Predictors of happiness and satisfaction with life in individuals from the Brazilian general population who use social networks: a cross-sectional study

This study aimed to identify possible conditions associated with the perception of happiness and satisfaction with life in a sample of the Brazilian population who use social networks. This was a cross-sectional study with participants recruited online in five regions of Brazil via Facebook and WhatsApp. Data were collected from October 2015 to October 2016. The instruments used were the Pemberton Happiness Index , the Satisfaction with Life Scale , and a questionnaire regarding sociodemographic and clinical characteristics and issues potentially associated with the feeling of happiness. In total, 2,151 participants were included. A total of five variables exerted the greatest influence on higher levels of happiness and satisfaction with life in the multiple linear regression model, in the multiple logistic regression analysis, and in the decision tree model. Being satisfied with financial circumstances, having a positive self-evaluation of health, having frequent family gatherings, engaging in physical activity ≥ 3 times a week, and having no previous psychological/ psychiatric diagnosis are variables that “seem” to positively influence Brazil-ians’ perception of happiness and satisfaction with life. We identified some predictors of happiness and


Introduction
Regardless of how happiness is understood, it is a desire of every human being, and, it can be considered the primary goal of life; humans have tried many paths to achieve it 1 . Several studies have been conducted to understand the pursuit of happiness, many of which have attempted to find "combinations" of variables that may provide people with greater chances of happiness 2,3,4,5,6,7 .
Happiness is a multidimensional and complex construct, mainly because it is a subjective individual experience. Thus, it is challenging to compare data on happiness and its multidimensional measures between different cultures and specific populations 8 . In recent years, happiness has gained increasing attention not only in the academic literature but also in journalistic and political debates 9 .
Happiness is closely associated with emotions, feelings, and moods, whereas satisfaction with life is associated with cognitive assessments and judgments about life, which may include assessments of many areas of life 10 . Satisfaction with life is a congruence between the present and an ideal situation, both of which are a reflection of one's own subjective appreciation of one's life 11 . Thus, whereas happiness and satisfaction with life are closely related constructs, they must be evaluated as independent variables. In this study, the terms happiness and well-being/subjective well-being will be considered synonyms for better understanding and interpretation.
Social networks have brought intense changes in the way people communicate and interact. However, it is not yet clear whether and how some of these changes, in the form of social interaction, can affect certain aspects of human behavior. Scientific studies still present contradictory results in terms of negative and positive effects of social networks on the mood swings and affections of its users 12 . However, it is a fact that "fake news" negatively affects the mental health of social network users, since they can provoke intense emotional responses, such as anger, fear, anxiety, sadness, impotence, and frustration 13 . The significance of the impact of social networks on Brazilian public health is evident considering that 70% of Brazilians have access to the Internet 14,15 and that Brazil is ranked second in terms of time spent per day on the Internet (approximately 9 hours and 29 minutes per day), with 40% of this time being spent on social media 16 .
Several studies have studied happiness (and its related constructs) in the search for associated factors, especially those that can be modified, both individually and collectively. Several conditions have been reported to be associated with the perception of happiness. However, besides the predisposing genetic conditions, the sociocultural factors, which are different between the populations, are probably modifiers of the "recipe" for happiness. In Brazil, a large country of multicultural traditions, the rates of happiness and satisfaction with life had not yet been measured within a global context. Thus, the factors that would most significantly influence the perception of happiness of Brazilians were unknown. This study was justified by this lack of scientific literature.
This study was conducted in the context of popular dissatisfaction in Brazil. The hypothesis of the study was that -despite existing in a context wherein people often use social networks for posting about dissatisfaction with violence and corruption -the variables associated with happiness and satisfaction with life are individual and related to healthy social interactions and simple everyday situations (such as leisure activities and contact with nature). Therefore, this study sought to identify possible conditions associated with the perception of happiness and satisfaction with life in a sample of individuals from the Brazilian population who use social networks.

Study design
This was a cross-sectional study performed with convenience sampling. The electronic tool Survey-Monkey (https://www.surveymonkey.com/) was used to collect data.

Study participants
Individuals from the Brazilian population who had an account on the Facebook social network and/ or used the WhatsApp software application were included.

