish-to-finish (FF). The successor can finish only after its predecessor finishes. For example, finish the pilot before you finish collecting all the feedback.
• Start-to-finish (SF). The successor can finish only after its predecessor starts. This relationship is rarely used.

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Graphical Evaluation and Review Technique (GERT)

GERT adapts network diagramming into a computer simulation technique that allows loops between activities. For example, after designing and testing a program, you may need to return to the design step, depending on the test results.

Types of Dependencies

• Mandatory dependency (hard logic). The work has a natural order or a contract requires the order. For example, you must send the print command before the printer can print.
• Discretionary dependency (preferred, preferential, or soft logic). The project manager and team choose this dependency. It is easier to change than other types and can help when compressing or fast-tracking the schedule.
• External dependency. The work depends on the needs of a party outside the project, such as a labor union or regulator.

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Leads and Lags

A lead lets an activity start before its predecessor finishes. For example, editing a book can start before the writing is complete.

A lag inserts waiting time between activities. For example, final rollout waits for the application testing to finish.

Sequencing can reveal new risks and lead to updates to the activity list and activity attributes.

Estimating Resources and Durations

Estimating Principles

• Use the WBS and historical information to improve accuracy. Have the people who will do the work provide the estimates when possible.
• Few or no changes to the scope, cost, and schedule baselines make estimates more accurate.
• Manage the schedule against the schedule baseline and the budget against the cost baseline. The project manager is responsible for meeting agreed estimates.
• Use integrated change control to approve or reject every change request. Issues involving schedule, cost, scope, quality, or resources can prompt a request. Revise the project management plan as changes are approved and the required work is completed.
• Analyze project requirements, use team input and experience from relevant projects to create new estimates, and resolve differences to set realistic objectives. The project manager is responsible for accurate, feasible estimates.
• Recalculate the estimate to complete (ETC) periodically to check whether the project has enough time, funds, and resources.
• Review estimates regularly for feasibility, padding, and risks. Do not pad estimates. Reducing or eliminating risks can lower estimates.

Estimate Activity Resources

After sequencing activities, determine the type and quantity of resources needed, such as equipment, materials, and people. Resource shortages are a common problem across projects. Plan and coordinate resources to avoid them. This process has two outputs:

1. Defined activity resource requirements.
2. A resource breakdown structure (RBS).

Estimate Activity Durations

Estimate how long each activity will take after defining and sequencing activities and identifying the resources needed for each one. Ideally, the people doing the work make the estimates. In practice, the estimators are often project team members who are especially familiar with the work.

Estimators need access to:

• Activity resource requirements.
• Resource calendars.
• Organizational historical data.
• Lessons learned about activity durations.
• Past project calendars.
• The defined scheduling methodology.
• Company culture and other enterprise environmental factors.
• Existing systems such as estimating software and productivity metrics.

Later in planning, use the time estimates and other information gathered during estimation to help create the risk register.

Padding and Risk Reserves

Padding is extra time or cost added to an estimate when the estimator lacks enough information. Many project managers use padding, which makes it harder to produce a realistic schedule and budget. Unknowns can justify additional time and cost. Address them with calculated reserves through risk management.

Risk management turns uncertainties into identifiable opportunities and threats. Estimators should bring these risks to the project manager’s attention. Padding many estimates produces an inflated schedule and undermines the usefulness of scheduling and budgeting. Projects use realistic schedule and cost baselines to measure performance, and project managers need to adhere to them. Padding reflects poor project management and can damage the project manager’s reputation.

You can avoid padding when:

• Estimators have the WBS and WBS dictionary.
• Project time and cost reserves come from calculations.
• Risks and unknowns have been identified.

Estimating Methods

Use methods such as analogous, parametric, and three-point estimating. Reserve analysis addresses the uncertainty that remains. The people doing the work should complete the estimates. The project manager:

• Gives the team enough information to estimate each activity properly.
• Works with estimators to agree on how refined their estimates need to be.
• Validates estimates and prevents padding.
• Sets a reserve.
• Records the assumptions behind estimates for later review.

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One-Point Estimating

Give a single estimate for each activity. An estimator might say the work will take one month, based on expert judgment, historical information, or a guess. This approach has drawbacks:

• If someone estimates 15 days and the work takes only 10 days, the estimator may appear untruthful or untrustworthy.
• The estimate can hide risks and uncertainty from the project manager.
• An unreliable-looking schedule can reduce support for the project management process.
• The approach pushes people to pad estimates.
• Estimators may work against project managers to protect their own interests.

Use a one-point estimate when the project can work with a less detailed, less reliable schedule. A three-point estimate is preferable.

Analogous Estimating

Use expert judgment and historical information from similar work. If the last few similar projects took nine months, you might estimate nine months for this one. If an activity took fifteen days each of the last three times and no other information is available, estimate fifteen days and review the estimate when more details are available.

Parametric Estimating

Calculate an estimate from the relationship between one or more variables (X) and an activity measure (Y). Data comes mainly from historical records, such as previous projects, industry requirements, standard metrics, and other sources. Two ways to create a parametric estimate are:

• Regression analysis (scatter diagram). Identify the effect of X on Y and develop a mathematical formula for future estimates.
• Learning curve. For example, as a call center employee gains experience, their average handling time falls because they become more efficient.

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Heuristics

A heuristic is a rule of thumb. The Pareto principle, or 80/20 rule, suggests that 80% of quality problems come from 20% of potential sources of problems. Results from parametric estimating can become heuristics.

