Keywords

1 Introduction

With the rapid development of mobile Internet, the long-term rental application is the combination of traditional rental agency service and mobile Internet, integrating large-scale housing into the online comprehensive platform. It makes up for the shortcomings of information asymmetry, high intermediary cost, cumbersome procedures and insufficient service standardization of traditional Chinese rental agency services. After the long-term rental industry entered an accelerated development period, many innovative business models have emerged in the segmentation field. The long-term rental application is a business model, through which the business landlord (individual or company) with legal charter rights provides users with institutional supply, management and operation services. Users can complete online searching, offline viewing, and online signing through the application. The long-term rental application attracts a large number of users because of its easy operation, low cost to find an apartment, large number of apartments and more standardized services.

Chinese long-term rental industry market is huge, but compared with the developed countries such as the United States, there is still a big gap in the maturity of the long-term rental service system. The Chinese rental industry is still in an accelerated development stage. According to the report released by National Health Commission P. R. China in July 2018, as of 2017, Chinese mobile population reached 244 million, occupying 17.55% of the total population [1]. According to the report released by iResearch, the scale of Chinese long-term rental market in 2017 has reached 1.43 trillion RMB, and is expected to reach 3.01 trillion RMB by 2025 [2]. However, at present there are still many usability problems in Chinese long-term rental application, including the lack of uniformity of the page logic, labels which affect attention of users, incomplete screening criteria, and so on [3].

The goals of interaction design include usability goals and user experience goals [4]. The long-term rental application matches the apartments and users through the network channel, the long-term rental apartments play a decisive role in satisfying the user’s physiological needs. Moreover, the limited cognitive ability of the public users and the high loss of decision-making failure also make the usability goals become the core goals of the interaction design of the long-term rental application. This paper intends to achieve the goal of improving product usability by studying the interaction design of long-term rental application.

2 Methodology and Results

2.1 Overall Procedures of Proposed Methodology

As shown in Fig. 1, through the focus group, non-participant observation and questionnaire survey, the experiment explored the user demand preferences and the user usage habits of long-term rental application. Summarizing the results of three steps, and proposed interaction design principles to assist long-term rental application to improve the interaction design level, so that the final presentation of the interface can effectively improve the application usability.

Fig. 1.
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The framework of the methodology

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2.2 Focus Group

A focus group is a group of individuals selected and assembled by researchers to discuss and comment on, from personal experience, the topic that is the subject of the research [5]. In order to determine the user focus of the interaction design of the long-term rental application based on usability goals, this study firstly explored the needs and suggestions for the usability of products when users used an existing long-term rental application through focus groups. The focus group targeted new graduates or newcomers from 21 to 26 years old who had rental needs in first-tier and second-tier cities. The focus group consisted of 13 users and they were discussed in two separate groups.

2.3 Non-participatory Observation

The non-participant observation has much potential for capturing social action and interaction as it occurs. And the objectivity of the non-participant observation makes it more acceptable as a research method [6]. Combining the results of the focus group with the usability goals, this paper conducted research through non-participatory observation. Observing and recording in the real environment that two users used two existing long-term rental applications, effectively discovering the real behaviors and psychological expectations of users in the real environment.

2.4 Questionnaire Survey

Combining the conclusions of the focus group and the non-participatory observation, this paper collected users’ views and perceptions through questionnaires [7]. The questionnaire adopted two methods: online distribution and offline distribution, and was distributed in three stages: pre-distribution, formal distribution, and supplementary distribution. The trap question was set. When the user triggered trap question and gave a wrong answer in the system, the questionnaire would be classified as an invalid one. And the questionnaire designed two questions to ensure that all valid respondents had rental requirements. Finally, 389 valid questionnaires were returned.

