4. Factors Influencing the Quality of Estimates Quality of Estimates Project Duration People Project Structure and Organization Padding Estimates Organization Culture Other (Nonproject) Factors Planning Horizon
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6. Macro versus Micro Estimating TABLE 5.1 Conditions for Preferring Top-Down or Bottom-up Time and Cost Estimates Condition Macro Estimates Micro Estimates Strategic decision making X Cost and time important X High uncertainty X Internal, small project X Fixed-price contract X Customer wants details X Unstable scope X
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9. Apportion Method of Allocating Project Costs Using a (High Level) Work Breakdown Structure FIGURE 5.1
10. Simplified Basic Function Point Count Process for a Prospective Project or Deliverable: Example TABLE 5.2 To pick nits: In this approach we are looking at durations, not costs (Which is dangerous before we take the considerations of Ch 6)
More sophisticated version of Apportioning Now we start to break down by WBS for the next couple…. 3 levels
Used in software more- consider all the major parameters and rate the complexity…. These parameters I haven’t personally worked with, we will assume as given. (You don’t have to memorize them). From them you can see that fields and interfaces are generally greater considerations…. Presumably this is the 2 nd or 3 rd tier of a WBS So if have 15 low comp inputs, 5 avg outputs 10 avg inquiries 30 high files and 20 avg interfaces, 30+30+40+360+200 = 660. Over half cost due to files (Answer on next page)
660 function points If 5 function points per person month, that’s 132 person months, if a person costs $4k/mo (low- must not be US) = $528K If have 10 people working on this, that’s 13.2 months.
Note- here we are switching to TIMES not costs. Still need to take into account some material from Ch6. 3 different estimators polled. Can see their estimates agreed more on engineering and base maps then on coordinate utilities, although he latter is mainly high because a difference of 1 day is significant when the task is so small. (But in reality it is sometimes these little tasks that get away).
Start in Phase 1 with only top-down estimate, then start flushing out details as we get into later into the project. (Sort of a 1x1 matrix here)
All three start out at 0 and end up at $6,000 . The project manager commits the costs before they are actually used. The budgeted cost occurs a bit later, but before actual costs. This may be an issue for shoestring companies, or for jobs that are so huge, that the time value of money of the difference [ (scheduled-budget = payment from client) – actual cost ] can make a project effectively a money loser even if the total cost and payments were as expected. So want to make sure actual cost is below budget, or factor this in as an additional cost!
Don’t forget the profit margin when making a bid. 20% might be a bit low, IMHO Also, G&A of 20% is somewhat low 25%
We use the same weighting structure Click on excel to see- but have 1290 function points, of which 58% are interface related Takes 258 person months (assume $5K/mo, means a $1,290,000 project ….woooo!) - so 43 mon with 6per team, 12.9 with 20per team ASSUMING everything scales In reality, may lose some team functionality once we get too large!