Quality Index (QI): Measure of Risk

Is it possible to capture the quality of an offering in a single metric, something like a Quality Index?

Before I answer this question, I'd like to reflect back on the definition of quality:

Quality: The totality of features and characteristics of a product or service that bear on its ability to satisfy stated or implied needs. (ISO 8402: 1986, 3.1)

Note that the definition refers to stated and implied needs. What that means is Quality of a product which is considered "high" today (because it totally satisfies stated and implied needs) can go down tomorrow because of changes in implied needs. How do we measure that? We probably can't!

Let's re-write the questoin then,

Is it possible to capture the intrinsic quality of an offering in a single metric, something like a Quality Index?

This sounds more reasonable. But, there are over 100 metrics that can be argued to impact the quality of an offering. How do we make sure that we are capturing everything and our QI is based on the perfect algorithm?

Good news is that we don't need to look into hundreds of metrics. 80/20 rule applies here too! We can take 20% of the top variables to get the 80% of insight into intrinsic quality.

What if there is an error in the algorithm we choose? It is possible that our QI is off by 10% or even 20%. If e represents the error, then QI(Observed) = QI (Real) +/- e

If we use the consistent mechanism to capture QI, same error (e) will exist everytime we take a snapshot. And the best part is that majority of this error will cancel out when we plot QI numbers to look at its trend over time. The whole graph will be offset by e.

Note: The key to quality is consistency and repeatability. It is not really important what process we follow, as long as we can make sure that we can make it repeatable. Same concept applies to QI.

So, the answer is YES. We can capture the intrinsic quality of an offering in a single metric and use the trend analysis to keep tab on improvement. Remember TQM, it is all about continuous measurement and continuous improvement!!

Why calculate QI?

QI is not just a measure of quality, it is also a measure of risk associated with quality for your product offering. Here are some of the real advantages of having a QI for all your projects:

• Get an insight into release readiness, especially in the agile development
• QI dependency matrix can help identify problems much quicker in the SOA world
• Mapping QI ranges with your Customer escalation data can give you an insight into what to expect when you release a product with QI less than 60 as compared to a product with QI greater than 90.
• QI trend provides continuous feedback - required for control. It is easy to monitor when process is going out-of-control.
• Easy for management to digest one number and drill down, if required.

Remember:

• QI like number in itself is probably not meaningful. It's the trend that is relevant.
  
• QI number can't be compared across companies in the industry, as there are a lot of variables in the "error" part, which won't cancel each other!
• QI probably can't even be compared across different teams with-in the same company

Further Reading:

• Read It all boils down to Metrics! for more information!