PERT/CPM
Network analysis techniques identify early and late start and finish dates for the uncompleted portions of project activities. The Program Evaluation and Review Technique (PERT) and the Critical Path Method (CPM) are examples of network analysis techniques.
The Program Evaluation and Review Technique (PERT) is an event-oriented technique used to show all the project tasks, dependencies, and earliest and latest start times for each task in graphical form. It is used to estimate project duration when there is a high degree of uncertainty with the individual activity duration estimates.
The Critical Path Method (CPM) is a technique used to predict project duration by analyzing which sequence of activities (which path) has the least amount of scheduling flexibility (the least amount of float). The critical path identifies the activities in the project plan which have the most potential to delay the project end date.
Gantt charts produced in this form are:
- graphical;
- easy to read;
- easy to update.
There are no widely accepted standards for Gantt charts. Automated tools are available which produce Gantt charts directly from activity networks or from a full definition of the tasks.
Automated tools have features which assist the planning function including:
- display of original and latest time for task;
- display of person(s) allocated to tasks;
- integration with other planning techniques (i.e. networks and milestones).
Task Analysis Methods: Observational Techniques
Overview
Observational techniques are a general class of techniques whose objectives are to obtain data by directly observing the activity or behaviour under study. A wide range of observational techniques are commonly used and combined according to the particular requirements of a study. Observations may be direct observations, where the investigator is actually present during the task (visual observations, remote observations via closed-circuit television), or indirect observations, where the task is viewed by some other means such as video recording or time-lapse photography.
Application
Perhaps the most obvious method by which the user can be analysed is to observe him or her performing the task in an operational situation. Although observational techniques can capture the details of many individual tasks, they may not elicit the work role. Thus, observational techniques are most appropriate when the information of primary interest is of visual or auditory form. Thus, observation methods can be especially useful for recording physical task sequence, or verbal interactions between several people. One method which can augment the information gathered is that of current verbal accounts. Here the user is asked to 'think aloud' and describe the activities he or she is performing as they are undertaken.
Advantages
Observational techniques produce information which cannot be collected in any other way. Indeed, detailed physical task performance, social interactions, surrounding influences can be recorded.
Observation methods allow the observer to become more familiar with the task. So they are very appropriate for exploratory studies because they allow the investigator to decide what to look for.
Observation studies can be used to identify and develop explanations of individual differences in task performance.
Observational techniques provide data which can be compared and contrasted with information collected by another investigator, or by another method.
Disadvantages
Real time observation requires trained ergonomists.
Observational data is the widest possible form of information, for this reason the effort which must be expended on classification and analysis is considerable.
Direct observation can be an intrusive technique. The user behaviour might be influenced by the presence of the observer,. Therefore the investigator must estimate whether the type of observation selected will significantly alter the task under study.
Observational situations which produce rich context data are rarely the ones which produce precise and controlled data. So data will be incomplete, inconsistent and sometimes unusable
Observational techniques cannot provide information about underlying thought-processes, and so they will be of very little use for highly cognitive activities.
The equipment needed for producing high quality observational data can be expensive and difficult to install, and video recording followed by later analysis is time-consuming.
Type of Observational Technique
Passive observation
At the simplest level passive observation, where the person conducting the observation quietly observes and records the user activity, can be used to record some details of the processes which the user undertakes. Passive observation has the advantage that it minimises the intrusion which the user experiences. One problem with passive observation is the practical difficulty in recording sufficient detail of the activity. This can be overcome through the video recording of user activity which, after transcription into textual form, can provide a highly detailed analysis.
Participant observation
The investigator takes part in the tasks alongside other operators. It may be a useful data collection approach if skilled performance is such that actions are "semi-automatic" in which case users may find it difficult to verbalise how they are achieving the task goals. This type of observation can also be useful if aspects of team performance are being investigated to understand how the team members are organised and perform their tasks.
Communication and conversational analysis
Investigation of the patterns in the organisation of people's interaction (it would be possible to use the principle of analysing a conversation between two travellers, or one traveller and one transport enquiry office operator in real situations, in order to identify the needs for the traveller in specific contexts, what are the difficulties encountered, how a system could resolve these difficulties,... ). One of these methods is the language / action approach which considers the language as a means by which people act. Advantage of this method : it provides a complete and logical conceptual frame in order to investigate all kinds of conversation. Disadvantage of this method : many situations are characterised by subtle communication processes not taken into account by the model. There is also a difficulty in labelling an interaction and a message especially if they do not fit into the request or promise categories.