Here's an example of price fluctuations produced by this code:
The following tarball contains additional code examples. In some source files, the price volatility can be regulated by setting a range for order volumes. In others, there's an example of front-running price prediction.
I would have to endow the investors in the simulation with some degree of intelligence in order to make it more realistic. But even if I followed the ideas in http://jasss.soc.surrey.ac.uk/6/3/3.html, there would be some fundamental flaws.
The agent-based simulations I've seen so far seem to only take into consideration past price fluctuations to determine artificial investors' buy/sell decisions. As if, in real life, real investors only took these things into considerations in their decision to buy and sell. In reality, investors also read the news. Some may even base their investment on irrational decisions, such as fortune-telling, the zodiac, or "gut-feelings".
A better model would look something like this:
Factors colored in red are ones I haven't seen taken into account in the studies I've read so far. They also seem extremely hard to predict. I think predicting the market requires predicting things such as wold events or human history. A natural catastrophe can drive stock and currency prices down, as can a civil war.
I should add that, at this point, I'm starting to think that successful investors are more the product of chance and luck, than the product of "intelligent investing". I'm extremely skeptical a to whether a thing such as "intelligent investment" even exists, in the traditional market sense.
This also makes me think that the attempts of so-called "economic analysts" to predict the behavior of markets, is also futile. They may think they're doing science, but I think they're far from it. I think economics is in a proto-scientific stage as of now. I see no near future breakthrus in market forecasting. I'm not saying it's hopless. Just very misinformed, and young. There may be a scientific future to market forecasting, but in the far, far future.
In a practical sense, to me, this means that economics is a field much younger than it's professionals might make it seem. At least scientifically. It sounds like an exciting field to try to do science in. But I should expect no significant advances as of today. There is still too much to be found out about human behavior, in order to make economics a viable science.
I will probably be taking a break from this line of research. Perhaps, never to return. It's been a pleasant experience nevertheless.