Premarital Education Needs Analysis of Adults Considering Marriage in Turkey

1. Introduction

Premarital relationship education programs are skill-based training processes designed to guide couples in improving their relationships after marriage (Murray & Murray Jr, 2004). These programs are considered beneficial because they provide couples in the dating, engagement, or pre-marital stages the opportunity to assess and reflect on various aspects of their relationships before getting married (Barnacle & Abbott, 2009). Stanley (2004) emphasized five benefits of premarital education programs: (i) they give couples time to make decisions about marriage; (ii) they demonstrate that marriage is a valuable relationship requiring cooperation and commitment; (iii) they open the door for couples to seek marital counseling in the future; (iv) they reduce the risk of divorce by enhancing conflict resolution and positive communication skills; and (v) they can rapidly improve relationship quality. The main goals of premarital relationship education programs are to inform couples about marital life, develop communication skills, and improve conflict resolution abilities. By fostering healthy communication skills and awareness, these programs aim to reduce the impact of stressors and risk factors in marriage at both the societal and couple levels (Deveci Şirin & Bayrakçı, 2020). According to researchers in the field of family therapy, participating in premarital education or counseling programs can decrease instability in marriage and contribute to more positive relationship outcomes (Stanley et al., 2006). Research emphasizes that couples entering into marriage are often insufficiently prepared for the lifelong demands of partnership, and premarital education seeks to bridge this gap by encouraging proactive strategies (Carroll & Doherty, 2003).

According to data from the Turkish Statistical Institute (TÜİK), 563,140 couples got married in Turkey in 2021, and 574,358 in 2022. The number of divorces was 175,779 in 2021 and 180,954 in 2022. Furthermore, TÜİK data show that marriage rates dropped from 8.35 per thousand in 2001 to 6.76 per thousand in 2022, while divorce rates increased from 1.41 per thousand to 2.13 per thousand during the same period (TÜİK, 2023). According to TÜİK reports, 32.7% of divorces in 2022 occurred within the first five years of marriage. Since the risk of divorce is higher in the early years of marriage, it is important to intervene early with couples (Murray & Murray Jr, 2004).

Premarital relationship education programs are generally categorized into three main groups: (i) theory-based programs (Gottman’s Sound Relationship House, IMAGO Couples Therapy, Emotion Focused Therapy); (ii) skill-based programs (Minesota Couples Communication Program, PETS – Premarital Education and Training Sequence, CCP – Couple Communication Program, PAIRS – Practical Application of Intimate Relationship Skills, CCET – Couples Coping Enhancement Training, RE – Relationship Enhancement, SYMBIS – Saving Your Marriage Before It Starts, PREP – Prevention and Relationships Enhancement Program); and (iii) inventory based programs (PREPARE/ENRICH, FOCCUS – Facilitating Open Couple Communication Understanding and Study, RELATE – Relationship Evaluation) (Ökten, 2022). Theory-based programs focus on the frameworks outlined by theories. Skill-based programs aim to develop couples' communication skills and raise awareness. In inventory-based programs, couples fill out the inventory for the relevant program. Based on the results of the inventory, the needs of the couples are determined, and feedback is provided to the couples on the areas where they are strong and where they can improve (Ökten, 2022). When the programs are examined in general, it is seen that the number of sessions varies between 6 and 11. In terms of theoretical foundations, modern approaches such as the Cognitive Behavioral Approach, Systemic Approach, Humanistic Approach, and Psychoanalytic Approach are mostly preferred. The target audience of the programs is couples who are not yet married and/or are preparing for marriage. Although traditional theoretical approaches have formed a very important basis for family and marital relationships, modern theories often overlook postmodern themes such as relativity, diversity, and identity questioning when addressing the changing structure of today's society, including digitalization, individualization, migration, and the relaxation of social gender roles (Noble, 1998). Postmodern theories emphasize that family structures have moved away from the uniform nuclear model and have become diverse structures such as extended families and single-parent families (Noble, 1995). They also argue that language and discourse play a role in the knowledge-building processes that shape family life, and that reality exists not as a single narrative but as multiple narratives (Gergen, 2001). As a result, traditional models may be inadequate in understanding the fluid emotions, roles, and identities of individuals in relationships. Especially in the post-industrial and digital age, individual needs such as conflict resolution, satisfaction, and stress management have become more complex, intertwined with gender, culture, and individualization. In such a context, educational programs must take this individual-thematic diversity into account (Rezeanu, 2016; Doherty, 1999). Therefore, premarital relationship education programs need innovative approaches based on postmodern approaches.

