The difference between work item types and classes of service

Understanding the difference between work item types and classes of service can sometimes be confusing to those who are new to Kanban. These are two different concepts and whilst there is often a 1:1 mapping between a work item type and class of service, they are distinguishable concepts. Here’s a reminder if you’re getting confused between the two which will help you out in future STATIK exercises.

Work Item types

The work item type is closely related to the request that’s coming from the customer. Customers can often have different types of requests / different types of services / work required. These requests can go through different types of workflow.

This is the key to work item types – the customer request / service needed and the process we go through to provide the service.

For example, if you were to take a coffee shop, a customer could request a take away coffee or they could order a coffee to have in the coffee shop. These two are conceivably different work item types – in the first example the customer will expect to get the coffee in a disposable cup that they can take away. In the second example, the coffee will come in a reusable mug and staff member will bring it out to the table at which you’ve been seated. Notice that both have different workflows. Also, in either case there might be different expectations as to the level of service. For take away, you might want to get it as soon as possible, whereas for dine in service, you might be happy to wait a little longer as you’ve likely got someone there with you that you’re having a conversation with.

Classes of Service

Classes of service represent different policies on how to deal with a customer request / work. For example, for an urgent or expedited item the policies may be:

  • Stop what you’re doing and focus on this task
  • Swarm on it (use as many people as required)
  • Don’t wait in queues
  • Release when ready

Policies for standard items might be:

  • Only pull this in when capacity is available
  • First in, first out (FIFO)
  • Release weekly

Note how the policies describe how the team is supposed to treat the request.

Compare and Contrast

Sometimes a work item type will have a class of service to itself. Some work item types naturally have a higher priority than others. I think this is where some people can get confused, when there’s a 1:1 mapping between a work item type and a class of service. However, please remember to distinguish based on what was discussed above so that you can get a better understanding of how the system is operating.

Alternatively, some work item types will have different classes of service. There are situations where certain requests will have a different cost of delay compared to others. Thus, with those different levels of urgency the team will need to handle it in a different way.

Both types taken together can make up the service level expectations. Take the following examples:

Work TypeClass of ServiceLead time
AStandardAverage lead time of 12 days, with 85% completed within 16 days.
BFixed DateAverage lead time of 6 days, with 90% completed within 8 days
BIntangibleAverage lead time of 10 days with 80% completed within 15 days.
Lead time expectations

As you can see from the above, they both have distinct elements, but they work together to help inform customers of service expectations.

Conclusion

Work item types and classes of service are two distinct concepts. They need to both be understood in order to form a kanban system. When designing your system, take the above into consideration and you should be able to walk through the STATIK steps more easily.

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