PSK-I Sample Questions & Answers

Little's Law is a queuing theory formula that holds true for any stable system. For the law to provide meaningful insights in a Kanban context, the system's key characteristics (like average arrival rate and average departure rate) should be stable. This means the workflow isn't undergoing constant, radical change, and the averages for WIP and Throughput are calculated over a sufficiently long period to be representative of the system's typical performance.

By limiting WIP in the 'In Progress' columns, Developers will eventually reach a point where they cannot pull new work without an existing item moving forward. If items are waiting in 'Peer Review', the system signals that the most valuable action is to perform a review to free up WIP capacity. This creates a pull system, improving flow and fostering collaboration by encouraging team members to help where the work is needed most.

Throughput measures the number of work items finished per unit of time (e.g., per Sprint). By analyzing historical Throughput data (e.g., the team has completed between 8 and 12 items in each of the last 5 Sprints), the team can create a probabilistic forecast for the upcoming Sprint. While Cycle Time is used to forecast single items, Throughput is used to forecast how many items can be completed in a fixed time period.

Limiting Work in Progress (WIP) directly supports the Scrum value of Focus. By setting WIP limits, the team agrees to concentrate on a small number of items at a time. This reduces context switching, prevents individuals from being overloaded, and encourages the entire team to focus on finishing work before starting new work. This collective focus helps in delivering a valuable Increment each Sprint.

The start and finish points for measuring Cycle Time should align with the process the team wants to improve and forecast. Typically, this starts when the team commits to working on an item (pulling it from the backlog into an active state like 'Analysis' or 'Development') and ends when the item delivers value or is ready for delivery (e.g., after 'Testing'). The 'To Do' state is often a queue of options, not committed work, and 'Deployment' might be a separate process. The key is that the team explicitly defines these points.

Leading indicators provide real-time information that can be used to make decisions and forecasts about the near future. Work in Progress (WIP) is a leading indicator because the amount of work currently in the system directly impacts future cycle times. Work Item Age is also a leading indicator because it helps identify items at risk of not finishing on time. Throughput and Cycle Time are lagging indicators as they measure past performance.

Leading indicators provide real-time information that can be used to make decisions and forecasts about the near future. Work in Progress (WIP) is a leading indicator because the amount of work currently in the system directly impacts future cycle times. Work Item Age is also a leading indicator because it helps identify items at risk of not finishing on time. Throughput and Cycle Time are lagging indicators as they measure past performance.

Using Kanban practices does not change the core rules of the Scrum framework. The Sprint Goal is a fundamental part of Scrum that provides focus, flexibility, and a coherent objective for the Sprint. Kanban practices like limiting WIP and managing flow help the team achieve the Sprint Goal more effectively and predictably, but they do not replace it.

The 'Player Character' feature has a work item age of 7 days, which is very close to breaching the 8-day SLE. Active work management in Kanban prioritizes finishing aging work to maintain a predictable flow. Since the WIP limit is also met, the team cannot start new work. Therefore, the most logical and effective action is to swarm on the oldest item to get it finished, thus protecting the SLE and freeing up WIP for other items to flow.

On a CFD, the vertical distance between the top and bottom lines of a band represents the Work in Progress (WIP) for that state. If the 'In Progress' band is widening over time, it means that work is entering that state faster than it is leaving. This indicates that WIP is increasing and suggests a bottleneck or impediment is slowing down the flow of work.

A Service Level Expectation (SLE) is a forecast, not a guarantee. It is derived from historical cycle time data and is expressed as a probability (e.g., '85% of items are finished in 8 days or less'). Its primary purpose is to create a shared understanding of expected delivery times for a single work item, improving predictability and helping the team identify items that are at risk of taking longer than expected.