Content, perceptions and impact of alcoholic drink promotions in nightlife venues that are targeted towards students.

BACKGROUND: Binge drinking is generally considered socially acceptable for students across Western culture. Social norms within the student population have meant that excessive drinking plays a key role in socialising and reinforcing peer group identity. Research has highlighted the United Kingdom (UK) as having elevated levels of alcohol consumption especially within the student population, and the role that drink promotions have in influencing consumption practices. This paper considers promotions of alcoholic drinks in UK nightlife venues and student perceptions of these promotions. Bourdieu's concepts of social and cultural capital are applied to the findings.
METHOD: Content analysis of social media posts by nightlife venues (n = 12), observations of nightlife venues (n = 20) and semi-structured focus groups and paired interviews with 32 undergraduate students, from one city in the North West of England.
RESULTS: Nightlife venues target promotions of alcoholic drinks at students through social media, advertisements throughout nightlife venues, and by promoters outside of venues. These promotions will often influence the course of a night out in terms of venues visited and the drinks consumed. Alcohol holds importance within mainstream student culture; it plays a key role in achieving cultural capital and is a means for students to obtain social capital through the creation of shared experiences, which are key for those who are new to university.
CONCLUSIONS: Nightlife venues will target alcoholic drink promotions at students and will use the notion of creating a shared experience as part of this targeted promotion. This contributes to the overall social and cultural capital that alcohol holds within the student population. This is an important consideration for alcohol policy - it demonstrates how prevention activities need to take into consideration the importance of shared experiences for the students; alternatives to excessive alcohol consumption need to offer a similar opportunity.

Introduction

Levels of alcohol consumption within the mainstream student population is a public health concern in many countries within the Western world, for example the UK (Gant & Terry, 2017; John & Alwyn, 2014; Quigg, Hughes, & Bellis, 2013), USA (Ali & Dwyer, 2010; Borsari, Murphy, & Barnett, 2007), Australia (Fry, 2011; Hepworth et al., 2016) and New Zealand (Hebden, Lyons, Goodwin, & McCreanor, 2015; Niland, Lyons, Goodwin, & Hutton, 2013). Social norms around drinking within the student population are an important international consideration as to why binge drinking has become commonplace; excessive drinking now has an important role in socialising and reinforcing peer group identity (Anderson, 2013; Gant & Terry, 2017; Griffin, Smith, Freeman, & Adams, 2018; Hebden et al., 2015). Peers often influence drinking practices prior to starting university and young people will often overestimate the amounts of alcohol that their peers are consuming (Ali & Dwyer, 2010) and this continues once young people start university. Holton (2016) has argued that student halls of residence are often advertised as having an important role in the student experience and offer new students the opportunity to make new friends, with fresher's week (i.e. the first few week[s] of a new university year, when events are held to welcome and orient new students) being seen as a key time within which to do this. Drinking within the student population is thought to be a way to make friends and reinforce social bonds (Atkinson, Ross, Begley, & Sumnall, 2015; Mackinnon et al., 2017).

Binge drinking is a behaviour, which is often considered to be common and socially acceptable for students in the UK (Measham & Brain, 2005; Dodd, Al-Nakeeb, Nevill, & Forshaw, 2010; Ham & Hope, 2003; Neighbors, Lee, Lewis, Fossos, & Larimer, 2007; Quigg et al., 2013) and is considered to contribute to the overall enjoyment of a night out (National Union of Students, 2016). Whilst there have been numerous public health campaigns that have aimed to reduce binge drinking in the general population, they often do not resonate with the student population who see alcohol consumption as a traditional aspect of student life and thus, because it is normalised, they usually do not identify themselves as problematic drinkers (Anderson, 2013).

Promotions of alcoholic drinks are prevalent across the UK. Research has highlighted how drink promotions can influence behaviour and lead to binge drinking and increased alcohol consumption in consumers, including young adults (Trawley, Bhullar, & Jones, 2017). Promotions of hedonistic products associated with identity formation, such as alcohol, encourage impulse purchasing (Pettigrew et al., 2015). These types of promotion will often appeal to students. Research has also shown that attending a venue where alcoholic drinks are on promotion influences students' expectation about the amount of alcohol that they will drink (Christie et al., 2001). Further, it will also encourage patrons to remain in an establishment and purchase drinks that are on promotion (McClatchley, Shorter, & Chalmers, 2014).