2.5 Results

The results of focus group are summarized as follows: (1) The users pay attention to the following information: the subway station and supermarket information around the apartment; the contract payment period; the information of other rooms when the house is shared; the information of the homeowner or broker; the layout in the rooms and the facilities information in the rooms. (2) The users need the following functions: viewing the visitor’s review comment; reporting the homeowner or broker; reserving the line to view the house; viewing the house through the video online; searching and viewing all the apartments in a certain district online; comparing information on two apartments online. (3) The users attach great importance to security. On the one hand, they hope that the system protects their personal information, and the security of rent and service fees online is guaranteed. On the other hand, the security of apartments, including door locks and community security, is highly valued. (4) The users are sensitive to the price information of the apartment, and are worried that the price is opaque due to information asymmetry, and the application changes the prices randomly and causes financial loss of users.

The results of non-participatory observation are summarized as follows: (1) During the process of finding an apartment online, the primary expectation of users is to find the basic information of the apartment, including the photo of the apartment, the geographical location, the rent of the apartment, the hardware of the apartment, and the orientation of the apartment. The deep expectation is to find an apartment that meet their own rental requirements, including the commuting time from apartment to their company, the payment methods, and the information of sharing roommates. (2) When looking at the apartment in the real scene, the users pay more attention to the time of the reservation, the authenticity of the apartment, the housekeeper information, the surrounding environment of the community, the safety of the apartment, the sanitation of the apartment, and the match degree between photos online and the real situation. (3) When users sign the contract online, they pay more attention to the contract regulations, the rental fee descriptions, the default statements, the rent payment channels, the payment amount details users’ and the fund transfer process.

The results of questionnaire are summarized as follows: (1) The users pay attention to the geographical location and traffic situation of the apartment, and the application should assist the user checking the traffic situation through the core operation. When searching for apartments, 66% of users tend to find apartment near the subway station, 63% prefer to locate houses through company position; 81% of users pay more attention to traffic problems. When comparing the information about the apartments, 69% of users care about the distance from the house to the subway station. (2) The users who focus on the shared apartment are different from that of the whole apartment. In the page displaying the shared apartments, the information displayed should be increased according to the users’ needs. The survey found that 77% of users are concerned about the basic information of shared roommates; 55% of users pay attention to whether there is a separate bathroom; 37% pay attention to the problem of water and electricity sharing; 24% of users pay attention to whether other rooms have been rented. (3) The introduction of the apartment in the long-term rental application can be based on short videos, panoramic pictures and photos, combined with live video and text in appropriate scenes. As the form of video is more intuitive than the picture, users are more inclined to understand the listing through short videos. The data shows that the proportion of users who prefer to browse the listing through short videos, panoramic pictures, and photos is 71%, 62%, and 55% respectively. (4) Users are concerned about security issues. Users want an apartment which security can be guaranteed. 58% of users think that security issue is the most important thing when selecting an apartment listing. 60% of users who choose to share an apartment are most concerned about personal security issues.

3 Usability-Based Interaction Design Principles of Long-Term Rental Application

The International Standardization Organization (ISO) defined usability as: “The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.” in ISO 9241-11 (1998) [8]. Preece et al. (1993) characterized six attributes of usability: feasibility, effectiveness, security, versatility, learnability, and memorization [9]. Arbran et al. (2003) established an enhanced usability assessment model, including five factors: effectiveness, efficiency, satisfaction, security, and learnability [10]. Being different from other applications, the long-term rental application has the characteristics of wide user scope, high capital relevance, and long trading period. Therefore, this paper proposes six usability elements, namely effectiveness, efficiency, satisfaction, learnability, security, and versatility, and these six elements are defined as their usability goals for the long-term rental application.

According to the availability target and experimental research results of the long-term rental application proposed above, this paper proposes the following long-term rental application interaction design principles, so that the products can improve their usability through designing according to the interaction design principles.

Meeting User Mental Models.