There are needs analysis studies in the literature for individuals who plan to participate in premarital relationship education programs. The aim of these studies is to reveal what individuals who want to participate in a premarital relationship education program expect from such a program, what kind of education they need, and how much time and budget they can allocate to the program. According to recent needs studies conducted in Western societies, individuals who will participate in these programs prefer that the program be led by a trained therapist and last between 4-6 sessions. In addition to this, the vast majority of individuals who participated in these studies stated that they want to participate in the relevant programs during their engagement period. They also indicate that they want to participate as couples and in small groups. The most prominent themes they want to be addressed in relationship development programs are communication, conflict resolution, communication training, awareness of their partner's concerns, resolving differences, and stress management. Other prominent topics include finance, parenting, family roles, and responsibilities (Tambling & Glebova, 2013; Borowski & Tambling, 2015; Sullivan & Anderson, 2002; Valiente et al., 2002). According to a study conducted by Sullivan and Anderson in 2002 to discover the program characteristics that influence engaged couples' decisions to participate in premarital education programs, engaged couples prefer leaders who are trustworthy, professional, and experienced. They place importance on the program content including educational content that transfers knowledge and develops skills, as well as content that provides insight into personality traits and family history. Couples considered elements such as role-playing/skill experiences, group discussions, and the gender or single/couple status of the instructor to be insignificant. Women found insight-enhancing content more meaningful, while men found pragmatic and skill-based content more meaningful. The research also revealed that couples in the high-risk group are not significantly different from those in the low-risk group in terms of their needs.

There are a limited number of studies on premarital needs in the Turkish literature. Hamamcı and their colleagues conducted a study on the premarital education needs of university students who were in relationships and those who were not. Their study revealed that university students wanted to receive education on developing commitment between couples, improving communication skills, learning to be parents, and reducing the risk of divorce. In addition, 31.1% of students stated that they wanted to receive such education when they were not in a relationship, while 29.5% stated that they wanted to receive it during the engagement period. In terms of the number of sessions, 24% of students preferred 4-5 sessions, while 22.8% preferred 2-3 sessions. Furthermore, a large majority of participants indicated that they would prefer to participate in such training with their partner (Hamamcı et al., 2011). Haskan Avcı (2014) conducted a study on the problems experienced by university students in relationships and considering marriage in their premarital relationships and their educational needs. The study revealed that students experienced the most problems in the areas of communication, conflict resolution, acceptance of differences, romance-sexuality, and social support, and that they wanted to receive education in these areas. The aim of the present study was to determine the educational needs of adults in relationships who are considering marriage regarding premarital relationships. In this respect, this study differs from other studies in the Turkish literature.

Studies have shown that premarital interventions reduce the risk of divorce, increase long-term relationship satisfaction, improve couples' communication and problem-solving skills, raise couples' awareness of their relationship, and improve relationship quality. However, they also report low participation rates (30% of the population) and high drop-out (early withdrawal from the program) rates. Sullivan and Anderson (2002) emphasized that while the majority of participants found premarital counseling positive, the actual participation rates were low. Tambling and Glebova (2013) and Borowski and Tambling (2015) also emphasized in their studies that individuals find premarital counseling reasonable but that voluntary participation rates are low. Researchers have suggested developing short, focused programs consisting of less than six sessions, organizing training in an online and accessible format, using reliable, impartial, and youth-friendly language, and using communication aimed at increasing risk awareness. It is recognized that studies similar to those conducted in Western countries on needs analysis are necessary to maintain and increase participation and retention rates in these interventions, which are currently offered on a limited basis in Turkey. In Western countries, participants' preferences regarding the format and focus of premarital relationship education programs are known. Therefore, studies are needed to learn about these preferences for the Turkish sample as well.

