Classic PM: 06 Time

Abstract

All cultures have a great deal of talk about time. This is due to the fact that it is one of those resources that cannot be returned. The most interesting thing about time is that it has a double form - it gradually kills life in every organism, but along with this, «there is no better remedy than time». As in ordinary life, in management, time can both create and destroy.

PMI considers 7 processes related to Time:

• 6.1 Plan Schedule Management
• 6.2 Define Activities
• 6.3 Sequence Activities
• 6.4 Estimate Activity Resources
• 6.5 Estimate Activity Durations
• 6.6 Develop Schedule
• 6.7 Control Schedule

6.1 Plan Schedule Management

The time frame of a project is always the headache of the Project Manager - the customer and the top managers are in a hurry, the performers are delayed as a result of time is always lacking. For time management, it is desirable to create a Schedule Management Plan, which is optional and can be included in the Project Management Plan. The plan answers the following questions: «Who will make the schedule?» and «Who will evaluate the operations? How?», «What rules will be used to evaluate the operation?» and «What tools will be used to create a schedule?», «How will time management will be implemented? Who will implement it?», «What deviations from the basic schedule are considered critical? What if the delay is 2 hours? And 2 days?» and etc. Agree, these are quite complex questions that need to be answered in advance.

This document is not mandatory, but nevertheless there are recommendations to harmonize its main points, such as, deviations from schedules with the customer and senior management - this will help to avoid problems in the future. Schedule Management Plan may include:

• Time management methodology;
• Rules for the evaluation of operations;
• Rules of reaction to deviations of the plotted schedule during the execution of the project;
• Enumeration of procedures that will be used for time management;
• Timing reporting rules.

Practically, there is no clear structure for this document, you can mention whatever you want related with time. As with accompanying documentation, the more nuances you describe, the more you protect yourself from problems in the future.

6.2 Define Activities

The task of this process is to analyze Work Packages from the previously compiled WBS in order to decompose them into even smaller, more manageable and simpler elements called Activities. This process can often be carried out in connection with the Create Work Breakdown Structure process, which is not a mistake in practice, but remember that PMI regards them as two separate but nevertheless interrelated processes.

During the Define Activities, as well as during the Create Work Breakdown Structure, WBS, it is possible to apply the method of Rolling Wave Planning - adding new Activities, changing and deletion of existing Activities. That will plausible during the Project Execution phase as more information becomes available on the project Scope.

As a source to determine the list of Activities the Project Manager and Project Team can use WBS and Work Packages. The result of this process is a list of Activities required to execute in sake of project success. This list can have any format and contain any auxiliary information. Example of the list Activities, you can see here. In addition to the Activities required to complete all the Work Packages, this list may contain some checkpoints that can be set by both the Team and the customer or any other key Stakeholder. The purpose of creating key points is to indicate the stages of the project that play an important role in its execution and characterize the quality of the work.

Rule 8/80

When decomposing Work Packages, PMI recommends compiling Activities according to Rule 8/80. The essence of this rule is that the Work Work Package must be broken down to such an extent that the duration of each of its Activity must be within 8 and 80 hours. In theory, this should help to gain more control over the Activity and facilitate execution by the performer, but in practice this does not always lead to what PMI implies.

6.3 Sequence Activities

Well, we figured out what Activities need to be performed in order to complete the project, we even know which Work Packages they belong to, and more importantly, we understand what will be the result of Activities execution. But if we do them in a straight line, the project will most likely fail. In order for this not to happen, it is necessary to determine the sequence of activities, because when we dress in the morning, first we put on underwear, then shirt and suit, and only then shoes and outerwear.

After the process of Define Activities, conditional-mandatory to perform is the process of [Sequence Activities]. The result of this process is the Network Diagram, which some Project Managers consider to be an outdated tool. Their judgment is based on the fact that «Microsoft has done everything before us and it is enough to open MS Project, put in Gantt operations and ready». But they forget that:

• PMI accepts that there may not be any technical tools at hand, but the project management should not suffer as a result;
• Gantt Diagram is based on the Network Diagram, similar to which is created in the background.

