Hindawi Mobile Information Systems Volume 2017, Article ID 1294193, 17 pages https://doi.org/10.1155/2017/1294193 Research Article A Systematic Evaluation of Mobile Applications for Instant Messaging on iOS Devices Sergio Caro-Alvaro, Eva Garcia-Lopez, Antonio Garcia-Cabot, Luis de-Marcos, and Jose-Maria Gutierrez-Martinez Computer Science Department, University of Alcala, AlcaladeHenares,Spain´ Correspondence should be addressed to Sergio Caro-Alvaro; [email protected] Received 15 June 2017; Revised 6 August 2017; Accepted 17 August 2017; Published 2 October 2017 Academic Editor: Porfirio Tramontana Copyright © 2017 Sergio Caro-Alvaro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nowadays, instant messaging applications (apps) are one of the most popular applications for mobile devices with millions of active users. However, mobile devices present hardware and software characteristics and limitations compared with personal computers. Hence, to address the usability issues of mobile apps, a specific methodology must be conducted. This paper shows the findings from a systematic analysis of these applications on iOS mobile platform that was conducted to identify some usability issues in mobile applications for instant messaging. The overall process includes a Keystroke-Level Modeling and a Mobile Heuristic Evaluation. In the same trend, we propose a set of guidelines for improving the usability of these apps. Based on our findings, this analysis will help in the future to create more effective mobile applications for instant messaging. 1. Introduction alternative (usually free or cheaper) to the traditional SMS messages [8, 10, 13]. Since there are so many apps for the Mobile devices have become an essential tool in our daily same purpose in the mobile markets, users have too many lives [1], to the point that the number of mobile users has alternatives to choose and therefore they are quite critical been increasing more and more in recent years, from 640 about how an app works. Users like simplicity to complete million of Android and iOS active devices in 2012 [2] to 2,562 tasks and ease of learning or less time consumption [14–16], million of devices in 2016 [3]. So considerable is this increase so they probably will choose the best app. that in the summer of 2016 Apple reported the sale of its Mobile app developers find it difficult to determine, from billionthiPhone[4].Theincreaseduseofmobiledeviceshas target users, their needs and potential feedback in order to led to a widespread diffusion of the number of applications improve the apps [17, 18]. Thus, a good usability is the key (henceforth, called apps) available in mobile markets in to increase the chances of an app to be chosen by users recent years. For example, the Apple App Store reveals an among many others. Usability is a science that is responsible increase in the number of available apps, from 1,200,000 (as of for studying the interaction between humans and computers July 2014) to 2,200,000 (as of January 2017) [5, 6]. Among all (HCI) and has been defined by different organizations and those applications there are some for written communication researchers. International Organization for Standardization that have become ubiquitous in contemporary society [7, (ISO) defines usability as “the effectiveness, efficiency, and 8], such as instant messaging (so called IM apps), social satisfaction with which specified users achieve specified goals networks, or email apps. in particular environments” [19] and Nielsen [20] defines IM apps are the newest and most popular evolution of it as “a quality attribute that measures the usability of user near-synchronous text technologies [9–11]; thus, they are interfacesandthereferencemethodstoimproveeaseofuse used to facilitate social relationships [12] and are one of the during the design process.” A poor usability is the main most widely used apps, since this type of app has become an discontinuing factor from app usage [11, 17, 21]; hence, it is 2 Mobile Information Systems important to study the usability in desktop applications, but The paper is organized as follows. Section 2 shows the it is even more important to address it in mobile apps because evaluation carried out and the results obtained in the system- mobile devices are the first and most used electronic devices atic evaluation. In Section 3, we provide some discussions of in the world [22, 23] with a large number of users [24]. the results. Finally, Section 4 draws some conclusions, while To this end, in this paper, we perform a systematic presenting the usability recommendations. evaluation of mobile IM apps over the iOS platform to identify some usability issues. Particularly, given the lack of agreement on usability recommendations and difficulties 2. Evaluation and Results toproperlyfindthem[25],thispaperistoprovidealist of recommendations for improving the usability of these Here, after having outlined the corresponding need to address applications, in order to be applied within the development the usability issues of instant messaging apps in mobile process [25]. devices, we show the systematic evaluation carried out and Mobiledeviceshavesomelimitationswhencompared the different results obtained in the steps. To do so, the iOS to personal computers (PCs) [26, 27], such as small-sized platform was used for the evaluation and an iPhone 4 was screens, limited input mechanisms, low and expensive band- used in the last steps because the evaluation requires testing width (in some cases), battery life, and a wide variety of the applications in a real mobile device. devices (including the diversity of hardware and operating Overview of the Process. It is important to underline that the systems). Hence, in order to ensure an appropriate usability systematic evaluation is comprised of five steps. Firstly, in assessment, mobile devices should be evaluated separately Step 1, all potentially relevant apps are identified from the from PCs. App Store (see Section 2.1). Consequently for the usability In order to cater for the usability evaluation in existing assessment, throughout Step 2, demos and old versions mobile apps in the online markets, Martin et al. [28] proposed fromthewholepotentiallistofappswerediscarded(see a mechanism for systematic evaluations of mobile apps, Section 2.2). A further aspect to be considered, in Step 3, which has been successfully applied in different fields, such concerns the identification of the main functionalities that as diabetes [29, 30] or spreadsheet [31] mobile apps. This characterize an IM app and, next, the exclusion of apps evaluation consists of five steps: not offering these functionalities (see Section 2.3). With the (1) Identify all potentially relevant applications. aim of identifying secondary functionalities, in Step 4, all characterizedIMappsareinspected(seeSection2.4).Finally, (2) Remove light or old versions of each application. alongwithStep5,themainfunctionalitiesaretestedwith (3) Identify the primary operating functions and exclude two methodologies: the Keystroke-Level Modeling (KLM) all applications that do not offer this functionality. to estimate time to complete tasks and the Mobile Usability According to the agreed definition of usability, this Heuristics (MUH) to detect more usability problems with step acts as a measure of effectiveness. mobile experts (see Sections 2.5 and 2.6). (4) Identify all secondary functionality. (5) Construct tasks to test the main functionality using 2.1. Step 1: Identify All Potentially Relevant Applications. To each of the methods below: begin with the systematic evaluation, in this first step poten- tial and relevant applications available in the iOS App Store (a) Keystroke-Level Modeling (KLM) is used to [35] are identified. Indeed, these apps will be used as input estimate the time taken to complete each task in further steps of the evaluation. In order to handle the to provide a measure of effectiveness of the broad diversity of available apps, and given the lack of an applications [32, 33]. IM category in the store, it was necessary to delimit the (b) Mobile Usability Heuristics (MUH) is used to sample data applying a proper search term. To do so, it identify more usability problems and measure was required to analyze the specifications provided by both user satisfaction. the most popular and commercial messaging applications, for example, “WhasApp Messenger,” “Telegram Messenger,” As we discuss later in detail, this evaluation, considered as and “LINE”. Thus, the “instant messaging” term was used a laboratory experiment [34], has some advantages [28, 29], to search in the app market. All the preliminary data was such as platform independence and flexibility [30]; that is, it crawledfromthestoreinthefallof2014.Asaresult,243 can be applied on different platforms (e.g., Android, iOS, and applications were classified as potential applications. Windows Phone). A further aspect to be taken into consideration concerns Previous work applying this evaluation, including dia- the rating of the apps by the users. To this end, each app betes management apps [29, 30] and spreadsheet apps [31], in the iOS market can be rated from a range of 1 to 5 showed that the combination of KLM and MUH allows (with midpoints), where a higher number means a better detecting a larger number of usability problems than when rating.