趋向指标DMI 计算及详解

DMI技术指标的计算方法DMI(Directional Movement Index)指标，中文名称为趋向指标，由技术分析大师威尔斯威尔德(JWellsWilderJr)发明，被认为是最有成就、最实用的一套技术分析工具。本指标最大的特点是它能准确地告诉我们行情是否启动。在技术分析领域中，很多技术指标必须搭配DMI指标来研判某只股票的涨跌。本指标的基本原理为，寻求股票价格涨跌、买卖双方力量的均衡点(Iquilibrium Point)，及价格在双方互动下波动循环的过程。 DMI指标是由四条线来组成一幅美丽的图表。这四条线分别为+DI（上升动向线）、-DI（下降动向线）、ADX(方向线)、ADXR(评估线)。 DMI公式原理： 计算DMI第一项工作，便是确认其基本的动向变动值(DM)是上涨还是下跌。+DM与-DM来表示涨与跌动向变动值。 动向变动值为当日价格波动幅度大于前一日价格的部分最大值。也就是说，动向变动值已能表示出价格波动的涨跌幅度。 1零动向(Zero Directional Movement) 经过计算+DM与-DM的值均为零。发生这种现象的情况有两种： a内移日(Inside Day) 当日最高价小于或等于前一交易日最高价，当日最低价大于或等于前一交易日的最低价，即为内移日，这时+DM与-DM值为零。 b买卖双方均衡日 当日最高价大于前一交易日最高价，其差的绝对值正好等于当日最低价与前一交易日最低价差额绝对值，这时买卖双方处于均衡之势，+DM与-DM值为零。 2上升动向+DM 如果当日最高价比前一交易日最高价更高，且当日最低价大于前一交易日最低价，则出现上升现象，动向值等于当日最高价与前一交易日最高价的差颁绝对值。 3下跌动向-DM 如果当日最低价比前一交易日最低价更低，且当日最高价小于前一交易日最高价，则出现下降动向 值，此值等于当日最低价与前一交易日最低价的差额绝对值。 4如果当日最高价大于或等于前一交易日最高价，而且当日最低价小于前一交易日最低价，若前者差额绝对值大于后者差额绝对值时，取前者差额绝对值+DM；若前者差额绝对值小于后者差额绝对值时，取后者差额绝对值为-DM。 第一项工作完成后，我们还要找出真正的波幅(True Ram)，这是我们要完成的第二项工作。 真正波幅(TR)，是当日价格与前一交易日收盘价格比较之后的最大变动值。 计算方式： (1)当日收盘价-当日最低价 (2)当日最高价-前一交易日收盘价 (3)当日最低价-前一交易日收盘价 1、2、3种计算结果，三者差额绝对值最大者，即为当日的真正波幅(TR)值。 第一项工作完成了动向变动值(DM)，第二项工作完成了真正波幅(TR)，第三项工作要完成的是动向指数线(Directional Indicator)。 动向线(DI)为检测价格上涨或下跌的指标，上升动向线以+DI来表示，下跌动向线用-DI来表示。 上升或下跌动向线的计算方法如下： +DI+DMTR -DI-DMTR 要使动向线具有参考价值，必须进行一定时期的累计运算，威尔德认为最适当的周期是14天，笔者则认为在中国大陆股市中其最具有使用价值的周期为 7天。 计算方法如下： 分别将7天内的+DM、-DM及TR平均，所得到的数值分别为+DM7、-DM7及TR7。因此7天的上升或下跌动向指数线的计算方法如下： +D17+DM7TR7 -D17-DM7TR7 需要说明的是负的动向变动值并不是负数，负号仅代表下跌方向，计算出正负动向指标(DI)的数值后，由于其数值永远介于0与100之间，因此为了方便图表的绘制，7天上升动向线(+DI7)表示最近7天以来实际上涨力量的百分比，而7天下跌动向线 (-D17)表示最近7天以来下跌力量的百分比。 如果股票价格持续下跌，那么负动向变动值不断出现，将使下跌动向线的数值不断出现，下跌动向线的数值不断升高。若价格持续上涨，则上述情况的相反导向即将出现于图形上。当股价在盘整时，上升与下跌动向线差异则非常小。 当上述情况出现时，就要借助动向平均线(ADX)来研判。 动向值(DX)计算方式为： DXDI差-DI和 DI差+DI-(-DI) DI和+DI+(-D1) 七天周期动向值的计算公式为： DX7DI7差-DI7和 D17差+DI7-(-DI7) D17和+DI7+(-DI7) 由于动向值的变动性大，因此以7作为平滑计算，即可算出ADX ADX(昨日动向平均值+今日动向值)7 ADX值算出后，方向就明显了，最后，我们将要计算ADXR评比线的值： ADXR(今日动向平均值ADX+7日前动向平均值ADX)2DMI技术指标的计算方法DMI指标的计算方法和过程比较复杂，它涉及到DM、TR、DX等几个计算指标和+DI（即PDI，下同）、DI（即MDI，下同）、aDX和aDXR等4个研判指标的运算。计算的基本程序以计算日DMI指标为例，其运算的基本程序主要为：1、按一定的天数将DX累加后平均，求得n日内的平均动向值aDX。2、再通过当日的aDX与前面某一日的aDX相比较，计算出aDX的评估数值aDXR。3、通过n内的上升指标+DI和下降指标DI之间的差和之比，计算出每日的动向值DX。4、将n内的上升动向值和下降动向值分别除以n日内的真实波幅值，从而求出n日内的上升指标+DI和下降指标DI。5、按一定的规则比较每日股价波动产生的最高价、最低价和收盘价，计算出每日股价的波动的真实波幅TR、+DI、DI，在运算基准日基础上按一定的天数将其累加，以求n日的TR、+DM和DM值。计算的具体过程【一】计算当日动向值动向指数的当日动向值分为上升动向、下降动向和无动向等三种情况，每日的当日动向值只能是三种情况的一种。a、上升动向（+DM）+DM代表正趋向变动值即上升动向值，其数值等于当日的最高价减去前一日的最低价。上升动向值必须大于当日最低价减去前一日最低价的绝对值，否则+DM=0。b、下降动向（DM）DM代表负趋向变动值即下降动向值，其数值等于当日的最低价减去前一日的最低价。下降动向值必须大于当日的最高价减去前一日最低价的绝对值，否则DM=0。c、无动向无动向代表当日动向值为“零”的情况，即当日的+DM和DM同时等于零。有两种股价波动情况下可能出现无动向。一是当当日的最高价低于前一日的最高价并且当日的最低价高于前一日的最低价，二是当上升动向值正好等于下降动向值。【二】计算真实波幅（TR）TR代表真实波幅，是当日价格较前一日价格的最大变动值。取以下三项差额的数值中的最大值（取绝对值）为当日的真实波幅：a、当日的最高价减去当日的最低价的价差。b、当日的最高价减去前一日的收盘价的价差。c、当日的最低价减去前一日的收盘价的价差。TR是a、b、c中的数值最大者【四】计算方向线DI方向线DI是衡量股价上涨或下跌的指标，分为“上升指标”和“下降指标”。在有的股市分析软件上，+DI代表上升方向线，DI代表下降方向线。