As noted earlier, the result of this process is a Network Diagram, built according to the rules of the Precedence Diagramming Method (other name Activity-On-Node). The elements of this diagram are the same Activities that we defined in the process of Define Activities. It can look like this:

Each element of the diagram must have at least one preceding Activity and at least one following (exceptions are elements symbolizing the beginning and end of the execution, «Beginning» and «End»). Much more interesting are the types of relationships between elements, thanks to which it is possible to build a logical model of Project Execution, their varieties are presented in the table below:

Representation	Caption	Description
	Finish-Start (FS)	The most common type of communication. Provides execution of «Activity B» immediately after execution of «Activity A»
	Start-Start (SS)	Symbolizes that «Activity A» and «Activity B» operations start simultaneously
	Finish-Finish (FF)	Shows that «Activity A» and «Activity B» operations end simultaneously
	Start-Finish (SF)	Indicates that «Activity B» ends when «Activity A» starts

What if the Activity can start just before the end of the previous one, say 3 hours before the execution? In this case, for the simulation is applied Lag and Lead. These parameters applied to Activities allow indicating how early, or later, the connection between the active and previous (or subsequent) Activities should proceed. For example, during the construction of a house wall, it is possible to purchase paint from another city in parallel so that it arrives by the date of completion of the wall. This saves us time waiting for the paint. The delta of the time between order and completion of wall construction will be the Lead.

Lag - indicates that the start of Activity should begin N periods after the event of the previous Activity (depending on the type of communication); Lead - for N periods before the event of the previous Activity (depending on the type of communication).

In the example presented, «Activity C» should start only 10 hours before the end of «Activity A», and «Activity B» should start 10 hours after the end of «Activity A».

There is an additional type of diagram which is extended by the Precedence Diagramming Method - Graphical Evaluation and Review Technique, GERT. The only interesting difference - GERT allows to show iterative operations:

Types of Dependencies

There are three types of operation dependencies:

• Mandatory Dependency (Hard Logic) - is defined as the presence of an Activity dictated by some mandatory factor, for example, it may be the environmental obligation, requirement of contract or requirements of technical execution. For instance, geodetic work is required to ensure the accuracy of the construction of a house;
• Discretionary Dependency (Soft Logic) - a dependence that is not mandatory. This includes those connections that are defined by the Project Team. They should be at the top of the list for optimization, as they are not associated with any external requirement. For example, the purchase of paint rollers is an example of Soft Logic, because this decision is determined by a team decision (the customer does not matter how a wall will be paint);
• External Dependency - the presence of an Activity caused by an external requirement, such as the requirement by a Stakeholder, a state or international standard, corporate rules, etc. For example, compliance with GOST 74-99, is an external requirement for glazing the house.

After creating the Network Diagram, you can proceed to the evaluation of operations.

6.4 Estimate Activity Resources

This and the next process will necessarily require the participation of a Team and some kind of regulated evaluation rules.

There is a fairly wide range of sources for assessments, Estimate Activity Resources process in most cases uses an expert assessment that is highly subjective. However, all the evaluation techniques that are described in the Estimate Activity Durations process can also be used to evaluate the resources required for the execution of an Activity.

The only important point to note is that this process uses Resource Calendars, which should contain information about what resources the company will be available for the project at any given time. For example, when building a house, you need to take into account the accessibility of the truck in order to plan walls construction, for example.

6.5 Estimate Activity Durations

This process, like the previous one, is highly subjective. Because the Planning Process Group is iterative, it is assumed that with each subsequent iteration, information about the Scope of the Project will be more reliable, technical details will be more detailed, and as a consequence the duration of Activities will be more precise.

As mentioned earlier, there is a large number of evaluation tools, but most of them are based on the assumptions of Team Members or external experts. What do we need to evaluate the duration? The content. The content should be as complete as possible, that’s why the process of creating a Create Work Breakdown Structure, WBS is so important for the project. The Project Manager should adhere to the fundamental requirements of the evaluation process:

• The evaluation should be done by the person who will perform the work. Of course, this is not always possible, but PMI believes that if a member of the team gave an assessment, it means he is confident in it and risks his reputation as a professional. Of course, this adds the risk that the performer’s rating will be overestimated - the risk of additional expenditures for the same Activity;
• The evaluation should be as realistic as possible. Any overestimation is considered unprofessional. As mentioned earlier, the content should be drawn up as accurately as possible, which will allow the examiner to give the most accurate estimation of the duration of the Activity and, therefore, the Cost;
• The quality of the resource should be taken into account when estimating costs. When evaluating the duration, it is necessary to take into account who will perform the work, what equipment, etc. For example, if you dig a trench excavator, this will take less time than if you do the same job with a shovel.