Social media has an important role in shaping young people's expectations about drinking practices (Barnes et al., 2016; de Bruijn et al., 2016; Hebden et al., 2015; McCreanor et al., 2013; Moreno, Parks, Zimmerman, Brito, & Christakis, 2009; Moreno, Briner, Williams, Walker, & Christakis, 2009; Niland, McCreanor, Lyons, & Griffin, 2017). Studies have shown that those who are under the legal age for purchasing alcohol will often engage with alcohol advertising on social media, which can influence their future drinking practices (Anderson, de Bruijn, Angus, Gordon, & Hastings, 2009; Jernigan & Rushman, 2014; McCreanor et al., 2013). Research has explored the way alcohol brands use social media to promote their products (Atkinson et al., 2015; Atkinson, Ross-Houle, Begley, & Sumnall, 2016; Brooks, 2010; Carah, Brodmerkel, & Hernandez, 2014; Carah, Meurk, Males, & Brown, 2017; Mosher, 2012; Nicholls, 2012). Often this is achieved through association with certain identities and drinking practices that will appeal to particular groups in society. Further, research has shown that alcohol brands that wish to engage with young people, such as students, will often elude to lifestyle and cultural identities that would resonate with young people (Atkinson et al., 2016). Fuller, Fleming, Szatkowski, and Bains (2017) also highlighted the occurrence of alcohol-related incentives that where offered to students attending a fresher's fair that encouraged interaction with venue social media.

This paper presents findings from a mixed method study that has included nightlife venue observations, content analysis of nightlife venue social media posts and interviews and focus groups with students. The aim of the research was to explore student drinking behaviours as well as the perceptions that students hold about drink promotions in nightlife venues. The findings from this study will also be used by the local council and two universities to inform an upcoming intervention that aims to address excessive alcohol consumption by students.

Theory

Young people, including students, will often associate social and cultural capital with drinking practices (Atkinson et al., 2015; Järvinen & Gundelach, 2007; MacArthur, Jacob, Pound, Hickman, & Campbell, 2017). The concepts of social and cultural capital are based on Bourdieu's (1984) wider framework of ‘capital’. Social capital refers to the importance of social networks, in this case the social networks that students create with peers at university. Cultural capital refers to the meaning attached to cultural artefacts (such as alcohol) and behaviours (such as drinking practices). The initial few weeks at university are seen as key in establishing what is considered to be ‘legitimate’ social capital that is appropriate for mainstream student culture (Holton, 2016) and social media in particular plays a key role in establishing what the appropriate social capital is. Previous research (Atkinson et al., 2015; Brooks, 2010; Mosher, 2012; Nicholls, 2012; Niland et al., 2017) has considered how social media has been used in a commercial sense to elude to lifestyle and cultural associations with particular products. These studies have demonstrated how different elements of the alcohol industry have successfully done this and have capitalised on the role that social media now has in people's (and especially young people's) everyday lived experiences.

Bourdieu's theory of capital is useful in the context of understanding how alcohol and drinking practices come to have both social and cultural meaning for peer groups such as students. Bourdieu (2000) refers to this as ‘implicit collusion’ and argues that it has relevance “among all the agents who are products of similar conditions and conditionings…each agent finding in the conduct of all his peers the ratification and legitimation (“the done thing”) of his own conduct, which, in return, ratifies and, if need be, rectifies the conduct of others” (2000: 145). Furthermore, Bourdieu's theory of capital can help to conceptualise the interaction between agency (an individual's own choice of actions, in this case alcohol consumption and drinking practices) and structure (i.e. the social construction of drinking practices and how they are promoted through nightlife venues use of social media) to help understand drinking behaviours.

Method

The research took place in one city located in the North West of England. The city has a large student population of approximately 70,000 and across the three universities there are 27,990 students under the age of 20 (Higher Education Statistics Agency, 2017). The city has an extensive and popular nightlife (approximately 250 on licenced premises), which is often used in promotional materials by the local universities. This paper reports on data that was collected through covert observations in twenty nightlife venues and content analysis of the Facebook and Twitter pages of twelve nightlife venues. The venues for both the observations and content analysis were identified through consultation with students and student union staff on the basis that the city's student population generally considers them popular. Furthermore, data from focus groups and paired interviews with undergraduate students is also included. The study was approved by the Liverpool John Moores Research Ethics Committee.

