Ultimate Guide to Reducing the Amount of Defects and other Waste in your Product

What’s a defect? I like this definition.

A defect is anything that threatens the value of the product.

Before we start, let’s agree that:

  1. we don’t want defects that threaten the value of our product
  2. we want to give our customers as much value as possible at all times.

If you don’t agree with 1 and 2 then, don’t waste your time and stop reading now.

Software defects aka Bugs

Testers are normally associated with finding defects. Some testers get very protective with the defects they find and some developers can be very defensive about the defects they wrote. Customers don’t like defects, developers don’t like defects, product managers don’t like defects, let’s be honest, nobody likes defects besides some testers.

Why would that be? The reason is that the focus of a lot of testers is on detecting defects, and that’s what they get paid for in a lot of organisations. If you are a tester and love your defects, you might find this article disturbing, if you decide to proceed, do so at your own peril.


Defects are waste

Let’s be clear from the start: defects are waste. Waste of time in designing defective products, waste of time in coding defective routines, waste of time in detecting them, waste of time in fixing them, waste of time in re-checking them. Even writing this sentence took a good while, now think how much time it takes you to produce, detect, fix, recheck defects.

Our industry has developed a defect coping mechanism that we call defect management. It is based on a workflow of detecting => fixing => retesting. Throughout the years it has become best practice (sic) to have defect management tools and to log and track defects. Defect management approaches are generally cumbersome, slow, costly and tend to annoy people no matter whether you are a tester that gets his defect rejected, you are a developer that gets a by design feature flagged as defect, or a product manager that needs to spend time prioritising, charting and trending waste.

Another dangerous characteristic of defects is that they can be easily counted and you will always find a pointy haired manager that decides he is going to shed light on the health of his product and on the efficiency of his team by counting and drawing colorful waste charts.

But, if we agree that defects are waste, why are we logging and tracking waste, creating waste charts seems even more ridiculous, wouldn’t it be easier to try to prevent them?

Oh, if only we could write the right thing first and reduce the number of defects we produce! I say we can, be patient and read on.

Software development teams have found many ways of being creative playing with defects, see some examples below.

Example 1: Reward waste

Reward for the wrong reason
Reward for the wrong reason

Some years back I was working on a business critical project in one of 5 scrum teams . Let me clarify first, that our scrum implementation was at best poor, we didn’t release every sprint and our definition of done was questionable.

Close to an important release, we found ourselves in a situation where we needed to fix a lot of defects before going into production. We had 2 weeks and our teams had collectively around 100 defects to go through. Our CTO was very supportive of the defect killing initiative and he was eager to deliver with zero defects. He put in place a plan that included free food all day and night and some pampering for the developers that needed to focus 100% on defect resolution. Then he decided to give a prize to the team that would fix the highest amount of defects.

I remember feeling frightened of the possible future consequences of this reward. I spoke to the CTO and told him that I would have liked more a prize for the team that produced the lowest amount of defects rather than the one that fixed the most. Our CTO was a smart guy and understood the value proposition of my objection, he changed his approach and spoke to the teams on how not introducing defects in the first place is much more efficient than fixing them after they have been coded. Soon after the release, we started applying an approach that focussed on preventing defects rather than fixating on detection. We never had the problem of fixing 100 bugs in 2 weeks again.

A typical defect prioritization meeting
A typical defect prioritization meeting

Example 2: Defects metrics

In my previous waterfall life, I remember when management introduced a performance metric directly linked to defects. Testers were to be judged on the Defect Detection Index calculated as (Number of Defects detected during testing / Total number of Defects detected including production)*100. An index lower than 90 would mean nobody in the test team would get a bonus. Developers were individually judged on the number of defects found in their code by the testers and business analysts were individually judged on the number of defects found by the testers in their requirements.

Welcome to the battlefield!

The bug prioritisation meetings were battles where development managers argued any bug was a missed requirement, product managers argued that every bug was a coding error or a tester misunderstanding and the test lead (me) was simply shouted at and criticised for allowing his testers to go beyond the requirements and make use of their intellectual functions outside a scripted validation routine.

