We briefly introduced the concept of relative sizing in Chapter 3, Introducing Scrum to Your Software Team, in the activity Using estimate buckets to size User Stories. This particular technique is useful for sizing a bunch of User Stories at once. It also makes the concept of relative sizing slightly more obvious because we're comparing User Stories to one another. Relative sizing in this setting is a simple question of "Is it bigger, smaller, or is it the same size?"

You're probably wondering why we use relative sizing for estimating, rather than time-based sizing such as hours, days, or weeks. Take a look at the following skyline, you might recognize it:

There is an arrow pointing to the tallest building in this picture. Resist the temptation to look this up and have a guess at how...