Sample project revisited

The last time we looked at progress on the blog's sample xProcess project we were looking at the way that project velocity measured simply as "points per sprint" can vary significantly (Calculating team velocity, 24.02.08). If we can gather accurate data about team availability and overhead activity, using a simple measure of productivity produces much better forecasts. Here's the burndown chart as last seen on 24th February.


This sprint completed the target 69 points although as can be seen by the slightly changed positions of the steps on the burndown, some individual tasks completed on different days to the forecast.

The following sprint also completed 77 points, again showing the problem of "yesterday's weather" forecasting, albeit within a reasonably acceptable 10% margin of error. However the productivity measure is much more stable, only varying from 0.91 to 0.90.

Here's the state of the current sprint. In this case we're forecasting 64 points to be completed.


To follow through a series of articles on Scrum in xProcess start with this article on "Using the pre-defined Scrum process".

Calculating team velocity

Why is it that agile methods use timeboxes containing broadly similar sets of activities - as opposed to phases favoured by more traditional methods, which contain different types of activity in each phase through the lifecycle? A key reason is that stakeholders in the project get quicker and more effective feedback on the progress and direction of the project. As a consequence planners can judge more accurately the effectiveness of the project and what it is likely to achieve over its full duration. One of the most useful metrics planners get from each timebox is the velocity of the team. Scrum projects usually use the velocity from previous sprints to forecast their likely progress - a technique often referred to as "yesterday's weather" since it effectively assumes the next period will be broadly the same as the previous. In this article we discuss what velocity is, how to calculate it in xProcess, and how to go beyond "yesterday's weather" by calculating and using simple productivity for improved forecasting.

Velocity is defined as the amount of required work delivered per time period. In the Scrum process for example, required work is called the Backlog, and its component parts, the Backlog Items, are individually sized and prioritised. The size of an item is not the same as the effort required to complete it, though size and effort are related and may - once the velocity of the team is known - be derived one from the other (see here for further discussion of size and effort). The size of backlog items is usually estimated in a team-specific measure called points (sometimes called Story Points, Feature Points or, if related to the amount of work a team member could carry out in a full uninterrupted day, Ideal Days). The size estimates therefore really only give a relative size for the backlog items. However once a timebox has been completed - in Scrum timeboxes are called Sprints - the team has a measure of how many points they were able to complete and so have the first reading for velocity in Points per Sprint.

When using xProcess for Scrum you can see the velocity of completed Sprints from the burndown chart. For example in the Sprint shown below you can see that a total of 91 points were completed, giving the team a velocity of 91 points per sprint.

Using the principle of yesterday's weather it might be natural for the team to commit to a similarly sized set of backlog items in the next sprint. Before doing so they might be wise to look at all the history on the project. Here are the burndown charts for the previous two months, first Sprint 02 and then Sprint 01...
As we can see from the respective velocities of 40 points per sprint and 73 points per sprint, velocity is not always constant and, if we look at the reasons behind this, we may be able to forecast the velocity for the next sprint more effectively. Why did Sprint 02 for example do so badly?

Well one clue is in the dates for this Sprint. This won't be the only team to have discovered their productivity was lower between mid-December and mid-January! All the team were on holiday for at least some of the Sprint, and when they were in they probably discovered someone they needed to speak to was away, or that there were other activities they had to attend to which were not related to the sprint backlog. Another factor was that this sprint had a number of items that had been worked on but not completed at the end of the sprint. Since they are not finished they cannot be counted in the size of work "done". Backlog items like this do not necessarily get done in the following sprint since other priorities may be introduced to the team at that point. However if they are carried forward (as they were in this case), there will be considerably less work left to complete in the following sprint. This at least partially explains why Sprint 03 was such a productive one.

So what velocity should the team predict for Sprint 04? This is where other information from xProcess comes in very handy in the planning process. xProcess allows team members to record when they were working on overhead tasks (like management meetings, email and admin, training courses and office parties) as opposed to backlog items themselves. xProcess also give us information about the amount of time spent on backlog items that were not completed in the sprint.

