Of course this title has everyone asking “What in heck is an inch pebble?”, right? Well I was first introduced to this term by Johanna Rothman in an article she wrote about a hundred years ago. While I read it, and intuitively understood it, it didn’t at first occur to me that it was a comparative analogy. Until today…Today I was reading Chip and Dan Heath’s excellent book on organizational change, “Switch“. In that reading I came across the term inch pebble and it hit me like a ton of bricks:
An inch pebble is a tiny, easy to see the goal, version of a mile stone.
Back in the day, mile stones were placed by roads as a marker of progress, so that travelers could know whether they were on track to arrive at their destination or not.
Traveling by foot or horseback, a mile would take from 15-25 minutes, and so the need to measure progress was important. Now we travel along at a mile per minute or more, and it seems somewhat superfluous to track progress that way. The other important aspect of a mile stone is visibility. Most frequently, I can’t see one mile ahead on my roadway. Curves, trees, hills, and other vehicles often obstruct my view. In that way, I don’t (even at 60 miles per hours) have a way to see what obstacles are coming in the roadway, or worse, when there is a traffic backup, whether it will be clear up in the next mile.
And this is where the analogy to projects becomes important. Milestones in a project are often big. They represent a big chunk of progress, and often, I can’t see all of the obstacles in the way of that progress. But milestones in a project plan are different:
Mile stones don’t represent a uniform amount of progress, the way most project plans are assembled.
They don’t reflect either a uniform and measurable amount of value or cost. So while they do reflect that progress is being made, the quantity of progress is harder to discern. They also don’t mean that we won’t have to go back and re-cover the same ground. I have completed a milestone but often, I find that I have taken a route that circles back around on itself causing me to make decisions again, redo documentation, retest the same features, etc.
What is the worst think about milestones is that I can’t always see what (ell of the work) needs to be done to make the progress. This is where inch pebbles come in. Maybe they are foot gravel, maybe meter rocks – but in either way, the shorter distance element means that when that work is started, I can see all the way to completion! I break my work down into smaller chunks that I can understand how to finish. If I find that there is work that I don’t know how to do, then I create a chunk of work to figure that out. For example, when I don’t have good requirements, I create an inch pebble to improve the requirements.
While one might say that inch pebbles and milestones both suffer from the need to sometimes go back and re-work things. Inch pebbles are better because I can reduce the amount of rework to the smallest amount. If inch pebbles suffer from the same lack of uniformity in size, it can be considered irrelevant, because when I add up the inch pebbles the differences in size compared to each other are “huge”, the differences compared to the sum of all inch pebbles is insignificant.