隨著市場競爭激烈，企業對於產品的開發都希望時間越短越好，這樣就能提早進入市場，一般生命週期短暫的科技產品，基於競爭的基礎下，會利用不斷推出新產品來創造市場地位。但軟體的開發通常會有一個主要產品，後期則不斷進行版本改良，不論是功能或效能的增加，只要是不同於原先產品，都可算是新產品。故不同版本軟體產品可視為一種多世代形式，越來越多不同領域產品也趨向多世代走向。針對多世代產品的擴散，近來許多學者探討結合產品生命週期做市場需求的預測分析。而以往對於擴散模型的應用，較少學者提出數量化的上市時間分析，大部分只估計模型的擴散參數，或以品牌和價格做為競爭因素並提出相關需求預測。
本研究將Bass擴散模型中單世代最佳銷售時間點之概念進行延伸，以市場潛量為考量因素提出在第二代出現後之最佳時間間隔擴散模式，並求出兩代產品銷售獲利最佳情況下之時間點。另外，為使產品銷售預測能力能獲得較佳結果，本研究也考慮加入市占率外生因子於多代與一般單代Bass模型中，最後以明顯具有世代版本交替之資訊軟體業作為實證對象，進行擴散參數求解及上市時間分析與探討。實證結果顯示，兩代產品至少須間隔四年以上時間推出新一代才不致使前一代獲利受影響。希望藉此提出的決策模式可使上市時間這個管理面的議題有另一個數量化模型參考。

As the market has become more competitive, firms also hope to reduce developing time. Especially for shorter life cycle technological products, firms usually continue to release new product to keep market. The development of software may release many versions, and the later version has been improved to differentiate from original product which called multi-generation product. More and more products have been multi-generation. Recently, for diffusion of multi-generation products, many researchers have combined the product life cycle to forecast the demand of market. But in studies of time-to-market diffusion model, most of them estimate diffusion parameters and discuss the factors of brand and price, few use quantitative method to analyze launch time.
This study extend the best sales timing in Bass diffusion model and consider market potential to create optimal period diffusion model. In this model, we could point out the timing for the best profit between the shift of old and new generation launching to market. Besides, we add market share as exogenous variable to multi-generation Bass diffusion model and general Bass diffusion model for better forecast ability. Moreover, we took empirical study in software products, obtaining diffusion parameters to investigate the launch time.
The results show that old and new generation products must wait at least four years to launch to avoid affecting the profit of old products. The decision-making model could offer time-to-market study another quantitative perspective.

中文文獻
陳逸如，歐體條約第八十二條之研究-以微軟作業系統搭售案為中心，國立中興大學科技法律研究所碩士論文，2008。
翁偉修、林信亨、王義智、李震華、黃正傑、洪聖敏，台灣資訊服務產業發展現況與趨勢，財團法人資訊工業策進會，2009。

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