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PUBLICATION TREND ON TRAVEL PREFERENCES OF SENIOR TOURISTS FROM 2000 TO 2020

This work is licensed under CC BY 4.0 The ageing population is the crucial phenomenon that has led to the new market segment in tourism known as 'senior tourists.' A senior tourist is determined as an older traveller or grey tourist. The number of elderly keeps growing throughout time; hence, grey tourists will be relevant preferences, differing from the younger tourists. This paper aims to evaluate the relevant studies regarding travel preferences that involve senior tourists. The objective is to understand the publication trend behind the development of travel preferences for senior tourists. The findings suggest that the overall travel preferences among senior tourists studied include 12 aspects of travel preferences. Researchers tend to focus on the aspect of accommodation among senior tourists compared to the other elements. At the end of the review, this paper is set out to outline the literature review analysis to provide greater insight into the development of travel preferences among grey tourists in tourism research from 2000 to 2020. This paper's output offers future directions to explore the offer trends and future direction in tourism and behaviour literature.


Introduction
In this day and age, the older generation is getting healthier and more well off than the more aged people in the previous generation (World Tourism Organization, 2013). This phenomenon has opened the door for a senior segment in the market of tourism. Senior tourist or using the terms' grey' according to Callan and Bowman (2000) is referring to the specific segment that is focusing on the older travellers.
Several studies have mentioned that senior tourists are a critical market in tourism as they have more net income and more free time than younger people (Bai, Jang, Losada et al. 2018;Alen et al. (2016). Despite the importance of the senior tourist segment in the tourism industry, there is a lacked empirical evidence in tourism studies on defining the value of the senior travel niche (Otoo, 2017). Senior tourists are also seen as a homogenous segment by some researchers; hence, they are assumed to have similar preferences and desires during traveling; therefore, they have fewer options and choices in tourism (Alen et al., 2017). This matter is also agreed by (Otoo & Kim, 2018), which there is a deficiency in the studies in what senior tourists want and need in tourism choices.
Therefore, It is essential to understand senior tourists' concept as the demand for this segment is growing in the market, and it requires a more in-depth study in terms of the travel preferences of senior tourists. Thus, this paper is set out to outline the analysis of publication trend to provide greater insight with a different scope of travel preferences of senior tourist research from the year 2000 -2020 with the following objectives: 1. To investigate the relevant publication on senior tourist's travel preferences from the year 2000 -2020. 2. To understand the publication trend of scope on travel preferences of senior tourists. 3. To identify the gaps and fields to be highlighted for future research.

Literature Review
The literature review will comprise the definition of senior tourists from previous researchers. It also explained the importance of the senior market in these current days and summarises travel preferences among seniors.

Senior Tourists
Senior tourist is one of the tourist segments mainly for the elderly generation aged above 55 years old (Lazer, 1986) and has also entered their retirement age. This tourist segment is also pronounced as a 'grey tourist,' 'silver tourist,' 'mature tourist,' and 'elderly tourist by researchers. There has been difficulty distinguishing a line in defining the same age group as a senior tourist as different researchers' opinions (Lazer, 1986;Gunter, 1998;Patterson, 2006). Therefore, Bartos (1980) stated that senior tourists' age group is over 49 years old, but gerontologists have decided that the older people are above 60. choices favoured by the elderly generation (Sund & Boksberger, 2007). There has been a study on the trends of expenditure for the senior generation during travelling, impacting the economic and tourism sector (Jung & Ham, 2009).
Other than that, the research on length of stay during vacation comforting to the elderly is also conducted (Miller, 1996). Littrell (2004) has explored the activities preferred by senior tourists during travelling and destination attraction studies. The older generation is also one of the variables for senior tourist's travel preferences (Chen & Shoemaker, 2014). In these modern days, most of the information is gained through technology, including tourism information, and therefore, the senior tourist's information sources are identified (Patterson, 2007). Therefore, more studies should explore senior tourist's travel preferences that will drive advantages to future tourism development.

The Importance of Senior Market
Highlighting senior tourism development is a must in the future as the market of grey tourism is growing as the World Tourism Organization (2013) statistically stated that older people keep on increasing over a year. It has been outlined that by the year 2030, one-quarter of the population are people age above 65 years old, and population ageing is likely to continue influencing the development of countries over the following decades. By 2050, this proportion is predicted to grow to one-third (United Nation, 2019).
This phenomenon occurred because the elderly generation during these eras has better access to healthcare. The senior market in tourism has expanded due to the physical condition of the elderly generation increasing. The healthier lifestyle portrayed by the current senior generation has led to the increases in senior travel. (Kendig & Browning 2016). As the number of older people increases, this particular group's demand has also grown in the hospitality, service, and tourism industries (Prayag 2012).
There is considerable scientific interest in the elderly generation in other areas, such as healthcare, gerontology, social sciences, welfare, and economics. There is a lack of evidence in tourism studies to define the senior travel niche's value (Otoo, 2018). Therefore, researchers are recommended to study the pattern of demand, motivation, and preference by older tourists as it will be changing the face of tourism in the future.

