Earlier quoted context omitted.
Real trades have transaction fees, latency, slippage, etc. - you can simulate all this, but it's hard to know if it's being simulated correctly or not. > their interpretation cannot be influenced by the fact that the trading orders are passed for real It's not going to make much difference with $5 trades, but the impact on the market is non-zero.
> fees, latency, slippage Whenever I trade, I somehow always get an adverse price. I figure it's the "no fee" brokerage chiseling a bit off for themselves. I compensate by being a buy and hold hold hold investor, so paying very little in aggregate for that. What I don't understand is how day traders avoid being eaten alive by this.
Probably not, they aren't allowed to do that and don't.