As UX practitioners, we all get roped into estimation meetings from time to time. But not all estimation efforts are the same. There are basically four different kinds of estimation, they all have different purposes, and they require different responses from us:

1. True Estimation:
   • What’s the ask? “Here’s exactly what we’re doing; how long does this take?”
   • What’s most important? Giving an accurate account of the work involved.
   • What’s really being estimated? Effort and resources.
   • What you should ask: What’s the scope? What are the tasks? What’s the timeline?
   • Recommendation: Ensure that scope and tasks are clearly defined before estimation begins. If scope is only broadly defined, go to #2. Estimate task by task and resource by resource. Pad each estimate to allow for meetings, reviews and edits, or estimate those activities separately, or delimitate the estimate by excluding those activities entirely.
2. Scoping + Estimation:
   • What’s the ask? “What can we do for this client, and how long does that take?”
   • What’s most important? Making appropriate recommendations, and making the business case for them.
   • What’s really being estimated? A list of recommended activities, and typical estimates per activity and resource.
   • What you should ask: What’s the goal of this project?
   • Recommendation: Ask to do scoping separately and get Account Management to commit to a fixed set of activities, and then add up the typical hours per activity. Give each activity an estimate in a range of hours, based on a high level complexity assessment. If scoping is not in the cards, go to #3.
3. Guesstimation:
   • What’s the ask? “Here’s roughly what we think we should do; how long does this take?” (a k a “How long is a piece of string?”)
   • What’s most important? Cost.
   • What’s really being estimated? Resources required, number of hours that can be allocated per day per resource, and the approximate calendar time required to get it done.
   • What you should ask: How specific does the guesstimate need to be? (If very specific, go to #1 or #2).
   • Recommendation: Ensure that the person asking for the guesstimate is aware that it will be very rough. Scope the effort in broad categories, and do not define specific deliverables. Put your estimate in a range, never a fixed set of hours. The less defined the categories are, the greater the range. Do not accept being challenged on the guesstimate – if the requester wants you to be more precise, they need to provide more detail, either by going to #1 or #2.
4. Adjustimation:
   • What’s the ask? “Here’s how long we have; what can you do in that timeframe?”
   • What’s most important? Speed to market.
   • What’s really being estimated? The priority of the project, how many resources can be freed up, and the time available.
   • What you should ask: How important is this? What is the client expecting? What’s the MVP?
   • Recommendation: Judge, based on prioritization, the percentage of hours available per resource within the allotted timeframe, and sum up how many hours can be spent on the specific project.Then ask each resource to define what they can accomplish in that amount of time. Be clear about the timeframe – if the due date is pushed out, the adjustimate has to be bumped up, since team members will continue working. Do not accept being challenged on the adjustimate – if the requester wants you to be more precise about what can be accomplished, they need to allow more time, either by going to #1 or #2.

Also, see: The Project Calculator™ (requires Flash)