留学生公共健康Dissertation Proposal范文：Obesity and Depression研究设计

对于学习公共健康、流行病学、医学统计、健康政策或心理健康相关专业的留学生来说，Dissertation Proposal写作往往是整个论文中最关键的一步。它不只是简单介绍一个研究主题，而是要说明研究背景、研究意义、研究假设、数据来源、变量设置和统计分析方法。

本文以 Obesity and Depression（肥胖与抑郁关系研究） 为主题，结合 2006 Behavioral Risk Factor Surveillance System Survey（BRFSS） 和 Patient Health Questionnaire（PHQ-8），整理一篇公共健康方向的留学生Dissertation Proposal写作范例。原文主要讨论美国成年人肥胖率上升、肥胖与抑郁之间的潜在关系，以及性别、年龄、种族、吸烟和饮酒状态是否会影响这种关系。

优客网 ukthesis 创立于1999年，是长期服务留学生的论文代写平台，可提供代写留学生论文、公共健康Dissertation代写、留学生Dissertation润色、医学统计论文辅导、流行病学论文润色、reference格式检查等服务。对于这类Dissertation来说，真正重要的不是把数据名词堆上去，而是把研究问题讲清楚，把方法设计写得有逻辑，让导师一眼看出这项研究为什么值得做、准备怎么做、最后可能有什么学术价值。

Abstract

The growing prevalence of overweight and obesity has become a major public health concern. Among the U.S. adult population, obesity increased noticeably during the early 2000s, and obesity has been linked to several chronic health problems, including diabetes, high blood pressure, high cholesterol, asthma, arthritis and poor general health status.

Previous research has suggested that obesity may be significantly associated with depression. Several studies conducted in the United States and Canada have reported associations between obesity and depressive symptoms, psychological distress, and history of depression. However, limited research has examined this relationship using the 2006 Behavioral Risk Factor Surveillance System Survey（BRFSS）, especially with depression measured by the Patient Health Questionnaire（PHQ-8）.

This proposed study will use data from 2006 BRFSS responders. The 2006 BRFSS dataset is selected because it includes a useful set of “healthy days” questions, optional modules and state-added questions. The study will investigate the relationship between obesity and depression, while also considering age, gender, race / ethnicity, smoking status and heavy drinking status.

Findings from this research may provide useful evidence for public health officers and policy makers when developing mental health services and obesity-related intervention strategies.

Key words: obesity, depression, PHQ-8, BRFSS, public health dissertation, epidemiology research

1. Specific Aims

The increasing prevalence of overweight and obesity is a major public health issue in the United States. Obesity is generally associated with many health problems, including diabetes, hypertension, high cholesterol, asthma, arthritis and poor health status. In many cases, overweight and obesity are understood as the result of energy imbalance, where energy intake exceeds energy expenditure.

Previous studies have also indicated that obesity may be associated with depression. Depression is one of the most common mental health disorders and has become an important concern in public health research. Several studies in the United States and Canada have reported links between obesity and depressive symptoms, psychological distress and history of depression.

However, the relationship between obesity and depression may not be the same across all groups. Some studies suggest that the association may differ by gender, age and race / ethnicity. For example, previous research has suggested that women may show a stronger positive association between obesity and depression than men. Other studies have reported that younger adults may be more likely to experience depression than older adults.

When it comes to race and ethnicity, previous findings are not completely consistent. Some research suggests that Non-Hispanic Whites have a higher rate of depression than Non-Hispanic Blacks, Hispanics and Asians. Other research suggests that Hispanics may be more likely to experience depression than Whites and Blacks.

This proposed Dissertation will therefore use the 2006 BRFSS dataset to further examine the relationship between obesity and depression. The study will also explore whether smoking status and heavy drinking status are related to depression among obese adults.

2. Background and Significance

Understanding the causes and consequences of obesity is important for improving public health and reducing obesity-related diseases. Many researchers argue that excessive food intake and sedentary lifestyle are two major reasons for the rapid increase of overweight and obesity in Western countries.

Although nutrition information is widely available in schools, medical settings, online resources and grocery stores, overeating remains a substantial problem. At the same time, dietary intake alone may not fully explain the rapid increase in obesity levels in many industrialized countries.

