We described how consumers process and evaluate comparative healthcare information. People applied various strategies to process the information they were provided with, especially when making hypothetical decisions. In line with the findings of Harris , variation was shown concerning consumers' willingness to use the information. Nevertheless, we detected a main line from consumers' thoughts, classified into twelve themes. These themes were categorized under four important areas of interest: (1) a response to the design; (2) a response to the information content, (3) the use of information, and (4) the purpose of the information.
Study strengths and limitations
Our study is the first to investigate in-depth consumers' own thoughts about Dutch comparative healthcare information. An important strength is that real online information was used, with all its complexities included. We used three different websites which are typical for websites internationally , and the results were of the same order for these three websites. The open qualitative approach resulted in detailed information about the interpretations and experiences of consumers themselves. Our findings therefore provide a thorough and valid understanding of consumers' experiences and the difficulties that they face. However, our small scale study does not allow for specific recommendations concerning presentation formats. More controlled experiments and observational studies are needed to further investigate decision making using online comparative healthcare information.
A limitation of our study is that neither low educated people nor ethnic minorities participated, although they were invited. This might suggest that certain consumer subgroups are not interested in comparative healthcare information, think that participating is too difficult, or that their jobs or lives are less flexible. Lower educated people are known to have more difficulty understanding healthcare quality information. In addition, the use of Internet is limited among lower educated people and ethnic minorities . This means that their use of the information might even be more complicated than was shown among our participants. Further research should be conducted to investigate these potential problems concerning accessibility of information and equity.
Our findings were also limited by the fact that our participants were not facing a real decision. We forced consumers to choose, which can bias the results towards the 'safer', more average option . Patients facing a real decision in healthcare might weigh other aspects than volunteers in hypothetical choices. Real healthcare consumers usually do not have a 'no choice' option either, though they can decide to leave the choice of a provider to their family doctor who refers them, or-in market research terms- who acts as a 'surrogate consumer' . Is it important to realize that real decisions in healthcare involve many factors within a healthcare trajectory, rather than merely visiting one website to get informed .
A key finding is the tension between the great amount of information consumers stated to find important and how sporadically they actually incorporated this information into their decisions. Furthermore, ideas on which quality aspects are important to consider changed during the course of the interview. This inconsistency between (initial) interest in certain information and (later) leaving out of consideration has been found previously [15, 16, 28]. It suggests that preferences are constructed gradually during the interview [16, 30, 47], and are not as predictable as is sometimes assumed. As already mentioned as a study limitation, the prescriptive nature of our question (what would you do.?) might contribute to differences in what people said to what they actually did. Another explanation might be found in the data itself; when there are few provider-differences on aspects that one considers important, that aspect is not weighted in the eventual choice, though it is still considered important.
Considering the difficulties that participants experienced when processing the amount of presented information and making a choice, we want to emphasize the perceived barrier of too much information. It is known that people can only process about six pieces of information at a time and are easily overwhelmed by information . Therefore, providing all available information is not the most effective way to stimulate informed choices [48, 49]. As argued by Eysenbach, websites do not always need to be complete and present the full information spectrum about a particular disease or healthcare topic. Indeed, consumers are able to gather information from various sources and sites [16, 50]. Therefore, websites should rather provide conceivable overviews with small numbers of providers and the most relevant quality aspects, and offer more detailed information into step-by-step pages, an approach corresponding to humans' need for generic to specific information [14, 51]. This deep-linking approach, which has been frequently cited in the broader context of consumer health informatics, [16, 23] could reconcile consumers' desire for more information without overwhelming them. Gerteis and colleagues  suggested to use evaluative formats (for example stars) on a first page and let consumers drill down to more detailed bar graphs.
Consumers found it hard to process contradictory information, such as a hospital with high performance on one quality aspect, and low on another aspect, which also corresponds to previous findings . Conflicting information asks for more cognitive effort, which forces consumers to make trade-offs of important aspects and to rely on intuitive heuristics. Comparative healthcare information usually contains contradictory information. Initiatives to prepare or train consumers about potential contradictions might remove some confusion. However, effectively processing contradictory information requires relatively complex strategies and will continue to be difficult.
Only a few consumers deliberately processed all information. More often, only parts of the information were considered, particularly information about familiar providers. This suggests that consumers are not interested in all information, but rather want to check how particular providers perform compared to others. This corresponds to what we know from cognitive science about interpretation in light of questions and information already in mind when viewing information, such as reviews of other patients or media reports [16, 26]. Therefore, it seems important to relate comparative healthcare information to alternative information that consumers find familiar . For example, anecdotal or patient review information (such as on NHS Choices in England  and Consument en de Zorg in the Netherlands ) might be an interesting source of additional consumer information. Further research is needed to assess whether and how these different types of information should be integrated.
Various strategies were applied to choose providers, varying from systematic reasoning to more intuitive, experiential reasoning using only parts of information. Both alternative-based reasoning and attribute-based reasoning were used, which are both known to be used when information is presented in a matrix format [55, 56]. In terms of web design, it means that pages presenting information need to be highly flexible, and preferably allow selections on both prioritized aspects and particular providers of interest.
A substantial number of the participants was interested in the presented information, and understood the purpose of the information. In line with a previous qualitative study , consumers appear to comprehend information among main lines, but have difficulty understanding more detailed information and concepts. Findings seem to contradict the notion of some researchers that consumers are not interested in comparative healthcare information. Perhaps the healthcare market is different from other markets where people prefer not to choose, e.g. the energy market [58, 59], in the sense that healthcare is a product that is of interest to people. There are many documentaries and talk shows about health and healthcare, and hardly any about gas and electricity. So even if consumers are not willing to choose, they can still find healthcare information interesting.