Content analysis

An adapted directed content analysis (Hsieh & Shannon, 2005) that focused on qualitatively coding data was applied to posts collected from social media sites from twelve venues that are popular with students. Content analysis has been used in previous research to explore how alcohol brands appeal to young people (Atkinson et al., 2016; Nicholls, 2012) and the content of material handed out to students at the start of the academic year (Fuller et al., 2017). The purpose of the content analysis for this project was to explore the way that venues use social media to promote alcoholic drinks and events to students in Liverpool.

Prior to data extraction, a count was taken of the number of ‘likes’ and ‘followers’ that each page had on Facebook and Twitter in order to gauge the reach that their posts would have. The data extraction involved taking screen shots of each post from September to November 2017 in order to capture posts that were targeting students during fresher's week and the first term of university. The posts were uploaded to QSR NVivo11 and thematically coded.

Covert venue observations

Unobtrusive observations of nightlife venues have been used previously to explore nightlife harms (Quigg et al., 2014). This project adapted the data collection tool used in these previous studies, which were designed to collect data on the basic characteristics of the venue, staff and customers, as well as any drinks and events promotions. The aim of the venue observations was to determine whether the venue advertised drinks and events that appeared to encourage excessive alcohol consumption.

Researchers attended the venues in pairs on a Wednesday and Friday night in February 2018 between the hours of 7 pm to 1 am. The researchers would first make initial observations such as the type and characteristics of the venue and the clientele (e.g. age, gender and intoxication level). The researchers walked around the venue and gave estimates based on the venue as a whole. Any drink (alcoholic and non-alcoholic) and event promotions were noted and photographed when possible, and the cost of selected alcoholic and non-alcoholic drinks was noted. If menus were available the researchers also took note of any drink promotions included. Following this, the researchers then went up to the bar and observed the layout of the bar in terms of the placement of alcoholic and non-alcoholic drinks (taking photographs when possible).

Focus groups and paired interviews

The focus groups (n = 4) and paired interviews (n = 9) were carried with n = 32 first and second year undergraduate students from two of the city's universities. The participants were aged between 18 and 38 years, with the majority (n = 26) between 18 and 21 years. The majority of the participants were White British. A convenience sample was used and students were recruited from local universities and student accommodation. The focus groups and paired interviews were semi-structured in nature in order to encourage participants to expand upon their answers and provide context to their responses. The focus groups and paired interviews were carried out with existing peer groups. Research has shown that this approach will often provide rich data through the discourse between participants (Kamberelis & Dimitriadis, 2013).

Thematic analysis was carried out using QSR NVivo11. Inductive and deductive codes were applied to the data using an iterative coding technique (Neale, 2016). Common themes throughout the interviews and focus groups were identified and collated. Illustrative quotations have been used throughout the results and discussion to highlight and evidence relevant themes.

Study limitations

The nightlife venues for the content analysis and venue observations were purposely selected in order to ensure appropriate venues were included in the sample. However, the city centre that was used as the site for this research has a large nightlife environment and therefore the small sample of venues included in the content analysis and venue observations is not representative of the city centre as a whole. Furthermore, as this research took place in a large city centre, the findings are not representative of students who attend universities in smaller towns and cities that do not have an extensive nightlife or a reputation associated with nightlife experiences.

The content analysis focused on publicly available data on venue Facebook and Twitter profiles across a three month period which included fresher's week. The inclusion of fresher's week was thought to be important in order to give an overview of the type of promotions that new students are exposed to, however this could mean that the reflection on the findings is not representative of the venues year round social media activity. Further, by only using publicly available posts it is not possible to gain an understanding of what venue marketing students are exposed to through private groups and targeted advertising on an individual level.

An opportunistic sampling method was adapted for the focus groups/interviews, which means that those recruited may not necessarily be representative of the UK student population. Additionally, the students that were recruited for the focus groups were not representative of the diverse local student population in terms of ethnicity. Whilst the research team did try to recruit students from a wide range of backgrounds, and all recruitment materials specified that non-drinkers were encouraged to take part, the majority of the students that were recruited were White British. For example, other studies have demonstrated how other groups of students, such as international students (Thurnell-Read, Brown, & Long, 2018) have very different experiences of alcohol consumption and this study is not representative of those that do not fit the mainstream stereotype of students in the UK. Furthermore, the focus groups and paired interviews were carried out with existing peer groups. Whilst this method may provide rich data (Kamberelis & Dimitriadis, 2013) there is the possibility of peer influence on participant responses.

