强力指数指标是由Alexander Elder 博士根据价格波动以及交易量开发而来，简称FI。它可以衡量市场中多头和空头的力量。该指标结合2日或者13日指数移动平均线（EMA）使用时会给出较好的交易信号。
• 2日EMA可以跟踪短期的买卖双方力量。
• 13日EMA被用来测量中期的口头和多头力量。
如果该指标大于零，则说明是买方市场，小于零则为卖方市场。如果该指标围绕在零轴周围波动，说明市场处于调整期，不在任何一方掌控之中。
• FI为正数时，它的值越大说明牛市力量越强。
• FI为负数时，它的值越小说明空头力量越大。
• 如果FI的绝对值小，说明交易量在下降或者大的交易量没有成功的推动价格上升。这两个原因都有可能带来反转。
2日FI被用作Eder 的三重滤网交易系统的一部分。
交易信号
始终要跟随趋势交易——可以根据13日EMA的斜率判断出。
• 如果出现看涨背离且FI值为负数时，做多。
• 如果出现看跌背离且FI为正数时，做空。
完整的交易策略可以在Alexander Elder 的《以交易为生》一书中找到。
示例：
澳大利亚综合股以及 13日EMA和 FI。
1. FI的快速下降预示着下降趋势的结束，同时它也发出关于价格试探前期低点的警告。
2. [L] 处看涨背离做多，同时等待EMA向上倾斜。
3. FI不断下降的高点预示着上涨动力正在逐渐减弱。此时，出现看跌背离，但不应该下单——EMA仍然呈上升趋势。
4. FI跌破零轴，说明买方丧失了控制力。[S] 处当EMA向下倾斜时做空。
计算公式
FI指标的计算方法是，当日的收盘价减去昨日的收盘价，然后再乘以交易量：
FI = (今日收盘价 – 昨日收盘价) * 交易量
Force Index
Developed by Dr Alexander Elder, the Force index combines price movements and volume to measure the strength of bulls and bears in the market. The raw index is rather erratic and better results are achieved by smoothing with a 2-day or 13-day exponential moving average (EMA).
• The 2-day EMA of Force is used to track the strength of buyers and sellers in the short term;
• The 13-day EMA of Force measures the strength of bulls and bears in intermediate cycles.
If the Force index is above zero it signals that the bulls are in control. Negative Force index signals that the bears are in control. If the index whipsaws around zero it signals that neither side has control and no strong trend exists.
• The higher the positive reading on the Force index, the stronger is the bulls' power.
• Deep negative values signal that the bears are very strong.
• If Force index flattens out it indicates that either (a) volumes are falling or (b) large volumes have failed to significantly move prices. Both are likely to precede a reversal.
The 2-day Force index is used as part of Dr Eder's Triple Screen trading system.
Trading Signals
Only trade in the direction of the trend - indicated by the slope of the 13-day EMA.
• Go long if the Force index is below zero and there is a bullish divergence.
• Go short if the Force index is above zero and there is a bearish divergence.
Complete trading rules for the Force index can be found in Trading For A Living by Dr Alexander Elder.
EXAMPLE
The All Ordinaries Index (Australia) is shown with 13-day exponential moving average (EMA) and Force Index.
1. A deep spike marks the end of a down-trend but it also warns traders to expect a re-test of the previous bottom.
2. Go long [L] on the bullish divergence. Wait for the EMA to turn upwards.
3. Declining peaks signal that bulls' strength is fading. No action is taken on the bearish divergence - the EMA is still rising.
4. The Force index falling below zero indicates that the bulls have lost control. On the strength of the bearish divergence - go short [S] when the EMA turns downward.
Setup
See Indicator Panel for directions on how to set up an indicator. The default settings for the Force index are :
• 13-day exponential moving average.
Formula
The Force index is calculated by subtracting yesterday's close from today's close, before multiplying by volume:
Force index = (Close [today] - Close [yesterday]) * Volume
本文翻译由兄弟财经提供
文章来源：http://www.incrediblecharts.com/indicators/force_index.php