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All right, thank you for coming to 'Retrospectives for Humans.' Before we begin, I want to acknowledge that this has been a really frightening and difficult few weeks for many people.
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With tragedy and violence touching many lives that I know, if you're one of those affected, I offer my sympathies. It can be difficult to function normally and pay attention to everyday business during such times, and even harder to learn new concepts. Please take care of yourself.
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I don't believe this talk requires any content warnings, but if it does and I miss it, I apologize. I would appreciate hearing from you afterward.
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Today, I'm here to talk about retrospectives. These are incident retrospectives, but most of what I’m going to discuss will also likely be useful for you in an agile retrospective, should you choose to engage in that.
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The subtitle of this talk could also be 'Words Mean Things'.
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Let's discuss disasters where no one was hurt. Seattle has the two longest floating bridges in the world, and in 1990, one of them sank over the Thanksgiving Day weekend during a storm while it was being repurposed.
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The public reporting on this incident remains extremely simplistic, but the official investigation found that five factors were involved, and all of these factors were required for the bridge to fail.
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At the time the bridge sank, they were scraping off the surface of the bridge using a method called hydro demolition. They were preparing to change the direction of traffic on the bridge due to nearby construction.
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The EPA had mandated that the water runoff should not flow into the lake, citing serious environmental concerns, which led them to find a different way to store that water.
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After much deliberation, they decided to store the water in the hollow pontoons of the bridge. A floating bridge is made up of these hollow sections, similar to a ship's hull, and in this case, made of concrete.
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However, the bridge was floating higher than it was designed to and had excess flotation capacity that they decided to utilize to store the water.
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Fortunately, no one was on the bridge during the holiday weekend. One pontoon sank slowly, dragging seven more down with it, resulting in a cascading failure.
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I'm going to play a video that covers some of the events surrounding this incident.
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Built in 1940, the Merle Bridge in Seattle was named after the director of Washington state's Department of Transportation.
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The bridge stood for 50 years, but in November of 1990, maintenance work led to this disaster.
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The Merle Bridge floated on a row of 25 hollow concrete pontoons, each measuring 350 feet long. These pontoons were bolted together for stability and anchored to the bottom of the lake.
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The water conditions were perfect for using such structures, as ice and heavy currents were rarely an issue.
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In the fall of 1990, the bridge was undergoing a facelift through hydro demolition, a process involving highly pressurized water used to break up the roadway.
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Due to environmental regulations prohibiting the dumping of contaminated water into the lake, it was temporarily stored in the empty pontoons via access holes. The water levels inside the pontoons were closely monitored to prevent structural compromise.
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However, during Thanksgiving weekend, with crews short-handed, a heavy storm hit Seattle. Rainwater began flooding the open pontoons, and the winds whipped up the lake's surface, adding to the water levels.
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On November 25th, eight waterlogged pontoons sank, taking those sections of the bridge down with them and severing 12 anchoring cables from a nearby bridge under construction.
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While fortunately no one was hurt, the damage was estimated at $69 million. The investigation into the accident concluded that concrete pontoons do not float when they are full of water.
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The Merle Bridge was rebuilt two years later. Although it appeared the same externally, the pontoons supporting the bridge were divided into smaller sections to minimize damage from leaks.
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This precaution highlights the structural similarities between floating bridges and floating ships, having multiple compartments to prevent a failure in one section from compromising the entire structure.
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As a result of this thorough investigation, I received a paper detailing what they determined to be the root causes. I'll read you some key findings.
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The loads on the bridge created significant leakage due to the accumulated water from rain and windstorms. Longitudinal flow on the bridge's surface and pumping led to pressure points that exceeded the threshold for leakage, causing existing cracks to open and allowing water in.
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The survey confirmed that although this bridge was built in the 1940s, it was in excellent condition for its age, with cracks that were expected but fewer in number than anticipated.
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Despite this careful monitoring and planning, the official investigation missed a critical social element. The crews were unable to pump the water out according to the schedule established by the engineers.
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While there is a mention of that in the paper, it lacks an explanation. We remain unaware of the reasons behind the schedule's breakdown. Perhaps there were not enough trucks or drivers, or perhaps there were pay issues or a strike.
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Regardless, it highlights the complexity of retrospective analysis. As thorough as the investigation was, there was still a gap in understanding.
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When analyzing these failures, it's essential to recognize that even seemingly simple mistakes can stem from intricate issues. Nobody intends for things to go wrong; they often make decisions based on the information they have at the time.