Results & discussion

Targeted promotions

Students who took part in the qualitative data collection reiterated that promotions of alcoholic drinks were common in nightlife venues that were popular with students. They discussed how they would often attend venues on specific nights as they had alcoholic drinks that were on promotion and that venues would label certain nights as ‘student nights’ which would often entail promotions on alcoholic drinks.

“I think they try and appeal to students not having much money so they try and make it as cheap as possible, so putting on more drinks deals to get people to have more shots”

“There's [name of venue] on a Wednesday, [name of venue] on a Friday, there's loads [of student nights]”

Data from the content analysis demonstrated how some nightlife venues purposely target students through posts on social media. Posts made reference to students and the stereotypical student lifestyle, and further posts also made reference to student related events such as ‘welcome week’ and the students' return to the city.

‘We're back! LOVE WEDNESDAYS returns tonight – what better way to celebrate returning to [name of city]??’

‘Woopsie…It's Tequila Time #[name of city] #Freshers £1 TEQUILA SHOTS from 9pm’

‘[Name of venue] and [name of venue]. The best Student Card deals in [name of city]’

Student participants discussed being approached by promoters outside nightlife venues. The research team also experienced this on five occasions across the two nights of covert observations. This is a further example of how excessive drinking is normalised and promoted in nightlife settings. Furthermore, as this occurred outside venues that are popular with students it is also evidence of how alcohol becomes associated with the social and cultural capital of students.

“I think with the promoters they definitely draw you in, as you walk in saying that you are going to one club and like you're heading there and someone comes over and says they have got an offer in there and hand you a voucher you'd probably go”

“People who hand out the little vouchers as well so you'll get this free drink if you go in and buy another drink”

Drink promotions were evident throughout out all of the venues that were visited during the observations. Fourteen out of 20 (70%) venues advertised cheap alcoholic drinks, 14 out of 20 (70%) venues advertised multi-buy offers on alcoholic drinks and 6 out of 20 (30%) venues offered a drink promotion alongside a meal. Half (50%) of the venues advertised alcoholic drinks around the venue. Furthermore, alcoholic drinks featured more prominently in displays behand the bar, with only one venue including a visual display that only featured non-alcoholic drinks. All of the nightlife venues that were observed stored soft drinks lower down (i.e. within the bar area) than alcoholic drinks. Alcoholic drinks were more likely to have been placed within the customer's eye line. In the majority of the venues that were open past midnight the non-alcoholic drinks that were available would traditionally be used as mixers. The prominence in terms of the visibility of alcoholic drinks could potentially reinforce the normalisation of alcohol consumption on nights out. Discussions with student participants further confirmed the influence that drink promotions had on their nights out and choice of venue.

“We went to [name of venue] once and they were giving out a free bottle of Prosecco and normally I don't drink Prosecco when I'm out, but because it was free I was like ‘let's go in here’”

However, it is important to note that not all of the participants felt that they were influenced by drink promotions. Some of the older participants discussed how they differed from mainstream student culture as they were not involved in certain social aspects of university, such as nights out drinking, as those that were younger and therefore were less likely to visit nightlife venues that were aimed at students. For these participants, student intoxication culture did not form part of their social or cultural capital, although they did recognise how it appeared to be important for those students that were younger and that were engaging with a more stereotypical student experience.

The data collected demonstrated how drink promotions can influence student's drinking practices in terms of the nightlife venues that they attend and the drinks that they consume. As discussed in previous research (Christie et al., 2001; McClatchley et al., 2014; Pettigrew et al., 2015; Trawley et al., 2017) this can effect expectations of how much alcohol will be consumed, influence drinking practices (such as types of drink consumed and nightlife venues visited) and potentially encourage impulse purchasing.

Shared experiences and alcohol consumption

The concept of drinking to socialise was particularly important to many of the student participants, and was seen as a key facilitator in making new friends during fresher's week, and thus formed a key part of their social capital. Again, this was more common amongst the younger participants and was less of a concern for those that were older and whose social and cultural capital did not include student intoxication culture.

