Comment by davidcuddeback | Hacker News Reader

Comment by davidcuddeback | Hacker News Reader

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> There is no evidence that TDD provides any benefit.

You originally said, "TDD has no benefits," which is a definitive claim and not supported by evidence. That's vastly different from saying, "There is no evidence that TDD provides any benefit." You seem to be conflating being unable to draw a conclusion with drawing a negative conclusion. They're not the same thing.

> If you've read it, why do I need to re-show it to you?

Because the research I've read doesn't support your conclusion that "TDD has no benefits." I'd like to know if there's a body of research out there that I haven't read yet.

You seem to have an axe to grind with TDD salesmen. That's fair enough. Salesmen aren't in the business of advancing knowledge. They're in the business of persuasion. If you want to criticize salesmen for not being scientifically honest, be my guest. Sometimes, this tactic causes harm. For example, if a salesmen persuades someone to buy homoeopathic remedies instead of traditional medicine, people could die.

I think it's good that you're skeptical of the salesmen, because they're business doesn't require them to be scientifically honest. But that shouldn't inform your opinion of TDD (or any other subject), because there are others in the world whose business does require them to be scientifically honest. And they're the ones whose words you should read to form your opinion. And that is why I asked for sources.

>You originally said, "TDD has no benefits," which is a definitive claim and not supported by evidence

No, you don't have to prove a negative. If it has not been proven, then it does not exist. Until TDD has proven benefits, it is correct to state that it does not have benefits. Just as until unicorns are proven to exist, it is correct to state that unicorns do not exist.

>Because the research I've read doesn't support your conclusion that "TDD has no benefits."

Yes it does, you just want to pretend that proof needs to work in reverse. It doesn't.

>But that shouldn't inform your opinion of TDD (or any other subject), because there are others in the world whose business does require them to be scientifically honest. And they're the ones whose words you should read to form your opinion

My opinion is based on the evidence, that's the point.

> No, you don't have to prove a negative.

That's equivalent to saying that a scientific claim doesn't have to be falsifiable. That's not true. A claim has to be falsifiable for a reason.

> If it has not been proven, then it does not exist.

So the Higgs Boson didn't exist six months ago? It wasn't proven, because there wasn't enough evidence for a statistically relevant result until March 2013. So does that mean that prior to March, you would have concluded that the Higgs Boson doesn't exist?

If I had to sum up my problem with your reasoning in one sentence, it would be "belief is scalar, not boolean." Evidence should adjust your belief state somewhere between 0 and 1, but it should almost never be exactly 0 or 1.

> Just as until unicorns are proven to exist, it is correct to state that unicorns do not exist.

That's a variant of the "existence of god" problem. It's a non-falsifiable hypothesis. That doesn't fall within the realm of science, because it's not subject to empirical evidence.

> My opinion is based on the evidence.

I still haven't seen the evidence to support your conclusion.

TDD's claimed benefits are falsifiable. Much like the Higgs Boson prior to March 2013, they have been neither proven nor falsified. But that doesn't mean we can't form a tentative belief based on the weight of the current evidence available.

The weight of the evidence I've seen leans toward indicating some real benefits beyond normal unit testing. It's inconclusive because the studies lack statistical power and procedural consistency, but that doesn't mean we should automatically jump to a hardline decision in either direction (positive or negative). (Again, belief isn't boolean.)

>That's equivalent to saying that a scientific claim doesn't have to be falsifiable

No it isn't. Simply stating the opposite of reality doesn't make it so.

>It wasn't proven, because there wasn't enough evidence for a statistically relevant result until March 2013.

That is up to interpretation. Many felt there was enough evidence. This is not a case like that, there is literally no evidence at all for TDD. None. And you are demanding that I prove it doesn't have benefits. Prove programming while wearing pink socks doesn't have benefits.

>I still haven't seen the evidence to support your conclusion.

That is your fault, not mine.

>TDD's claimed benefits are falsifiable

And have been falsified, like in the link I provided you. But TDD salesmen use that falsification as evidence supporting it.

You're contradicting yourself:

> there is literally no evidence at all for TDD

> And have been falsified

Falsification requires evidence.

You can't say there's no evidence and then turn around to draw a conclusion two seconds later.

> like in the link I provided you

That is but one blog post. Science doesn't work by cherry-picking results. That's a tactic used by climate change deniers and homoeopathic medicine supporters. The evidence must be taken in full.

In addition, I skimmed the paper cited in that article [1]. It appears to be measuring TDD's effects on external quality. That is not a purported benefit of TDD. Most of the research I've seen agrees with that paper: TDD doesn't improve external quality (defined by passing acceptance tests). The contention is over whether it improves internal quality. Also note that the paper cites "process conformance" as a threat to validity, which is what I've been saying is one of the major problems with TDD research all along [2]. The experiment also used students, which is known to be a problem when generalizing results. With TDD in particular, some research indicates that it's more effective with mature developers and ineffective with inexperienced developers. If you've read the rest of the research instead of cherry-picking, you would have known that.

I'm not trying to make a bold claim about TDD. The evidence doesn't support that. I'm trying to help people like you look at the subject objectively. You can't form an objective opinion without evidence (which you claim) or while cherry-picking evidence (which you've done). But frankly, I don't think you want my help, so the last word is yours if you want it.

[1] https://ieeexplore.ieee.org/application/mdl/mdlconfirmation....

[2] That was my first bullet point in my first comment on this thread: "there's little confidence that TDD was applied correctly in many of the studies."

You are trolling right? There is no evidence to support the claims made about TDD (that it helps in any way). The claim that it helps has been falsified, by people doing TDD and non-TDD and there being no difference. These things are in no way contradictory, and I am no longer able to suspend disbelief and pretend you are actually trying to make a good-faith attempt at a real conversation here.

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