DEPRESSION

[Association of Vigorous physical activity with Depression: An Examination of NHANES Data 2007-2008]

by

Methods

Current research is a qualitative study done through using the instrument of survey. Univariate and Multivariate analysis of the dross sectional data is performed. As the data collection thorough surveys are discrete and non-scale, nonparametric tests are needed to test the following hypotheses stating the research problems.

Hypotheses

Question# 1: Is there an association between vigorous physical activity and depression in subjects in NHANES 2007-2008?

Null Hypothesis # 1: There is no association between vigorous physical activity and depression in subjects in NHANES 2007-2008.

Alternate Hypothesis # 1: There is an association between vigorous physical activity and depression in subjects in NHANES 2007-2008.

Question #2: Among those who are depressed in NHANES 2007-2008, are there significant differences in the prevalence of no exercisers, insufficient physical activity, moderate physical activity, and vigorous physical activity?

Null Hypothesis # 2: There are no significant differences in the prevalence among those who are depressed of no exercisers, insufficient physical activity, moderate physical activity, and vigorous physical activity.

Alternate Hypothesis # 2: There are significant differences in the prevalence among those who are depressed of no exercisers, insufficient physical activity, moderate physical activity, and vigorous physical activity.

Question # 3: Is the prevalence of vigorous physical activity the same for subjects in NHANES 2007-2008 who are depressed compared to those who are not depressed?

Null Hypothesis # 3: There is no significant difference in the prevalence of being vigorously physically active among those who are depressed compared to those who are not in NHANES 2007-2008.

Alternate Hypothesis # 3: There is a significant difference in the prevalence of being vigorously physically active among those who are depressed compared to those who are not in NHANES 2007-2008

Data Analysis

Data of the survey is used to obtained the summary statistics of the independent variables of the study that are physical activity, gender, age, race, substance use, Body Mass Index (BMI), alcohol use and education level. Responses for moderate and vigorous exercise are used to make the variable physical activity which is divided into moderate physical activity, vigorous physical activity, no exercise, and insufficient physical activity. Substance use refer to the use of cocaine, heroin, and/or methamphetamine

In order to test the listed hypothesis, Odds ratio and non-parametric test of Chi-square are used. Odds Ratio is a measure of association between nominal variables. The method followed for acquiring the results through odds ratio is as follows.

Odds ratio of depression in exposed group = prevalence of depression in exposed/prevalence of no depression

Odds ratio of depression for not exposed = prevalence of depression in not exposed/prevalence of no depression

Odds ratio (OR) = Odds ratio of depression in exposed group / Odds ratio of depression for not exposed

Confidence interval is calculated as follows,

Confidence Interval (CI) =Exponential of (Point Estimate ± Confidence Coefficient *Standard Error)

Where, Point estimate = Natural log of OR

Standard Error = Square Root of sum of the inverses of the prevalence of depression and no depression in exposed and non-exposed ...