其计算方法如下：+DI=（DMTR）100DI=（DMTR）100；要使方向线具有参考价值，则必须运用平滑移动平均的原理对其进行累积运算。以12日作为计算周期为例，先将12日内的+DM、DM及TR平均化，所得数值分别为+DM12，DM12和TR12，具体如下：+DI（12）=（+DM12TR12）100DI（12）=（DM12TR12）100；随后计算第13天的+DI12、DI12或TR12时，只要利用平滑移动平均公式运算即可。例如：当日的TR12=11/12前一日TR12当日TR上升或下跌方向线的数值永远介于0与100之间。【五】计算动向平均数aDX依据DI值可以计算出DX指标值。其计算方法是将+DI和DI间的差的绝对值除以总和的百分比得到动向指数DX。由于DX的波动幅度比较大，一般以一定的周期的平滑计算，得到平均动向指标aDX。具体过程如下：DX=（DI DIfDI suM） 100。其中，DI DIf为上升指标和下降指标的价差的绝对值。DI suM为上升指标和下降指标的总和；aDX就是DX的一定周期n的移动平均值。【六】计算评估数值aDXR在DMI指标中还可以添加aDXR指标，以便更有利于行情的研判。aDXR的计算公式为：aDXR=（当日的aDX前一日的aDX）2。和其他指标的计算一样，由于选用的计算周期的不同，DMI指标也包括日DMI指标、周DMI指标、月DMI指标年DMI指标以及分钟DMI指标等各种类型。经常被用于股市研判的是日DMI指标和周DMI指标。虽然它们的计算时的取值有所不同，但基本的计算方法一样。另外，随着股市软件分析技术的发展，投资者只需掌握DMI形成的基本原理和计算方法，无须去计算指标的数值，更为重要的是利用DMI指标去分析、研判股票行情。dmi指标原理和计算方法一、dmi指标的原理dmi指标是通过分析股票价格在涨跌过程中买卖双方力量均衡点的变化情况，即多空双方的力量的变化受价格波动的影响而发生由均衡到失衡的循环过程，从而提供对趋势判断依据的一种技术指标。dmi指标的基本原理是在于寻找股票价格涨跌过程中，股价藉以创新高价或新低价的功能，研判多空力量，进而寻求买卖双方的均衡点及股价在双方互动下波动的循环过程。在大多数指标中，绝大部分都是以每一日的收盘价的走势及涨跌幅的累计数来计算出不同的分析数据，其不足之处在于忽略了每一日的高低之间的波动幅度。比如某个股票的两日收盘价可能是一样的，但其中一天上下波动的幅度不大，而另一天股价的震幅却在10%以上，那么这两日的行情走势的分析意义决然不同，这点在其他大多数指标中很难表现出来。而dmi指标则是把每日的高低波动的幅度因素计算在内，从而更加准确的反应行情的走势及更好的预测行情未来的发展变化。二、dmi指标的计算方法dmi指标的计算方法和过程比较复杂，它涉及到dm、tr、dx等几个计算指标和+di（即pdi，下同）、di（即mdi，下同）、adx和adxr等4个研判指标的运算。1、计算的基本程序以计算日dmi指标为例，其运算的基本程序主要为：（1）按一定的规则比较每日股价波动产生的最高价、最低价和收盘价，计算出每日股价的波动的真实波幅tr、+di、di，在运算基准日基础上按一定的天数将其累加，以求n日的tr、+dm和dm值。（2）将n内的上升动向值和下降动向值分别除以n日内的真实波幅值，从而求出n日内的上升指标+di和下降指标di。（3）通过n内的上升指标+di和下降指标di之间的差和之比，计算出每日的动向值dx。（4）按一定的天数将dx累加后平均，求得n日内的平均动向值adx。（5）再通过当日的adx与前面某一日的adx相比较，计算出adx的评估数值adxr。2、计算的具体过程（1）计算当日动向值动向指数的当日动向值分为上升动向、下降动向和无动向等三种情况，每日的当日动向值只能是三种情况的一种。a、上升动向（+dm）+dm代表正趋向变动值即上升动向值，其数值等于当日的最高价减去前一日的最低价。上升动向值必须大于当日最低价减去前一日最低价的绝对值，否则+dm=0。b、下降动向（dm）dm代表负趋向变动值即下降动向值，其数值等于当日的最低价减去前一日的最低价。下降动向值必须大于当日的最高价减去前一日最低价的绝对值，否则dm=0。c、无动向无动向代表当日动向值为“零”的情况，即当日的+dm和dm同时等于零。有两种股价波动情况下可能出现无动向。一是当当日的最高价低于前一日的最高价并且当日的最低价高于前一日的最低价，二是当上升动向值正好等于下降动向值。（2）计算真实波幅（tr）tr代表真实波幅，是当日价格较前一日价格的最大变动值。取以下三项差额的数值中的最大值（取绝对值）为当日的真实波幅：a、当日的最高价减去当日的最低价的价差。b、当日的最高价减去前一日的收盘价的价差。c、当日的最低价减去前一日的收盘价的价差。tr是a、b、c中的数值最大者（3）计算方向线di方向线di是衡量股价上涨或下跌的指标，分为“上升指标”和“下降指标”。在有的股市分析软件上，+di代表上升方向线，di代表下降方向线。其计算方法如下：+di=（dmtr）100di=（dmtr）100要使方向线具有参考价值，则必须运用平滑移动平均的原理对其进行累积运算。以12日作为计算周期为例，先将12日内的+dm、dm及tr平均化，所得数值分别为+dm12，dm12和tr12，具体如下：+di（12）=（+dm12tr12）100di（12）=（dm12tr12）100随后计算第13天的+di12、di12或tr12时，只要利用平滑移动平均公式运算即可。例如：当日的tr12=11/12前一日tr12当日tr上升或下跌方向线的数值永远介于0与100之间。（4）计算动向平均数adx依据di值可以计算出dx指标值。其计算方法是将+di和di间的差的绝对值除以总和的百分比得到动向指数dx。由于dx的波动幅度比较大，一般以一定的周期的平滑计算，得到平均动向指标adx。具体过程如下：dx=(didifdisum)100其中，didif为上升指标和下降指标的价差的绝对值disum为上升指标和下降指标的总和adx就是dx的一定周期n的移动平均值。（5）计算评估数值adxr在dmi指标中还可以添加adxr指标，以便更有利于行情的研判。adxr的计算公式为：adxr=（当日的adx前一日的adx）2和其他指标的计算一样，由于选用的计算周期的不同，dmi指标也包括日dmi指标、周dmi指标、月dmi指标年dmi指标以及分钟dmi指标等各种类型。经常被用于股市研判的是日dmi指标和周dmi指标。虽然它们的计算时的取值有所不同，但基本的计算方法一样。另外，随着股市软件分析技术的发展，投资者只需掌握dmi形成的基本原理和计算方法，无须去计算指标的数值，更为重要的是利用dmi指标去分析、研判股票行情。