estimate-tasks

Given the individual tasks' estimations, calculates the total estimation for the whole project

npm install estimate-tasks
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About

Given the individual tasks' estimations (in hours), calculates the total estimation for the whole project. It attempts to do the right thing, when summing up estimations, treating each individual estimate as a continuous random variable (see Math), and applying a formula from Steve McConnel's book "Software Estimation: Demystifying the Black Art".

Doing the math right though requires providing a range for an individual estimate instead of a single number: you'll be asked for the best case, the most likely case, and the worst case hours.

By the way, the probability of a task taking exactly X hours to finish is exactly zero (see Math again ;).

Also, a subjective confidence factor is provided for each task's estimation, in percent, within the range (0, 100) -- excluding 0 and 100. Normally, you should be pretty confident in the most of your tasks' estimations, specifying confidence factors above 90% for them. Only a smaller part of tasks should have 90% and below. Anyway, that's a just fine tuning mechanism; you may well ignore it, and simply assign, say, 95% confidence to all the tasks.

The number E you get from total75PercentLikelyHours() means that there's a 75% probability that your project will take not more than E hours.

Installation

Node.js:

$ npm install estimate-tasks

Web browser:

$ bower install estimate-tasks

API

Node version:

var et = require("estimate-tasks"),

    total = et.total75PercentLikelyHours([{
        bestCaseHours: 1,
        mostLikelyCaseHours: 1.5,
        worstCaseHours: 4,
        confidencePercent: 99.9
    }, {
        bestCaseHours: 8,
        mostLikelyCaseHours: 10,
        worstCaseHours: 12,
        confidencePercent: 66
    }, {
        bestCaseHours: 2,
        mostLikelyCaseHours: 3,
        worstCaseHours: 4,
        confidencePercent: 95
    }]);

In the browser you have to include Underscore and the lib/calc.js script. Then:

var et = window["estimate-tasks"];

Testing

Test-driven with Mocha. Under Node, say:

~/estimate-tasks(master)$ npm test

License (MIT)

Copyright (c) 2013 Ivan Krechetov

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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