Although it has been possible to infer from the goods and services actually produced what manufactures and servicing trades thought their customers wanted，only a study of relevant personal documents written by actual consumers will provide a precise picture of who wanted what.
盡管有可能從實(shí)際制造的商品和服務(wù)中可推知制造商和服務(wù)業(yè)認(rèn)為他們的顧客所需要的是什么，但只有對由實(shí)際顧客撰寫的相關(guān)的個(gè)人文件進(jìn)行一番研究，方能提供一幅精確的圖畫，藉以說明"什么樣的人"需要什么樣的東西。