The examiner can use the following tools to assess:

One-point Estimating

This is an estimate that is used in most cases, although it is considered to be extremely inaccurate. This can be both expert evaluation and information from previous similar projects, it can also be just an assumption. It is necessary to remember that an examiner may try to overestimate the valuation in order to protect himself, which will cause a failure to evaluate objectively (at a good quality) the risks of the Activity.

It is recommended to make this assessment only in the early phases of the project. When there is too little information about the Scope.

Analogous Estimating (Top-down)

As the name suggests, this assessment is based on looking at historical information to find previous similar Activities.

Parametric Estimating

An estimate based on any parameters, performance standards, etc. For example, the standard time for building one wall of a house is 2 days, then four walls should be ready in 8 days. The examiner can make an assessment in one of the following ways:

• Regression Analysis (Scatter Diagram) - the diagram is plotted points with performance indicators from previous similar Activities and shows the average;
• Learning Curve - when performing similar Activities, the performer will learn better and better to perform this Activity, which will lead to an increase in speed and quality of execution.

Heuristics Estimating

Evaluation, which is expressed as the share of the project’s Activity. For example, laying the foundation takes about 20% of the time to build a house, building walls - about 30%, painting - 5%, etc.

Three-point estimating (PERT Analysis)

This type of assessment requires special attention. This assessment is similar to the One-point Estimating not only in name, but also in content, but is based on three assessments - the Most Pessimistic (P), the Most Expected (M) and the Most Optimistic (O). All three estimations can be obtained using any of the tools described above. The evaluation itself is formed by these three indicators, applied according to the formula:

$$''EAD''=\frac{''P\; +\; 4M\; +\; O''}{6}$$

, where Expected Activity Duration, EAD is the most likely duration of Activity according to PERT Analysis.

$$''ASD''=\frac{''P\; -\; O''}{6}$$

, where Activity Standard Deviation, ASD - an indicator of how much the Activity can deviate from PERT.

$$''SSAV''={\frac{''P\; -\; O''}{6}}^2$$

, where Standard Square Activity Variance, SSAV is the scattering rate relative to the standard deviation.

Estimation example (hours are used as time units):

Activity	P	M	O	PERT	SD	SSAV	Total Duration
Foundation laying	28	23	22	23.(6)	1.5	2.25	23.(6) +/- 2,25
Building walls	52	48	39	47.1(6)	3.25	10.56	47.1(6) +/- 10.56
Painting walls	18	12	9	12.5	2.25	5.06	12.5 +/- 5.06
Roof installation	20	17	15	17.1(6)	1.25	1.56	17.1(6) +/- 1.56

With the calculation of operations is clear, and the duration of the project also count the same way? No, the duration of the whole project is considered slightly different, although the principle is one. To do this, we need to take a little step forward and understand what the critical path is. Critical Path is the longest path on the Network Diagram from the first Activity to the last.

• In order to calculate the Expected Project Duration, EPD, it is necessary to count the sum of the Expected Activity Duration, EAD lying on a critical path;
• To calculate the Project Standard Deviation, PSD, it is necessary to calculate the square root from the sum of the Activity Variance, AV of each Activity lying on a Critical Path of the project;
• Standard Square Project Variance, SSPV is the Project Standard Deviation, PSD in a square;
• The possible duration of an Activity is calculated in the same way as for standard Activity.

All these parameters, both for a single Activity and for the entire project, are applied to calculate the reserved resources for the project (see Project Reserves). For example, all the Activities listed in the table above, the Building walls Activity is at the highest risk and will require more attention by the Project Manager and the Team.