Going to that meeting was a nightmare, people completely forgot about our customers and simply wanted to get their metrics right. The amount of time we wasted arguing and defending our bonuses was astonishing. Our customers were normally unhappy because instead of focusing on value delivery we focussed on playing with defects, what a bunch of losers we were!

Our customers were very unhappy.

Example 3: Defects as non-conformance to requirements

Let the nitpicking season start
Let the nitpicking season start

In the same environment as Example 2, testers, in order to keep their Defect Detection Index high used to raise large amounts of minor or non-significant “defects” that were in reality non-conformance to requirements. Funnily enough such non-conformances  were generally improvements.


Testers didn’t care if they were requirements, code defects or even improvements, to them they were money, so they opened them. Improvements were filed as defects as they were in non-conformance to requirements. In most of the cases, these were considered to be low severity and hence low priority defects to make the testers happy and had to be filed, reviewed, prioritised and used in trends, metrics and other useless calculations.

This activity could easily take 30% of the tester time. Such defects would not only take testers’s time, but would also affect developers, product managers, business analysts and eventually clutter the defect management tool.

Waste that creates waste, exponentially, how wonderful.

A colourful dump
A colourful dump

 Example 4: Defect charts, trends and other utter nonsense

Every week I had to prepare defect charts for management. These were extracted from our monstrous defect management tool and presented in brightly coloured useless charts. My manager got so excited at the prospect of producing useless information that she started a pet project to create charts that were more colourful than the ones I presented. She used 2 developers for 6 weeks to create this thing that was meant to wow the senior executives.

In the process of defining the requirements for wowing the big guys, she introduced a few new even more useless charts and consolidated it into an aggregating dashboard. She called it the product quality health dashboard, I secretly called it the dump.

Nobody gave a damn about the dashboard, nobody used the numbers for any reason, nobody cared that they could configure it, but my boss was extremely proud of it. A legend says that she got a big raise because of it. If you play with rubbish, then you will start measuring rubbish and eventually you will end up doing data analysis and showing a consolidated view of the rubbish you store in your code.

How can we avoid this?

1. Focus on defect prevention

Many development teams focus on delivering features fast with little consideration for defect prevention. The theory is that testers (whose time is sometimes less expensive than developers) will find the defects that will be fixed later. This approach represents a false economy; rework disrupts developers activities and harms the flow of value being delivered. There are many approaches available to development teams to reduce the amount of rework needed.

Do you want to prevent defects? You can try any combination of the below:

  1. With BDD/ATDD/Specification By Example or other test first approach, delivery teams test product owners assumptions through conversations and are more likely to produce the right feature the first time.
  2. The ability to have fast feedback loops also allows for early removal of defects, automated unit and integration tests can help developers quickly identify potential issues and remove them before they get embedded into a feature.
  3. Tight collaboration between business and delivery teams helps teams be aligned with their real business goal and reduce the amount of unnecessary features. This means less code and as a consequence less defects. Because, your best piece of code is the one you won’t have to write.
  4. Reducing complexity is very powerful in preventing defects, if we are able to break down a complex problem in many simple problems we are likely to reduce the amount of defects we introduce. Simple problems have simple solutions and simple solutions have less defects than complex ones.
  5. Good coding standards like for example limiting the length of a method to a low number of lines, setting limits on cyclomatic complexity, applying good naming conventions to help readability also have a positive impact on the number of defects produced
  6. Code reviews and pair programming greatly help reduce defects
  7. Refactoring at all times also reduces defects in the long run

Moral of the story: If you don’t write defects, you will not have to fix them.

2. Fix defects immediately and burn defect management tools

If like me years back, you are getting tired of filing, categorising, discussing, reporting, ordering defects I have a very quick solution. Fix the defects as soon as you find them.

It is normal for a developer to fix a defect he finds in the code he is writing as soon as he finds it without having to log it, but as soon as the defect is found by a different individual (a tester for example) then apparently we need to start a strict logging process. Why? No idea really. People sometimes say: “if you don’t do root cause analysis you don’t know what you are doing, hence you need to file the defects”, but in reality nobody stops you from doing root cause analysis when you find the defect if you really want.

What I am suggesting is that whoever finds a bug walks to a developer responsible for the code and has a conversation. The consequence of that conversation (that in some cases can involve also a product owner) should be let’s fix it now or let’s forget about it forever.

