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2/21 Project Management. Roll call/ collect homework Go over homework(?) Project management: Critical Path Method Small groups Assign homework Discuss midterm exam. Project Modeling. Project: build a house. Various tasks to be accomplished to achieve this goal: get permits
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2/21 Project Management • Roll call/ collect homework • Go over homework(?) • Project management: Critical Path Method • Small groups • Assign homework • Discuss midterm exam
Project Modeling • Project: build a house. • Various tasks to be accomplished to achieve this goal: • get permits • pour foundations • install electrical systems • install plumbing systems • connect systems to public systems • frame walls • install flooring
Project Modeling: CPM • How to organize? How to plan? • How long will the entire project take? • Critical Path Model - Terms • Activity on Node • predecessor • duration
Project Modeling: CPM • How to organize? How to plan? • How long will the entire project take? • Critical Path Model - Terms • Activity on Node • predecessor • duration
Project Modeling: CPM • How to organize? How to plan? • How long will the entire project take? • Critical Path Model - Terms • Activity on Node • predecessor • duration As long as the longest (duration) series of activities takes -- also call the CRITICAL PATH.
Critical Path Method - Terms. • Activity on Node Arc: precedence A 6 B 8 Start Finish Duration (EX: hrs., days) Nodes: activities
Critical Path Method: Terms • “Activity A must be done before B can begin.” - Activity A is a PREDECESSOR of B. A 6 B 8 Start Finish Arc: precedence Nodes: activities
Critical Path Method: Terms • “Activities A and B must be done before C can begin.” - A & B are PREDECESSORS of C. A 6 C 5 Start Finish B 8 Arcs: predecessors Nodes: activities
Critical Path Method • “Activity A must be done before C and B can begin.” B 8 A 6 Start Finish C 5 Nodes: activities Arcs: predecessors
EX: build a house • Project tasks: • install landscaping • pour foundations • frame walls • install plumbing systems • get permits • install electrical systems • move in.
EX: build a house: tasks in order • get permits • pour foundations • frame walls • install plumbing systems • install electrical systems • install landscaping • move in.
EX: build a house: durations Durations: • get permits • pour foundations • frame walls • install plumbing systems • install electrical systems • install landscaping • move in. 2 6 5 4 6 9 3
EX: build a house: label activities Durations: Durations: • A: get permits • B: pour foundations • C: frame walls • D: install plumbing • E: install electrical • F: install landscaping • G: move in. 2 2 6 6 5 5 4 4 6 6 9 3 3
EX: build a house: create table Durations: • A: get permits • B: pour foundations • C: frame walls • D: install plumb. • E: install elec. • F: install landscaping • G: move in. 2 Act. Dur. Preds. Post. A 2 -- D B 6 -- C,F C 5 B D D 4 A,C E E 6 D G F 9 B G G 3 E,F 6 5 4 6 9 3
EX: build a house: create graphic CPM A D E C G start finish B F
EX: build a house: add in durations A 2 D 4 E 6 C 5 G 3 start finish B 6 F 9
But what is the Critical Path? (We must tell the family when the house will be done -- how soon?) A 2 D 4 E 6 C 5 start G 3 finish B 6 F 9 The critical path is the path of activities that takes the longest amount of time; the path with the activities that cannot be altered time-wise without changing the overall project duration.
What is the Critical Path? Add up all the paths possible; see what path is the longest. That path is the critical path. A-D-E-G = 12 B-C-D-E-G = 24 B-F-G = 18 A 2 D 4 E 6 C 5 start G 3 finish B 6 F 9
Defining slack, ES, EF, LS, LF • Slack: how much extra time you have available for a particular activity. • ES -- early start: the earliest possible time you could begin a particular activity. • EF -- early finish: the earliest possible time you could finish a particular activity. • LS -- late start: the latest possible time you could begin a particular activity. • LF -- late finish: the latest possible time you could finish a particular activity.
Calculating slack, ES, EF, LS, LF • Slack = (time available) - (duration) • ES = (calc. time at the beginning of the node) • EF = ES + duration • LS = LF - duration • LF = (calc. time at the ending of the node)
Calculating slack Any activity on the critical path has NO SLACK. Any others are based on when they meet the critical path. EX: Activity A requires two days, but there are 11 days available ( Activity A meets the critical path at “start” (0) and at D. 11 days have passed on the critical path before getting to D (B+C=11). A 2 D 4 E 6 C 5 start G 3 finish B 6 F 9
Calculating ES (Early Start) Early start is the earliest possible time the activity could start. EX: Activity A could start (at the earliest) at 0. Activity D could start (at the earliest) at 11 (CP – No slack) Activity F could start (at the earliest) at 6. A 2 D 4 E 6 C 5 start G 3 finish B 6 F 9
Calculating EF (Early Finish) Early finish is the earliest possible time the activity could finish. EF = ES + Duration. EX: Activity A could finish (at the earliest) at 2 (0 + 2). Activity D could finish (at the earliest) at 15 (11 + 4) (CP). Activity F could finish (at the earliest) at 15 (6 + 9). A 2 D 4 E 6 C 5 start G 3 finish B 6 F 9
Calculating LF (Late Finish) Late finish is the latest possible time the activity could finish without affecting the overall project time. EX: Activity A could finish (at the latest) at 11. Activity D could finish (at the latest) at 15 (Crit path – no slack). Activity F could finish (at the latest) at 21. A 2 D 4 E 6 C 5 start G 3 finish B 6 F 9
Calculating LS (Late Start) Late start is the latest possible time the activity could start w/o affecting the overall project time. LS = LF – Duration. EX: Activity A could start (at the latest) at 9 (11 – 2). Activity D could start (at the latest) at 11 (crit. path – no slack). Activity F could start (at the latest) at 12 (21 – 9). A 2 D 4 E 6 C 5 start G 3 finish B 6 F 9
A 0 2 2 9 11 Labeling the CPM Basic model: D 10 15 4 10 15 E 15 21 6 15 21 C 6 11 5 6 11 start G 21 24 3 21 24 finish B 0 6 6 0 6 F 6 15 9 12 21
Small Group Exercise • Installation of a computer system comprises eight activities. Draw the network model, calculate the ES, EF, LS, LF, and slack for each activity.
Homework Ch. 10 #2 (just draw the CPM model in Excel) Ch. 10 #4 (draw the CPM model in Excel, calculate the critical path.) Ch. 10 #8 (draw the CPM model in Excel, calculate and label all activities with ES, EF, LS, LF. Calculate the critical path. Calculate the slack for each activity.) Ch. 10 #9 (calculate the critical path, calculate the ES, EF, LS, LF, and slack for each activity)
About the Midterm Exam • Three versions – make sure you do the right one. • NO COLLABORATIONCollaboration=Cheating • When you open the spreadsheet, click on “Enable Macros” (if it comes up). • The midterm is posted (by 9 p.m. Thursday) athttp://www.adbook.net/teach022/305/m.htm • It is due by 9:00 p.m. on Saturday, Feb. 23rd. • Read the directions very carefully!