model 是什麼？

有人譯做「模式」，但也許譯為「模型」比較好。諾貝爾經濟學獎得主保羅．克魯曼（Paul Krugman）在所著The Return of Depression Economics and the Crisis of 2008一書，給了model精簡的解釋：

The only way to make sense of any complex system, be it global weather or the global economy, is to work with models—simplified representations of that system which you hope help you understand how it works. Sometimes models consist of systems of equations, sometimes of computer programs (like the simulations that give you your daily weather forecast); but sometimes they are like the model airplanes that designers test in wind tunnels, small-scale versions of the real thing that are more accessible to observation and experiment.

中文的意思是：

要 理解任何複雜的系統，不管是全球氣象，還是世界經濟，唯一的方法是使用模型（models）──以簡化的方式呈現那個系統，希望有助於了解它是怎麼運作 的。有時模式由方程式組成，有時由電腦程式（就像每天的氣象預測所做的模擬）構成；但有時則像模型飛機，設計師拿來在風洞中測試。這種模型是實物的縮小 版，更容易觀察和實驗。