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: Sampling Methods for Web and E-mail Surveys 
Chapter Title:  Looking to the future 
1. Abstract of Cited Paper (BIB001):  The way market research is conducted has changed dramatically over the past 30 years, as a result of both the development of the prevailing view of best practice and the state of technology available to researchers. While it is clear that the World Wide Web (WWW) will increasingly be used as a medium for conducting market research, the full implications of this new channel are not yet fully understood. This paper examines the potential for an Internet‐based financial services firm (Xenon Laboratories) to analyse conduct market research using the WWW. The case demonstrates that, by employing a novel approach to market research, Xenon Laboratories is in a unique position to understand the charging structures in its market, the market for international payments using credit or charge cards. In doing so, the paper highlights the opportunity to unobtrusively gather market information from an international group of customers by providing Internet‐based value‐added services.

Literature Review:
So, what does the future hold for Internetbased survey sampling? At this point in the Internet's development, with its rapid expansion and continued evolution, it's truly impossible to say. Yet we can hazard a few guesses. First, if the Internet continues to expand but largely maintains its current structure, then advances in sampling methods that will allow random sampling of, and inference to, general populations will be at best slow and difficult to develop. This follows from the fact that Internet-wide sampling frames are simply unavailable under the current Internet structure/organization, and no general frameless sampling strategies yet exist. Unless the way the Internet is organized and operated changes, it seems this will continue to be the case into the foreseeable future. That said, survey sampling methodologists should endeavour to develop new sampling paradigms for Internet-based surveys. The fundamental requirement for a probabilitybased sampling scheme is that every member of the target population has a known, non-zero probability of being sampled. While in traditional surveys this can be achieved via various frame and frameless sampling strategies, it does not necessarily follow that Internet surveys must use those same sampling strategies. Rather, new sampling methods that take advantage of the unique characteristics of the Internet, such as the near-zero marginal cost for contacting potential respondents, should be explored and developed. In addition, researchers considering conducting an Internet-based survey should consider whether the capabilities of the web can be leveraged to collect the desired data in some other innovative fashion. For example, BIB002 present a case study of Xenon Laboratories, an Internet-based financial services firm that employed a novel approach to market research. Xenon Laboratories wanted to collect data on foreignexchange charges by credit-card companies on business travellers. They recognized that neither the travellers nor the creditcard companies were likely to respond to a survey on this topic, whether fielded over the web or otherwise. Instead Xenon Laboratories developed the Travel Expenses Calculator (www.xe.com/tec) and the Credit Card Charges Calculator (www.xe.com/ccc) and posted them on the web for anyone to use for free. These tools help foreign business travellers to accurately calculate the cost of a business expense receipt in terms of their own currency. BIB002 say, 'On the basis of this information [input by those using the calculators] it is possible to conduct basic market research by aggregating the inputted calculations. Xenon is now in the unique position to analyse whether or not the different card providers employ the same charging levels and whether or not these companies' charge structures vary according to geographical region.' They go on to conclude, 'This value-added approach, which is mutually beneficial to both parties, is an important and novel approach to market research.' Second, it is also possible that technological innovation will facilitate other means of sampling for Internet-based surveys (and for conducting the surveys themselves, for that matter). For example, current trends seem to point towards a merging of the Internet with traditional technologies such as television and telephone. It is quite possible that sometime in the future all of these services will merge into one common household device through which a consumer could simultaneously watch television, surf the web, send e-mail, and place telephone calls. Depending on how this evolves, various types of random sampling methodologies, as well as new survey modes, may become possible. For example, it may become feasible, and perhaps even desirable, to sample respondents via RDD (or something very similar), have an interviewer call the respondent, and then in real time present the respondent with an interviewer-assisted, web-based survey. It is also possible that, as the technology matures, these combined television-Internettelephone appliances will become as ubiquitous as televisions are today, with service offered only by a few large companies. If so, then it may ultimately be possible to use the companies'subscriber listings as sampling frames (much as telephone directories were used pre-RDD in the mid-1900s). Or it may be that some other state emerges that lends itself to some form of sampling that is not possible today. The point is that the Internet is still very much in its infancy, and the current difficulties surrounding sampling for Internet-based survey described in this chapter may or may not continue into the future. To put this in a historical context, note that while the telephone was invented in the late 1800s, and telephone systems developed and expanded rapidly through the early 1900s, it was not until the mid-1900s that telephone coverage was sufficiently large and standards for telephone numbers adopted that made RDD possible. In fact, the foundational ideas for an efficient RDD sampling methodology were not proposed until the early 1960s BIB001 , after which it took roughly another decade of discussion and development before RDD as we know it today became commonplace. 4 Thus, in total, it was roughly a century after the invention of the telephone before RDD became an accepted sampling methodology. In comparison, the web has been in existence, in a commercial sense, only for little more than a decade or two. As with the telephone in the late 1800s and early 1900s, we are in a period of technological innovation and expansion with the Internet. However, unlike the telephone, given today's pace of innovation, the Internet and how we use it is likely to be quite different even just a few years from now. How this affects sampling for Internet-based surveys remains to be seen.