本研究主要在探討國內五家名列全球銷售量前十大的DRAM廠商力晶半導體、南亞科技、茂德科技、華邦電子及晶豪科技股價之間的關連性，再進一步探討B/B 值與這五家廠商的價報酬率之間的關連性。
本研究以向量自我迴歸模型的三個應用：因果關係檢定、衝擊反應分析以及誤差變異分解再加上共整合檢定進行分析。
研究結果顯示：B/B Ratio 與DRAM 各厰股價存在長期均衡的關係，但是以B/B Ratio 作為DRAM 的景氣指標效果不佳，未來研究可再尋求更適當的變數，提供予投資人參考。
The purpose of this research is to discuss the relationship between the stock price of five Taiwan DRAM companies of the world top ten Chart: PSC, NTC, PROMOS, WINBOND, ESMT and B/B Ratio.
This research using three applications of the Vector Autoregression Model: Granger Causality Test, Impulse-Response Function, Forecast Error Variance Decomposition and the Cointergrating Test as a tool to find out the relationship between stock price of Taiwan Dram companies and B/B Ratio.
The research shows that B/B Ratio moves in the same direction with the stock price of Taiwan DRAM companies in the long-run, in other words, there is a long-run equilibrium correlation between stock price of Taiwan Dram companies and B/B Ratio. But it is ineffective using B/B Ratio as a leading indicator of the stock price of Taiwan Dram companies. It needs further research to find a substitute variable of B/B Ratio.