Accordingly, the aim of this study is to analyze the premarital education needs of individuals planning to marry their partners and to contribute to the gap in the literature. It is believed that the results obtained from this study may contribute to the content of education programs to be developed for individuals preparing for marriage. To this end, the following questions were addressed in the study: (i) What is the level of willingness of individuals considering marriage with their romantic partners to receive premarital education in the near future? (ii) What are the views of individuals considering marriage with their romantic partners regarding the format of premarital education? (iii) Is there a gender difference in the views of individuals considering marriage with their romantic partners regarding the format of premarital education? (iv) What focuses of education do individuals considering marriage with their romantic partners need prior to marriage? (v) Is there a gender difference in the focuses of education that individuals considering marriage with their romantic partners want to receive prior to marriage?

2. Method

In this study, the premarital relationship education needs of individuals considering marriage with their partners were identified using a descriptive survey model. According to Karasar (2012), the descriptive survey model is a research approach that aims to describe a situation as it was in the past or as it currently exists.

2.1 Participants

Data for the study was collected between February and April 2024 via an online Google Forms survey. Inclusion criteria for the study were: individuals residing in Turkey, aged 18 or older, who had been with their partner for at least 6 months, had never been married before, and were currently considering marriage with their partner in the near future. Only data from volunteers who completed the entire survey were included in the study. A total of 58 participants completed the survey in full, and no participants left the survey incomplete. The final sample size was determined to be N=58. Convenience sampling was used as the sampling method. This sampling method involves sampling individuals who are easily accessible, located in the immediate vicinity, and are volunteers (Erkuş, 2019). Participants were asked to complete an informed consent form before the survey.

The sample size of the study is relatively small (N = 58). There are several reasons for this: (1) the sensitivity of the topic and reluctance to participate (pre-marital personal attitudes/self-reporting), (2) the low participation rate also noted in the literature (Tambling & Glebova, 2013; Hawkins, 2017), and (3) the pilot/exploratory nature of the studies. Furthermore, studies in the field of premarital education and relationship education have often been conducted with small samples; for example, certain premarital program evaluations and case studies have reported samples in the range of N ≈ 50–60 (Yılmaz & Kalkan, 2010; Lucier-Greer & Adler-Baeder, 2012; Arnold et al., 2016; Rajabi et al., 2017; Hawkins et al., 2008). These limitations reduce the generalizability of the findings. However, as similar studies conducted with small samples have shown, such research plays an important role in providing preliminary information in the early stages of the field. Therefore, the findings are considered to contribute at a basic level to the literature, particularly in the Turkish context. Consequently, this study has an exploratory/pilot nature that will form the basis for broader quantitative studies, and the results should be interpreted within this framework.

Of the 58 individuals who participated in the study, 60.3% were women and 39.7% were men.  The participants' ages ranged from 19 to 37, with an average age of 25.75. The duration of their relationships ranged from 6 months to 96 months (8 years), with an average of 28.86 months (2.4 years). 5.2% of the participants had a high school education, 84.5% had a bachelor's degree, and 10.3% had a postgraduate degree. None of the participants had an education level lower than high school. 56.9% of participants are in the dating/flirting phase of their relationship, while 43.1% are engaged/betrothed. 17.2% of participants have a low income, 75.9% have a medium income, and 6.9% have a high income. The table below summarizes the demographic characteristics of the participants:

Table 1: Demographic Characteristics of Participants in the Needs Analysis Study

2.2 Data Collection Tools

Premarital Education Needs Analysis Questionnaire: Prepared by the researcher, this survey consists of open-ended and closed-ended questions about what individuals who have been in a romantic relationship for at least six months and are considering marriage with their partners expect from a premarital relationship education program, as well as their needs and desires. The survey also collects demographic information from participants, including age, gender, relationship duration, educational status, romantic relationship status, income level, and whether they have been married before. In addition to this demographic information, participants are asked about the format of the relationship education program, including which stage of the relationship they would like to participate in, how they would like to participate in the program (alone or with their partner), how many sessions they would prefer the education program to last, where they would like to take the program (online/in person), how they would like to take the program (in a large group/small group/individually), on which days they would like to take the program, and at what time of day they would like to take it. For the focus of the relationship education program, participants were asked which topics they would like to see included in the education program. Options for program focuses are: developing conflict and problem-solving skills, developing communication skills, learning to cope with stress and anxiety, increasing satisfaction and happiness in relationships, recognizing warning signs in relationships, learning to be a parent, establishing a balance between “I” and “we” in relationships, learning to forgive each other in relationships, the distribution of roles and decision-making within the family, recognizing the strengths and positive aspects of the relationship, developing anger management skills, recognizing unrealistic beliefs about marriage, sexual life and sexual problems, balancing relationships with the family of origin and friends, and learning to express gratitude and appreciation for each other. Finally, participants were asked whether they would prefer to participate in such an educational program in the future. The questions in this survey were prepared based on similar studies in the international and domestic literature (Tambling & Glebova, 2013; Borowski & Tambling, 2015; Sullivan & Anderson, 2002; Valiente et al., 2002; Hamamcı et al., 2011).

