你不要总是在指数上花太多时间，但是一定要确定这些代表着每一只个股的平均指数的位置和状态。保险业要使用平均法则，保险精算师可以计算1000个不同年龄的人并可以告诉你他们之中每年有多少人将死去，但是精算师不可能根据平均指数来推算并告诉你每个人什么时候会死，因为事实上不同时间出生的人聚合在一起具有相同的平均出生率。股票指数也同样由那些5, 10, 20, 30, 50, 和 100年历史的上市公司的股票所组成。具有很大的成立时间上的不同，产业定位于不同国家和领域，并受当地的其他环境条件影响，它们之中的一些将与指数趋势形成反方向运行仅仅是其自然本性的原因。
Therefore, in order to get a reliable Forecast, each company and its stock must be analyzed separately, judged and forecast individually and not collectively."
1.Leave queer-acting stocks alone. Stick to the ones that favor you.
"The kind of stocks to trade in are those that are active and those that follow the rules and a definite trend. There are always queer acting stocks and some stocks that don^t follow the rules. These stocks should be left alone." W. D. Gann, New Stock Trend Detector, p. 34
" When you find that a stock does not seem to work well for you, leave it alone. Quit trading in it, and stick to the ones that favor you. I could explain to you the cause for this, but it is not necessary, and many of you would not believe it.
It makes no difference whether you know or do not know the reason why a thing works or does not work; just as soon as experience teaches you that there is something that works against you, the only thing to do is quit." W. D. Gann, Truth of the Stock Tape, p. 75
2.Know when to quit. Determine when your trend is changing one way or the other.
"A man^s life runs in cycles just the same as stocks. He reaches his apex and does not know it. His time for money making ends, and he should keep what he has already made, rather than try to make more.
There is a seasonal trend and a mathematical scientific cycle which determines the time and limits to which a man can go and when he bucks the law and the tide turns against him. The most important thing for every man to know is when to quit. After a man has made money, he must know when he has enough, stop and keep what he has. …
"Man^s seasonal trend changes just as the market and he has his good and bad cycles. By keeping a record of your own trades, you can determine when your trend is changing one way or the other. I have been able to make as many as 200 consecutive trades without a loss. If I had no way to forecast it, what sign should I watch to tell when the tide had turned against me and I should get out and wait? The first indication that something was wrong would be the first trade on which I made a loss. …
"There is no use staying in, holding on and hoping, when things go against you. Take your loss quickly and get out. You will make money by staying out of the market and waiting for an opportunity when the market is right, your physical condition good and your mind at its best. To beat the stock market is a battle of wits. Your mind must be active, keen and alert. You must be able to change your mind and act quickly. When you find that your mind gets sluggish and you cannot act quickly, you are in no position to be in the market." W. D. Gann, Wall Street Stock Selector, pp. 34, 35