The Wideman Comparative Glossary of Common Project Management Terms describes estimating cost as, "the process of forecasting a future result in terms of cost, based upon information available at the time."

In his book 'How to be a Better Project Manager', Trevor L Young defines estimating as "A decision about how much time and resource are required to carry out a piece of work to acceptable standards of performance."

Many techniques, books and software packages exist to help with estimating project costs. A few simple rules will also help ensure you create an accurate and realistic estimate.

  • Assume resources will only be productive for 80 percent of their time.
  • Resources working on multiple projects take longer to complete tasks because of time lost switching between them.
  • People are generally optimistic and often underestimate how long tasks will take.
  • Make use of other people's experiences and your own.
  • Get an expert view.
  • Include management time in any estimate.
  • Always build in contingency for problem solving, meetings and other unexpected events.
  • Cost each task in the Work Breakdown Structure to arrive at a total, rather than trying to cost the project as a whole.
  • Agree a tolerance with your customer for additional work that is not yet defined.
  • Communicate any assumptions, exclusions or constraints you have to your customer.
  • Provide regular budget statements to your customer, copying your team, so they are always aware of the current position.

Much data exists about the length of time particular items of work take, especially in the construction industry. A useful database of production rates can be found atPlanning Planet 

Common Mistakes

These are some of the common mistakes that can lead to inaccurate estimates.

  • Not understanding what is involved to complete an item of work.
  • Starting with an amount of money and making the project cost fit it.
  • Assigning resources at more than 80 percent utilisation.
  • Failing to build in contingency.
  • Failing to adjust the estimate following changes in scope.
  • Dividing tasks between more than one resource.
  • Providing estimates under pressure in project meetings.
  • Giving single-data-point estimates rather than range estimates.

Three Point Estimating

Three point estimating is a technique that helps project managers produce better estimates. Rather than a ballpark estimate, project managers can use three point estimating to gain a greater degree of control over how the end value is calculated. The end value is the weighted average of three estimates.

To do three point estimating for a particular task or activity, ask the resource for their best-case, most likely and worst case estimates. Add the best-case estimate to four times the most likely, then the worst case and divide by six. This gives you your estimate (E value) which is a slightly more balanced view of how long the task or activity is likely to take.

The formula is expressed as:

E = (B + 4 M + W)/6

  • B = best-case (1/6)
  • M = most likely (4/6)
  • W = worst case (1/6)

Estimating Project Costs的更多相关文章

  1. Project Management Process

    Project Management ProcessDescription .............................................................. ...

  2. 10 Golden Rules of Project Risk Management

    The benefits of risk management in projects are huge. You can gain a lot of money if you deal with u ...

  3. PMP模拟考试-2

    1. Increasing resources on the critical path activities may not always shorten the length of the pro ...

  4. PMP用语集

    AC actual cost 实际成本 ACWP actual cost of work performed 已完工作实际成本 BAC budget at completion 完工预算 BCWP b ...

  5. PMBOK及PMP考试精要

    PROJECT MANAGEMENT KNOWLEDGE AREAS项目管理知识体系 2 PROJECT LIFE CYCLE / PROJECT MANAGEMENT PROCESS GROUPS项 ...

  6. P6 Professional Installation and Configuration Guide (Microsoft SQL Server Database) 16 R1

    P6 Professional Installation and Configuration Guide (Microsoft SQL Server Database) 16 R1       May ...

  7. 对比其它软件方法评估敏捷和Scrum

    一般来说,选择一种软件开发方法,更像是加入一个邪教组织,而不像是做出了一个技术决策.许多公司甚至从未试图去评估这些方法,而仅仅是盲目采用最流行的方法,这就造成了如今五花八门的各种敏捷方法.因此本文将使 ...

  8. 2017.10.30 Epicor -ERP

    1 公司新用ERP系统,做使用培训,mark... This course reviews the project management flow in the Epicor application. ...

  9. 12 Tips for Accurate Project Estimating

    Projects typically involve many dynamic aspects, yet they're often constrained by finite conditions. ...

随机推荐

  1. 【TYVJ】1359 - 收入计划(二分)

    http://tyvj.cn/Problem_Show.aspx?id=1359 一开始是一眼看出是二分的,因为这里有单调性,因为取钱是一次取完并且是连续的. 所以最优取法就是准备达到某个价值再取.最 ...

  2. NOIP200107统计单词个数

    NOIP200107统计单词个数 难度级别: A: 编程语言:不限:运行时间限制:1000ms: 运行空间限制:51200KB: 代码长度限制:2000000B 试题描述 给出一个长度不超过200的由 ...

  3. ext4 文件系统的一些记录

    https://www.kernel.org/doc/Documentation/filesystems/ext4.txt ext4 权威说明 http://computer-forensics.sa ...

  4. JavaScript_判断浏览器种类IE、FF、Opera、Safari、chrome及版本

    function myBrowser(){ var userAgent = navigator.userAgent; //取得浏览器的userAgent字符串 var isOpera = userAg ...

  5. sum()over()和count()over()分析函数

    创建测试表 ),sales ),dest ),dept ),revenue number); 插入测试数据 ); ); ); ); ); ); ); commit; 查看表记录 SQL> sel ...

  6. 转载--thinkphp框架的路径问题 - 总结

    转自:http://blog.sina.com.cn/s/blog_827ddd950100ulyv.html TP中有不少路径的便捷使用方法,比如模板中使用的__URL__,__ACTION__等, ...

  7. Html - Bootstrap Panel面板

    http://v3.bootcss.com/components/#panels Bootstrap Panel面板 <div class="panel panel-default&q ...

  8. 如何用Apache POI操作Excel文件-----如何在已有的Excel文件中插入一行新的数据?

    在POI的第一节入门中,我们提供了两个简单的例子,一个是如何用Apache POI新建一个工作薄,另外一个例子是,如果用Apache POI新建一个工作表.那么在这个章节里面,我将会给大家演示一下,如 ...

  9. HDU 1003 基础dp 最大连续序列和

    常常做错的一道题.. 因为总是要有一个长度的 所以一开始的s与e都是1 maxx也是a[1] 然后再求 从i=2开始 在这里注意 me永远是当前i 而ms则可能留在原地 可能直接等于i 判断条件就是当 ...

  10. 39. 求分数序列前N项和

    求分数序列前N项和 #include <stdio.h> int main() { int i, n; double numerator, denominator, item, sum, ...