1. “The Goal” and Agile
An attempt at mapping concepts from “The Goal” by Eliyahu Goldratt (Theory of Constraints) to the Agile Software Development Process.
Ash Tengshe

2. Define Inventory in the proper way
The Goal: Inventory is the gap between the first person and the last person in a hike. It is all the parts in between the last step of a manufacturing process and the first step.
Agile: Inventory is all the features (User Stories) in process. It is the gap (time and features) between the Analyst and the end QA or Production Deployment. i.e. What is analyzed today is tested after 1.5 months and deployed after 2. So we have 2 months worth of inventory. Sometimes this number is as high as 1 year worth of inventory.
Even though the storage (holding costs) may not be as high in Agile as in a Manufacturing plant, the other problems related to large inventories exist
Capacity utilized in creating the inventory is capacity not utilized in delivering current order fast
Inventories become stale with changing markets

3. How to deal with late orders
Changes to batch are difficult or impossible
Large Batch Process
Sprint 1
Sprint 2
Only fully completed batch can be shipped; if batch is not complete, shipping needs to be postponed
Analysis and Development
Testing
Deployment
Changes are easy. You can start a different batch than the one planned
Small Batch Process
Sprint 1
Sprint 2
Completed batches can be shipped on time, the incomplete batches can wait for next shipment A A T A T T A T A T A T A T A T
Deployment

4. Understand the Impact of Bottlenecks on your Throughput
The Goal: A Bottleneck controls the flow of the process. The flow is limited by the capacity of the Bottleneck.
Agile: Understand that if the testers can only test 5 stories in a sprint, then your throughput per sprint is 5, even if the developers code 7 stories. The developers may seem productive but they are building inventory instead of helping to increase throughput.
Keeping people busy does not mean they are more productive. Understand your bottlenecks. Keeping people ahead of the bottlenecks producing all the time results in excess inventory. Try to build extra capacity as you go down the process to be able to cope with the statistical variations (slippages) of the groups coming before them.

5. Maximizing the Bottleneck Time - 1
The Goal: A Bottleneck should not be working on defective parts. This is a waste of the bottleneck’s time. QC (Quality Control) should be placed before the bottleneck.
Agile: A wrong (unnecessary, low-priority, ambiguous, volatile) requirement causes all next process steps (coding, testing and deployment) to work on a feature (part) that wasn’t really needed for the final assembly of the current backlogged order. The Customer group (Product Owner, QA, BSA) should formally double check the User Stories and acceptance criteria to understand if the Story (part) is really necessary and if all the acceptance criteria (e.g. heat treatment) are actually necessary process step for the part.
Don’t waste precious time of the process steps by working on the wrong part or doing extra unnecessary steps on the part. Be clear as to what the end assembly needs in order to ship.

6. Maximizing the Bottleneck Time - 2
The Goal: A Bottleneck should not be idle, flow through the bottleneck should be managed. Remember that bottleneck control the throughput of your products. If flow through the bottleneck is not managed well, it could impact the entire capacity of your manufacturing organization.
Agile: For example, if environments (Dev/Test/Pre-prod) are the bottlenecks then the flow should be managed to increase the throughput. I.e. sometimes the environments are idle and sometimes overloaded, this should not happen. Advance planning and calendar should be created to maximize the flow.
Focus on the bottlenecks. Ensure that they are being maximized by evening out the flow to meet the market demand.

7. To be continued…