3.7 Activities, Milestones, Schedule Quality, and Basis Documentation

AACE Planning and Scheduling Professional PSP

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1 Chapter 0: Introduction & AACE PSP Exam Structure

0.1 Current AACE PSP Exam, Eligibility, and Certification Facts 0.2 Planning and Scheduling Professional Roles and Competencies 0.3 Cost Engineering and Scheduling Terminology per RP 10S-90

2 Chapter 1: Scope Definition & Planning Fundamentals

1.1 Work Breakdown Structure (WBS) Architecture & RP 33R-15 1.2 Organization & Resource Breakdown Structures (OBS, RBS, RAM) 1.3 Project Planning and Activity-Logic Development 1.4 Contract Requirements and Delivery Constraints 1.5 Stakeholder Identification, Needs, and Plan Review 1.6 Constructability Methods and Value Engineering 1.7 Resource Identification and Project Variables 1.8 Scope, Goals, Project Plan, and Phase Definition 1.9 Cost Breakdown Structure and Cost Estimate Development 1.10 Phase Relationships, Baseline Plan, Forecasts, and Risk/Recovery Planning

3 Chapter 2: Critical Path Method Mechanics & Network Logic

2.1 Activity Definition and Logic Relationships 2.2 Activity Durations, Productivity, and Work Calendars 2.3 Forward and Backward Pass Mathematical Mechanics 2.4 Float Calculations and Critical-Path Identification

4 Chapter 3: Advanced Network Techniques & Schedule Constraints

3.1 Schedule Constraints and Their Impact on Dates and Float 3.2 Advanced Logic Modeling: Ladders and Fragnets 3.3 Schedule Levels of Detail and Schedule Basis Documentation 3.4 Schedule Scope and Schedule Specification 3.5 Breakdown-Structure Relationships and the Cost Estimate Model 3.6 Stakeholder Feedback and Types of Schedules 3.7 Activities, Milestones, Schedule Quality, and Basis Documentation

5 Chapter 4: Resource Management & Leveling

4.1 Resource Planning, Allocation, and Histograms 4.2 Resource Leveling vs. Resource Smoothing 4.3 Cumulative Resource S-Curves & Productivity Tracking

6 Chapter 5: Baseline Management & Schedule Updating

5.1 Baseline Establishment, Forecasts, and Controlled Revision 5.2 Progress Measurement and Data Date Mechanics 5.3 Out-of-Sequence Logic: Progress Override vs. Retained Logic 5.4 Schedule Update Review and Quality Verification per RP 53R-06 5.5 Cost/Resource Management, Schedule Change, and Feedback 5.6 Acceleration and Recovery Scheduling per RP 54R-07 5.7 Control Schedules, Variance Analysis, Forecasts, and Management Summaries

7 Chapter 6: Schedule Risk Analysis & Monte Carlo Simulation

6.1 Schedule Risk Principles, Risk Drivers, and Three-Point Estimates 6.2 Monte Carlo Simulation, Criticality, Correlation, and Merge Effects 6.3 Risk Outputs, Confidence Dates, Sensitivity, and Contingency

8 Chapter 7: Earned Value & Earned Schedule Management

7.1 Earned Value Foundations: PV, EV, AC, and Variances 7.2 Traditional EV Performance Indices & Late-Project Quirks 7.3 Earned Schedule (ES) Theory, SV(t), and SPI(t) 7.4 Independent Schedule Forecasting & IEAC(t)

9 Chapter 8: Forensic Schedule Analysis & Delay Claims

8.1 Delay Classification, Criticality, and Contract Questions 8.2 RP 29R-03 Taxonomy, Data Validation, and Method Selection 8.3 TIA, Windowed Analysis, and Subtractive Models 8.4 Concurrency, Pacing, and Float: Technical Analysis Before Entitlement

10 Chapter 9: Executive Communication & Practical Scenario Applications

9.1 Official PSP Memo Writing Framework 9.2 Structured Technical Problem-Solving for PSP Scenarios 9.3 Current Exam Strategy and Core Calculation Review

3.7 Activities, Milestones, Schedule Quality, and Basis Documentation

Key Takeaways Explain This Topic AI

Activities translate scope into measurable work with clear start/finish criteria, duration, responsibility, calendar, and logic.

Milestones are zero-duration events used for commitments, interfaces, gates, and acceptance—not substitutes for unmodeled work.