2.3 Analysis of the Data

Data was collected on the expectations, needs, and desires of adults in romantic relationships who intend to marry their partners regarding the format and focus of a premarital relationship education program if they were to participate in such a program, using the “Premarital Education Needs Analysis Questionnaire” created online by the researcher. Descriptive statistical techniques and the chi-square test statistical analysis method were used to analyze the data and analyze demographic variables.

3. Results

The willingness of individuals participating in the study to receive premarital education and their opinions regarding the format of the education program are presented in the table below:

Table 2: Opinions on the Format of Pre-Marital Relationship Education

Table 2 shows that 44.8% of participants would like to take such a course while engaged or betrothed, 37.9% while dating or flirting, and 17.2% while not in any relationship. 77.6% of participants prefer to attend such training with their partners, while 22.4% prefer to attend alone. In terms of the duration of the training, 41.4% of participants preferred 2-3 sessions, 34.5% preferred 4-5 sessions, 13.8% preferred a single session, and 10.3% preferred 6 or more sessions. 79.3% of participants stated that they would like to take the training in person, while 20.7% stated that they would like to take it online. 56.9% of participants stated that they would like to receive the training individually, 39.7% in small groups with other couples, and 3.4% in large groups with other couples. In terms of the days of the training, 74.1% of participants preferred weekends, while 25.9% preferred weekdays. 32.8% of participants preferred to take the training during the afternoon, 29.3% in the evening, 24.1% in the late afternoon, and 13.8% in the morning. 56.9% of participants indicated that they would like to participate in premarital training in the near future, while 43.1% indicated that they would not.

The needs of individuals participating in the study regarding the focus of premarital relationship education programs are presented in the table below:

Table 3: Pre-marital Relationship Education Focus Needs 

Table 3 shows that the vast majority of participants (93.1%) feel they need training in conflict and problem-solving skills. This is followed by communication skills development (74.1%), learning to cope with stress and anxiety (72.4%), increasing satisfaction and happiness in relationships (69%), and recognizing warning signs in relationships (67.2%).

The distribution of participants' willingness to receive education and their opinions on the format of the education program according to gender is presented in the table below:

Table 4: Opinions on the Format of Pre-Marital Relationship Education – Distribution by Gender 

When Table 4 is examined, the majority of men (47.8%) stated that they preferred to receive education while dating or flirting, while the majority of women (48.6%) stated that they wanted to receive education while engaged or betrothed. The majority of men (34.8%) preferred the training to consist of 4-5 sessions, while the majority of women (51.4%) preferred the training to consist of 2-3 sessions. Regarding training hours, the majority of men (34.8%) preferred afternoon hours, while female participants preferred afternoon and evening hours equally (31.4%). No gender differences were observed in terms of participation method, training environment, training method, and training days. Regarding willingness to participate in training, 52.2% of men indicated that they were willing to participate in such training in the near future, while 60% of women indicated that they were willing to participate.

The distribution of participants' needs regarding the focus of the education program by gender is presented in the table below:

Table 5: Pre-marital Relationship Education Focus Needs – Distribution by Gender

Table 5 shows that the topics men most want to receive education on are, in order, developing conflict and problem-solving skills (91.3%), increasing satisfaction and happiness in relationships (73.9%), improving communication skills (69.6%), learning to cope with stress and anxiety (69.6%), establishing a balance between “I” and “we” in relationships (69.6%), and developing anger management skills (69.6%). For women, the topics they most want to receive education on are, in order, developing conflict and problem-solving skills (94. 3), improving communication skills (77.1%), learning to cope with stress and anxiety (74.3%), recognizing warning signs in relationships early on (68.6%), learning to be a parent (68.6%), and increasing satisfaction and happiness in relationships (65.7%).

