Metrics Fixations: How People Feel About Numbers

The tweet that inspired this post:

Metrics that are not valid are dangerous.

TL;DR

My blog posts sometimes branch and overlap like legacy code that no one feels confident enough to refactor. So, new feature: the Too Long, Didn’t Read summary:

  1. Metrics are useful tools for helping evaluate and understand a situation. They have similar problems to other kinds of models.
  2. People believe metrics provide facts for reasoning, credibility in reporting, and safety in decision-making.
  3. Questioning metrics remains an important mission of our community.

Metrics are Models

A metric is a model. I see modeling here as a way of representing something so that we can more easily understand or describe it. They have value in expressing a measurement of data, but they need context to be information.

nerfherder
She Chooses Whoever Shoots Last?

I could look into my pasture full of hundreds of nerfs grouped in their pods, and communicate what I see as “There sure are lots of them.” Or, I might say “There are 1138 of them in 82 pods. Well, there were 1138 when I counted them all up last week. Oh wait, there have been seven calves, one death, and two missing since them. Yes, 1142, definitely 1142. I think. Unless some died or came back. And there are a few pregnant females out there. Still, only males for meat until wool production recovers.”

Other people have dug into the validity of metrics in great detail previously, and I don’t want to get sidetracked into (just) validity. We will get to the use of metrics shortly, but to get us into the right state of mind:

  • If I were to say that after implementing goat pairing in one pod of nerfs as a trial, nerf losses were at 7%, is that a good or bad number?
  • If nerf losses were 14% in the period before introducing goat pairing, does that help? What if I point out that there are an average of 14 nerfs in a pod? Are you going to ask where in the sample period today is?
  • Did I mention that wool production is down 38% because of the goats snacking on nerf fur clumps?
  • Meat revenue is up 3% this season.
  • Per animal? No, overall.
  • Meat prices are down relative to wool prices lately , but still up 5% this year to about $5.25.
  • How many animals butchered? I record that separately, but usually just divide pounds sold by 600 and use that for investor reports and taxes.
  • “All models are flawed. Some are useful.”
  • Remember not to confuse models for what they represent, lest you get the metrics – as opposed to the results – that you are looking for.
  • Correlation is not causation. It’s especially suspect when you are trying to explain something in retrospect.
  • The last, hardly subtle point: make sure what you measure matters.

And….time. It’s not that helpful to pick apart specific metrics – whether they measure something real, or if they are based on CMM Levels, KLOCs, defect densities, nerf herd finances, and other arbitrary/imaginary constructs. It’s not that helpful because it doesn’t necessarily change minds. Let’s instead discuss why people are so enamored with metrics, how they use them, and speculate on what they might be getting from them.

Quantifying With Measurement

By measuring something, we may feel like we are replacing feel with facts, emotions with knowledge, and uncertainty with determinism. By naming a thing, we abstract it; the constant march of computer science is to reduce complexity by setting aside information we don’t need, and simplify things to fewer descriptors. Everybody enjoys the idea of being a scientist.

894 story points, 37 story points per dev per sprint...
894 story points, at 37 story points per dev per sprint, is….

Similarly, we feel more control when we can point to a number. We can say that a thing is a certain height, length, size, etc, and we feel like we understand it. We’ve reduced the complexity to where we can describe a thing, removing the need to try to transfer some bit of tacit knowledge if we understand what we are looking at, or deceiving ourselves about how much we actually understand if we don’t. Everyone likes to feel clever.

We can then discuss quantities, group things that seem to be similar, and so forth. This means we can put it in spreadsheets, we can talk about how many people are needed to produce certain quantities, etc.

Of course, once something is represented by a number, it invites dangerous extrapolation: “Once we implement goat pairing across all pods, we’ll make $252,000 more!”

You Can’t Argue With Facts

When we can cite a number, wherever it comes from, we might feel like we are making quantitative judgments, removing our judgment and opinions. Something that is a fact isn’t open for interpretation, right?

leprechaun_on_the_loose

This provides us with cover and safety. Instead of stating an opinion, we can claim we’re simply pointing at reality. If you make a mistake in judgment, metrics can be the justification for why you did it. Wouldn’t anyone else have made that choice with those facts at hand?

Where did my facts come from? If they are measurements, how do I take them, and what do I discard? Why do they mean what I say they mean, and why do they mean that here and now? This is the slippery stuff that allows us to frame a discussion with our version of “facts” and interpretation of what they mean, inserting our biases and opinions while maintaining the illusion that we are making completely quantitative decisions, using only logic and reason, denying our influence in stacking the deck in the first place.

“Quantitatively, we’ve had the same experience as everyone else – goat pairing is essential for maximizing wool production.”

We Have to Measure Our Progress Somehow

If you do get a person pursuing metrics to admit problems with validity, a common deflection for reframing these conversations is to claim that however flawed they might be, metrics are an external requirement that is not open for discussion. When the boss’ boss demands metrics – or when we say that they do, we are attempting to end the conversation about the validity/need for metrics. Persisting with these questions past this signal that this is not open for discussion is going to reduce future influence, or worse.

Is this Accurate? Precisely.
Is this Accurate? Precisely.

This resolve comes from the experience of being asked to report status, which is essentially answering the following set of questions:

  • Is there progress being made?
  • Is the schedule still accurate?
  • Do you need help with anything?

If the answer is No, No, or Yes, there will need to be additional supporting detail. You are persuading another person to act or not act, committing personal credibility, and taking the risk that what you claim is correct enough that they won’t look foolish for endorsing it and you.

Reporting, Cloaked in Metrics

We often have limited opportunities to prove ourselves. We want our bosses, and our boss’ bosses, to believe that we are smart and capable. Presenting metrics to bolster our conclusion makes us feel more credible – and it can’t be denied that when the subject isn’t understood, almost any metrics are going to sound impressive and credible, making everyone involved feel smarter.

Many of us have found ourselves in discussions where a stakeholder is looking at a chart where the underlying measurements are barely – or not at all – understood, but they will still question the shape of curves and graph lines, asking for explanations when any troughs appear. This can be a powerful mechanism for having a discussion about the relevant issues, but there is a tradeoff in presenting a single metric – and having that become the standard.

Good reporting communicates facts, risks, context, and recommendations. Metrics that don’t support one of these are not in the mission of reporting.

What Does it All Mean?

Is it really true we can’t run a business without metrics? I don’t think I am advocating that, but I am suggesting we can help make it disreputable to manage to flat, two-dimensional metrics as if they were reality.

Managers have been simmered in the pot of using best practices to manage to metrics for at least a generation. Questioning metrics, both in formulation and usage, is an important mission of our community. We need to be thoughtful about when and how we raise these issues, but understanding the components of our reasoning is necessary to be confident that we are reasoning well.

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