5 Things Meme, Pure Time Delay and Aggregation

I got tagged. I just noticed.

So, one of Richard Ball’s tag targets has a 80+ day response time. The effect is that a meme can lie low and then burst into life again. Rather like Quellism, or the Black Planner.

Five Things About Me you probably don’t know, then Five Blogs Tagged and a short article on Pure Time Delay and Paid Search Bidding Systems.

1. I was the main researcher for Europe’s largest low energy housing experiment, at Pennylands in Milton Keynes. I also worked on the Great Linford experiments. My main focus was to make sure we collected all the data we could and to devise ways to analyse it.
2. I’ve lived in the south of England (Surrey, Bucks and Beds), LA, Austin (TX) and Denver.
3. I used to score very highly in Physics at school, until just before the critical exams, when I found precise values of all sorts of constants to at least five places, and used them in exam answers. Stuff like the value of the gravitational constant where the school was located… Sometimes an answer correct to an order of magnitude is better, at least for examiners. I still prefer detailed information, because I find unexpected and interesting stuff in the details.
4. I used to own a racing dinghy called “Nemesis”, with the sail number 169 (13 squared).
5. I read a lot of science fiction, apart from technical and business books. You’d think that’d make me open to speculating about the future. But if there’s a way to measure a response, or a piece of information that could be collected to remove the conjectured future options, I get really uncomfortable talking and even thinking about it, until the information is collected. On the gripping hand I’ll gleefully read about the Rapture of the Nerds.

Five blogs. Coming at yer.

1. John K - good search marketing news gathering and interesting perspectives
2. Adelino de Almeida - Stumbled into this blog while doing ever more digging into multivariate data analysis and marketing
3. Ken MacLeod - displaced LeGuin’s “The Dispossessed” for a fascinating read of altered future politics
4. Richard Jones’ eclectic cookery - including the military rank photo of the year for… “Major Warr”
5. Aigars Mahinovs, who did some deep magic using Neural Nets and other techniques.

Paid Search Bidding Systems with Quantisation, Pure Time Delay and Aggregated Results

Pure time delay can be difficult to deal with in paid search. Take a simple example. Say you bid $5.00 on AdWords. You check and there’s no sales. So you crank up to $10.00. Check and there’s nothing happening. Up to $15.00. Check and… whoaaa! You’ve got clicks, and they are expensive. In fact, they’ve blown your daily budget, already!

What happened?

You made the dangerous assumption that just because your advert started running immediately, that the AdWords interface will immediately reflect the impressions and clicks. There’s a pure time delay. You won’t see any results for at least 30 minutes. You need to wait a minimum of 45 minutes to get plausible data, and even that time-lagged information can still be adjusted by Google many hours later.

Watch the data carefully - notice that it doesn’t change faster than every 15 minutes? It can change more slowly than that if Google’s servers get busy. Additionally, if you see updates to, for example, a new day of advertising in less than 45 minutes, it can be misleadingly wrong. For example you may discover that you have clicks without impressions. This reveals some information about how Google’s systems are probably put together… but that’s a topic for another time.

The first thing to think about is that 15 minute quantisation granularity. The Nyquist-Shannon Sampling Theorem has an important piece of news for you. You can’t rationally bid faster than every 30 minutes. It’s actually a bit more complex than that, because this is quantised information about discrete events, rather than the analogue signals that Nyquist et al were looking at. It’ll do as a starting point.

Then, that 45 minute time delay has implications on bidding speed. If the fastest that you can see changes in bids is a 45 minute time lagged version, and if you only get aggregated data (you do - positions, prices, impressions and clicks are aggregated for 24 hours before being reset at local midnight)… then the fastest that you can take decisions on changing measurements is actually an hour. When you get to the last aggregation period in the day, just before midnight, with much less than 1% of the traffic affecting the numbers, the inferred position and price changes are pretty tiny, with huge error bars. Even an hour is a pretty short time to measure the effect of changes.

Strictly speaking, of course, the sampling theorem isn’t directly applicable, because we’re looking at discrete events, with quantisation. I wanted to simplify it… The basic principle is that when you change the bid, you won’t see the effect for 45 minutes, and the effect is buried in aggregated data going back to local midnight. So extracting a meaningful signal that tells you that a bid change late in the day has had a useful effect, takes more user activity than judging a price change earlier in the day, and that means allowing longer times to collect results, when you do things late in the day. Wierd, eh?

There are some tricks that can allow faster paced bidding. Pretty much anything you can do to beat that lengthy time involves retaining a history, which can negate immediate competitive advantage in fast paced markets, or the tricks will burn up the API quota usage. Perhaps I’ll describe the tricks at some other time. Getting way off topic for the 5 Things Meme here!