The chi-square table below shows whether there is a statistically significant difference between the premarital relationship education needs of the individuals participating in the study according to gender:

Table 6: Pre-marital Relationship Education – Chi-square Table of Differences by Gender

Chi-square analyses were conducted to examine participants’ preferences regarding premarital relationship education. Results indicated no significant differences in demographic-related preferences such as time of education (χ² = 1.649, p = .438), participation format (χ² = .010, p = .920), duration of education (χ² = 5.729, p = .126), training environment (χ² = .026, p = .873), training format (χ² = 2.006, p = .367), training days (χ² = .001, p = .975), training hours (χ² = .631, p = .889), and desire to participate in training (χ² = .347, p = .556). Similarly, no significant differences were found in preferences for skill development, including conflict and problem-solving (χ² = .192, p = .661), communication (χ² = .416, p = .519), coping with stress and anxiety (χ² = .155, p = .694), increasing relationship satisfaction (χ² = .436, p = .509), recognizing warning signs (χ² = .071, p = .790), learning to be a parent (χ² = 1.585, p = .208), balancing “I” and “we” in a relationship (χ² = .910, p = .340), learning to forgive each other (χ² = .684, p = .408), distribution of roles and decision-making within the family (χ² = 1.279, p = .258), recognizing strong aspects of the relationship (χ² = .002, p = .963), anger management (χ² = 2.494, p = .114), unrealistic beliefs about marriage (χ² = .351, p = .553), sexual life and sexual problems (χ² = 1.076, p = .300), balancing relationships with family of origin and friends (χ² = .004, p = .947), and expressing gratitude and appreciation for each other (χ² = .023, p = .879). Overall, participants’ preferences were consistent across variables, highlighting stable patterns in premarital education needs. This finding indicates that women and men participants have similar attitudes regarding the duration, content, implementation method, and willingness to participate in education programs.

4. Discussion

This study analyzed the premarital education needs of adults who are currently in a romantic relationship and considering marriage. Their willingness to participate in premarital education, their views on the structure of the education, and the topics they feel they need education on were examined.

The findings from the study revealed that individuals in relationships prefer to participate in premarital education programs not during the dating phase but at a more serious stage of the relationship, such as engagement or betrothal. Additionally, they preferred short programs consisting of 2-3 sessions and indicated that they wanted to participate in these programs with their partners. These results are consistent with those of other studies in the literature (Silliman et al., 1992; Duncan et al., 1996; Tambling & Glebova, 2013; Hamamcı, 2011). These findings suggest that short premarital education programs consisting of 2-3 sessions should be organized for engaged/betrothed couples in the future. In this study, unlike Duncan and colleagues' (1996) study, and similar to Hamamcı and colleagues' (2011), Sullivan and Anderson's (2002), Borowski and Tambling's (2015), and Tambling and Glebova's (2013) studies, participants requested individual counseling. This may be due to the belief that individuals feel more comfortable opening up and expressing themselves more confidently in individual counseling than in a group setting. Researchers suggest that participants work in small groups when individual interventions do not align with the nature of group-based psychoeducation programs (Tambling & Glebova, 2013). McGeorge and Carlson (2006) compared an 8-week premarital relationship education program in both individual and group formats and found that both formats equally enhanced the relationship's preparation for marriage.

According to the findings obtained from the research, the primary areas where individuals feel they have educational needs are conflict resolution, communication skills, coping with stress and anxiety, and increasing satisfaction and happiness in relationships. These results are similar to those of other studies in the literature (Tambling & Glebova, 2013; Borowski & Tambling, 2015; Sullivan & Anderson, 2002; Valiente et al., 2002; Hamamcı et al., 2011; Haskan Avcı, 2014). In this study, no gender differences were observed in terms of the duration, content, implementation method, and willingness to participate in education programs. This indicates that female and male participants have similar attitudes and expectations regarding premarital relationship education programs. Studies in the literature support this finding. For example, Dişli and colleagues (2023) found that when premarital counseling services are provided, individuals have similar counseling and education needs regardless of gender. Similarly, Tambling and Glebova (2013) and Sullivan and Anderson (2002) observed no significant gender differences in premarital education needs. However, some studies have identified gender differences. Hamamcı and colleagues (2011) reported significant gender differences for many items under the heading of “premarital education needs” among university students. In Şen's (2009) study, engaged couples applying to institutions to get married were examined, and it was found that women believed more in the benefits of premarital education than men and read more books on communication, marriage, and problem-solving. Similarly, Duncan and colleagues (1996) found that women's desire for education was higher than that of men. These differences may stem from sample size, cultural context, or demographic differences in the relevant study.