The user mental model is a simple way for the users to understand the interface through self-creating [11]. According to the report “2018 Young People Renting House Big Data Report”, 69% of the current Chinese rental population is a young group born after 1990 [12]. The rental experiences of these users started from their graduation. The long-term rental application is a new system for them, which can improve the users’ acceptance degree by simulating users’ mental model to their common system. The traditional offline rental mode has some problems in renting service system, apartment management system and credit evaluation system. Therefore, the user mental model of long-term rental application can simulate the user mental model of the mobile shopping application with a larger number of users, instead of the user mental model of the traditional offline model. There are some similarities between mobile shopping and online rental transactions, for example, users find their targeted products and trade online. The long-term rental application can be referred to the user mental model of the mobile shopping platform during designing, including searching products, viewing product details, and collecting products.

Focusing on the Analysis and Design of Different Touchpoints.

Touchpoints occur whenever a customer “touches” a system across multiple channels and at various points in time [13]. The user use process of long-term rental application is complicate, and the touchpoints which distributed throughout the system are numerous. As shown in Fig. 2, the information touchpoint is formed between the user and the information platform, the interpersonal touchpoint is formed between the user and the housekeeper, the physical touchpoint is formed between the user and the apartment, and the hidden touchpoint is formed between the user and the landlord. At the beginning of the design, designers need to analyze the touchpoints of different functions in the application and give targeted design plans. Take the most important rental service as an example: (1) It will form a hidden touchpoint between the landlord and the user before the user uses the rental service. Users will not be in direct contact with the landlord, and they can only communicate with the application. The application renovates and shows the apartment information online. Applications should pay attention to that the information published online must be in completely matched to the real situation information of the apartment. (2) At the beginning of using the rental service, the information touchpoint will be formed between the user and the application. The user will be anxious when filtering an apartment from massive information. At this stage, the application should assist the user in making decisions more efficiently through many means, such as filtering information based on user preferences, optimizing information hierarchy, distinguishing information category and so on. (3) When finding an appropriate apartment, the user will make an appointment to view it. During the appointment processing, the user and the housekeeper will form a human touchpoint. Language, behaviors and dressing of the housekeepers will affect the overall evaluation of the application. This part also should be intervened by design. (4) When the user views the house offline, it will form a physical touchpoint between the user and the apartment. The application should guarantee the apartment is consistent with the online descriptions, including the apartment facility information, the roommate information and so on. Information about whether the house has been rented or not, online information needs to be synchronized with the offline situation. At this time, there is an interpersonal touchpoint between the user and the housekeeper. The housekeeper should maintain a friendly attitude and respond to users’ questions in time. (5) When the user signing the contract, the information touchpoint with the application is formed through the online system. Application should provide clear feedbacks for different time points in the process of fund transfer. (6) When the user successfully enters the house after signing the contract, there is a physical touchpoint with the house, an interpersonal touchpoint with the housekeeper (when the housekeeper transfers the materials of the apartment to the users), and an information touchpoint with the application (the door lock password information is obtained by the application). The application needs to provide assistance when the users complaint or give feedbacks on issues.

Fig. 2.
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The touchpoints between user and long-term rental application

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Completing Information Searching Path.

The long-term rental application should provide a corresponding path for directed browsing, semi-directed browsing, and undirected browsing [14]: the search bar is the main path provided to the directed browsing behavior; the apartment classification list entrance is the primary path provided to the semi-directed browsing behavior; and the recommended apartment list is the primary path provided to the undirected browsing behavior. It is known from the experiments that the users attach great importance to whether the house is suitable for daily commuting. The application should provide the function of searching the apartment based on commuting. The users can directly find the apartment which is nearest to their companies, or the traffic routes of the apartment meet the users’ requirements. Application should minimize the search paths to avoid the anxiety of users when using the application.

Reasonable Information Display Methods.

When displaying information, you should select an appropriate form according to the users’ requirements. For example, in the apartment detail page, application can increase the form of short video viewing, and play it automatically when the telephone is in the Wi-Fi environment. Adding the apartment comparison function, the user can compare all dimensions of the apartment information to make a satisfied decision. Showing more relevant information of the shared apartment, including the basic information of the shared roommates, whether there is a separate toilet or not, the sharing method of utilities, whether other houses have been rented. In addition, the long-term rental application should also provide a reasonable way to display information, such as using artificial intelligence technology to transform passive information into active information [15], and providing users with personalized recommendations to assist users in decision-making efficiency. User-generated data stands for those acquired from online reviews/comments, audio or video-based text [16]. After obtaining the user’s personal data and renting demand, the long-term rental application establishes the user’s personal demand model and uses the demand model to recommend actively. After receiving the recommendation result, the user will have operational behaviors (such as browsing, collecting, ignoring an apartment, etc.). The system updates the model according to the user behavior, and quickly uses the updated model for recommendation.

