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Activity Duration Estimation and Work Value Assessment
Project Management · Chapter 9: Project Monitoring, Control, and Performance ManagementSection 9.4 · lesson 58 of 7315 min · free with a free account
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In this lesson
Turn effort into working days, measure progress fairly, and re-forecast the finish.
- Distinguish effort, duration and elapsed time, and convert work hours into working days using team availability
- Compare progress measurement rules such as 0/100, 50/50, weighted milestones, units complete and level of effort
- Calculate work value as budgeted hours times percent complete under each item's agreed rule
- Re-estimate remaining duration from the observed productivity rate and state the assumption behind it
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Transcript
Everything said in the video, section by section (1,909 words). Read along, or search it.
Opening Question
Stuck at Sixty Percent for Three Weeks
Elena is writing a 20-section patient-services manual for Willowbrook, planned at 40 working days. The figures are made up. At the end of weeks 4, 5 and 6, she reports the same thing: 60% complete. Priya, her project manager, needs to know how far along the manual really is, and when it will be done. How should she measure it?
Key Terms
Effort, Duration and Elapsed Time
First, three words people mix up. Effort is the amount of work, in work hours of one person's labor. It's the same whether one person works slowly or several share it. Duration is the working time from start to finish, in working days. Elapsed time is calendar time, including weekends, holidays and waiting. A briefing note needs 24 work hours of effort. The writer has 6 productive hours a day, so the duration is 24 / 6 = 4 working days. Start on a Thursday, and it's done Thursday, Friday, Monday, Tuesday: an elapsed time of 6 calendar days. Effort drives cost. Duration, placed on a calendar, drives dates.
Productivity Rates
Planned Rates Versus Observed Rates
A productivity rate is output per unit of working time, like boxes cataloged per working day. Duration equals the quantity of output, divided by the output per day. Rates vary across people, conditions and time, as a team learns the task. A planned rate is an assumption made before work starts. An observed rate is output actually completed, divided by working time actually used, by this team, on this work. It's better evidence, like your speed over the last hour, rather than the speed limit. Three cautions. A rate from very little output is unreliable. Count only output that meets a stated definition of finished. And understand a low rate's cause before projecting it. A one-off interruption shouldn't be projected forward. A standing condition, like a part-time team, should.
Worked Example
Converting 288 Work Hours Into Days
Now a conversion. Willowbrook is cataloging 1,440 boxes of old paper records, at 0.2 work hours per box. That's 288 work hours of effort. Duration equals effort, divided by the team's hours per day. Team hours are people, times productive hours each, times availability: the share of those hours open to this activity. Three records clerks each have 6 productive hours, but they also cover the front desk, so only 80% is available. 6 x 0.8 = 4.8 hours each. Three clerks make 14.4 hours a day. 288 / 14.4 = 20 working days. Round any fraction up to the next working day. Starting Monday, July 13, with no holidays, day 20 is Friday, August 7. That's 26 calendar days: 20 working days plus three weekends. Leave availability out, and you'd get 288 / 18 = 16 days, ending August 3: wrong from day one. And the planned rate is 1,440 / 20 = 72 boxes a day.
Common Trap
The Late 90 Percent Pattern
Then the work starts, and someone has to judge progress. Percent complete is the share of an activity's work reported as done. For physical work you can look. For writing, analysis or cataloging, it's a judgment, and it drifts. People report time spent, not work remaining. Easy parts go first. And a reported figure is hard to lower. The result is the late 90 percent pattern: the figure races to about 90%, then sits there, while the last tenth takes as long as the first nine. The remedy is a progress measurement rule: an agreed method, fixed before work starts, for turning observable events or counted output into percent complete.
Progress Rules
0/100, 50/50 and Weighted Milestones
Under the 0/100 rule, an activity earns nothing until it's finished, then full credit. It suits short activities and events with no half-done state, like a delivery. On long work, it gives no early warning. Under the 50/50 rule, it earns half on starting, and half on finishing. It suits short and medium activities. But starting is easy and finishing is hard, so many starts overstate progress. Under weighted milestones, it's split into a few checkpoints, each with a test someone else can verify, and a weight agreed in advance. The weights sum to 100%. It suits longer work with natural checkpoints, like draft, review and approval. But the weights are judgments, and credit moves in steps.
More Progress Rules
Units Complete and Level of Effort
Under units complete, percent complete is units finished divided by total units, each unit similar in size, with a stated test for when it counts. A box counts when its entry is complete and has passed the check. With 540 of 1,440 boxes done, that's 540 / 1,440 = 37.5%. But doing easy units first can flatter it. Level of effort is for support work with no defined output, like coordination. Credit follows the planned time passed: budgeted hours, times time elapsed over planned duration. Its limit is decisive. Credit follows the calendar, so the activity is on schedule by construction, and can never show a delay. Keep it small, and never use it for work with an output.
Quick Check
Crediting 30 of 120 Intake Forms
Quick check. A new item, entering 120 patient intake forms, has a budget of 80 hours. So far, 30 forms are entered and checked. Under units complete, how many hours of work value does it earn: 20, 40, or 60? Pause and predict. 20 hours. 30 of 120 forms is 25%, and 25% of 80 hours is 20. 40 hours is what the 50/50 rule would give, for an item that's merely started. That's the overstatement units complete avoids.
