## 1 Introduction  
An aging population and changes in population structure directly impact social systems, such as the labor market, retirement planning, and the medical care system, and can lead to an economic crisis, such as a recession or government bankruptcy [1]. Therefore, population factors have become closely watched important issues in developed countries [2]. Taiwan's population of older adults exceeded 7% in 1993, making it an aging society [3], exceeded 14% in 2018, categorizing it as an aged society [4], and will exceed 20% in 2025, making Taiwan a super-aged society [5]. Long-term care (LTC) involves a variety of services designed to meet people's health or personal care needs during a short or long period of time. These services help people live as independently and safely as possible when they can no longer perform everyday activities on their own [6]. LTC is a very important issue for everyone in an aging society [5]. With the advancement of technology and medical treatments, the global average age has been extended to 75 years [7]. Taiwan is no exception. The continuous extension of life has resulted in changes in population structures [8]. The aging phenomenon is a problem that developed countries must face, along with related problems regarding the care of older adults [9]. In recent years, late marriage, bachelorism, and infertility have continued to intensify. Coupled with extended average life expectancy, low fertility, and population aging, they have also become concerning and unavoidable issues [10]. The implementation of LTC policies is based on the manager perspective rather than the user or customer point of view. In other words, LTC implementation ignores the voice of the customer (VOC). In the present study, the user point of view was used to explore service demands in LTC in Taiwan. Those who require LTC were divided into two groups: healthy older people, who are only interested in living happily, and older people with disabilities or dementia, who require medical interventions [11]. As the demands of these two groups are different, a service demand design would be ineffective, and could even affect national life, if it was viewed from an official perspective. Furthermore, the Taiwanese government has limited resources, and the needed resources would not necessarily be utilized at the same time. To address these issues and prioritize the efficient use of LTC resources, the importance-satisfaction (I-S) model and the revised performance evaluation matrix (PEM) can be used. Such a practice could fulfill LTC service demands by building a complete set of service design measurement methods. [PERSON] [12] developed the I-S model with reference to the importance performance analysis (IPA) method. The I-S model is the best tool for quality improvement [12; 13]. [PERSON] and [PERSON] [14] proposed the performance evaluation matrix (PEM) to determine the importance of logistical service quality factors and the performance of companies based on these factors. PEM-related applications have been used in the machinery industry and in education; few applications have been used in long-term care. The PEM can help industries find service items that need improvement. The present study found no analyses on combining the I-S model and the PEM method for LTC service demands in the relevant literature. Due to insufficient studies and that the fact that currently LTC service demand policies are considered to be very important and urgent, the I-S model and PEM are introduced in the present study. It is hoped that this will provide more accurate quality service design and improve the essentials of LTC services to better meet the needs and expectations of the older adult population in Taiwan. We conducted in-depth interviews in more than two sessions of discussions with experts and scholars through a focused discussion method to understand the LTC demands of the public and further confirm the service demands of caregivers, and we distributed 350 questionnaires.