Weight regulation is complex and influenced by many individual-level and social-level factors. In the United States, obesity is often reported to be more common among middle-aged and older adults than younger adults. Some studies also suggest that obesity may be more common among women than men. In developed countries, obesity is often inversely related to income and education level.

Previous research has suggested that obesity may be significantly associated with depression. Depression is one of the most prevalent mental disorders. Studies conducted in the United States and Canada have reported associations between obesity and depressive symptoms, psychological distress and history of depression.

However, the exact relationship between obesity and depression is still not fully clear. Some studies suggest that the relationship depends on gender, age and race / ethnicity. For example, one previous study reported a significant positive association between obesity and depression among women, but not among men. Another national study based on BRFSS data reported a stronger relationship between obesity and depression among people younger than 65 years old.

The association between obesity and anxiety or substance use disorders is also not well understood. Some epidemiological studies suggest that anxiety symptoms may have a moderate positive association with obesity in community and clinical samples. Alcohol abuse, however, has been associated in some studies with a lower risk of obesity.

Because previous findings are not fully consistent, this proposed research aims to examine these questions using the 2006 BRFSS dataset. Compared with earlier BRFSS data, the 2006 BRFSS includes the PHQ-8, which provides a more detailed measurement of depressive symptoms than a single depression question. This makes the dataset useful for a public health Dissertation focusing on obesity and depression.

3. Research Hypotheses

This Dissertation proposes the following research hypotheses:

Young obese women are more likely to report depressive symptoms than non-obese women.

Hispanics may be more likely to report depression than Whites and Blacks.

Non-Hispanic Whites may have a higher rate of depression compared with Non-Hispanic Blacks, Hispanics and Asians.

Smokers are more likely to report depressive symptoms than non-smokers.

Heavy drinkers may have a higher rate of depression than people who are not heavy drinkers.

These hypotheses are based on previous research, but the study will use the 2006 BRFSS dataset to test whether these patterns can be observed in this specific population sample.

4. Research Design and Methods

Data from the 2006 Behavioral Risk Factor Surveillance System（BRFSS） will be analyzed for this study. The BRFSS was established by the Centers for Disease Control and Prevention（CDC）in 1984. It is one of the largest continuously conducted telephone health survey systems in the world.

The BRFSS is designed to identify and monitor risk factors for diseases and health conditions such as diabetes, cancer, obesity, asthma, nutrition-related problems and mental health concerns. The survey collects information about individual-level health behaviors among U.S. adults each year.

During the survey, participants are asked questions related to health behaviors and risk factors, including dietary intake, nutrition, physical activity, tobacco use, alcohol use, health care access, hypertension, height and weight.

This study will use the BRFSS data to examine whether obesity is associated with depression and whether this relationship varies across demographic and behavioral groups.

5. Study Subject

The proposed study participants will be responders from the 2006 BRFSS who answered questions related to anxiety and depression. The 2006 BRFSS is selected because it includes a useful set of “healthy days” questions, optional modules and state-added questions.

Participants who have valid information on body mass index, depression-related questions, demographic characteristics, smoking status and heavy drinking status will be included in the analysis.

This section is important in a Dissertation Proposal because it tells the reader where the data come from and who will be included in the research. For public health and epidemiology papers, sample selection must be written clearly, otherwise the later statistical analysis will look weak.

6. The Patient Health Questionnaire（PHQ-8）

The Patient Health Questionnaire（PHQ-8） was used in 41 states and territories. It consists of eight questions based on the DSM-IV criteria for depressive symptoms. In the 2006 BRFSS, the PHQ-8 was modified from a self-report paper format to a telephone interview format.

Responders were asked how many days during the past two weeks they had experienced emotions or behaviors related to depression, such as little interest or pleasure in doing things, feeling down or hopeless, sleep problems, tiredness, poor appetite, feeling bad about themselves, trouble concentrating, or moving and speaking unusually slowly or restlessly.