Three-Point Estimating (PERT Analysis)

A project is unlikely to finish on one exact estimated date. A range often better reflects what could go right or wrong and helps the project manager understand variation in both activity estimates and the overall project estimate. For each activity, estimate time or cost in three ways:

• Optimistic (O).
• Pessimistic (P).
• Most likely (M).

Take a simple average or use the Program Evaluation and Review Technique (PERT) to take a weighted average of the three estimates. The result is a risk-based expected duration or cost.

Reserve Analysis

Estimating helps identify risks. Completing risk management can eliminate risks, improve estimate accuracy, narrow ranges for time and cost, and save time and money.

The project manager sets an initial reserve during risk management planning. After planning risk responses to reduce risk, revise the reserve to cover remaining risks. This is one way project planning is iterative.

• Management reserves are additional funds for unforeseen risks.
• Contingency reserves cover risks that remain after Plan Risk Responses.

Padding comes from an arbitrary guess about how much extra to add. Reserves use available information to calculate how much additional time or money the project may need.

Develop Schedule

Once the network diagram and activity estimates are ready, enter the information into a calendar-based schedule. To finalize it:

• Check stakeholder priorities.
• Identify different ways to complete the work.
• Identify risks and effects on other projects.
• Negotiate resource availability with managers.
• Apply leads and lags.
• Use crashing, fast-tracking, and reestimating to compress the schedule.
• Adjust the relevant parts of the project management plan.
• Use a scheduling tool and calculations to determine the best schedule.
• Use models such as Monte Carlo analysis to simulate the project and identify a completion date.
• Level resources if necessary.
• Ask the team that created the schedule to approve it.
• Seek stakeholder buy-in and formal management approval.

Many Develop Project Management Plan actions from Integration Management also take place when developing the schedule.

Schedule Network Analysis

Analyze the initial schedule to develop the final schedule. Techniques include the critical path method, schedule compression, what-if scenario analysis, resource leveling, and the critical chain method.

Critical Path Method

The critical path is the longest path through the network diagram. The method involves three steps:

1. Find the longest path through the network diagram.
2. Determine each activity’s earliest and latest start times.
3. Determine each activity’s earliest and latest finish times.

Near-Critical Path

A near-critical path is close in duration to the critical path. The closer the paths are in length, the greater the project risk. Monitor and control activities on both paths to avoid delaying project completion.

Float (Slack)

Float and slack mean the same thing. The three main types are:

• Total float. The time an activity can be delayed without delaying the project end date. This is the primary type.
• Free float. The time an activity can be delayed without delaying the early start of any successor.
• Project float. The time an activity can be delayed without delaying a project completion date imposed by management or the customer.

Critical path activities have zero float in the schedule described here. Delayed projects or projects with imposed dates can have negative float.

Float shows the time flexibility available for an activity and helps the project manager manage the work and allocate resources. For example, assign a new team member who is still learning to the activity with the most float. If they need more time, the project is less likely to finish late.

Use either formula to calculate the same result:
Float = Late Start (LS) − Early Start (ES)
Float = Late Finish (LF) − Early Finish (EF)

Schedule Compression

A customer or stakeholder may request an unrealistic date, or work may fall far behind the baseline. The project manager should challenge an unachievable deadline, present options, and use schedule network analysis to see whether the requested date is achievable and what would have to change to meet it.

Schedule compression can be used during planning and during integrated change control. In change control, consider how changes to cost, scope, risk, resources, quality, or other parts of the project affect the schedule. The objective is to shorten the schedule while keeping the project scope intact.

Fast-Tracking

Run critical path activities in parallel that were originally scheduled in sequence. Fast-tracking leads to rework, increases risk, and requires more attention to communication.

Crashing

Keep the project scope intact and evaluate cost and schedule trade-offs. Aim for the greatest schedule reduction at the lowest additional cost. Crashing always increases cost because it trades money for time.

What-If Scenario Analysis

Test whether a change in a project factor could produce a shorter schedule. As assumptions change, activity durations can change too. Monte Carlo analysis is one way to calculate the effect.

Monte Carlo Analysis

Computer software simulates the project using a network diagram and the optimistic, pessimistic, and most likely estimates for each activity. The simulation estimates:

• The probability of completing the project on a particular day.
• The probability of completing it at a particular cost.
• The probability of a given activity being on the critical path.
• Overall project risk.

Monte Carlo analysis is more accurate than other methods because it simulates the project’s details and calculates probabilities. It helps address path convergence, where several paths lead into one or more activities and increase risk. It can also be used to analyze risks quantitatively.

Resource Leveling

Use resource leveling to create a schedule that reflects resource limits. If resources are limited, leveling lengthens the schedule, increases cost, and affects other constraints.

Critical Chain Method

Use the network diagram and schedule activities as late as possible while still meeting the project end date. Add resource dependencies and calculate the critical chain. Starting at the end date, build duration buffers into the chain at critical milestones. These reserves cushion delays across the project. Manage them to meet each milestone and the project completion date.

Project Schedule

A project schedule can include logical dependencies or omit them, depending on what the project needs. Common formats are network diagrams, milestone charts, and bar charts.

Milestone Chart

Milestone charts resemble bar charts and show events only. They work well for reporting to management and customers.

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Bar Charts (Gantt Charts)

Bar charts are effective for reporting and controlling progress. They have limited use in planning and organizing the project. Use the WBS and network diagram to organize the work, then produce the bar chart. Keep the full project management plan as a separate document.

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Control Schedule

Look for what is causing schedule changes and act on those sources. If the project can no longer meet the agreed completion date in the schedule baseline, the project manager may recommend ending the project to avoid wasting more company time.