The study observed a 56.9% willingness to participate in a premarital education program. According to Tambling and Glebova (2013), the willingness to participate in premarital education programs among engaged couples is 30% in the general population, and 30-50% of couples refuse to participate. The researchers stated that the reason for this is the excitement and time pressure of engagement, and that the “if there is no problem now, why should we go to counseling?” approach is common. Hawkins (2017) also states that only 30 to 40% of engaged couples apply for and actively participate in premarital education programs. In this study, the willingness to participate exceeding the rate observed in the literature may again be due to the small sample size and cultural differences.

5. Recommendations and Limitations

This study was conducted with adult couples who have been together with their partner for at least 6 months and are planning to get married soon. The limitations of this study are as follows: the small sample size (N = 58) and the use of convenience sampling limit the generalizability of the results; data were collected using self-report methods; and the sample is limited to a single cultural context (Turkey). The questionnaire used in the study was developed by the researcher. Therefore, it may have psychometric limitations in terms of validity and reliability. The findings should be interpreted in light of these limitations. These limitations require caution in interpreting the findings, and larger, representative samples and mixed-method designs are recommended for future studies. Therefore, it would be beneficial to repeat the study in the future with different sample groups. At the same time, the study could be conducted specifically with couples who are dating or engaged. Thus, premarital education needs can be identified for these specific samples. At the same time, such studies can also be conducted for individuals in risk groups to identify their needs. For future research, it is also recommended to develop a comprehensive measurement tool with validity and reliability studies to measure needs in the field of premarital relationship education or to adapt and use existing scales.

Future studies should involve larger and more representative samples; qualitative data should be supported by quantitative findings using mixed methods; the effects of premarital education interventions should be examined more rigorously using pre-post test experimental designs; and measurement tools should undergo comprehensive psychometric re-evaluation. There is a need for short premarital education programs consisting of no more than 2-3 sessions to be developed for engaged couples in Turkey and in international literature. It is expected that the content of the education programs will be skill-building and pragmatic. The content is expected to focus on developing conflict and problem-solving skills, improving communication skills, learning to cope with stress and anxiety, and increasing satisfaction and happiness in the relationship. In the future, such pre-marital relationship education programs can be developed and their effectiveness tested. There is also a need in the literature for premarital relationship education programs based on innovative postmodern approaches and theories that take into account the requirements of the post-industrial and digital age. Relationship education programs for individuals preparing for marriage should be provided by institutions such as municipalities, family counseling centers, and psychological counseling centers, and the number of such programs should be increased

Author Contributions: Conceptualization, Author 1 and Author 2; Methodology, Author 1 and Author 2; Software, Author 1; Validation, Author 1 and Author 2; Formal Analysis, Author 1.; Investigation, Author 1 and Author 2; Resources, Author 1 and Author 2; Data Curation, Author 1; Writing – Original Draft Preparation, Author 1; Writing – Review & Editing, Author 1 and Author 2; Visualization, Author 1; Supervision, Author 2; Project Administration, Author 2.

Funding: This research received no external funding.

Conflicts of Interest: The authors declare no conflict of interest.

Informed Consent Statement/Ethics approval: The relevant study is a section of the doctoral thesis titled “Developing and Testing the Effectiveness of a Pre-marital Education Program” [tr: Evlilik Öncesi İlişki Eğitim Programının Geliştirilmesi ve Etkililiğinin Sınanması] at İstanbul University - Cerrahpaşa. Ethical approval for the research was obtained from the Ethics Committee for Social and Human Sciences Research at İstanbul University - Cerrahpaşa.  Rectorate on December 3, 2024, with approval number 2024/578. I declare that the research was conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study. There is no conflict of interest in the research. The authors received no financial support for the authorship, research, and/or publication of this article.

Declaration of Generative AI and AI-assisted Technologies: This study has not used any generative AI tools or technologies in the preparation of this manuscript.