To separate different levels of depression, the CDC developed scoring algorithms for the PHQ-8. In this study, Algorithm 3 will be used because it is simple and useful for detecting depression in the general population. Depression severity scores will be divided into two groups:

Depression severity score less than 10

Depression severity score 10 or greater

In addition to the eight PHQ-8 questions, the BRFSS also includes questions asking whether a healthcare provider has ever told the respondent that he or she had an anxiety disorder or depressive disorder.

7. Demographic Characteristics and Variables

Demographic characteristics will include age, sex, race / ethnicity, height and weight. These variables are obtained from participants’ self-reports.

Obesity will be defined by body mass index（BMI）:

Non-overweight / non-obese: BMI < 25

Overweight: 25 ≤ BMI < 30

Obese: BMI ≥ 30

Previous studies have suggested that self-reported height and weight are highly correlated with physical measurements, although self-reports may underestimate weight and overestimate height. This may lead to lower estimates of overweight and obesity.

Age, sex, race / ethnicity and health status will be treated as important variables in this study. Age groups will be defined as:

Young adults: 18-64 years

Older adults: 65 years and above

Race / ethnicity will be classified as:

White / Non-Hispanic

African American

Hispanic

Other

Health behavior variables will include:

Smoking status

Heavy drinking status

Socio-economic variables will include education level, income level and marital status. These variables are important because depression and obesity may both be influenced by social and economic background.

8. Statistical Analysis

A normalized weight will be applied to each participant based on the sample weight variable provided in the BRFSS dataset. This helps ensure that the estimates are more representative of the general population.

Descriptive data on depression will be treated as prevalence rates and will be examined by age, sex, race / ethnicity, smoking status and heavy drinking status.

Logistic regression models will be used for comparative and moderator analyses. Socio-economic variables will be controlled in the models. The results of comparative analyses will be presented as odds ratios（OR）with 95% confidence intervals.

Confidence intervals will be used to determine statistical significance and to assess whether there are meaningful differences between variables and the prevalence of depression.

For moderator analysis, interaction terms will be tested, including:

obesity × age

obesity × sex

obesity × race

obesity × smoking status

obesity × heavy drinking status

This analysis will help determine whether the relationship between obesity and depression changes across different population groups.

9. Appendix：PHQ-8 Questions in BRFSS

The PHQ-8 questions ask respondents to think about how many days during the past two weeks they experienced the following symptoms:

Little interest or pleasure in doing things.

Feeling down, depressed or hopeless.

Trouble falling asleep, staying asleep or sleeping too much.

Feeling tired or having little energy.

Poor appetite or eating too much.

Feeling bad about oneself, or feeling like a failure.

Trouble concentrating on things, such as reading or watching television.

Moving or speaking so slowly that other people could have noticed, or being so restless that one moved around more than usual.

The BRFSS also asks whether a doctor or healthcare provider has ever told the respondent that he or she had an anxiety disorder or depressive disorder.

10. Conclusion

This proposed Dissertation focuses on the relationship between obesity and depression among U.S. adults using the 2006 BRFSS dataset. The study is meaningful because obesity and depression are both important public health concerns, and previous research has not fully explained how this relationship may differ by gender, age, race / ethnicity, smoking status and heavy drinking status.

By using PHQ-8 data from the 2006 BRFSS, this study can provide a more detailed measurement of depressive symptoms than studies using only a single depression question. The findings may help public health researchers and policy makers better understand which groups are more vulnerable and how mental health services can be planned for people affected by obesity and depression.

For留学生来说，这篇文章是一个比较典型的公共健康Dissertation Proposal写作案例。它的优点是结构完整，有研究背景、研究假设、数据来源、变量设置和统计分析方法；需要改进的地方是原文中有明显乱码、部分句子机翻感较重、个别统计表达不够自然，发布到网页前一定要整理好。

优客网 ukthesis 创立于1999年，长期提供代写留学生论文、公共健康Dissertation代写、留学生Dissertation润色、医学统计论文润色、流行病学论文辅导、Reference格式检查和dissertation结构优化等服务。如果学生在写Obesity and Depression、BRFSS数据分析、PHQ-8量表研究或公共健康Dissertation时遇到结构和统计分析问题，可以通过专业辅导先把研究设计理顺，再进行正式写作。