The key metrics we want to derive in order to better predict the next sprint are these:

• simple productivity (size of work done in points per ideal person-day)
• overhead percentage (what proportion of people's time is applied to non-backlog-item tasks)
• availability (when are people available to the project)

We'll leave discussion of overhead tasks and availability to another occasion, though they can be set simply in xProcess. The simple productivity measure of Size/Effort can be calculated automatically by xProcess. I say simple productivity measure since, as Putnam and Myers point out, it is more complex to derive a true process productivity for a project, taking into account that size and effort do not follow a linear relationship when the duration under consideration varies. This non-linearity can be broadly discounted however if the duration of the sprint does not vary. (One of the reasons why agile methods recommend fixed durations for timeboxes is to ensure that feedback from one timebox is applicable to the next.)

Simple productivity for a given period (a sprint for example or the whole project) takes into account all the non-overhead tasks booked to during the period. It also takes into account tasks which were incomplete at the start and end of the period. Once the simple productivity factor has been calculated for previous sprint (or for the project so far), the value can be use to set new effort estimates based on size using the Set effort to match size UI Action described in a previous article.

The simple productivity currently being used on this project is 1.0 - in other words a backlog item estimated as size 1 will be scheduled with an estimated required effort of 1.0 ideal person-days. Using this factor the current state of the burndown chart for Sprint 04 is as shown below.


However using the history from the previous 3 sprints, xProcess can calculate the actual productivity in points per ideal person-day. In this case it was found to be 0.91 - in other words historically a task of size 1 has taken on average about 8.8 person-hours to complete. Using the Set effort to match size action, we can quickly adjust the estimates of all the open tasks in the project to reflect this factor. Once all this is applied (see burndown chart below), the state of Sprint 04 now reflects the true situation that certain tasks are at higher risk of not completing.

Midway through Sprint 01

Time to revisit our example Scrum Project started a couple of weeks back. How's our team doing? Here's the burndown as it was 2 weeks ago.

When we left it, the Sprint was red indicating an overcommitment based on current estimates. Either the team would need to negotiate a slight reduction in scope for the Sprint or risk disappointing the project stakeholders at the end of the period.

Here's the situation today (click for an enlarged view).

The status of the Sprint is now amber. Comparing the charts carefully one can tell from the reduced size of the work that there is a reduction in scope (also visible from the task lists) but there is good progress visible from the closed tasks to date. Other things to note in the screenshot are:

• Alerts (showing where some open tasks have exceeded their "best-case" estimates - they are prompts that the 3-point estimates for these tasks may need review);
  
• Closed tasks in the Explorer view (show with check mark); and
  
• The task list for the Sprint (sorted by end date so that the at-risk backlog item is highlighted at the top).

Prioritising the backlog

The key point about priority-driven planning approaches like Scrum - common in fact to all agile processes - is that the set of tasks undertaken by the team are ordered by priority rather than by a pre-determined procedure. (Priority is usually assessed based on business benefit and risk.) This article focuses on this particular aspect of using Scrum with xProcess and it covers:

• Adding backlog items to specific Sprints
• Showing a Sprint in Burndown and Gantt charts, and finally
  
• Prioritising the backlog

Having created a Scrum project with resources and a set of backlog items (see the previous post in this series) our next step is to prioritise the backlog. Our starting point here is a project which has three Sprints defined and a number of backlog items that have been estimated for approximate size. For simplicity in this example I've created 26 backlog items (with single character names from 'a' to 'z') with sizes of between 1 and 5 "points" (points being nominal units of size corresponding approximately to an ideal day's work for the average worker - see earlier post for more about this topic). Here's a view of my project at this point (click on the image to make it larger).

