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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

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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

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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

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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

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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.

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Critical Path Method - Terms. Activity on Node Nodes: activities Arc: precedence Duration (EX: hrs., days) Start A6A6 B8B8 Finish

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Critical Path Method: Terms Activity A must be done before B can begin. - Activity A is a PREDECESSOR of B. Start A6A6 B8B8 Finish Arc: precedence Nodes: activities

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Critical Path Method: Terms Activities A and B must be done before C can begin. - A & B are PREDECESSORS of C. Start A6A6 B8B8 Finish Arcs: predecessors C5C5 Nodes: activities

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Critical Path Method Activity A must be done before C and B can begin. Start A6A6 B8B8 Finish Arcs: predecessors C5C5 Nodes: activities

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EX: build a house Project tasks: –install landscaping –pour foundations –frame walls –install plumbing systems –get permits –install electrical systems –move in.

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EX: build a house: tasks in order –get permits –pour foundations –frame walls –install plumbing systems –install electrical systems –install landscaping –move in.

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EX: build a house: durations –get permits –pour foundations –frame walls –install plumbing systems –install electrical systems –install landscaping –move in. Durations:

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EX: build a house: label activities –A: get permits –B: pour foundations –C: frame walls –D: install plumbing –E: install electrical –F: install landscaping –G: move in. Durations:

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EX: build a house: create table –A: get permits –B: pour foundations –C: frame walls –D: install plumb. –E: install elec. –F: install landscaping –G: move in. Durations: Act.Dur.Preds. Post. A2-- D B6-- C,F C5B D D4A,C E E6D G F9B G G3E,F

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EX: build a house: create graphic CPM start A B C DE F G finish ActDurPrePost A2-D B6-C,F C5BD D4A,CE E6DG F9BG G3E,F

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EX: build a house: add in durations start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish ActDurPrePost A2-D B6-C,F C5BD D4A,CE E6DG F9BG G3E,F

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But what is the Critical Path? 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. (We must tell the family when the house will be done -- how soon?) start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish

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What is the Critical Path? start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish 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

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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.

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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)

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Calculating slack start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish 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).

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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. start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish

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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). start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish

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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. start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish

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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). start A2A2 B6B6 C5C5 D4D4 E6E6 F9F9 G3G3 finish

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Labeling the CPM Basic model: start B C D E F G finish ActivityESEF DurationLSLF A

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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. ActivityImmediate Predecessors Duration A-3 B-6 CA2 DB, C5 ED4 FE3 G 9 HF, G3

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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)

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About the Midterm Exam Three versions – make sure you do the right one. NO COLLABORATION Collaboration=Cheating When you open the spreadsheet, click on Enable Macros (if it comes up). The midterm is posted (by 9 p.m. Thursday) at It is due by 9:00 p.m. on Saturday, Feb. 23 rd. Read the directions very carefully!

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