Skip to main content

Metric or Treat


A friend lent me two books on metrics. One was so thumpingly wrong I could not finish it. One was so joyfully right I had to read it end-to-end, despite the author's recommendation not to.

Dave Nicolette will be pleased to know that his book, Software Development Metrics, was the second of the two. Why so right? Because immediately I felt like I was in the hands of a pragmatist, a practitioner, and a personable guide. By page 8 he's chattily differentiated measures and metrics, identified a bunch of dimensions for projects, and then categorised metrics too. Along the way, he drops this piece of wisdom (p. 5):
The sort of development process you're using will influence your choice of metrics. Some metrics depend on the work being done in a certain way. A common problem is that people believe they're using a given process, when in fact they're working according to a conflicting set of assumptions. If you apply metrics that depend on the process being done correctly you won't obtain information that can help you steer the work or measure the results of process-improvement efforts. You have to measure what's really happening, regardless of the buzzwords people use to describe it.

For Nicolette, metrics face forwards (towards an emerging solution) or backwards (towards a predefined plan), are trailing indicators (give feedback on work done) or leading indicators (forecast future work), can have any of three functions (prediction, diagnosis, motivation), and can be used to steer work in progress or process improvements.

He provides axes on which to plot projects, acknowledging that the real world isn't quite as neat as the breakdown might suggest:
  • process model: linear (proceeds through gated phases), iterative (repeated refinement of the solution), time-boxed (iterative in increments), continuous flow (controls work in progress).
  • delivery mode: project (with a start and end date and some goal to achieve before delivery) or ongoing (repeated, frequent, incremental delivery).
  • approach: traditional (up-front planning followed by implementation) or adaptive (evolving plans based on implementation so far).

A set of metrics for both steering and process improvement are presented with Top Trump-style summaries to permit quick reference and comparison. (This is the point at which he advises not reading from start to finish.) These details include factors that are crucial for the success of the metric, and it's striking that they tend to require someone to make some effort to generate and/or record data. Good data.

There is no such thing as a free lunch.

The book has a table describing the applicability of metrics to project types but I found myself wanting some kind of visualisation of it, I think so that I could look for similarities and differences across the traditional and adaptive approaches:


I was interested by the similarities, although there are subtleties and caveats about usage in particular contexts that it's important to take note of. Other commentary on each of the metrics includes warnings about common anti-patterns and examples based on data provided in an accompanying spreadsheet.

The wisdom comes at regular intervals. For example when management wants a particular metric regardless of its validity (p. 42): "If you're required to report progress in this way then do so; just don't assume that you can use the numbers to make critical decisions about your work." There are other, more worthwhile, hills to die on.

If you (or your superiors) find yourselves tempted to attribute magic to the numbers, heed this warning: "metrics won't directly tell you the root causes of a problem; they'll only indicate when reality diverges from expectations or exceeds limits you've defined as 'normal.'" (p.108) Perhaps it's your expectation or your view of normal that needs refinement.

Finally, a motivation to try to find metrics that work for your stakeholders to help them work for you: "One of the key benefits of tracking planning predictability is that it can enhance stakeholder satisfaction ... When stakeholders know they can count on receiving more or less what they're told to expect, they feel confident in the delivery organization and offer greater autonomy and trust to development teams." (p.131)

As you might expect for a book that's designed to be dipped into the content can be repetitive across metrics which serve similar purposes. Despite this, and chapters which talk about using and reporting metrics in practice (with warnings), the book still comes in at a tight 160 pages and is an extremely easy read. A real treat.
Image: Manning

Comments

Popular posts from this blog

Can Code, Can't Code, Is Useful

The Association for Software Testing is crowd-sourcing a book,  Navigating the World as a Context-Driven Tester , which aims to provide  responses to common questions and statements about testing from a  context-driven perspective . It's being edited by  Lee Hawkins  who is  posing questions on  Twitter ,   LinkedIn , Mastodon , Slack , and the AST  mailing list  and then collating the replies, focusing on practice over theory. I've decided to  contribute  by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me?   --00-- "If testers can’t code, they’re of no use to us" My first reaction is to wonder what you expect from your testers. I am immediately interested in your working context and the way

Meet Me Halfway?

  The Association for Software Testing is crowd-sourcing a book,  Navigating the World as a Context-Driven Tester , which aims to provide  responses to common questions and statements about testing from a  context-driven perspective . It's being edited by  Lee Hawkins  who is  posing questions on  Twitter ,   LinkedIn , Mastodon , Slack , and the AST  mailing list  and then collating the replies, focusing on practice over theory. I've decided to  contribute  by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me?   --00-- "Stop answering my questions with questions." Sure, I can do that. In return, please stop asking me questions so open to interpretation that any answer would be almost meaningless and certa

Not Strictly for the Birds

  One of my chores takes me outside early in the morning and, if I time it right, I get to hear a charming chorus of birdsong from the trees in the gardens down our road, a relaxing layered soundscape of tuneful calls, chatter, and chirrupping. Interestingly, although I can tell from the number and variety of trills that there must be a large number of birds around, they are tricky to spot. I have found that by staring loosely at something, such as the silhouette of a tree's crown against the slowly brightening sky, I see more birds out of the corner of my eye than if I scan to look for them. The reason seems to be that my peripheral vision picks up movement against the wider background that direct inspection can miss. An optometrist I am not, but I do find myself staring at data a great deal, seeking relationships, patterns, or gaps. I idly wondered whether, if I filled my visual field with data, I might be able to exploit my peripheral vision in that quest. I have a wide monito