For the backlog items to be scheduled they must be moved from the "Unscheduled Backlog" task to one of the Sprints. Maybe you have an idea at this stage about the most important tasks, or maybe you want to see how long they would all take given the current estimates and resources. In either case just select the backlog items in the task list and drag-and-drop them to the first sprint ("Sprint 01"). As you'll see in the screenshot, I've opened the Project Explorer pane to do this. It's a view that can be selected from the "Window" menu - or simply click on the project icon next to the project name on the "Tools" pane. Once the backlog items are in a Sprint you'll begin to see the forecast start and end dates for them. You can now hit the "Priorities" button on the Tools pane and begin to put them in priority order. First though let's look at the Gantt chart for "Sprint 01" having added backlog items 'a' to 'v' to it. Double-click on "Sprint 01" to see its details and click on the "Gantt Chart" button. You can view other charts for the Sprint in a similar way, for example by clicking on the "Burndown Chart" button. In the screenshot below you'll also see that I've put the task list in reverse End Date order (by clicking on the column heading) and on the Gantt chart I've scrolled down to show the tasks at the end of the Sprint.

The Gantt Chart shows the forecast start and end dates of the tasks based on resources and estimates so far defined. As time progresses and tasks are started, re-estimated, completed or changed this chart will also change of course - it gives us a view of the likely outcomes based on information currently available. The risk element of the estimates is shown by the 75/95% extensions on the Gantt bars (see "Why I use 3 estimates..." for a discussion of this feature). Given that the target end date for this Sprint is December 19th, we can see that 2 items ('n' and 'a') are in the red zone and not forecast to finish in time and several others are in the amber zone and at risk of not finishing. This would therefore prompt review with the team and the client to whom commitments are being made so that expectations are set appropriately.

Now what if 'n' and 'a' are actually the most important items to get done in this Sprint, or what if there are dependencies between some of the tasks? How are these handled? Well dependencies can be added simply by dragging-and-dropping a task on the task it is dependent on. But it's important for flexibility to keep such dependencies to a minimum. The main way to order tasks in the Scrum process is by priority. To see and change priorities click on the "Priorities" button on the Tools pane. Here's what you might see...

The priorities of all the tasks in "Sprint 01" are all the same (they're all priority one!). As a result the scheduling of the tasks is effectively random. Let's prioritise then in alphabetical order. Here's what the priorities list looks like then...

Changing priority changes the order that the tasks are scheduled, so the Gantt chart now reflects the alphabetical priority ordering. Here's the resulting Gantt chart for "Sprint 01".

And here's the projected Burndown chart for the same Sprint. It still shows a red status as we've not removed tasks by prioritising, but it reflects when the newly ordered tasks are forecast to close. For more on how burndown charts are used as the Sprint progresses, see "Don't burn out - burn down!".

The next article in this series looks at the significance of Top-down or Bottom-up planning for Sprints.

Searching the blog by topic

Blogspot offers some useful facilities for finding blog entries by topic. Below most entries there are a series of labels. Clicking on any of these will bring up other related articles on the same topic. Try it our with the labels below this post.

Latest patterns for Scrum

xProcess 2.8 is being released this week and among the exciting new capabilities are some new sample processes, including updates to the Scrum patterns. Here are some of the highlights.

Firstly the project pattern for the "Basic Scrum" process is now built from composite tasks so that there is a standard structure that is provided for all its projects. The Hierarchy diagram shows the structure, having top-level tasks for: General and Scrum administration overheads (overheads are unplanned or unplannable tasks that take up a proportion of everyone's time); the Sprints (a composite task which contains an iteration of Sprint instances); and the Unscheduled Backlog (a composite which contains a collection of Backlog Items).


You can also see from this diagram the structure of the Sprint and Backlog Item patterns. Sprint is a collection of the Backlog Items to be scheduled over the period, and consists of a single task. The beuty of xProcess of course is that these patterns can be modified to match the way your team is working or the particular application of Scrum that you are using. For example if you are using Scrum with XP you might want to rename the Backlog Item pattern to User Story and perhaps provide some structure to the set of tasks and role types that corresponds to0 the way you are using the method.