Methodology
The literature review will comprise the definition of senior tourists from previous researchers. It also explained the importance of the senior market in these current days and summarises travel preferences among seniors.

Article of Filtering Process
The process of filtering the relevant articles are started by extracting articles related to the subject matter from several platforms with a wide range of articles, such as Google Scholars, Science Direct, and Scopus databases. Table 1 shows the amalgamation of selected keywords used to determine the articles. Some keywords are applied to find, clarify, and categorise the relevant articles on senior tourists' preferences in tourism and leisure. The next stage of selection focuses on the paper's criteria where review papers, dissertations, conferences, papers, and more are filtered, and only an empirical referred paper is selected in this study. On the next step of paper selection, this study only concentrated on the subject of travel preferences or in some studies, travel characteristics are used by researchers (Alén, Losada & Domínguez, 2016). It will also consider the paper that studied the scope of travel preferences such as accommodation choices, expenditure, activities, planning of a trip, and partner during travel, transportation choices, length of stay, source of information used by the seniors, type of tour, time to travel, food and tourism attraction preferred by senior tourists.
Content analysis and statistical analysis are used to analyse the articles to get the publication that only focuses on senior tourist's travel preferences in tourism and leisure. The model showed in Figure 1 are summarised as a guide in selecting the relevant articles for this paper.

Publication Source Platform
A total of 35 publications related to senior tourist's travel preferences are extracted from numbers of tourism, leisure, and hospitality journals. The results in figure 3 showcase that 16 articles (45.7%) are published in a top 30 rank journals in quartile 1 (Q1) for the tourism subject area. Figure 3 shows the distribution of article publications according to the different source platforms. There are also 19 articles related to travel preferences of senior tourists in the other platform such as Advances in Hospitality and Leisure, Information Technology and Tourism,

Review and Discussion
The result is discussed by seeing the overall trend on travel preferences among senior tourists for the past 20 years. Besides that, the method, analysis technique and study settings are also explored. Lastly, the outcomes on the scopes of travel preferences studied by researchers are being reviewed to get the pattern on the studies.

Overall Publication Trend on Senior Travel Preferences
The studies on senior tourists have been done since 1998 (Pestana, Sánchez & Moutinho, 2019) and are still being explored by researchers or tourism experts. Figure 2 showed the trend in published articles of travel preferences among senior tourists from 2000 until 2020. The result shows that only a few research focuses on travel preferences, specifically for senior tourists.
The pattern of articles published are seen peek during 2001 with four (4) publication and the number of research decreases and are seen unsteady until the year 2014 where the research on this matter escalate. There is lack of studies in what senior tourist wants and needs in tourism choices (Otoo & Kim, 2018) hence; it shows that the studies of senior travel preferences are require. Others Tourism Review (28) Journal of Vacation Marketing (23) Journal of Hospitality and Tourism Management (21) International Journal of Tourism Research (19) Journal of Travel & Tourism Marketing (10) Journal of Hospitality Marketing and Management (9) International Journal of Contemporary Hospitality… International Journal of Hospitality Management (4) Annals of Tourism Research (3) Tourism Management (1) No. of Publication