Study site
Data were collected from October 2015 to October 2016. Participants from the five regions of Brazil were recruited online through the Facebook and the WhatsApp. The survey was administered using the SurveyMonkey platform.

• Via Facebook
For the application of the instruments of data collection through the Facebook, an online program called SurveyMonkey was legally acquired by registration on the site https://pt.surveymonkey.com.
For data collection via Facebook, three different methodologies were used. These are described as follows: (i) Methodology 1: the authors used their personal Facebook pages to share the research post. (ii) Methodology 2: municipalities were selected according to the demographic and Human Development Index profile of each Brazilian state. To promote the research, we created Facebook pages specific to the study entitled Happiness Research, Happiness Research II, and Happiness Research III. A total of 100 individuals from each municipality were invited. When identifying one or more of these individuals, first contact was made through an inbox message on the person's page and a friend request.
(iii) Methodology 3: researchers without connections to the researchers of this study in the North, Northeast, Central-West, and South were contacted to serve as "poles" for dissemination of the research by Methodology 1 with the objective of propagating the research and reaching populations outside the Southeast region, ultimately reaching a significant number of cities in Brazil.

• Via WhatsApp
Some people known by the researchers residing in different regions of the country were contacted through the WhatsApp. Explanatory text about the study was sent together with the research link. Besides being asked to answer to the online questionnaire, they were encouraged to share the study text/link with their WhatsApp contacts.

Eligibility criteria
The inclusion criteria were as follows: Brazilian nationality, dwelling in a Brazilian municipality, a Facebook account and/or use of the WhatsApp.
The only exclusion criterion was individuals younger than 18 years.

Sample size calculation
The sample size calculation considered an a priori coefficient of determination (effect size) of R 2 = 0.01 in a multiple linear regression model with seven predictors and an α = 0.05 level of significance (or type I error), and 95% a priori statistical power.

Data collection instruments
• Questionnaire of sociodemographic and clinical characteristics and issues potentially associated with the feeling of happiness For the development of this questionnaire, the items were defined after meetings among researchers from the Palliative Care and Quality of Life Research Group (GPQual) and were based on a literature review and discussions about potential factors related to happiness. Before proceeding to the main data collection, the first 50 individuals who completed the questionnaire had their answers checked to assess accuracy, to determine the frequency of missing items, and to verify the functioning of Sur-veyMonkey. The questionnaire included sociodemographic characteristics, such as age, sex, marital status, religion, and region, as well as clinical characteristics, such as personal perception of health and previously diagnosed health problems. Several items addressed issues potentially associated with the perception of happiness (Supplementary Material; http://cadernos.ensp.fiocruz.br/static//arquivo/ suppl-e00164020_9472.pdf).

• Pemberton Happiness Index
The Pemberton Happiness Index (PHI) is composed of 11 items related to different areas of remembered well-being (general; hedonic; eudaimonic; and social well-being) and 10 items related to recently experienced well-being (previous day events). The items are answered on a Likert scale, and the higher the scores, the greater the happiness. The sum of the scores produces a combined well-being index (PHI-total) 17 . The Portuguese version is valid and reliable to use with the Brazilian population through online surveys 18 . In this study, the PHI-remembered score (PHI-r), with a cut-off score of 7, was used to define happiness, according to a validation study in Brazil 18 . Cronbach's α value was 0.877.

• Satisfaction with Life Scale
This instrument consists of five items that evaluate a cognitive component of life satisfaction, and participants answer it based on a 7-point scale, ranging from 1 (totally disagree) to 7 (totally agree).
In the Brazilian validation, the scale presented a Cronbach's α value of 0.89 19 . It is the most widely used scale for assessing overall satisfaction with life and has been implemented in several languages and cultures, providing good psychometric indexes 20,21 . In this study, Cronbach's α value was 0.873.

• Study endpoints
Using the PHI-r, the happiness score was analyzed as both a continuous variable (for the linear regression analysis) and a categorical variable (< or ≥ 7 for the logistic regression analysis).
Measuring with the Satisfaction with Life Scale (SWLS), the satisfaction with life score was analyzed as a continuous variable (for the linear regression analysis).

