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Comment by hinkley | Hacker News Reader

I’ve been in this industry a long time. I’ve read Lying with Statistics, and a bunch of Tufte. I don’t think it would be too much hyperbole to say I’ve spent almost a half a year of cumulative professional time (2-3 hours a month) arguing with people about bad graphs. And it’s always about the same half dozen things or variants on them.

The starting slope of the line in your carefulness graph has no slope. Which means you’re basically telling X that we can turn carefulness to 6 with no real change in delivery date. Are you sure that’s the message you’re trying to send?

Managers go through the five stages of grief every time they ask for a pony and you counteroffer with a donkey. And the charts often offer them a pony instead of a donkey. Doing the denial, anger and bargaining in a room full of people becomes toxic, over time. It’s a self goal but bouncing it off the other team’s head. Don’t do that.

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> The starting slope of the line in your carefulness graph has no slope. Which means you’re basically telling X that we can turn carefulness to 6 with no real change in delivery date.

This strikes me as a pedantic argument, since the graph was clearly drawn by hand and is meant to illustrate an upward curving line. Now, maybe there's essentially no clear difference between 5 and 5.1, but when you extrapolate out to where 6 would be (about 65 pixels to the right of 5, if I can be pedantic for a moment), there actually is a difference.

This is a conversation about human behavior, not pixels.

A flat line will lead to bargaining, as I said. Don’t paint yourself into uncomfortable conversations.

If you don’t want the wolf in the barn don’t open the door.

Doesn't the flat line in this context mean that you're at a local minimum, which is where you want to stay? Where being less careful would take more time due to increased number of incidents.

If you can explain to me how you convince a nontechnical person why 6 is not free, I’ll concede the point.

But if not then my original thesis that this is needlessly asking for a pointless argument that costs social capital stands.

Curve higher at one hand and one finger more.

I think the pointless argument here is the one you make.

Mostly free is not the same thing as free, and the scale of ‘carefulness’ is already completely arbitrary. How much more careful is 6 than 5?

You don’t have to argue about it, because the scale doesn’t represent anything. The only thing to say is, sure, we’ll set the carefulness to 6.

I agree with both of you, but consider that if this was a real meeting, you’ve both just wasted 10-15 minutes arguing about a line on the graph of a metaphor. (and yes I’ve seen this behaviour in meetings).

I agree with the original comment, as professionals we can do better than simplified analogies (or at least we should strive to)

Good insight, thanks for that

> you’ve both just wasted 10-15 minutes arguing about a line on the graph of a metaphor

So goddamned many times. And multiply your 2-10 minute sidebar by the number of people in the room. You just spent over $200 on a wobble in a line.

Plus you’ve usually lost the plot by that point.

> If you can explain to me how you convince a nontechnical person why 6 is not free, I’ll concede the point.

"I said the minimum is at 5, but if you want me to trace the line more accurately then let's take a 2 minute break and I'll do that".

Maybe we need to start with Zeno. Doing anything at all is relatively impossible.

Maybe an excellent joke for the pre meeting.

I don’t think the boss will find it funny though.

It's true, though: accomplishing anything at all is relatively a feat. You have two ways to contrast a retrospective: what if we had been perfect, and what if we had done nothing. Sometimes a comparison against the latter is more informative.

Is it really that hard for you to intuit the intent that it's a graph that slopes upwards?

I’m saying people suck, particularly when you’re trying to give them what they see as bad news.

You seem to be concerned over a non-issue: I'm pretty sure you're the only person in this entire discussion who misinterpreted the graph. Does that mean the people you're talking about are yourself? :P

And I've done high school calculus. It's a picture of a parabola, the derivative is very small near the minimum, and it can look kinda flat if the picture isn't perfectly drawn.

Principles of Product Development makes the point that a lot of real world tradeoffs in your development process are U-shaped curves, which implies that you will have very small costs for missing the optimum by a little. A single decision that you get wrong by a lot is likely to dominate those small misses.

It’s a picture of a parabola if someone put the y axis at the dotted line not the origin. If you want to bargain with people - and this fictional conversation is a negotiation - then don’t anchor the people on bad values.

The article stipulates that 5 is the value that minimizes execution time. So the value between 0 and 5 would’ve been higher. It doesn’t intersect the x-axis because you can’t finish the task in zero time.

See the quote below.

That said, while I didn’t think it was a confusing drawing, I now wish he’d drawn the rest of the parabola, because it would’ve prevented this whole conversation.

> EM: Woah! That’s no good. Wait, if we turn the carefulness knob down, does that mean that we can go even faster?

> TL: If we did that, we’d just be YOLO’ing our changes, not doing validation. Which means we’d increase the probability of incidents significantly, which end up taking a lot of time to deal with. I don’t think we’d actually end up delivering any faster if we chose to be less careful than we normally are.

How is it a bad value?

If you centered it on the y axis, that would mean your carefulness scale goes from -5 to 5, and that's just confusing.

A more sensible way to present the idea is to put the turning point of the parabola at the origin of the graph and then show that 5 is somewhere on the line of super-linearly increasing schedule risk.

The article stipulates that 5 is the value that minimizes execution time.

It could have put that on the y-axis, and labeled the left “extremely rushed” and the right side “extremely careful”. Maybe that would’ve been clearer, though I really think it’s clear if are charitable and don’t assume the author has made a mistake.

I guarantee you the boss in this scenario hated calculus or a skipped it.

Also parabolas are algebra not calculus, but the same counter argument stands.

It's a U shape, you don't need either one for a U shape.

Is "self goal" meaningful? I suspect you mean "own goal", but I can't tell from context

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