Testing (AI) is Testing

Last November I gave a talk, Random Exploration of a Chatbot API , at the BCS Testing, Diversity, AI Conference .  It was a nice surprise afterwards to be offered a book from their catalogue and I chose Artificial Intelligence and Software Testing by Rex Black, James Davenport, Joanna Olszewska, Jeremias Rößler, Adam Leon Smith, and Jonathon Wright.  This week, on a couple of train journeys around East Anglia, I read it and made sketchnotes. As someone not deeply into this field, but who has been experimenting with AI as a testing tool at work, I found the landscape view provided by the book interesting, particularly the lists: of challenges in testing AI, of approaches to testing AI, and of quality aspects to consider when evaluating AI.  Despite the hype around the area right now there's much that any competent tester will be familiar with, and skills that translate directly. Where there's likely to be novelty is in the technology, and the technical domain, and the effect of

Postman Curlections

My team has been building a new service over the last few months. Until recently all the data it needs has been ingested at startup and our focus has been on the logic that processes the data, architecture, and infrastructure. This week we introduced a couple of new endpoints that enable the creation (through an HTTP POST) and update (PUT) of the fundamental data type (we call it a definition ) that the service operates on. I picked up the task of smoke testing the first implementations. I started out by asking the system under test to show me what it can do by using Postman to submit requests and inspecting the results. It was the kinds of things you'd imagine, including: submit some definitions (of various structure, size, intent, name, identifiers, etc) resubmit the same definitions (identical, sharing keys, with variations, etc) retrieve the submitted definitions (using whatever endpoints exist to show some view of them) compare definitions I submitted fro

Testers are Gate-Crashers

  The Association for Software Testing is crowd-sourcing a book,  Navigating the World as a Context-Driven Tester , which aims to provide  responses to common questions and statements about testing from a  context-driven perspective . It's being edited by  Lee Hawkins  who is  posing questions on  Twitter ,   LinkedIn , Mastodon , Slack , and the AST  mailing list  and then collating the replies, focusing on practice over theory. I've decided to  contribute  by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me?   --00-- "Testers are the gatekeepers of quality" Instinctively I don't like the sound of that, but I wonder what you mean by it. Perhaps one or more of these? Testers set the quality sta

Vanilla Flavour Testing

I have been pairing with a new developer colleague recently. In our last session he asked me "is this normal testing?" saying that he'd never seen anything like it anywhere else that he'd worked. We finished the task we were on and then chatted about his question for a few minutes. This is a short summary of what I said. I would describe myself as context-driven . I don't take the same approach to testing every time, except in a meta way. I try to understand the important questions, who they are important to, and what the constraints on the work are. With that knowledge I look for productive, pragmatic, ways to explore whatever we're looking at to uncover valuable information or find a way to move on. I write test notes as I work in a format that I have found to be useful to me, colleagues, and stakeholders. For me, the notes should clearly state the mission and give a tl;dr summary of the findings and I like them to be public while I'm working not just w

Build Quality

  The Association for Software Testing is crowd-sourcing a book,  Navigating the World as a Context-Driven Tester , which aims to provide  responses to common questions and statements about testing from a  context-driven perspective . It's being edited by  Lee Hawkins  who is  posing questions on  Twitter ,   LinkedIn , Mastodon , Slack , and the AST  mailing list  and then collating the replies, focusing on practice over theory. I've decided to  contribute  by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me?   --00-- "When the build is green, the product is of sufficient quality to release" An interesting take, and one I wouldn't agree with in general. That surprises you? Well, ho

Make, Fix, and Test

A few weeks ago, in A Good Tester is All Over the Place , Joep Schuurkes described a model of testing work based on three axes: do testing yourself or support testing by others be embedded in a team or be part of a separate team do your job or improve the system It resonated with me and the other testers I shared it with at work, and it resurfaced in my mind while I was reflecting on some of the tasks I've picked up recently and what they have involved, at least in the way I've chosen to address them. Here's three examples: Documentation Generation We have an internal tool that generates documentation in Confluence by extracting and combining images and text from a handful of sources. Although useful, it ran very slowly or not at all so one of the developers performed major surgery on it. Up to that point, I had never taken much interest in the tool and I could have safely ignored this piece of work too because it would have been tested by

The Best Laid Test Plans

The Association for Software Testing is crowd-sourcing a book,  Navigating the World as a Context-Driven Tester , which aims to provide  responses to common questions and statements about testing from a  context-driven perspective . It's being edited by  Lee Hawkins  who is  posing questions on  Twitter ,   LinkedIn , Mastodon , Slack , and the AST  mailing list  and then collating the replies, focusing on practice over theory. I've decided to  contribute  by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me?   --00-- "What's the best format for a test plan?" I'll side-step the conversation about what a test plan is and just say that the format you should use is one that works for you, your coll