"Good news, this is something of a specialty."

Graphs!!!

Laithan is a quick study and after asking some questions dashes off to another room and comes back with two binders full of market records and some paper for attempting new graphs in addition to copies of old ones.

Pelape is familiar with the theorems saying that in a perfectly efficient market it is literally impossible to predict price changes because all the information you could use to do that is priced in, and she explains this, but of course few markets are perfectly efficient.

He is pretty sure this one isn't - he's had to work hard to get people to provide prices based on things besides gut instincts, even for goods with occasional spikes in demand it's smart to keep some excess reserves ready for, like antibiotics.

"The gut instincts are probably encoding some useful information, and if nothing else they're rendering these people resistant to market manipulation of the form 'someone has a convincing logical argument for why the price should be different in the way they suggest'."

"Yeah, I've mostly just been getting people to keep records so they can have something to inform their instincts better."

Do they have double-entry bookkeeping? She can explain that.

They don't! And also Laitan never understood till now whether people were serious about falling for someone right after meeting them.

To be clear, she did not invent double entry bookkeeping.

"Does everyone know it where you're from?"

"Not everyone does bookkeeping at all so some people never pick it up or promptly forget it, but it was covered in school."

"Well, I'm definitely happy you remembered it."

"I can tell!"

"I just really like clever accounting practices."

"I can remember a few things about how making book for betting works?"

"I'm not sure what that means, but it sounds possibly interesting?"

"Do people bet on things here?"

"Sometimes as entertainment. There's more going on in places that allow gladiatorial games I think, but we don't have those here."

"...gladiators specifically, nobody's playing a ball game or having a race or anything?"

"We have football and frisbee - ball and disc games respectively - and you can bet on the football but the towns that draw large crowds for this sort of thing offer gladiatorial games in addition to those."

"Okay. When people bet on football or frisbee do they bet directly with one another or is there someone centralizing it?"

"Directly against one another."

"Huh. ...how much money are they moving all told?"

"Not much? People will bet a day or two earnings at most I think, maybe a dozen people bet regularly. I guess during the bigger games a few times a year a couple thousand people might place some sort of wager with their friends."

"So I guess it's not astonishing nobody's making book if there's not a lot of volume. The general idea is that the bookie will decide how likely they think various outcomes are - somebody wins, somebody else wins, points margin, game duration, someone gets injured, whatever. Suppose you're talking about something simple, a race between ten gr- between ten people..." She sketches out a possible array of odds. "And they offer these bets to anyone who wants them, and update the numbers if they learn more - including if one of the racers is more popular than they were expecting as somebody to bet on. In general they have the odds right and have enough money to cover the bets and keep at it for a while they'll make money."