Directional Movement Index (DMI)DescriptionThe Directional Movement Index (also known as DMI) is a momentum indicator that was developed by J. Welles Wilder. It is calculated using the price, compares the current price with the previous price range, and displays the result as an upward movement line (+DI), and a downward movement line (-DI), between 0 and 100. The DMI also calculates the strength of the upward or downward movement, and displays the result as a trend strength line (ADX).The DMI is displayed on its own chart, separate from the price bars, and is the lower section in the chart shown above.Calculation Description:The DMI is the ratio ofexponential moving averagesof the greater of the upward (U) and downward (D) price movements, and the true range (TR). Calculation:U = Hn - Hn-1D = Ln-1 - LnTR = (Hn - Ln) | (Hn - Cn-1) | (Cn-1 - Ln)EMAUP = EMAUn-1 + (2 / (n + 1) * (Un - EMAUn-1)EMADOWN = EMADn-1 + (2 / (n + 1) * (Dn - EMADn-1)EMATR = EMATRn-1 + (2 / (n + 1) * (TRn - EMATRn-1)+DI = EMAUP / EMATR-DI = EMADOWN / EMATRDX = ABS(+DI - -DI) / (+DI + -DI)ADX = EMADXn-1 + (2 / (n + 1) * (DXn - EMADXn-1)Trading UseThe Directional Movement Index can be used in bothrangingandtrendingmarkets. In general, when the +DI line is above the -DI line, the market is moving upwards, and when the -DI line is above the +DI line, the market is moving downwards. The ADX line shows the strength of the move, and the market is considered to be trending when the ADX line is above 30, and ranging when the ADX line is below 30. There are several trading systems that use the DMI, so there are several alternative uses of both the DI lines, and the ADX line.（ranging and trending markets Definition:Day trading markets are referred to as either ranging or trending depending upon the type of price movement that is currently occurring. The descriptions of these types of markets are as follows :RangingA ranging market is a market where the price is moving back and forth between a higher price and a lower price. The higher price would be acting as resistance because it prevents the price from moving above it, and the lower price would be acting as support because it prevents the price from moving below it.The price range of a ranging market can be small or large, and if the range is very small the market would be considered to be in chop (moving sideways with very little upward or downward movement).TrendingA trending market is a market where the price is moving in a single direction, either up or down, but not sideways.There may be several small price reversals, but nothing large enough to prevent the price movement from continuing in its original direction. A day trading trend may last for a few minutes or a few hours, and longer term trends may last for several weeks or months.）DMI Points The Way To ProfitsByCandy SchaapAAA|The primary objective of the trend trader is toenter