Fixing it now, means normally that the developer is fresh on the specific code that needs to be fixed, surely fresher than in 4 weeks, when he won’t even remember he ever wrote that code. Fixing it now means that the issue is gone and we don’t have to worry about it any longer, our customer will be thankful.

Forgetting about it forever means that it is not an issue worth fixing, probably it doesn’t threaten the value of the project and the customer won’t care if we don’t fix it. Forgetting about it forever also means that we won’t carry a stinky dead fish in a defect management tool. We won’t have to waste time re-discussing the same dead fish forever in the future and our customers are happy we are not wasting time but working on new features. If you decide to fix it, I’d also recommend you write an automatic test for it, this will make sure that if the issue happens again you’ll know straight away.

I have encountered huge scepticism when suggesting to burn defect management tools and fix just in time. Only very few seem to think this is possible. As a matter of fact all my teams were able to do this for the last 6 years and nobody ever said, “I miss Jira and the beautiful bug charts”.

Obviously this approach is better suited for co located development teams, I haven’t tried it yet with a geographically distributed team, I suggest you give it a try and let me know how it goes.

Playing with defects waste index:


Epidemic: 90% – The only places that don’t file and manage defects I have ever encountered are the places where I have worked and have changed the process. In the last couple of years, I have heard of two other places where they do something similar but that’s just about it. The world seems to have a great time in wasting money filing, categorising, reporting, trending waste.

Damaging: 100% – Using defects for people appraisal is one of the worst practices I have ever experienced in my long career, the damage can be immense. The customer becomes irrelevant and people focus on gaming the system to their benefit. Logging and managing defects is extremely wasteful as well, it requires time, energy and can among other things, endanger relationships between testers and developers. Trending and deducting release dates from defect density is plain idiotic, when with a little attention to defect prevention defects would be so rare that trends would not exist.

Resistant: 90% – I had to leave one company because I dared doubt the defect management gospel and like an heretic I was virtually burned at the stake. In the second company I tried to remove defect management tools I was successful after 2 years of trying, quite resistant. The third one is the one where people were happy to experiment and as soon as they saw how much waste we were removing it quickly became the new rule. I have had numerous discussions with people on the subject and the general position is that defect management must be done through a tool and following a rigid process.

Because “that’s the way we do things here!”

Recommended Reading

Lean Software development – An Agile Toolkit (Mary and Tom Poppendieck)



This is a reviewed and improved version of an article I first wrote in 2015 (old version here)

Some quality metrics that helped my teams

Measuring_Tape_Inch+CMI’ve been asked the question “what are the best metrics to improve software quality?” (or similar) a million times, this blog post is a selfish time saver, you are probably reading this because you asked me a similar question and I sent you here.

Firstly, i am not a fan of metrics and I consider a good 99% of the recommended software quality metrics pure rubbish. Having said that there are a few metrics that have helped teams I worked with and these are the ones I will share.

Secondly, metrics should be used to drive change. I believe it is fundamental that the metric tracked is clearly associated to the reason why the metric is tracked so that people don’t focus on the number but on the benefit that observing the number will drive.

Good metric#1: In order to be able to re-factor without worrying about breaking what we have already built we decided to raise the unit test coverage to >95% and measure it. Builds would fail if the metric was not respected.

Good metric#2: In order to reduce code complexity, improve readability and make changes easier, we set a limit and measured the maximum size of each method (15 lines) and the cyclomatic complexity (don’t remember the number but I think it was <10). Builds would fail if the metric was not respected.

Good metric#3: In order to continuously deliver low complexity easily testable units of work and help with predictability we started measuring the full cycle time of user stories from inception to production with the goal of keeping it between 3 and 5 days. When we had user stories that took more than 5 days we retrospected and examined the reasons.

In the 3 cases above, the focus is on the goal, the number is what we think will drive the change and can always be changed.

If people don’t understand why they write unit tests, they will achieve unit test coverage without guaranteeing the ability to refactor, for example by writing fake tests that don’t have assertions. We should never decouple the metric from the reason we are measuring something.

These are the good metrics, for me. If you want to see some of the bad ones, have a look at this article I wrote some time ago on confrontational metrics and delivery teams that don’t give a damn about their customers.