Now let’s summarize the understanding of the Estimate Activity Resources processes and Estimate Activity Durations processes with the following rules:

• The estimates should be based on a WBS that is correctly and as detailed as possible;
• Assessment should be carried out by the performer;
• Historical information is a good helper to increase the accuracy of the assessment;
• The Integrated Change Control procedure should be followed to avoid problems with the Schedule;
• Three-point estimating (PERT Analysis) is the most preferred tool to estimate both resources and duration;
• Activities «overestimation» is not allowed;
• Evaluations should be as objective as possible;
• Upon completion of the assessments, a full Risk Analysis should be performed;
• The Project Manager is fully responsible for the approved project schedule and planning of each Activity.

6.6 Develop Schedule

For many project managers, the schedule is associated with the Gantt Diagram, although PMI’s management methodology concerns it very superficially, considering it only as one of the tools of the graphical representation of the Schedule [Schedule].

So what is the process of creating a schedule in the PMI view? In principle, all previous processes - Define Activities, Sequence Activities, Estimate Activity Resources and Estimate Activity Durations, are preliminary to the main scheduling process - Develop Schedule.

Before the schedule is approved, it must be analysed and constructed as effectively as possible. One or more of the following methods are used:

• Critical Path Method;
• Schedule Compression;
• What-if Analysis;
• Resource Leveling;
• Critical Chain Method.

Critical Path Method

First, let’s deal with some terms.

Critical Path is the longest path from start to finish in the Network Diagram. In all subsequent examples, the Critical Path will be highlighted by a bold line. Of course, for all Activities lying on the Critical Path, special attention should be paid by both Team and Project Manager, but in order to accelerate the Execution of the Project, it is necessary to shorten the Critical Path.

Path close to critical - Near-Critical Path is the second longest path.

Float / Slack - from the name everything is clear what it is talking about. There are three types:

• Total Float / Slack - is a kind of Float / Slack, which is available for Activity given that the operation will not delay the Execution. For example, if you drive from point A to point B 1 hour and doing some activity simultaneously (say, listen to the audio recordings) for 40 minutes, then the Total Float / Slack will be equal to 20 minutes;
• Free Float/ Slack - a Float / Slack that will not delay the execution of an Early Start, ES of all subsequent Activities. The concept of Early Start, ES will be considered later;
• Project Float / Slack - a Float / Slack that will not violate the Requirements of the interested Stakeholders, terms in the contract or any other external to the content of the project’s duties.

It is quite logical that those Activities that are on a Critical Path do not have a time reserve. If the operation is delayed during the execution of the Project, you should update the Network Diagram and indicate that these Activities have a negative Float / Slack - that will entail negative reserves. This is better to highlight such Activities somehow (for example in a separate document), because definitely no negative Floats/Slacks are plausible.

Considered a Float / Slack is simply the difference between Early Finish, EF and Late Finish, LF or Early Start, ES and Late Start, LS. So what is Early Start, ES and Late Start, LS? This is a time indicator that shows the most favorable Activities flow, that will allow to begin the Activity. Late Start, LS demonstrates when an Activity can be completed in the worst case. The opposing view is for Early Finish, EF and Late Finish, LF.

We’re done with the terms, but still a bit complicated, isn’t it? It will be clearer when we analyze the example of the Critical Path bellow. So, let’s say we have the following diagram for one of the Work Package of our project:

1. First, it is necessary to specify the estimated duration for each Activity in the process of Estimate Activity Durations. In the middle cell of the top row:

2. Next, for each Activity we have to define Early Start, ES and Early Finish, EF. Everything is very simple - moving left to right, we indicate Early Start, ES as the maximum Early Finish, EF among all previous Activities; Early Finish, EF - is a sum of Early Start, ES and duration of a prticular Activity:

3. After that, we have reached the last element (the «End»), the direction is reversed. Now the «pass» through is executed from right to left and we count Late Finish, LF as the maximum Late Start, LS among all subsequent Activities (those that are to the right of the reviewed Activity). The Late Start, LS will be the difference between Late Finish, LF and Activity duration:

4. The last action will be to count the temporary reserve for the Activity. Remember that this is the difference between Early Finish, EF and Early Start, ES or Late Finish, LF and Late Start, LS.

