Step 3 – Identify milestones Project planning

4.3 Project planning 71 performed during the last eight weeks of the project. In reality, however, you would probably be working on your project’s report throughout the lifetime of your project and the activity identified here really represents the final drawing together of the report; checking and completing your references, writing your abstract and contents listing, proofreading and spell-checking. There are three additional markings to Figure 4.5 that are not shown in the example of Figure 4.4, which have yet to be explained. The first point to note is that the milestones identified earlier have been included as diamonds called M1 and M2; M1 being the com- pleted literature survey and M2 representing the completed project. Notice how these have been placed in the relevant positions on the diagram and represent the completion of the significant step they are identifying. The second point to note is that dates and durations have been added to each task node. Each activity now has two figures – the start date of the activity, shown at the top left of each node, and the duration of the activity in weeks, shown on the top right. These durations are taken from the time estimates made earlier in Table 4.1. It is up to you what time ‘granularity’ you use for your project hours, days, weeks, months or even years but, in a student project of this size, weeks or months are suitable. For simplicity it will be assumed that a month consists of exactly four weeks and there are no breaks in the project for holidays However, in reality holidays, sickness, revision, field trips and the like can often impede your progress and these events should be considered when forming project plans. The date, which is noted at the top left-hand corner of each activity, represents the time at which that activity can start. For activities that can start straight away i.e., they do not need any other activities to have completed beforehand this is simply the start date of the project. In the example, three activities can start straight away – Literature search, Get stock market data and Investigate and evaluate ANNs. All these activities have the same start time – 1 January – which represents the start date of the project overall this start date has been chosen for simplicity. To calculate the start times of subsequent activities it is necessary to look at the tasks leading into them. For example, in this simple case, Literature review can begin as soon as the Literature search has completed. As the Literature search takes eight weeks to complete approximately two months the Literature review can begin from 1 March onwards. The first milestone M1 – complete literature survey occurs when this review is completed and consequently, as the review takes four weeks to complete approxi- mately one month, M1 will should occur on 1 April. Notice how M1 has no duration associated with it because it does not represent any work but simply an event in time. Calculating the start time for activities with more than one task leading into them is not quite so straightforward. When two or more tasks lead into another, that task can only start when all its preceding tasks have completed. For example, in Figure 4.5 notice that Train ANN starts on 14 March – this is when you would expect Develop and test ANN to complete, not when Get stock market data has completed which is due to finish on 7 January. Remember that subsequent activities can only begin when all preceding activities leading into them have completed. Continuing with the calculation of start times for each activity in the project, the final milestone, M2 completed project, is reached. Thus, it is possible to conclude that the project should be completed by 1 August. However, this may be optimistic, as it does not account for any delays or problems that might occur. 72 Chapter 4 n Project planning and risk management The final additional marking to this network diagram is the critical path which still requires explanation. This path is the longest route through the project network and is represented in Figure 4.5 by the bolder arrowed lines. It identifies the activities in the project that must not be delayed, as to do so will delay the project overall. For example, if Complete report were to take twelve weeks instead of eight, the project would finish on 1 September – four weeks later than before. This is because Complete report lies on the critical path and any delay to this activity will therefore affect the project overall. To identify the critical path you work backwards through the network diagram from the project’s final milestone. Begin, therefore, at M2 and look to see which tasks leading to this milestone is causing it to occur on 1 August. There is only one activity in this case leading into M2, Complete report, so this task is on the critical path. Looking next at Complete report we see, once again, that only one task leads into it – Analyse and evaluate. Consequently, Analyse and evaluate must also be on the critical path. You continue to work your way backwards through the network, along the critical path, until you either reach the project’s start or an activity that has two or more activ- ities leading into it. In the latter case, Review statistical tests is the first activity in this situation. However, just as before, you look back through the network to see which activityies is are forcing Review statistical tests to start on 14 April and see that, in this case, it is Use stock market models not Train ANN. Use stock market models is also, therefore, on the critical path. Continue in this way, working backwards through the network, until you reach the start of the project – in this case ending up at the Literature search . The critical path is thus identified by the bolder arrowed lines linking each of these critical activities together. There is no reason why you cannot have more than one critical path in your project network. In some cases, two or more activities may force a subsequent task to start on a particular date. In these cases, proceed as before, following all critical paths back to the start of the project or to a point where they rejoin. The activity network is now complete. This representation has made several assumptions. The first is that you can perform several tasks simultaneously. This often happens in computing projects where you might, for example, be performing aspects of your literature search and literature review alongside an initial systems analysis or program design. This also allows you to avoid becoming bored with one activity or another because you can switch between them as your project progresses. However, although identifying several simultaneous tasks may be satisfactory for group projects, where several members of the project team can work on tasks separately, for individual projects this can cause a problem. To identify instances when you are expecting to work on too many activities simultaneously and to see how you can deal with this problem, you must use a Gantt chart, which is intro- duced in the following section. The second assumption made is that once activities are completed, they are finished with and your project moves on. In reality, however, many activities are ongoing throughout the lifetime of your project, for example, the literature survey and report writing. However, emphasis on these ongoing activities changes as the project pro- gresses. There are also situations where activities are repeated and you find yourself performing a loop – for example, the literature search and literature review, which are part of the repetitive literature survey process discussed in Chapter 5. An example of loops occurring within software development projects is when an evolutionary prototyping approach is used. This approach is discussed in detail in Chapter 6.