道氏理论——趋势
道琼斯意识到价格曲线的高点和低点反转时，就代表趋势的改变。
牛市趋势
牛市趋势可以通过一轮又一轮的反弹来识别，反弹后每一轮都有新高，并且低点也比前一轮高。
牛市的开始：新高+更高的低点
牛市结束：高点和低点都比前一轮降低
熊市趋势
每一次的反弹都没有超越前一轮的高点，并且低点都低于前一轮的低点：不断下降的高点和低点。
熊市通常开始于牛市之后：当反弹没有突破上一轮的高点，并回落到上一轮的低点之下。熊市结束和牛市开始的形态特征一致。当不断下降的高点和低点被更高的高点打破之后怎么办？这是一个灰色区域，下面是对大规模调整的介绍。
大规模调整
牛市趋势时的调整是当价格低点低于前一轮的低点，或者是熊市中高点高于上一轮高点。
一些纯粹主义者认为，当新高和逐渐上升的低点这一规律被打破时，牛市就意味着结束。另外一些人认为，熊市只有一系列的不断降低的高点和低点出现之后才能确认，同时也只有出现一系列升高的高点和低点出现才能确认牛市趋势。
从实用性角度考虑，应当把价格调整视为原趋势的改变。
• 当价格走出新高时，牛市确立。
• 价格低点低于上一轮低点时，牛市结束。
• 牛市结束后，熊市开始，反之亦然。
Dow Theory - Trends
Dow recognized that trends changed when the pattern of peaks and troughs reversed.
Bull Trends
A bull trend is identified by a series of rallies where each rally exceeds the highest point of the previous rally. The decline between rallies ends above the lowest point of the previous decline. A series of successive higher highs and higher lows.
The start of an up trend is signaled when price makes a higher low (trough), followed by a rally above the previous high(peak):
Start = higher Low + break above previous High.
The end is signaled by a lower high (peak), followed by a decline below the previous low (trough):
End = lower High + break below previous Low.
What if the series of higher Highs and higher Lows is first broken by a lower Low? There are two possible interpretations - see Large Corrections.
Bear Trends
Each successive rally fails to penetrate the high point of the previous rally. Each decline terminates at a lower point than the preceding decline. A series of successive lower highs and lower lows.
A bear trend starts at the end of a bull trend: when a rally ends with a lower peak and then retreats below the previous low. The end of a bear trend is identical to the start of a bull trend.
What if the series of lower Highs and lower Lows is first broken by a higher High? This is a gray area - see Large Corrections below.
Large Corrections
A large correction occurs when price falls below the previous low (during a bull trend) or where price rises above the previous high (in a bear trend).
Some purists argue that a trend ends if the sequence of higher highs and higher lows is broken. Others argue that a bear trend has not started until there is a lower High and Low nor has a bull trend started until there is ahigher Low and High.
For practical purposes, only accept large corrections as trend changes in the primary trend.
• A bull trend starts when price rallies above the previous high;
• A bull trend ends when price declines below the previous low;
• A bear trend starts at the end of a bull trend (and vice versa).
文章翻译由兄弟财经提供
文章来源：http://www.incrediblecharts.com/technical/dow_theory_trends.php