And, that’s it - the analysis of the Critical Path Method is complete. In the example above, you can see that the project is supposed to last 40 time units. There are few notes on the Critical Path Method bellow:

• Project may include several Critical Paths, but it is desirable to avoid this - that will increase the project’s Risks;
• The Reserve can be negative, it is necessary to indicate this after the completion of Activity. If this event has occurred, it is necessary to make adjustments to the work plan and seek compensation for lost time in subsequent operations, and how this can be done is discussed below;
• Network Diagram should not be linked to calendar dates. However, it depends a lot on them - if the project start date is changed, the Resource Calendar may be changed as well, which can cause a change in the duration of the Activity. But with constant estimates of duration, there should be no influence;
• The resulting Network Diagram, can be applied to the calendar and used as start and end dates of the project.

Schedule Compression

That’s eternal headache - what can be reduced, shortened, accelerated and etc. PMI highlights several techniques that the manager should apply before the mentioned above.

Fast Tracking

This technique allows to reduce the execution time of Activities in the Work Package or the whole project by parallelizing the works. But only those Activities that are on the critical path need to be parallelized. For example, if we do have enough resources, it will not be useful to build a wall and then paint it. Combining works plrinciple assumes that during the building a wall the painting process will be processed immediately after construction each tiny part of a wall.

Crashing

This technique exchanges money for speed of Execution, in other words we buy the acceleration of work. How it will be carried out, PMI does not say, because there are many ways, for example, you can hire additional employees to perform a specific Activity, give the Work Package on contract work, pay Team Members overtime, etc.

Remember that this approach to compressing the schedule is considered a backup in case there are no other options left. The PMI does not make a clear statement, but suggests that we should negotiate and try to avoid Budget increases in every way possible and conduct high-quality Risk Analysis.

What-if Analysis

This tool with a familiar name, allows to predict the possible flow of the project when an event occurs. The best known method is the Monte Carlo Method. Below are some of its key features:

• It provides an understanding of the likelihood of completion within a given Budget and time frame;
• Allows to calculate the overall Risks of a project.

Resource Leveling

This techinique applied on projects with very limited resources. Many projects have a single resource load that «leaps throughout the project. This tool allows you to balance the load on a loaded resource by shifting work to other resources, thereby reducing the duration of Activities on a Critical Path.

Project Schedule

There are several ways to display a schedule and each one is designed for specific purposes.

Milestone Chart

This diagram shows checkpoints called Milestones that correspond to a critical event for the project. For example, for the house Milestones can be considered Foundation laying, building walls, roof installation, windows installation, adjusting heating system, fencing installation, and etc. The result of Milestone plotting should be tangible, i.e. better indicate one of the Deliverables, but it can also be some important event for the project (such as the scheduled date of audit, inspection or equipment documentation and others). The Milestone Chart is very convenient as a plan for management or customer. It can look like this:

Gantt Diagram

This diagram is well-known by every Project Manager, so it makes no sense to stop at it, we will give only an example:

The only thing to note is that this diagram is best used to present your Project Team as a tool for planning and managing the project.

Schedule Baseline

As noted earlier, the evaluation of Team and Project Manger performance is done through three tools, one of which is the Schedule Baseline. The Schedule Baseline is the current version schedule (the version of a schedule that is currently accepted). It can be presented in any way (preferably one of the above ways), but it must be officially approved. The Schedule Baseline cannot be modified by a change that didn’t pass through the Integrated Change Control process.

6.7 Control Schedule

The main purpose of this process is to measure, measure and measure again the current state of the project against to the planned. There are a number of indicators that show the speed of project execution - Schedule Performance Indicator, SPI and Schedule Variance, SV. They are discussed in more detail in the article on the knowledge area of Cost.

Another action that can (or will most likely) be carried out is to find the source of the problems and try to eliminate them. For example, one member of the Team is not able to properly install fencing for the house, which causes delays. The solution is to create a request to replace an executable resource (this particular person). The PMI also recommends to completely abandon the project, if it is obvious that its execution (in particular within a limited time frame) is impossible.

The secondary responsibilities of the Project Manager in managing the schedule are:

• Revaluation of Activities and Work Packages;
• Analysis of reports from the executors (Team Members and contractors);
• Use of Time Management knowledge tools to identify opportunities for project acceleration.

All this can initiate a Change Request, both in the area of schedule and in any other area such as Human Resources, Cost, Quality, etc.