As I explained in previous sections, cost components where the work of people is involved, are hardest to calculate. Time & material based items in your spreadsheet need some time component to create a number…
| "How long would it take you to walk the marathon?" If some one asked me this question, am I able to answer it? I never walked 42 kilometres, but I think so. I once did half a marathon, so I have some indication (believe me, this was years ago). I would just multiply that time by two and add a little thing. So, although I didn't do the job previously, I can give a reasonable estimation on the duration. "How long would it take to make your own dress?" If some one asked me this question, I am in trouble. First, I would be worried by the question itself, and second, even if I tried, I would be unable to give you a proper estimate. I would know how to make a small web site. I would know how to make a excellent spaghetti. My best guess would be something in between the site and the pasta. Yep, we are now talking all about estimating. So, pick up the dice, and start rolling them… Getting an estimate The best people to provide you with an estimate, are the people who will have to perform the task. First of all, they probably know what they are talking about. But most of all, it will be their estimation. Otherwise, if you have to work with the people later on in the project, and you provided the estimate, they normally will not agree and will not feel committed to do the work in your estimated time. Getting a good estimate from e.g. a programmer is not just a task for the programmer himself. The project manager plays a critical role in getting quality numbers. He has to talk with the guy (or gal), to see why he thinks it will take 7 days… So, the project manager is a kind of shrink for the programmers. That's right. They just have to kick back and tell what comes to their minds, and that's it. Yeah, right, duh! The programmer, in this case, should take steps to ensure that his estimates are getting more and more accurate. He can do this by keeping statistics on how much time he spend on what. How accurate were his previous estimates, etc. I dug this quote up on an internet newsgroup: "My experience is that people work to deadlines. If an engineer estimates a task will take 4 weeks, they do *not* mean 4×40=160 Hrs. They mean its feasible that it will be done 4 weeks after the start, and the Engineer will put in as many or few hours as necessary to get it done. On one hand, the Engineer will be factoring in such things as other workload going on, planned days off, etc. On the other, most people will underestimate the time it actually takes, and the experienced manager will know how to "pad" (or in some cases shrink) the estimate based on the track record of the individual." |
So basically, ask the people who will be involved. Make assumptions explicit. This will help some people to give you a number if they are not sure. Let them put large disclaimer notices on their statement. It's a guess. But that's enough for you right now.
3.4 Refining until the end
You have now a first rough draft of your spreadsheet, filled with number that will not be the truth. The coming period you will take steps to make sure it will not be far from the truth.
Now you know you need some complex interface between systems. Later on, you will know what kind of data will be exchanged, you will have a vendor to make a better estimate. You will end up with a better number.
Hardware specs will become more clear. Software licenses will become more detailed if you have narrowed down your potential vendors. Stick with the calculation. Remember always it's a way to communicate with the actual decision makers, as it's money that talks, it's in the end the only language they will understand.
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