Statistical analysis
The data are described using absolute and relative frequencies. The normality of the data was tested using the Kolmogorov-Smirnov test. The Mann-Whitney or Kruskal-Wallis chi-square and Fisher's exact tests were used to analyze the relationship of the instruments with the variables (univariate Cad. Saúde Pública 2021; 37(12):e00164020 analysis) and to compare the scores between the groups. For the multivariate analysis, logistic (dichotomous independent variables) and linear (continuous independent variables) regression models were applied. A significance level of 5% was adopted for the tests, and the analyses were performed using SPSS, version 21.0 (https://www.ibm.com/).
To create decision rules for discriminating between the two groups (PHI-r ≥ 7 vs. PHI-r < 7), we fitted a model using the decision tree technique by the CHAID method 22 .
Univariate analyses were performed for each of the instruments used (PHI and SWLS). Variables with p-value < 0.05 were included in the linear regression and multiple logistic models, which were adjusted for age, sex, income, and educational level. The detailed results of the univariate analyses are shown in the Tables 2, 3 and 4.
A multiple logistic regression analysis was also performed with the dichotomized PHI-r (happy vs. not happy) as the independent variable. Individuals aged 50 to 59 years (odds ratio [OR] = 2.4; p < 0.001) and residing in the South region (OR = 1.9; p < 0.001) of the country were also associated with higher levels of happiness, as well as satisfaction with financial circumstances (OR = 2.7; p < 0.001), more positively self-rated health (OR = 2.3; p < 0.001), a greater influence of spiritual/religious life (OR = 1.8; p < 0.001) and engaging in physical activity ≥ 3 times per week (OR = 1.8; p < 0.001). A previous psychological/psychiatric diagnosis (OR = 0.4; p < 0.001) and being female (OR = 0.7; p < 0.005) were negatively associated with happiness scores (Table 6).

Decision tree model
A tool was also generated through the decision tree technique using the CHAID method 22 to discriminate between two groups according to the PHI-r (happy vs. not happy). Among groups, the decision tree model generated simple decision rules to differ their respective probabilities of correct differentiation. This type of model can be particularly useful for rapid assessment. Among the variables, five remained the most important: satisfaction with financial circumstances, self-assessed health, previous psychological/psychiatric diagnosis, frequency of family gatherings, and engagement in physical activity (Figure 1).
The five important variables that remained in the decision tree model also stood out in the linear regression and logistics analyses, in which everyone had an influence on satisfaction with life (SWLS) and the perception of happiness (PHI-r) ( Table 8).

Discussion
This study aimed to identify possible predictors of the perception of happiness and satisfaction with life in a sample of individuals from the Brazilian population who use social networks. We found a set of variables that positively influence the feeling of happiness and satisfaction with life, including satisfaction with financial circumstances, self-assessed health, previous psychological/psychiatric diagnosis, frequency of family gatherings, and engagement in physical activity.

Main findings
Regarding the sociodemographic variables, sex and age are noteworthy. Sex is a sociodemographic variable associated with inconsistent findings in the literature regarding happiness since it can be influenced by social origins and the cultural contexts of each country 5 . Some of the differences Table 8 Influence of variables on happiness and satisfaction with life scores.

