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# Classical estimating methods

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### Classical estimating methods

1. 1. Usage 0f the Classical estimating approaches <br />byeugene.veselov@magento.com<br />
2. 2. Goal<br />To reinforce Magento team with some knowledge at estimating methods<br />To share positive knowledge<br />
3. 3. Theory. Expert Judgment<br />Subtypes: Brainstorming, Delphi, NGT (see my presentation about this)<br />General idea: Experts (internal/external or even 3rd party company) estimates your project/task<br />Applicable: <br />single activity estimation, <br />WBS development, <br />Choosing right estimating method for a task <br />As a part of another estimating method<br />
4. 4. Theory. Bottom-Up Estimating<br />Subtypes: WBS, CPA.<br />General Idea: <br />breaking the task down into its smallest work components;<br />estimating the effort, duration, and cost of each; and<br />Aggregating them into a full estimate.<br />Applicable:<br /> For very precise estimation delivery of a task or entire project<br />Problem of the approach: very slow, requires full understanding of the task.<br />
5. 5. Theory. Analogues Estimating<br />General idea: Analogous is an estimating technique that uses the values of parameter, such as scope, cost, budget, and duration or measures of scale such as size, weight, and complexity from a previous, similar activity as the basis for estimation of the same parameter for a future activity. This is a form of expert judgment.<br />Applicable: <br />This technique is primarily used when there is a limited amount of detailed information about the project or program.<br />When you have enough historical data to avoid bottom-up<br />Problem: it provides a lower degree of accuracy than other estimating techniques, historical data needed<br />
6. 6. Theory. Parametric Estimating<br />General Idea<br />Parametric Estimating uses a statistical relationship between historical data and other variables to calculate an estimate for activity parameters, such as cost, duration, and budget<br />Example: a support team usually fixes 10 bugs per day, so that we expect them to fix 220 bugs this month<br />Applicable <br />Total project/some segments estimation <br /> As a part of other estimating methods<br />Problem: accuracy depends on complexity of the mathematical model and historical data.<br />
7. 7. Theory. Reserve Analysis<br />General idea :<br />1. All the estimates may include contingency reserves to compensate schedule uncertainty. The contingency reserve may be a %% of the estimated activity duration, fixed number of work periods and etc.<br />2. As more precise information about the project available, the contingency reserve may be used, reduced or eliminated.<br />
8. 8. Theory. Three-point estimates (PERT)<br />This is your homework, guys <br />
9. 9. Task: develop an estimating strategy for the project described below<br />One of our clients wants a Magento based solution to be integrated with his ERP system (MBS). The frontend (FE) should be almost the same as for one of our previous clients. Unfortunately, the client has self-written ERP system so that we have to implement unique synchronization module (SM) to connect our system and the ERP. The client also wants 20 reports (RPT) but they are very similar to each other.<br />Extra info that came from our top management: <br />Contract type : Fixed price<br />SM should be developed by just created team of 1 client’s developer, 1 our veteran and 1 our newcomer. Other parts will be developed by our stable old teams.<br />Estimation should be delivered ASAP otherwise we’ll get a risk to lose the client<br />Test task. Brainstorm<br />
10. 10. MBS, Bottom up<br />FE, Analogues<br />SM, bottom-up + Delphi<br />RPT #1 bottom up + brainstorm or NGT<br />RPT #2 - 30 parametric<br />Test task. A solution<br />
11. 11. ?<br />Resources :<br />1. PMBOK 4th edition<br />2. My team work training materials<br />3. http://rpl-blog.blogspot.com<br />
12. 12. The end.<br />Questions ?<br />eugene.veselov@magento.com<br />