4 Usability Testing

The main purpose of the usability test is to verify the interaction design principles proposed and observe whether the interaction design principles can improve the usability of the application by redesigning a long-term rental application to make it more consistent with the interaction design principles. Usability testing is used to inspect if the improved application has improved its usability (the improved high-fidelity model is shown in Fig. 3).

Fig. 3.
figure 3

The improved design prototype (Interface Designers: Jia-xin Lu, Jia-yi Fu, Qi Zhao, Ruo-lun Yang, Shi-qi Zhou, Zhi-yuan Zheng, Zi-you Qiu)

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Jakob Nielsen proposed that measured person can find 80% of the usability problems of the design when the number of samples is 5 in the usability test [17]. Based on the predictions using the observed data with a variety of experimental conditions, a general rule for optimal sample size would be ‘10 ± 2’ instead of ‘4 ± 1’ [18]. This experiment selected the number of samples as 13. The test first required the measured person using the online version and the improved design prototype to experience separately, and observed whether the user could successfully complete the entire operation process, then required the measured person filling in the system usability scale.

In order to facilitate the understanding of the users, a slight improvement was made for the system usability scale compiled by the scholar John Brooke by replacing ‘system’ with ‘application’. As shown in Table 1, the scale is a 5-level Likert scale, giving 10 attitude statements. The first, third, fifth, seventh, and seventh statements are forward description statements, and the second, fourth, sixth, eighth, and fourth statements are reverse description statements. The user chooses the degree of recognition of the statements [19]. The fourth and fourth statements in the scale measure the learnability of the application [20].

Table 1. The usability scale
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To calculate the SUS score, for items 1, 3, 5, 7, and 9, the score contribution is the scale position minus 1. For items 2, 4, 6, 8 and 10, the contribution is 5 minus the scale position. Multiply the sum of the scores by 2.5 to obtain the overall value of usability [19]. The learnability score is the sum of the 4th and 10th scores multiplied by 12.5.

After calculation, the average usability score of online version is 49.423, and the average learnability score of it is 59.615. The average usability score of improved design prototype is 70.962, and the average learnability score of it is 75.962. According to the average score, usability and learnability can be divided into six levels from A to F from high to low [21]. As shown in Fig. 4, the online version usability and learnability are Level F and Level D. The improved design prototype usability and learnability are Level C and Level B. The usability and learnability level of prototype are both significantly higher than the online version, indicating that the redesigned interaction design has improved usability and learnability, and verified the correctness and usability of the interaction design principles.

Fig. 4.
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The average score and the level between the online version and the improved design prototype

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5 Conclusion

Starting from the usability of the long-term rental application, combining with focus group, non-participatory observations and questionnaire survey, the principles of interaction design are summarized. Through design practicing and usability testing, it is found that adherence to the interaction design principles can effectively improve the usability and learnability of the long-term rental application and will lay a theoretical foundation for the interaction design of the long-term rental application. For the one thing, the usability goals of the long-term rental application are proposed, including effectiveness, efficiency, satisfaction, learnability, security, and versatility. For another thing, the interaction design principles of the long-term rental application are proposed, including meeting user mental models, focusing on the analysis and design of different touchpoints, completing information searching path and reasonable information display methods. The limitation of this study is that the measured person is all working or studying in metropolis cities of China. In future, the collection of person from small and medium-sized cities are necessary in order to increase the sample size and representative of the entire population of China. Due to the limitations of this study, i.e. time and resource constraints, a collection would be conducted to gather more samples in the future.