Studies of Senior Travel Preferences
The details of studies in senior travel preferences in terms of authors, year of publication, analysis technique, method, settings of the studies, subject of the studies, and the target respondent are summarised in Table 2. The result explained that the method used to study seniors' travel preferences is often the quantitative method (25) by collecting the information through the distribution questionnaire form in a particular location to the senior tourist or citizen.
The qualitative method (8) is also used in the studies by interviewing the senior respondents to gain information on their travel preferences. One study used a focus group discussion method to get a more accurate answer from the senior respondents (Ramos, Martínez & Campill, 2019). However, there are only two (2) studies that use both quantitative and qualitative methods. Therefore, it can be seen that the studies lack the usage of the qualitative method, which is crucial as there are a variety of preferences, opinions, and thought among each senior tourist. The typical analysis technique utilised in the studies of travel preferences among senior tourists is Linear Regression analysis which is seen as a standard way to analyse information. Other techniques such as ANOVA Test, Multinomial Logit Models, and Negative Binomial Model are also used in the studies.
The result also reveals that the studies of travel preferences among senior tourists are primarily conducted in the United States of Spain (6), America (5), Australia (4), Turkey (4), Thailand (3), and South Korea (2). The rest of the studies are done once in each country. The number of studies conducted reflected the number of seniors in the countries. According to UNWTO, by 2050, the population over 60 will account for more than 2 billion international journeys, up from 593 million in 1999. (Patterson, 2006) and countries such as the Spain, United States of America, and Australia have one of the highest senior citizens.  In the comprehensive studies of travel preferences among senior tourists, it has discovered twelve (12) scope of travel preferences, which is accommodation choices, expenditure, activities, planning of a trip, and partner during travel, transportation choices, length of stay, source of information used by the seniors, type of tour, time to travel, food and tourism attraction preferred by senior tourists. Alén, Losada & Domínguez (2016) stated that travel preferences alongside the tourist motivation could determine tourist behaviour. Hence, the study of senior tourist behaviour will include the scope of travel preferences. Table 3 shows the scope of studies in travel preferences among senior tourists included in the articles published.
Based on the result, most researchers gravitate toward incorporating one or two scopes of senior tourist's travel preferences in their studies. The majority of studies are emphasising the in-depth knowledge on one specific scope; for example, the study on the length of stay of senior Spanish tourists explore the choices made by respondents on the number of days preferred by the senior tourist to spend in a particular tourism destination (Salmasi, Celidoni & Procidano, 2012).
Meanwhile, a small number of studies comprehend more than five (5) travel preferences in their studies. For instance, a study on tourist behaviour will often include the scope of travel preferences, or characteristics and Batra (2009) stated that there are eight (8) travel preferences in studying senior tourist behaviour visiting Thailand. Ten (10) variables of travel characteristic that is considered relevant according to Alén et al. (2016) in a study of senior tourist's profile are also similar to the scope of travel preferences. In the study of senior millionnaire tourists, ten (10) scope of travel preferences are also included (Bulut & Nazli, 2020).
12 9 8 6 4 7 7 8 2 3 2 6 Note: 1-35 = The number of articles that are stated in Table 2 a = The number of scope on travel preferences included in one article b = The number of studies on scope of travel preferences Figure 4 shows the number of studies on each scope of travel preference for senior tourists. It can be concluded that the number of studies done by researchers for each scope is seen as unbalanced. For example, there is a significant gap in the number of studies done for accommodation choices (12 articles) with the type of tour (2 articles) and food selection (2 articles). The lack of study in a particular scope can be considered an opportunity for a future research area.

Scopes on Senior Travel Preferences
The accommodation choices among senior tourists are seen as the most studied scope by the researcher. 12 articles have included accommodation as one of the elements in their research.
Most of the researchers choose to focus on the study of accommodation choice by senior tourists. There is a study specifically on the hotel and the services that senior tourists prefer (Mungall & Labben, 2009;Callan & Bowman, 2000).
The travel expenditure included in 9 articles is also one of the critical scopes that researchers choose. The elderly generation happens to be the group with higher purchasing power than the younger people, which has made the group seem relevant and essential to the industries, including the tourism sector (Nikitina & Vorontsova, 2015). Hence, more researchers incline towards this scope of travel preferences.

Figure 4: The Number of Studies on Scope of Travel Preferences Limitation
The limitation in this study is that the articles are extracted from Google Scholar, Scopus, and Science Direct only. The other database platform may contain a study related to travel preferences of senior tourists as well. Besides, this study only focuses on English-written articles. Therefore, a journal written in the country's original language is excluded; for instance, this study did not emphasise the study of senior tourists in Japanese. Moreover, the subject is still unclear on the concept as there are limited resources to the studies.

Conclusion and Recommendation
The publication on the travel preferences of senior tourists is a topic that is still growing and capturing in the interest of tourism experts. Hence, this paper discussed the publication trend on the scope of senior travel preferences.
This study demonstrated that the subject had not been explored thoroughly since the citation burst only started in 2014. Hence, there are more opportunities to be explored. Besides, it is revealed that most of the studies done by researchers for travel preferences are using a quantitative method which is distributing the questionnaire to senior tourists for information.
There is a lack of study that focuses on the overall scope for travel preferences. It can be seen that researchers tend to study on each scope and the unbalances happen where only particular preferences are covered more than the other such as accommodation choice and expenditure.
The future recommendation for this study is to utilize a qualitative method and use in-depth interviews to gain information from the senior tourist. Several researchers also agreed that this method should be the medium for studying senior tourists (Pestana, Wang & Parreira, 2020;Otoo & Kim, 2018). The information gained could be more diverse and accurate instead of using the standard survey method. Lastly, researchers should lean towards a study that includes the overall scopes of travel preferences in one research as each of the scopes is vital to determine the demand and supply for what's senior tourists need.