“It's just so much easier [during fresher's week] because when everyone has had a drink they're more confident, so you're more likely to go up to someone and start a conversation”

A small number of the participants who did not drink or were infrequent drinkers when they started university discussed how they initially struggled during fresher's week because of this, as they found it difficult to join in and make new friends as the majority of the activities involved alcohol. The majority of these participants discussed how they did start drinking more alcohol as it made socialisation with their new peers easier. These participants, as well as some participants who were frequent drinkers, also discussed the need for there to be more structured activities aimed at students that do not focus on excessive alcohol consumption but also offer the opportunities to create shared experiences. In general, there was a lack of confidence amongst the students in going against their peer group norms when it came to abstaining from drinking alcohol on a night out. This was not necessarily due to peer pressure, but more of a need to feel part of a shared experience of which alcohol consumption played a key role. This was further reflected in the discussions during which the students reflected on their perceptions of other peers who did not drink alcohol and who appeared to struggle with fitting in to university life and thus lacked the appropriate cultural capital.

“I think mostly people drink because other people drink as well, so they just want to follow or else they don't feel they would fit into the group”

“I was actually talking to a girl on my course today and she said she is very alone and isolated because she doesn't drink”

The normalisation of student alcohol consumption was discussed by students who recognised the important role alcohol has in student culture and in the creation of shared peer group experiences (Mackinnon et al., 2017). This notion supports existing literature that has discussed and demonstrated the role that social drinking practices have in group identity formation and the creation of ‘social capital’ through drinking (Atkinson et al., 2015; Järvinen & Gundelach, 2007). Additionally, some of the participants also recognised and commented on how the city's nightlife may be a contributing factor on a potential student's decision to attend a particular university.

“A lot of people come to uni just for the nightlife”

Social media was considered by the students as being an important promotional tool used by nightlife venues. Students who were new to the city in particular discussed how they would often use social media to find out about local venues and events. Hence, social media played a key role in the development of students' social and cultural capital as it influenced the networks and venues that they were exposed to. Social media was also a means of finding out about the different drink promotions that venues might have which in turn could potentially influence where they went on their nights out.

“I search Facebook, I just type in [name of city] events and I think Facebook is programmed to filter all of them through”

Furthermore, some students discussed being included in unofficial social media groups prior to starting university. They explained how some students would share their expectations of how much they would go out and how much they would drink. Some of the students recognised that this could cause some people to feel uncomfortable if they were unwilling to engage in similar drinking practices.

“I remember in the [name of halls of residence] group chat before I even moved here, there was a chat that was created and it was some people who were obviously apprehensive about drinking were like ‘I don't think I'm going to drink’ and then the other people who were like the popular ones who were going to go to all the clubs kind of roasted them a little bit”

This highlights how those that were more engaged with the expected student intoxication culture were generally perceived as being more successful in obtaining the appropriate social and cultural capital that are associated with the stereotypical student experience. This also supports findings of previous research that has demonstrated how social media has an important role in shaping young people's expectations about drinking practices (Carah et al., 2014, Carah et al., 2017; de Bruijn et al., 2016; McCreanor et al., 2013; Moreno, Briner, et al., 2009; Moreno, Parks, et al., 2009; Niland et al., 2017). This is further exasperated by the promotional material that students receive (as discussed in the previous section), which confirms the role and cultural capital that alcohol is perceived to have in UK student culture.

The social media posts by nightlife venues also highlighted drinking practices in terms of social capital through promoting social aspects of drinking practices. This was often done through competitions where those who entered would be encouraged to tag friends in the post and the prize being an experience that could be shared with others.

‘DO YOU FANCY WINNING FREE COCKTAILS FOR YOU AND BAE? We're giving FIVE different winners the chance to win FREE COCKTAILS for you and a friend!’

‘Tag your friends and hit share for a chance to win a bottle of vodka and a free shootercake for Tuesday [student night]’

Through sharing posts related to nightlife venues and drinking practices, students reflect their own social and cultural capital. This reflects similar findings from studies that have considered how alcohol brands utilise user engagement on social media to further advertise their products (Anderson et al., 2009; Carah et al., 2017; Nicholls, 2012).

Furthermore, nightlife venues would also put emphasis on the experiences that those who attended events would have and would encourage students not to miss out.

‘Another huge night on the way tonight. Don't miss out. LOVE Wednesdays [student night] at [name of venue]’

‘It's sure to be another wonderful start to the weekend, so don't miss out’

Often these events would hold high cultural capital within the local mainstream student population as they were promoted as being key to the overall student experience. Student participants discussed the fear that they may miss out on shared experiences if they were to miss a night out.

