Author: Xu industry ceremony
The schedule is to plan the project from the perspective of time, and the cost estimate is planned from the perspective of fees. The cost here should be understood as an abstract concept, which can be worker, material or personnel, etc.
Cost estimation is an estimate and plan to complete the cost of the project is an important part of the project plan. To implement cost control, we must first conduct cost estimates. Ideally, the cost required to complete a task can be estimated according to historical standards. But for many industries, due to the multi-end of the project and plan, the previous activities is almost impossible to compare the previous activities. The information of the fee, regardless of whether or not according to historical standards, it can only be used as an estimate. Moreover, in a large-scale large project, it should also take into account whether the employee wage structure will change in the next few years. How is the rise in raw material costs in the next few years, the business foundation, and the management fee will not be in the life cycle of the project. Problem. Therefore, cost estimates are obviously in an environment that cannot be expected in highly reliable. In the process of project management, in order to make the resources within the time, costs, and the range of work, people have developed a lot of cost estimation methods to try to get better estimates. Here is a brief introduction to the following.
1. Empirical estimation
The estimated person should have expertise and rich experience, which proposes an approximate number. This method is the most original method, it is not yet estimated, just an approximate guess. It is ok to request a probably digital item soon, but it is obviously not satisfied with the requirements for detailed estimation.
2. Factor estimation
This is a relatively scientific traditional estimation method. It predicts the future, and uses mathematical knowledge. Its basic method is to utilize scale and cost diagrams. As shown in the figure, the line on the figure represents the relationship between the scale and cost. The point on the graph is depicted according to the data of similar items, according to the lines depicted in these points, reflecting the basic relationship between scale and cost. It is a straight line here, but it may be a curve. Costs include different components, such as materials, manual and freight, etc. These can have different curves. After the project size knows, you can use these lines to find approximate numbers of the cost of each different components.
It should be noted here that there is a "benchmark year" to find these points to eliminate the influence of inflation. The point drawn on the figure should be the adjusted number. For example, in 1980, the number of other years is adjusted for 1980, and then the scribe is described. After the project size is determined, the corresponding point is found from the line, but this point is the number based on 1980, but also needs to be adjusted to the same year, it is the estimated cost number. In addition, if the project cycle is longer, it should also take into account the factors such as inflation and material price increases in the next few years.
To do this cost estimate, premise is the information similar to the project, and these information should be comparable on the same basis.
3. Comprehensive detailed estimation based on WBS
That is, the WBS method is used, and the project task is first subdivided, and the extent to which you can confirm, such as some kind of material, some device, a moving unit, and the like. The cost of each WBS element is then estimated. Prerequisites or prerequisites for adopting this method are:
1 A complete limit for project requirements. 2 Develop the logic steps necessary to complete the task. 3 Prepare the WBS table.
The complete limit of project requirements should include a work report, a specification, and a total schedule. The work report refers to the narrative description of the work required to implement the project, which should confirm the necessary goals. This information should also be included if there is a restriction of funds. Specifications are based on workers, equipment, and material prices. It should be able to make the project staff and users to understand the basis of the equipment and materials. The overall schedule should clarify the main stages and split points of the project implementation, including long-term order, prototype test, design review conference, and any other key decision point. If possible, the total schedule for guiding cost estimates should contain the calendar time of the project start and end.
Once the project demand is paoraped, the logic steps necessary to complete the task should be developed. In modern large-scale complex projects, it is usually used to indicate the logical program of the project task, and use this as the next step to draw the CPM or PERT chart and the WBS table according to the next step. The easiest way to prepare the WBS table is based on the arrow map. Take each activity on the arrow chart as a task, and then draw a sub-work task on this basis.
After the schedule and the WBS table are completed, the cost is estimated. In large projects, the results of cost estimation finally appear in the form of the report:
1 Estimation of detailed costs for each WBS element. There should also be a summary table for each sub-work, division task, and the accumulated statement of the project and the entire program. 2 Planning time curve of each department. If the departmental working time curve contains "peaks" and "valley", it should be considered several changes to progressive to obtain work hours. 3 Summary of working hours on month by month. In order to cut the project, the project leader can take advantage of this table and work time curve. 4 Annual cost distribution table. This table is divided by WBS elements, indicating costs required for annual (or quarter). This table is essentially a summary of project cash flow for each activity. 5 raw materials and expenditure predictions, it indicates that the supplier's supply time, payment method, obligation, and cash flow for payment raw materials.
This method is used to estimate the cost needs to make a lot of calculations, and the workload is large, so it also requires a certain amount of time and cost itself. However, this method is high, and these reports made in this method are not only the expression of cost estimation, but also as a basis for project control. The highest management can use these reports to select and approve the project to assess the priority of the project. More than three cost estimates are described above. In addition, several methods can also be used in practice. For example, the main part of the project is estimated, and other parts are estimated by past experience or by factor estimation.