Worked Example
One Project, Five Different Work Values
Work value is the share of budgeted work credited as done, here in budgeted hours. For each item: budgeted hours, times percent complete under its rule. Add the items for the project. Pick the rule at planning, and don't switch. A more generous rule changes the report, not the progress. Four items, at the end of day 10. A, the template, 40 hours, is finished. B, cataloging, 288 hours, has 540 boxes done. C, checking, 60 hours, has 10 of 30 batches checked. D, coordination, 40 hours, is halfway. The totals: 0/100 credits only the finished item, 40 hours. 50/50 credits half of everything started: 234. Weighted milestones give 144. Units complete, 188. Level of effort, 224. Out of a 428-hour budget, that's anywhere from 9.3% to 54.7%, for the very same work.
Why Totals Differ
Checkpoints and Calendars Distort Credit
Look at item B. Its milestones are at 360 and 720 boxes. With 540 done, weighted milestones credit only 72 hours, 36 less than units complete, because work between checkpoints earns nothing yet. Level of effort credits B with 144 hours: half the planned time has passed, so it credits half the value, 36 hours more than its output supports. For C, output keeps pace with the calendar, so units and level of effort agree at 20. The totals under the chosen rules become the work value used in earned value.
Re-estimating
Forecasting the Finish From Observed Rates
Now the finish. A remaining duration is the working time still needed, counted forward from the status date. It's not the original duration minus the time used. Remaining duration equals remaining units divided by the observed rate, rounded up. The revised finish is the status date plus that. For cataloging, at the end of day 10, Friday, July 24: the observed rate is 540 / 10 = 54 boxes a day, 75% of the planned 72. 1,440 - 540 = 900 boxes remain. 900 / 54 = 16.67, so 17 working days. Day 10 plus 17 is day 27, which is Tuesday, August 18. The plan said day 20, Friday, August 7. That's a slip of 7 working days, or 11 calendar days.
Weaker Forecasts
Why Planned Rates Mislead a Forecast
Two other forecasts are weaker. Assuming the plan holds gives day 20, ignoring that only 37.5% of the boxes are done after half the time. Repeating the original optimism divides by the planned rate: 900 / 72 = 12.5, so 13 days, and day 23. That needs the rate to jump from 54 to 72 for no stated reason. A cross-check in effort agrees with the observed rate. The team supplied 10 x 14.4 = 144 hours for 540 boxes: 0.267 hours a box, not 0.2. 900 more boxes need 240 hours, and 240 / 14.4 = 16.67 days, the same result. A re-estimate assumes the observed rate continues, and should say so. If the cause was one-off, the next measurement will show it. If it's standing, like lower availability, the new figure stands.
Quick Check
Re-estimating a Proofreading Job
Quick check. A team must proofread 1,800 pages, planned for 15 working days. At the end of day 6, 540 pages are finished. What's the re-estimated remaining duration: 9, 11, or 14 working days? Pause and predict. 14 working days. The observed rate is 540 / 6 = 90 pages a day. 1,260 pages remain, and 1,260 / 90 = 14. The finish moves from day 15 to day 20. 11 days comes from the planned rate of 120 a day, which repeats the original optimism. And 9 is just 15 minus 6, the plan minus the time used.
Estimator Bias
Optimism, Anchoring and Pressure to Agree
Why do estimates miss in one direction? Estimator bias is a systematic tendency to err one way. Optimism expects work to go as planned, so delays and rework get too little weight. Anchoring is the pull of a first number: state the sponsor's desired date first, and estimates cluster near it. Pressure to agree moves the figure toward what a forceful person prefers. One view puts the correction in the method: compare estimates with records of similar work, collect them independently before discussion, and switch to observed rates as soon as they exist. The other view says the setting produces the bias. Separate estimating from target-setting, make it safe to report a slow rate, and give estimators feedback on past accuracy. Which reduces error more is an empirical question, with no result cited here. How far people should answer for their own figures is about values. No side is taken.
Status Updates
Updating the Schedule in a Fixed Order
At each status date, update the schedule in a fixed order. Record progress under each item's rule. Re-estimate each unfinished activity from its observed rate. Recalculate the following activities through the dependencies, so a longer remaining duration on cataloging moves everything that depends on it. Then compare the new forecast with the unchanged baseline, and record each variance with its cause. A re-estimate is a forecast and a signal, not an approved change.
Case Resolved
Measuring the Manual by Approved Sections
Back to Elena's manual, at day 30. Her judgment, 60%, matches 12 sections started: 10 finished, 2 in draft. Priya tries two rules. 50/50 on sections gives 10 finished, plus 2 started at half credit, over 20: 55%. Units complete, counting sections the editor approved, gives 10 / 20 = 50%. The plan expected 15 sections, 75%, by day 30. So the real gap is 25 points, not 15. Priya uses the approved count: countable, and verified by someone other than the writer. The observed rate is 10 / 30 = 0.333 sections a day. 10 sections remain, so 30 more days: day 60, the end of week 12, four weeks late. Over the last two weeks, the rate was only 0.3, which gives 34 days, finishing Thursday of week 13. Priya reports day 60, with that downside, and the assumption behind it. The cost: Elena sees a lower figure than she reported. The gain: the sponsor learns of the slip two weeks before the planned finish, not at it.
Key Takeaways
Effort, Rules and Re-estimates in Brief
To recap. Effort is work hours, duration is working days, and elapsed time is calendar days. Duration equals effort over people, times productive hours, times availability. Fix a progress rule before work starts. The rule decides the work value credited. Re-estimate remaining work from the observed rate, not the planned one, and state the assumption.
About Project Management at UPI Study
Project Management (Business 230) is a self-paced online course of 73 video lessons in 12 chapters, from starting and defining a project to planning, budgets, scheduling tools, proposals, contracts, execution, monitoring, closure, teams and certification. It carries a NCCRS credit recommendation for 3 semester credits.
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