The difference between Work Item Type and Classes of Service in Kanban

One of the first challenges for those who are new to Kanban is to differentiate between Work Item Type and Classes of Service (CoS).

First, we need to step back and see why we need these concepts in the first place. In Kanban, everything is organised around the customer and a service delivery team that focus to fulfil the customer’s request. 

The customer always has a request and accepts it when it’s fulfilled by Service Delivery Team.

Work Item Type is what the customer wants.

Classes of Service is how Service Delivery responds to customer’s needs (or Work Item Type) to ensure the most valuable work is delivered to the right customer at the right time and reduce the cost of delay.

Example

To clarify let’s assume that there is an application, which recently has gone live and there is a team, which is responsible to maintain and improve this application. Imagine this team has 3 customers explained below:

• Customer service; who needs stability and expect bugs and production issues resolved within 12 days.
• Sales; who needs new functionalities to compete with other competitors and stay in the market. They are the main revenue line of this company. They can wait for a longer period to see something happens, however, due to the demo to the client and some key milestones some of their requests must meet the deadline. 
• Engineering manager; who is looking after security and platform improvement. His requests are mostly not too urgent, however, sometimes there is a hard deadline due to license expiry and other issues.

According to the above example, there are 3 Work Item Types raised by customers and now Service Delivery Team needs to prioritise them so they have the following policies which help them to prioritise customer requests.

Classes of Service	Policies
Expedite	– This request can’t wait – Drop everything and focus on this one – Release when it’s ready (on demand)
Fixed Date	– This request MUST meet the deadline – This request can wait – Might be released on demand
Standard	– This request can wait – Pull and start when capacity available – Release based on release cycle – FIFO

As you noticed, Service Delivery maps Work Items to Classes of Service to be able to prioritise the requests to satisfy the customer.

Here is their work distribution histogram and below explained what that means:

Average Lead Time
10	85% of their works completed within 10 days Lead Time
15	92% of their works completed within 15 days Lead Time
20	99.2% of their works completed within 15 days Lead Time

That helps team to prioritise and also have a good service level agreement with the customer. For example, in the above example, the team knows that if they pull the work today, there is 85% chance that it will be completed and delivered to the customer in 10 days, if 85% is not acceptable and 90% is, then pull it 15 days in advance 

Conclusion

Work Item Types and Classes of Service are two completely different concepts, Work Item Types represent customer needs and Classes of Service represent how the deliver team wants to treat customer request, to deliver the right work at the right time.