Characteristics
Happiness  related to satisfaction with life may be due to the different weights attributed by men and women to different dimensions of life, such as occupational, social, health, or housing factors 23 . The relationship between age and happiness has also been investigated, and the distribution of happiness levels was depicted as a U-shaped curve 24 . This indicates that younger and older adults tend to have higher levels of happiness than middle-aged adults 24 . In this study, more than 75% of participants were aged from 18 to 39 years. According to the results, individuals aged between 40 and 70 reported being happier than the younger people. Analysis of individuals aged over 70 years was hampered by the small number of participants in this stratum.
In this study, having a job and being happy with it were significant factors for participants' happiness and satisfaction with life. Consistent with this finding, we found positive associations between being employed and happiness indexes 25,26 . Furthermore, job satisfaction has been strongly correlated -among other things -with happiness and satisfaction with life 25 . Moreover, the chances of a person reporting happiness may be greater if the individual evaluates the nature of their work positively 25 . This is because, likely for many individuals, work also contributes to the development of identity and because the assessment of work can affect other spheres of life 26 .
Cad. Saúde Pública 2021; 37(12):e00164020 Although several studies provide evidence of an association between volunteer work and increased levels of happiness 27 , these effects have greater meaning for older adults than for younger individuals 27,28 , and the positive influences on happiness are greater in those with a lower socioeconomic status 27,29 . Being involved in some type of volunteer activity in this study was associated with satisfaction with life but not with happiness, which may be explained by the fact that most participants were young, with a high educational level and a high income.
Enjoyable leisure activities have been associated with psychosocial and physical measures relevant to health and well-being 30 . In our study, we associated leisure activities with both happiness and satisfaction with life. Besides facilitating moments of relaxation, leisure activities often provide social interactions, which are positively conducive to happiness and satisfaction with life 31,32 . In a Japanese cohort of middle-aged adults, mental health status was significantly associated with leisure activities (cultural activities or sports), especially those involving others, suggesting the importance of social interactions 33 .
Family relations are another form of social interaction, since these are fundamental for providing, among other things, financial and emotional support and, consequently, social and psychological support 34 . The search for family harmony is considered a significant purpose of life that is also essential for maintaining the happiness of individuals regardless of culture and age group 34,35 . We found evidence of an association between positive family relations and happiness 34 . The frequency of family gatherings (e.g., family lunches or dinners) was positively associated with happiness and life satisfaction and it was also an important item in the decision tree. A previous study associated having companionship during meals with higher happiness scores 35 .
A very widespread issue in Western society is whether "money can buy happiness". Our results show that although family income was associated with higher satisfaction with life, personal satisfaction with the earned money tended to be more relevant, as it was positively associated with happiness and satisfaction with life; it was also one of the items present in the decision tree. How much money the individual earns alone does not predict satisfaction in other areas of life 5,36 . Therefore, it is possible to find happy people with very low incomes, which could explain why they experience great satisfaction in other areas of their lives 2,36 . However, the existence of a positive relationship between family financial satisfaction and happiness is known 6 . Although money cannot buy happiness, it can, for example, make health care accessible, especially in regions with exacerbated socioeconomic inequalities and scarce healthcare resources 37 . Therefore, the transition from poverty to moderate income is fundamental for a family to meet its basic needs 38 . After meeting basic needs, however, the additional income does not serve deeper needs in a lasting way, at least when it is directed toward acquiring more material goods 39 . Experiential purchases (such as vacations, travel, concerts, and meals in restaurants) tend to bring more lasting happiness than material purchases. This is because, compared to material goods, experiences are less prone to hedonic adaptation 40 .
We positively associated self-assessed health, also called self-reported health, with happiness 2,3,4,6,34 , even after controlling the results by relevant socioeconomic phenomena 2,9,37 . In our study, self-assessed health seemed to influence happiness and satisfaction with life, and to be a relevant item in the decision tree. What matters in the self-assessment of health, which is a subjective assessment of the individual, is the individual's feeling of being in good or poor health, regardless of the actual number of illnesses present 2,3 .
Scientific evidence indicates that the practice of physical activity is also positively correlated with happiness scores 41 , and that individuals are happier at times when they are more physically active 41 . Such momentary happiness could be related to underlying social interactions, since reports of more positive effects when individuals are in social situations 42 . Physical activity is also probably linked to happiness by internal processes, as it provides a revitalizing effect, which can increase the availability of resources for the pursuit of personal goals 42 . In this study, practicing physical activity more than three times a week was associated with happiness and satisfaction with life and was one of the relevant items in the decision tree.
Being happy is not necessarily the opposite of being depressed. In any case, it seems natural to assume that happiness is negatively associated with negative emotional traits 8 , as well as other mental disorders 43 . Average happiness seems to be higher in countries that invest more in mental health, both in absolute terms (more mental health professionals) and relative terms (share of investment in Cad. Saúde Pública 2021; 37(12):e00164020 mental health care in the total health care budget), especially in developed countries 43 . Our results corroborate those of previous studies showing that a diagnosis of depression or anxiety is associated with a lower level of happiness 7 . Likewise, satisfaction with life is also strongly influenced by mental health 44 .
Spirituality/religiosity was another significant factor of the happiness and satisfaction with life of the participants from the general Brazilian population. The relationship between spirituality/ religiosity and satisfaction with life has been found to be positive 1,6 . Scientific evidence suggests that individuals who regularly attend religious institutions build social networks, but that the effect of the social relations arising from such encounters is contingent on the presence of a strong religious identity; moreover, it may occur differences in the experience of happiness and satisfaction with life in different spiritual/religious groups 6 . At the same time, spirituality/religiosity is a way to achieve purpose in life, to improve mental health, to establish well-being, and to gain inner peace, which can lead to happiness 1 .
Scientific publications have demonstrated that a healthy and creative emotional life is a protective factor against disease and plays an important role in the favorable evolution of chronic diseases. The search for well-being and happiness is inherent to the human condition. The identification of conditions associated with a greater perception of happiness can provide subsidies for national public policies aimed at improving the population's living conditions. We still do not know what should be encouraged (or discouraged) for individual happiness, especially in the Brazilian's life. Furthermore, during the data collection period, Brazil was going through a time of political and economic instability. Thus, the results of this study are able to help understand the impact of such a crisis on people's lives.
The work philosophy of every health professional should focus on the humanization of care. Regardless of the profile of potential patients served by them, this professional should see the Brazilian citizen as deserving of adequate health care, respect for individuality, and encouragement for healthy living practices, including the variables associated with happiness and life satisfaction reported in this study (related to healthy social interactions and simple everyday situations). Furthermore, the decision tree model cited is simple and easy to interpret as well as can offer a convenient application in clinical practice to identify possible risks of unhappiness and preventive actions against those risks.
Issues related to happiness have become an important topic for public policy, economics, and psychology in recent years 45 . The United Nations (UN) even passed a resolution recognizing the pursuit of happiness as a fundamental human objective. More than an individual desire, the UN establishes the importance of creating public policies for this purpose 46 , encouraging each country to develop measures that reflect its characteristics. For this reason, happiness was considered, contemplated or even incorporated into public policies in several countries.

