You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A Survey of Outlier Detection Methods in Network Anomaly Identification 
Chapter Title:  Characterizing ANIDS 
1. Abstract of Cited Paper (BIB001):  Since the first introduction of anomaly-based intrusion detection to the research community in 1987, the field has grown tremendously. A variety of methods and techniques introducing new capabilities in detecting novel attacks were developed. Most of these techniques report a high detection rate of 98% at the low false alarm rate of 1%. In spite of the anomaly-based approach's appeal, the industry generally favors signature-based detection for mainstream implementation of intrusion-detection systems. While a variety of anomaly-detection techniques have been proposed, adequate comparison of these methods' strengths and limitations that can lead to potential commercial application is difficult. Since the validity of experimental research in academic computer science, in general, is questionable, it is plausible to assume that research in anomaly detection shares the above problem. The concerns about the validity of these methods may partially explain why anomaly-based intrusion-detection methods are not adopted by industry. To investigate this issue, we review the current state of the experimental practice in the area of anomaly-based intrusion detection and survey 276 studies in this area published during the period of 2000-2008. We summarize our observations and identify the common pitfalls among surveyed works.

Literature Review:
An ANIDS is an anomaly based network intrusion detection system. A variety of ANIDSs have been proposed since the mid 1980s. It is necessary to have a clear definition of anomaly in the context of network intrusion detection. The majority of current research on ANIDS does not explicitly state what constitute anomaly in their study BIB002 . In a recent survey BIB001 , anomaly detection methods were classified into two classes: generative and discriminative. Generally, an ANIDS is characterized based on the following attributes: (i) nature and type of the input data, (ii) appropriateness of similarity/dissimilarity measures, (iii) labelling of data and (iv) reporting of anomalies. Next, we discuss each of these issues.