a trade in the direction of thetrend. Reading directional signals from price alone can be difficult and is often misleading because price normally swings in both directions and changes character between periods of low versus high volatility.Thedirectional movement indicator(also known as the directional movement index - DMI) is a valuable tool for assessing price direction and strength. This indicator was created in 1978 byJ. Welles Wilder, whoalso createdthe popularrelative strength index.DMI tells you when to be long or short.Itis especially useful for trend trading strategies because it differentiates between strong and weak trends, allowing the trader to enter only the strongest trends. DMI works on all time frames and can be applied to any underlying vehicle (stocks, mutual funds,exchange-traded funds, futures, commodities and currencies). Here, well cover the DMI indicator in detail and show you what information it can reveal to help you achieve better profits. (For background reading, seeMomentum And The Relative Strength Index.)DMI CharacteristicsDMI is a moving average of range expansion over a given period (default 14). Thepositive directional movement indicator(+DMI) measures how strongly price moves upward; thenegative directional movement indicator(-DMI) measures how strongly price moves downward. The two lines reflect the respective strength of the bulls versus the bears.Each DMI is represented by a separate line (Figure 1). First, look to see which of the two DMI lines is on top. Some short-term traders refer to this as thedominantDMI. The dominant DMI is stronger and more likely to predict the direction of price. For the buyers and sellers to change dominance, the lines must cross over.Acrossoveroccurs when the DMI on bottom crosses up through the dominant DMI on top. Crossovers may seem like an obvious signal to go long/short, butmany short-term traders will wait for other indicators to confirm the entry or exit signals to increase their chances of making a profitable trade.Crossovers of the DMI lines are often unreliable because they frequently give false signals when volatility is low and late signals when volatility is high. Think of crossovers as the first indication of apotentialchange in direction. (For more insight, read theMoving Averagestutorial.)Source: TDAmeritrade Strategy DeskFigure 1: The +DMI and -DMI are shown as separate lines. There are several false crossovers ( Point 1) and one crossover at Point 2 that leads to an uptrend with +DMI dominant. Note:The calculations for DMI are complicated and are referenced elsewhere. Also, DMI is normally plotted in the same window with the ADX indicator, which is not shown.DMI is used to confirm price action (see Figure 2). The +DMI generally moves in sync with price, which means that the +DMI rises when price rises, and it falls when price falls. It