Schedule quality combines completeness, credible logic, realistic durations/resources, controlled constraints, and traceable status.

The schedule basis explains execution strategy, assumptions, calendars, constraints, resources, critical paths, risks, and exceptions.

Last updated: October 2026

3.7 Activities, Milestones, Schedule Quality, and Basis Documentation

An activity is a discrete element of work used to model time and sequence. It should be specific enough to status objectively and broad enough to manage. A milestone is a zero-duration event marking a significant start, finish, decision, handoff, or commitment.

Define activities well

Each activity should have:

unique identifier and action-oriented description;
authorized scope and WBS mapping;
responsible organization;
measurable start and finish criteria;
suitable duration and calendar;
resources or quantity basis where relevant;
predecessor and successor logic; and

coding needed for control and reporting.

“Mechanical work” is too vague. “Install and inspect chilled-water piping in Area B” has clearer boundaries. Avoid creating activities solely to make a report look detailed; detail should improve planning, status, or decisions.

Use milestones intentionally

Milestone types can include notice to proceed, design release, equipment delivery, beneficial occupancy, system turnover, substantial completion, and final acceptance. Because a milestone has no duration, any work needed to achieve it must appear as predecessor activities.

Distinguish contractual milestones from internal targets and interface milestones through codes and descriptions. A hard constraint is not required on every milestone; logic should calculate dates unless an external commitment must be represented.

Quality dimensions

Schedule quality is multi-dimensional:

Dimension Review question

Scope Is all required work represented once?

Logic Are relationships complete, necessary, and physically credible?

Time Are calendars, durations, lags, and constraints justified?

Resources Is the execution plan feasible with available capacity?

Status Are actuals and remaining work valid at the data date?

Control Can changes, variance, and forecasts be traced?

Compliance Does the model satisfy governing requirements or explain exceptions?

Metrics can locate suspect features such as open ends, negative lags, high float, long durations, or constraints. They are screening tools, not automatic verdicts. Review the underlying activity before deciding whether it is defective.

Schedule basis documentation

The schedule basis explains how the model was built. Include:

scope and execution strategy;
source documents and status date;
WBS, coding, and levels of detail;
calendars, shifts, holidays, and weather treatment;
duration, quantity, productivity, and resource assumptions;
procurement and stakeholder interfaces;
constraints and lag justification;
major paths and milestone logic;
risk, contingency, and exclusions;
software settings and calculation conventions; and

known limitations and exceptions.

The basis should match the native file. A narrative saying there are no hard constraints is not useful if the file contains several unexplained mandatory dates.

Example review

A delivery milestone has no predecessor and is constrained to 15 August. The reviewer asks whether it represents owner-furnished equipment. If so, add an interface from the responsible procurement or owner milestone, document the source date, and decide whether an external constraint is still required. The fix restores causal visibility.

Baseline and update use

At baseline, the quality review tests whether the model can support commitment. During updates, it also checks progress validity, logic changes, remaining durations, new constraints, and forecast reasonableness. Update the basis or narrative when material assumptions change, while preserving the original baseline documentation.

A high-quality schedule is understandable, calculable, executable, and auditable. Activities and milestones provide the model; the basis tells reviewers what the model means.

Applied review: make the schedule explainable

An activity should describe measurable work with a clear start and finish, a responsible party, an appropriate calendar, and enough detail to assign credible duration and status. Milestones are zero-duration events representing decisions, deliveries, approvals, starts, finishes, or contractual commitments. They do not perform work. The activities and relationships that cause a milestone must be present if the model is to forecast it.

Quality review combines completeness, logic, dates, calendars, constraints, resources, coding, and status integrity. Diagnostics such as open ends, excessive lags, long durations, unusual float, hard constraints, or invalid actual dates are screening tools. Investigate each result in context; a justified exception should be documented, while an unexplained exception should be corrected. Passing a numerical threshold alone does not establish quality.

The basis document makes the model reproducible. Record scope, data date, calendars, coding, duration and productivity sources, logic strategy, constraints, milestones, resource and cost-loading methods, exclusions, risk treatment, update rules, and known limitations. During review, select sample activities and trace each date to its logic, calendar, status, and assumption. A high-quality exam response preserves this evidence and distinguishes a schedule calculation from the management assumptions that gave the calculation meaning.