ELC 347 DAY 8

Agenda Questions Assignment 3 Corrected  4 A’s, One non-submit Assignment #4 Due Capstone Proposal Due Group Progress report due Exam 2  Slight Change 10 M/C (5 points each) 5 essays (10 points each) 1 hour 15 minutes Open book, Open Notes  Ghattas 4-8, Project 8-10 Group Project Meeting (30 Min) Discussion on Network Analysis and Duration Estimating

Network Analysis and Duration Estimating Laying the Groundwork for Commitment Setting Duration Estimates Determining the critical Path Meeting external deadlines

Groundwork for commitment Ask the people that actually doing the work If more than one is capable ask the one with the most experience Be realistic Be an advocate for your team

Duration Estimating Duration – the elapsed time from the start of an activity until it is finished Effort -- the actual time spent on the project Example  Tony work on a project task for 20 hours at 4 hours per day starting Monday mourning. The project task was completed Late Friday Effort – 20 hours Duration – 5 days

Techniques for Estimating Duration Experience Historical data Research Modeling Experiments Breakdown/roll-up Delphi Method  Panel of experts Consultants Three outside Estimates Ranging Other techniques

Special Cases (Out of your hands) Inspections Deliveries Breakdowns and repairs Approvals

Normalizing Duration Goal is most “cost-efficient” plan  Determine the most cost-efficient technical approach  Make and estimate of long the most cost efficient method will take to complete  Selectively adjust you estimate for any activity that is subject to common problems.

CPM versus PERT PERT was developed by US Navy in the 1950s’ CPM was developed by Remington Rand and DuPont around the same time. Only difference is in durations estimating  Pert uses 3 cases Most optimistic, most pessimistic and most likely and determines probability for each D o P o + D p O p +D e P e = final duration  CPM use only the most likely duration

Calculating a Project Duration Determine each activity and its predecessors Determine an estimated duration for each activity Find the “Critical Path”  Add up the durations along the critical path

Whats the “Critical Path” The longest path based on precedence of activities and durations through a PERT/CPM network It’s critical because  Its combined length determines the length of the project  It has NO slack  Delay of any activities on the critical path delays the entire project

Finding the critical path Use “forward pass” Calculations Each activity should have  EPS  earliest possible Start time  EPF  earliest possible finish time  DUR  duration  EPF = EPS + DUR EPSDUREPF Activity

Example 347 A 7512 B

Special Case If an activity has more than one processor its EPS is set to the latest EPF of all its processors 347 A 7512 C 055 B

An example of forward pass 000 Start F 044 D C Finish 055 A I J 448 E H G 549 B

Backwards Pass Use to calculate Slack  LAS -> Latest start time  LAF -> Latest finish time  TS -> total slack EPSDUREPF Activity LASTSLAF

An example of backward pass 000 Start F D C Finish A I J E H G B

Examine Critical Path for Reality Check Is the total duration typical? Are the durations of the CP activities typical? Reexamine all CP activity durations Reexamine assumptions

Optimizing the plan Would bringing more expert talent to bear on the project speed it up? Are there changes we could make in the resource procurement process to shorten wait times? Would round the clock scheduling shorten duration? Would more money motivate the team to work faster? Would an organizational change speed things up? Do we think it will take this long just because it always has, or are there other ways to so this, which we haven’t thought of yet, that would shrink the timetable?

3 Lines of defense Relieve the critical path Sharpen your pencil Crash activities

Summary Construct a CPM Estimate normal durations Do a forward pass Identify Critical Path Optional  Do a backward pass to identify slack times Conduct a reality check Optimize the plan  1 st line of defense - relieve the critical path  2 nd line of defense - sharpen your pencil  3 rd line of defense - crash activities