tailieunhanh - Project Planning Control 4 Episode 7

Tham khảo tài liệu 'project planning control 4 episode 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The case for manual analysis forward pass. Almost invariably the total time is longer than the deadlines permit. This is when the real value of network analysis emerges. Logics are reexamined durations are reduced and new construction methods are evolved to reduce the overall time. When the final network - rough though it may be -is complete a sense of achievement can be felt pervading the atmosphere. This procedure which is vital to the production of a realistic programme can of course only be carried out if the blocks are not too large. If the network has more than 300 activities it may well pay the planner or project manager to re-examine that section of the programme with a view to dividing it into two smaller networks. If necessary it is always possible to draw a master network usually quite small to link the blocks together. One of the differences between the original PERT program and the normal CPM programs was the facility to enter three time estimates for every activity. The purpose of the three estimates is to enable the computer to calculate and subsequently use the most probable time on the assumption that the planner is unwilling or unable to commit himself to one time estimate. The actual duration used is calculated from the expression known as the p distribution a 4m b t where te is the expected time a the optimistic time b the pessimistic time and m the most likely time. However this degree of sophistication is not really necessary since the planner himself can insert what he considers to be the most probable time. For example a foreman upon being pressed estimated the times for a particular operation to be Optimistic - 5 days Pessimistic - 10 days Probable - 7 days The planner will probably insert 7 days or 8 days. The computer using the above distribution would calculate 5 4 X 7 10 te 6 - days 159 Project Planning and Control With the much larger variables found in real-life projects such finesse is a waste of time and a single entry is all .