What is RSI

相對強弱指數 (Relative Strength Index, RSI) 是一種最常用的輔助指標，主要是用來衡量巿況走勢的強弱、超買還是超賣。它的製作，是以一個很大的假設為依據──投資於大巿或某股的資金於某段時間內是不變的，所以在資金不變下，愈多人買入，則代表餘下的資金有限，形成了超買情況及股價有待調整；另一方面，若愈少人買入，則代表現金太多，投資者需要入巿，所以那是一個超賣情況，股價隨時反彈。

RSI 有不同的週期可供選擇，普遍採用 9 天或 14 天。而 RSI 的數值範圍介乎 0 至 100 之間，當 RSI 升至 70 以上時，表示股價已出現超買，後市可能有回吐壓力；相反當 RSI 在 30 以下，則表示股價已出現超賣，後市可能會止跌回升。不過要注意，超買和超賣只是給我們一個警覺，並不代表巿況會立即逆轉，因此建議 將 RSI 與保力加通道一起運用，效果會更理想。

此外，當 RSI 向上或向下突破中間線 50，分別是走勢轉強或轉弱的分水嶺。RSI 在 50 以上利好；在 50 以下利淡。


相對強弱指數的計算方法：

RSI = 100-100/(1+RS)

RS = (設定時間內上升價格的平均值 ) / (設定時間內下跌價格的平均值)

A repetitive strain injury (RSI), also called repetitive stress injury, cumulative trauma disorder or ocupational overuse syndrome, is any of a loose group of conditions from overuse of the computer, guitar, knife or similar motion or tool. It is an occupational overuse syndrome affecting muscles, tendons and nerves in the arms and upper back; hence it is also known as work related upper limb disorder or WRULD. The medically accepted condition in which it occurs is when muscles in these areas are kept tense for very long periods of time, due to poor posture and/or repetitive motions.

It is most common among assembly line and computer workers. Good posture, ergonomics and limiting time in stressful working conditions can help prevent or halt the progress of the disorder. Stretches, strengthening exercises, massages and biofeedback training to reduce neck and shoulder muscle tension can help heal existing disorders.