is important to note that the -DMI behaves in the opposite manner and moves counter-directional to price. The -DMI rises when price falls, and it falls when price rises. This takes a little getting used to. Just remember that the strength of a price move up or down is always recorded by a peak in the respective DMI line.Reading directional signals is easy. When the +DMI is dominant and rising, price direction is up. When the -DMI is dominant and rising, price direction is down. But the strength of price must also be considered. DMI strength ranges from a low of 0 to a high of 100. The higher the DMI value, the stronger the prices swing. DMI values over 25 mean price is directionally strong. DMI values under 25 mean price is directionally weak.Source: TDAmeritrade Strategy DeskFigure 2: DMI is weak at Point 1 and price is choppy. The +DMI rises strongly above 25 at Point 2 and the uptrend follows. Note how +DMI moves with price at Point 3 and -DMI moves counter-directional to price at Point 4.DMI MomentumThe great feature of DMI is the ability to see buying and selling pressure at the same time, allowing the dominant force to be determined before entering a trade. The strength of aswing high(bulls) is reflected in the +DMI peak, and the strength of aswing low(bears) is seen in the -DMI peaks. The relative strength of the DMI peaks tells the momentum of price and provides timely signals for trading decisions. When the buyers are stronger than the sellers, the +DMI peaks will be above 25 and the -DMI peaks will be below 25. This is seen in a strong uptrend. But when the sellers are stronger than the buyers, the -DMI peaks will be above 25 and the +DMI peaks will be below 25. In this case, the trend will be down.The ability of price to trend depends on continued strength in the dominant DMI. A strong uptrend will show a series of rising +DMI peaks that remain above the -DMI for extended periods of time (Figure 3). The opposite is true for strong downtrends. When both DMI lines are below 25 and moving sideways, there is no dominant force and trend trades are not appropriate. However, the best trends begin after long periods where the DMI lines cross back and forth under the 25 level. A low risk trade setup will occur after DMI expands above the 25 level and price penetrates support/resistance.Source: TDAmeritrade Strategy DeskFigure 3: The +DMI crosses above 25 at Point 1 and remains above the -DMI as the uptrend develops. Note the absence of any crossover by -DMI during the uptrend. Here, the buyers are strong (+DMI 25) and the sellers are weak (-DMI 25).DMI ConfirmationDMI lines pivot, or change direction, when price changes direction. An important concept of DMI pivots is they must correlate with structural pivots in price. When price makes a pivot high, the +DMI will make a pivot high. When price makes a pivot low, the -DMI