在生態學及生物學的研究中，「物種個數」(Number of Species)通常是「生物多樣性」(Species Diversity)的重要測量值，物種個數的多寡、分布與多樣性有相當的關聯。「物種」的概念不侷限於生物，舉凡網路搜尋引擎(Search Engine)使用的關鍵字詞、圖書館分類的數目種類、國際疾病代碼等，都可視為物種。 本文著眼於寫作風格的比較，研究中國知名小說「紅樓夢」，主要探討前八十回與後四十回是否為同一個作者，以估計物種個數的觀點作為寫作風格的比較標準，並以金庸的武俠小說為對照組，驗證分析的結果。本文除了使用除了Efron and Thisted的隨機模型，也考慮藉由區塊抽樣估計母體種類數之Jackknife、Bootstrap、Chao(1992)等估計方法。研究發現Efron and Thisted的模型的估計量容易呈現不穩定的震盪，可能會有無法收歛的問題；而Bootstrap、Jackknife與Chao(1992)則會有高估母體種類數的現象。利用涵蓋機率的概念發現Jackknife與Chao皆在抽出特定比例的樣本數時，估計值涵蓋母體種類數之機率值非常接近1。 / The number of species is frequently used to measure the species diversity of a population in studying ecology and biology. There are such relationships between numbers of species and its diversities. The idea of species diversity is not restricted to biology, it receives more applications in recent years. For example, the applications also include key words in search engines, classification's numbers in a library, and disease types in Measuring health. This article studies the well-known Chinese novel “The Dream of Red Chamber”, and the goal is to study whether the first 80 and last 40 chapters are from the same author. In particular, methods related the number of species are used to evaluate the goal of study. Also, some Chinese martial novels, by the famous writer Jin Yong, are used as the control group for the methods used. Methods considered in this study include Efron and Thisted’s Model, Jackknife, Bootstrap, estimation method from Chao (1992). We found that Efron and Thisted’s estimates tend to be less stable and slow in convergence. On the other hand, the estimates of Jackknife, Bootstrap, and Chao are likely to be over-biased. However, after some modifications, we found that the Jackknife and Chao’s estimates can be used to provide reliable predictions for the number of species of a finite population, given that part of the population is observed.