Comments on: Why conversion rate uplift percentages can be confusing

By: Quimp

Quimp — Mon, 09 May 2011 14:20:24 +0000

You’d have a conversion rate of 1/1000 but a conversion ratio of 1:999. For 1 conversion, there were 999 non-converts.

From ratio to %: 1:999 = 1/(999+1) = 1/1000 = 0.1%

Otherwise you’d get 1:1000 = 1/1001 = 0.0999001%

It doesn’t make a big difference here but consider 200:800 = 1:4 = 20% vs 200:1000 = 1:5 = 16.7%,
or 500:500 = 50% vs 500:1000 = 33%. That’s enough to perceive a false statistical significance if one of the before-and-after numbers isn’t calculated correctly.

Just nitpicking; very solid article.

By: F**K CAPTCHA

F**K CAPTCHA — Fri, 25 Mar 2011 14:08:21 +0000

[...] of roughly 48%. They then removed the CAPTCHA, and it boosted the conversion rate up to 64%. In conversion rate lingo, that’s an uplift of 33.3%! They replaced the CAPTCHA with honeypot fields and timestamp [...]

By: Kilka ciekawych artykułów marketingu internetowego

Kilka ciekawych artykułów marketingu internetowego — Sat, 01 Aug 2009 11:39:37 +0000

[...] konwersji może być mylący? – przed wyciąganiem wniosków z wyższego wskaźnika konwersji warto sprawdzić, czy test strony docelowej spełnia wszystkie warunki prawidłowego [...]

By: Harry Brignull

Harry Brignull — Wed, 29 Jul 2009 11:12:54 +0000

Carlo, you’re absolutely right – there was a typo in the example. I’ve edited the post!

By: Carlo Valbonesi

Carlo Valbonesi — Wed, 29 Jul 2009 10:51:54 +0000

Isn’t the increase = 100% instead of 200%?

Considering that you compare

Day 1: number of users = 1

and

Day 2: number of users = 2

The difference is = 1

and 1 is exactly the total number of user of day 1, i.e. 100% of day 1

On day 2 we have double the users buying, but the increase itself compared to day 1 is 100%.

Or am I suddenly dumb?

rgrds

Carlo

By: Harry Brignull

Harry Brignull — Fri, 24 Jul 2009 16:21:47 +0000

I think I might buy myself a copy of that, thanks! User Experience design – and web design in general these days – sits at the intersection of science and “craftsmanship”. Even if you’re trained in both, it’s easy to forget to wear both hats simultaneously.

By: Leif Kendall

Leif Kendall — Fri, 24 Jul 2009 16:12:12 +0000

I’m reading Bad Science by Ben Goldacre, in which the author demonstrates how the media like to manufacture health scares by using misleading stats. It’s frighteningly easy to manipulate numbers to give the desired impression.
And you’re right – it’s always worth looking behind the headline to see what the numbers really mean.

By: Harry Brignull

Harry Brignull — Fri, 24 Jul 2009 10:32:43 +0000

I forgot to mention - many thanks to James Page of FeraLabs and Andy Baker of Ixxy for reviewing the draft of this post!