Limitations of the study
This study has some limitations. We recruited the participants only through social networks (Facebook and WhatsApp), which can contribute to internet access bias because not all Brazilians have online access. The spontaneous interest in the subject may serve as another selection bias insofar as the individuals were free to participate when receiving the invitation through the social network. The discrepancy in the number of respondents of the female sex is another limitation, besides the inequality in the number of participants by region of the country, although all the Brazilian regions were represented. To minimize potential sampling bias, we adjusted all analyses for age, sex, income, and educational level.

Strengths and practical perspectives
This study benefits from strengths with regard to its originality -namely, in Brazil, we did not find other study evaluating the specified predictors -and the large number of its participants, all of the same nationality but residing in different regions. Since the relevant predictors was identified, it was possible to stimulate increases in their frequency of occurrence in the daily life of Brazilians in an attempt to raise individual levels of happiness and satisfaction with life.
Cad. Saúde Pública 2021; 37(12):e00164020 In individuals with a history of psychological/psychiatric disorders, therapeutic strategies focused on improving self-perceived health, as well as cognitive adjustment regarding expectations of financial gain (i.e., satisfaction with financial circumstances), may be important for the individual perception of happiness. Encouraging individuals to seek closeness with family members can also be helpful in this context. However, these therapeutic strategies need to be delineated and tested in future studies.

Conclusions
A set of variables predicted the perception of happiness and satisfaction with life of a sample of individuals from the Brazilian population in general through social networks. Being satisfied with financial circumstances, having a positive perception of one's self-evaluated health, having frequent family gatherings, engaging in physical activity ≥ 3 times a week, and not having a previous psychological/psychiatric diagnosis are variables that "seem" to influence, in a positive way, the perception of happiness.
The decision tree model is simple and easy to interpret, as well as it can offer a convenient application in clinical practice to identify possible risks for unhappiness and preventive actions against these risks.