“All our flat went [to a particular club night] because we thought we can't miss this it sounds really good”

This further reflects findings from previous research into how young people will often use social media to reflect upon their nights out and the experiences that they shared with their peers, thus reinforcing the social capital accrued through engagement with particular drinking practices (Atkinson et al., 2015, Atkinson et al., 2016; Barnes et al., 2016).

Conclusion

The findings from this study support those of previous research that have demonstrated the role that alcohol can have in young people's social and cultural capital, as well as the nature of drink promotions that are targeted towards students. This is the first study that has considered the content of alcohol promotions on social media and in nightlife venues alongside student's perceptions and experiences. Alcohol consumption plays a key role in socialisation and peer bonding, which is of particular importance to young people who are starting university. Further, this study demonstrates how nightlife venues will promote alcoholic drinks in line with normalised perceptions of students' social and cultural capital, for example through the promotion of alcohol and its association with shared experiences. The use of Bourdieu's theory of social and cultural capital provides researchers with a way to understand the nuances of alcohol and intoxication culture for different groups in society, such as students (Atkinson et al., 2015; Järvinen & Gundelach, 2007). In relation to this study, the application of Bourdieu's theory of capital demonstrates how excessive alcohol consumption is associated with mainstream student culture, and those students who do not engage with stereotypical drinking behaviours are often perceived to be on the periphery of the student experience.

The promotion of cheap alcoholic drinks that are aimed at students, along with the promotion of the cultural and social capital that are associated with student intoxication culture needs to be addressed through policy. Currently in the UK, the Advertising Standards Agency (ASA) regulates the way that alcohol is advertised. For example, in relation to broadcasting adverts, the ASA states that: “Advertisements must not imply that drinking alcohol is a key component of social success or acceptance or that refusal is a sign of weakness” (ASA, 2016a:4). Despite this, and the fact that research has demonstrated the impact that advertising can have on young people's drinking practices, regulations such as these can only be applied to ‘measured media’ (Babor et al., 2010). Regulating promotions by venues is more problematic and ambiguous, with the ASA stating that marketing communications should “take care not to condone or encourage excessive drinking” (ASA, 2016b). This research has demonstrated how nightlife venues will often use social media to promote concepts of social capital relating to socialisation and celebration and will link this to the overall cultural capital of student intoxication by aligning these concepts with drink promotions. In order to address excessive drinking within the UK and the wider international student population, policy needs to address the way venues promote drinks and how these promotions are often associated with desirable concepts relating to social and cultural capital.

The information disseminated from nightlife venues was key in shaping the students perceptions of the city's nightlife culture, and several of the students discussed receiving promotional material during Fresher's Fair as well as via social media. Additionally, students received some material before they started university. This research has demonstrated how the promotional material (whether official or unofficial) affects the perceptions that new students have in the transitional period between finishing school and starting university. Therefore, future research and policy considerations need to address the content of promotional material received by students during this time and how it affects their expectations of intoxication culture at university. In addition to this, the students promoted their own ‘intoxication culture’ through social media (for example private Whats App group discussions) prior to starting university during which they would discuss their expectations of the nightlife culture and their intended intoxication levels. This demonstrates how alcohol consumption within the student population has become normalised, as there is generally an expectation that students will reach high levels of intoxication, in particular during their first year at university and that this forms a key part of the social and cultural capital of new students. Whilst alcohol policy could further regulate the way that venues promote alcoholic drinks and universities can influence the events featured as part of their official Fresher's Fair schedule, the unofficial groups present a much more complex problem for policy makers and university staff. These are often closed groups and therefore difficult to monitor and regulate, thus the cultural capital which promotes student intoxication culture can be further promoted. Further research is needed that considers the content and impact of such groups.

Role of Funding Sources

Study implementation was funded by Liverpool City Council (LCC). Support for preparation of the manuscript was provided by Liverpool John Moores University. LCC provided initial comments on the design of the methodology for the study. Neither funder had a role in the study data collection, analysis or interpretation of the data, or the writing of the manuscript.

Contributors

Both KRH and ZQ designed the study and wrote the protocol. KRH managed the data collection and conducted the analysis. KRH wrote the first draft of the manuscripts and both authors have contributed to and have approved the final manuscript.

Conflict of interest

There are no interests to declare.