The biggest problem I’ve encountered in the past is something that sends shivers down the spine of most IT professionals – the dreaded question of how long a piece of work is going to take. I’m not talking about quoting for year long projects – they’re a whole different kettle of fish – but about the tasks that you have to do that are on the project plan. Software development is inherently dealing with unknown quantities – new technologies, unencountered bugs, changing requirements… the list seems to be unending. No two projects ever seem to be the same yet you are expected to give an accurate estimate every time. Even the meaning of the word changes depending on who is using it – programmer “best guess based on available understanding of the problem”, client/PM “fixed quote cast in concrete”.
The Software Engineering Profession has waxed lyrical on the topic for years, yet there is still no easily applicable model. Yes, there are tools such as function points and Cocomo, but they are no help for the most part. Heavy, complex, don’t take the nuances of the technology into account and they’re not really useful at the day-to-day scale of estimating. Is a web database system going to take the same amount of time to complete whether you use standalone JDBC, Spring templates, Hibernate or Ruby on Rails? Is it going to take the same amount of time to complete regardless of whether you are using the stable version of your favourite open-source package, or the new one with those brand new time-saving features you just have to use? No.
I approach the problem as per the XP boys. Implement a slice of functionality using the software stack, work out your “velocity” and extrapolate to a larger scale. In order to work out how long the work is taking I use a tool called ToDoList (http://www.abstractspoon.com/tdl_resources.html). Break down a task into it’s various steps and time how long each one takes. You can then base estimates of future work using the same technology by looking back on the task list for previous projects. It’s a variation on estimation
by experience, but slightly more formal since you’re not relying on memory. It would be interesting to see whether a larger resource that would let you see how long other people took to complete similar tasks would help, or whether it’s an inherently personal thing. My guess is the latter, which makes keeping a record of previous work all the more important. It’s not a panacea, but it will help.