will make a pivot high (remember -DMI moves counter-directional to price).The correlation between DMI pivots and price pivots is important for reading price momentum. Many short-term traders watch for the price and the indicator to move together in the same direction or times theydiverge. One method of confirming an assets uptrend is to find scenarios when price makes a new pivot high and the +DMI makes a new high. Conversely, a new pivot low combined with a new high on the -DMI is used to confirm a downtrend. This is generally a signal to trade in the direction of the trend or a trend breakoutDivergence, on the other hand is when the DMI and pricedisagree, or do not confirm one another. An example is when price makes a new high, but the +DMI makes a lower high. Divergence is generally a warning to manage risk because it signals a change of swing strength and commonly precedes aretracementorreversal. (For more on this topic, readDivergences, Momentum And Rate Of Change.)Source: TDAmeritrade Strategy DeskFigure 4:This is an example of when the price and indicator agree (Point 1), where price makes a new high and +DMI makes a new high, signaling a long entry. There is also an example of divergence (Point 2), where price makes a new high and the +DMI makes a lower high; the result is a trend retracement at Point 3.DMI Contractions and ExpansionsThe DMI lines are a good reference for pricevolatility. Price goes through repeated cycles of volatility in which a trend enters a period ofconsolidationand then consolidation enters a period of trend. When price enters consolidation, the volatility decreases. Buying pressure (demand) and selling pressure (supply) are relatively equal, so the buyers and sellers generally agree on the value of the asset. Once price has contracted into a narrow range, it will expand as the buyers and sellers no longer agree on price. Supply and demand is no longer in balance and consolidation changes to trend when price breaks belowsupportinto a downtrend or aboveresistanceinto an uptrend. Volatility increases as price searches for a new agreed value level.Volatility cycles can be identified by comparing the slopes of the DMI lines that move in opposite directions whenever range expansion or contraction occurs (Figure 4). Many short-term traders will look for periods when the DMI lines move away from one another and volatility increases. The farther the lines separate, the stronger the volatility.Contractionsoccur when the lines move toward one another and volatility decreases. Contractions precede retracements, consolidations or reversals.Source: TDAmeritrade Strategy DeskFigure 5: The first expansion at Point 1 is part of the downtrend. The subsequent contraction at Point 2 leads to a reversal that begins with another expansion at Point 3. The next contraction at Point 4 leads to a consolidation in pr