在交易股票的时候，投资者通常会使用扭曲的逻辑：
哪类股票价格上升后必然下降？
那些价格上升幅度陡峭，并创出新高的股票通常被认为是价格过高。有时它们的却如此，但你也经常会发现例外：股价上涨了500%或1000%。股价上升后下跌的可能性比那些下跌之后反弹的可能性要小得多。
哪些股票价格下降后必然反弹？
价格迅速下降，创出新高的股票被认为“便宜”同时也显示出了股票的真正价值。有时是这样的，但是有很多股票下降后便不再回升，市场有句名言：死猫不反弹！也就是通常所说的抄底。寻找被低估的股票是市场专业人士的任务：它需要大量的研究和专业知识。
整体下降
一个相关的策略是，当价格低于之前买入价格时，买入更多的股票：如果之前的高价都乐意买入，那么，目前的低价就算是捡着便宜了。然而接下来通常是股价继续下跌…直至从雷达屏幕上消失。没有人比杰西•利弗莫尔理解得更透彻，他在埃德温•勒菲弗的《股票作手回忆录》一书中说道：让他先买入目标股票数量的1/5，如果这没有给他带来利润，那么他就不应该增加持有量。因为一开始他就很明显的错了：错误的情况下不可能盈利。
建议和传闻
股票市场上的建议总体带来的结果较差。投资者通常对所持有的股票情有独钟，以至于不能对它们的前景做出客观预期。他们认为所持有股价将上升更多情况下是出于希望而不是事实。
策略建议
利用股票屏幕：
• 搜索那些价格创新高的股票；
• 根据过去12个月的相对性能研究将它们排序。选择表现最好的10只股票做深入研究。
新高
利用价格比率指标绘出股票近3年来的相对性能。该指标应该高于0，并且仍然在升高。
好转
它们是从游泳池底部逐渐浮出水面的游泳者。它们大多因失去了方向而失宠。
• 寻找新的管理模式或重大的重组，近来一两个季度的盈利迅速增长。
• 比较预期盈利和目前的价格收益率：预期收益应该比预期盈利高。
• 利用价格比率指标绘出股票近3年来的相对性能，价格比率指标应该为正值并不断升高。然后，等待突破信号。
总体上升而不是下降
在初次购买盈利之后，增加购买量。
行情不会说谎
不要将注意力集中在建议或谣言上。同样的，每日新闻或者电视媒体似乎都是根据小时图在预测市场走势。避免信息超负荷，只有市场才是值得信任的：市场上股票价格的变动真实的显示了正在发生的事情。专注于你所交易的框架，不要试图去抓住短期价格波动。
Investor's Logic
Investors often use distorted logic when buying stocks:
What goes up must come down?
Stocks that rise steeply in price and make new highs are viewed as expensive and overpriced. Sometimes they are, but you will also find the real winners here - stocks that rise 500 or 1000 per cent. What goes up is more likely to be a winner than stocks that are going down!
What goes down must come back?
Stocks that fall steeply in price, making new lows, are seen as being cheap and showing real value. Sometimes they are, but many stocks never recover. The market has a saying:
Dead cats don't bounce!
Commonly referred to as bottom-fishing, searching for undervalued stocks should be left to the experts: it requires a lot of research and expertise.
Averaging down
A related strategy is to buy more of a stock if the price falls after your initial purchase: if it was a good buy at the higher price it must be a real bargain now. What often follows is that the stock keeps falling ...... disappearing from the radar screens.
No-one has put it better than Jesse Livermore in Edwin Lefevre's book Reminiscences of a Stock Operator
Let him buy one-fifth of his full line. If that does not show him a profit he must not increase his holdings because he has obviously begun wrong; he is wrong temporarily and there is no profit in being wrong at any time.
Tips and Rumors
The quality of stock market tips is generally poor. Investors often become emotionally attached to the stocks that they hold and are not always objective about their prospects. They talk their stocks up, more out of hope than conviction.
Suggested Strategies
Use Stock Screens:
• Search for stocks making New Highs; or
• Rank stocks using Relative Performance over the last 12 months. Select the top 10 per cent for further study.
New Highs
Chart the relative performance of the stock over 3 years, using the Price Ratio indicator. The indicator should be well above zero and still rising.
Turnarounds
These are bottom-swimmers that have started to rise to the surface. Often they are previous darlings of the market that have lost direction and fallen from favor.
• Look for new management, or a major restructuring, and one or two quarters of exceptionally strong earnings growth.
• Compare earnings forecasts to the current Price/Earnings ratio: expected growth must be comfortably higher than the P/E ratio.
• Chart the relative performance of the stock over 3 years, using the Price Ratio indicator. The indicator should have returned to above zero and be rising steeply.
Then wait for a breakout signal.
Average up - not down
After your initial purchase, only buy more of a stock if your existing holding shows a profit.
The tape never lies
Pay scant attention to tips or rumors. Likewise to the daily press and television media who seem to call the direction of the market on an hourly basis. Avoid the information overload and place your trust in the tape: actual price movements are the most objective information on what is actually happening in the market.
Focus on the time frame that you are trading and avoid trying to catch the short-term fluctuations.
本文翻译由兄弟财经提供
文章来源：http://www.incrediblecharts.com/trading/investors_logic.php