Quote from jnbadger:
Well, I make money just about every day, so I must know something about "taking money" from others.
But I have to say your inclusion of "expectancy" in your last comment got me thinking, as expectancy is an assumption about the future based on the recent past. And since the markets are so dynamic in their behavior, we need to be much more dynamic in our thinking to adapt.
Am I getting warm?
Randomness and perception
"We do not come into this world with an innate sense of how the random part of
our world works. We talk about probabilities casually and think we understand.
When the weatherman forecasts 60% chance of rain today we do not
have a precise definition of what that means. Does it mean a 60% chance that it
will rain here at my office, or 60% chance of rain somewhere in the city? Does it
mean a 60% chance every part of the city will get at least a drop of rain, or that
each point in the city will get rain 60% of the time? Some of these possible
meanings may be absurd but the point is that we deal with statements like
these with only an intuitive sense of what they mean.
We mostly have unreliable notions and perhaps some wrong conclusions when it
comes to randomness in our lives. For instance, few of us know that if a group
of 25 randomly selected people are asked their birthday that the chance of at
least two of them having a birthday on the same day of the year is better than
50%. I met a man who knew all the odds of drawing various hands in poker.
When I told him this little known fact he was in disbelief and gave me 2 to 1
odds on a bet. The 14th person he queried for a birth date matched one of the
previous ones. He declined to repeat the bet.
A trader needs tools for finding what kind of results work now and are likely
work in the future. He would like to know what is more important, the probability
of success on a trade, or the average profit to risk ratio. He would like to
know what would happen if losers were exited early."