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Thus, our challenge in retrospectives is to look beyond the immediate failures and understand the underlying factors that contributed to these failures.
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Now, let's shift gears and delve into facilitation.
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As facilitators, your job is to keep the conversation blame-free, guide discussions towards constructive outcomes, and foster psychological safety for all participants.
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In order to achieve this, let's first discuss Miller’s Law: to understand what another person is saying, you must assume it is true and try to discern what it could be true of.
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This requires imagining the other person's perspective, which is crucial to understanding systems, environments, or events that you may not have directly experienced yourself.
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Next, let's address the topic of blame. English is often a blame-heavy language. Phrases that start with 'you' draw a line between yourself and the person you're addressing.
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Statements like 'You knocked over that vase; why did you do that?' place the other person on the defensive and can lead to adversarial exchanges.
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In a retrospective, it's best to avoid 'you' and 'why' questions, as they can create hostility and defensiveness. Instead, ask questions like 'How could you have approached this differently?' or 'What information did you have at the time?'
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Such questions are more constructive and invite a shared exploration of the incident.
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Here are some other phrases to avoid: 'You always...', 'You never...', and 'How come you didn't fix it last time?'
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These phrases carry blame and negativity. Instead, try to ask questions that promote reflection and dialogue, like 'What could have been done differently?' or 'What other options were available to us?'
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In retrospectives, we often seek remediation items—ideas for changes in code, documentation, or processes that can improve future outcomes.
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It's important to remember that complex systems lead to complex failures, and looking for a single root cause may limit our understanding.
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For example, human error is often cited, but it's essential to dig deeper and understand what led to that error and how it influenced the system.
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Questions like 'What contributed to this error?' or 'How could it have been detected sooner?' help us identify areas for improvement.
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Now, let's address a common fallacy: the idea that once we recognize a mistake, we can simply avoid it moving forward.
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The truth is that relying on human vigilance is unrealistic. People cannot be constantly alert or perfect, and we need to plan for human variability.
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So, how can we ensure our retrospectives are effective? Facilitators should have an agenda and stick to it.
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This helps participants understand what will be covered and ensures that all voices are heard. Digressions can detract from this.
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As a facilitator, watch for those who may not be contributing. Some participants may be shy or have trouble interjecting.
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It's essential to recognize non-verbal cues and invite those who haven't spoken up to share their thoughts.
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Note-taking should be fair and distributed. It should never fall solely on the facilitator, as this can prevent them from engaging fully with the group.
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As a facilitator, you must practice interrupting when necessary to keep the meeting on track.
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It may be uncomfortable but remember that unchecked digressions can derail the meeting.
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Keep an eye on the clock and remind participants to stay focused.
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Finally, let’s address humor. Humor can be tricky in retrospectives—what's comedic to one could be hurtful to someone else.
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It’s better to keep the tone respectful and avoid jokes that may make anyone uncomfortable, especially discussions surrounding sensitive topics.
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Focus instead on positivity, calling out successes, and expressing gratitude to keep the environment warm and constructive.
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What if you or someone else makes a mistake during the retrospective? Acknowledge it, and move on—don't dwell on guilt or embarrassment.
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A simple apology without ostentatious displays of regret is best. This maintains the meeting's momentum.
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If someone is inclined to blame themselves, intervene gently and redirect the focus back to the purpose of the retrospective.
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Remind everyone that this is a blameless environment.
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Reviewing our retrospectives is essential for organizational growth. They serve as communication structures that reflect the systems we operate on.
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Let’s foster a culture where we are encouraged to make bigger, more interesting mistakes.
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I want to acknowledge the many people who've influenced me, particularly in areas of linguistics and social concepts, as well as in effective teaching.
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Thank you all for being here. It looks like I have some time left for questions.
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When dealing with senior individuals who may be blaming junior staff in retrospectives, I recommend having an executive sponsor who supports a blameless culture.
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This senior endorsement can help foster a healthy retrospective environment. You can also approach the person privately if your relationship allows for it.
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Interrupting someone who doesn't take pauses can be challenging. During remote meetings, try to interject when you can.
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In physical meetings, consider standing to reassert your presence and redirect the discussion.
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Find the resources you need for further learning and share useful materials with your teams.
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Remember to keep conversations flowing and productive. If discussions veer too deep into technical details, set a plan for follow-ups.