When you make a new Scrum Project in xProcess you'll be prompted for values of the parameters of the pattern. You can see these in this screenshot, where as well as defining the name of the project the start date, duration (the number of 4 week Sprints) and the Wiki location.
The Wiki location is not a required field but we've found many people find wikis are a convenient way to group documentation. By providing the location of the wiki in this dialog the descriptions of your backlog items are automatically transferred to a wiki page while also being browsable and editable in xProcess views.

Having created your Scrum project from this pattern, the next thing to do is add your resources. You need to add someone with a Scrum Master role and the others with Participant roles - let's say six participants in this example.

Because the tasks in the Scrum pattern are defined as top-down, even at this stage xProcess is able to provide a project schedule, based on the specified duration of the project. More usefully though, this is the time to create the first Sprint (right-click on the Sprints task and select New...) and then create some Backlog Items, either in the Sprint or in the Unscheduled Backlog if we don't yet know which Sprint we want them to be completed in. Backlog Items are prioritized, firstly from the particular Sprint into which they are created or moved, and secondly by the priority order of the tasks within a Sprint. You can edit this priority order by opening the Sprint editor, clicking on the priorities tab and either dragging and dropping or changing the priority number.

Once you have a Sprint which contains the items the team will be implementing, open the Burndown view. This provides both the history of how much work has been completed so far in the Sprint and a forecast of what should be completed. You'll see immediately for example if there's too much work in there and forecast dates are beyond the end of the Sprint. Here's an example of just one such Sprint... (click on the image to see more detail)Looks like some discussion needs to go on as to whether all the functionality is vital this time round!

Have you earned value today?

There are many ways to track progress on projects - see "Don't burn out - burndown" for example. Burndown is particularly useful in agile projects with timeboxes where the targets are set at quite short notice - month by month for example. Earned Value (EV) analysis on the other hand is a great technique for tracking progress against a stable plan (ultra-agile teams go and read that burndown article instead of this one - stable plans are a luxury you rarely see!).

With EV tracking the value of completing tasks is calculated from its originally planned cost. There are some disadvantages of this - not least that the whole method relies on having the well-estimated plan to start from - however its advantage is that efficiency of execution can be measured day by day on the project.There are two relevant measures of efficiency that EV analysis provide: cost efficiency (how much better or worse you are doing than the baseline plan with regards the cost of the tasks you have delivered so far); and schedule efficiency (how much more or less value you have delivered at this point in time compared to the baseline plan).


xProcess supports EV analysis in the Executive Dashboards client (see screenshot). The Executive Dashboards provide an overview of multiple projects (or just one project if you like) so it's an ideal place to look at these efficiency levels in different projects. We may revisit how to use the views provided in later blog entries so watch this space.

Don't burn out... Burn Down!

Following in the tradition of you heard it here first, here's another sneak preview of soon to be released functionality on xProcess. The burndown chart is a key visualisation that was developed in Scrum and now used with a number of agile methods. Currently you can use the reporting feature in xProcess to generate a burndown chart for your project or timebox. However there's a new feature in the wings that shows you the burndown instantly (history and forecast) on any project, parent task or folder. Here's an example:


This timebox (Timebox 01) runs for about 3 weeks and the scope of work targeted is forecast to complete right at the end of the timebox -- indeed a couple of the tasks are alread critical. (This diagram is looking forward, predicting when tasks will close, and thus when the work in each task will burn down). Look at the same time box a couple of days later.

Now -- perhaps because tasks have been re-estimated or resources changed -- we can see some tasks are forecast to finish beyound the end of the timebox. The chart is consequently shown as "red" status. Even at this early stage in the timebox we can predict that some deliverables are at risk and so take appropriate action. In this case some additional resources have been found and the some tasks excluded from the targets. Once the changes have been made, the effect can be seen and assessed immediately...

The timebox is "green" and all systems are go! Day by day as the timebox progresses we can monitor our progress and ensure the whole team stays on track!

When we visit the team half way through the timebox we can see from the burn down chart that they are still very much on track and confidence will be high that this team will deliver on its promises.