Overview
Hello, so my thesis statement is: To compare the rates of depression in different smoking status among the U.S. population of adult individuals aged 18 and above. In particular, this research will examine how gender might attenuate, strengthen, or not affect the link between smoking and depression, statistically controlling for age, education level, and race/ethnicity. The general hypothesis is that U.S. adults who smoked are more likely to report depressive symptoms, controlling for age, education level, and race/ethnicity, and this relationship will be moderated by gender, with female smokers being more likely to report depressive symptoms than male smokers.The dataset that I will be using is he NHANES 2017-March 2020 Pre-pandemic dataset (attached below, I also attached the codebook as well.)
The main exposure of interest is smoking status. This variable is based on the question posed in the NHANES survey regarding lifetime smoking behavior (SMQ020), where individuals are normatively identified as smokers if they have smoked more than one hundred cigarettes: “have you smoked at least 100 cigarettes in your life?”. Participants are instructed to respond either (Yes): If they have smoked at least 100 cigarettes in their lifetime they must go to the next question; otherwise, they must go to the last question but one or (No): this element applies only if the respondent has not smoked a hundred cigarettes in his or her lifetime.
The main outcome of interest is depressive symptoms. In the NHANES dataset, depression is asssessed using the PHQ-9 survey and scale, which is designed to diagnose and evaluate the severity of depression over the past two weeks. The PHQ-9 consists of nine questions about the presence and frequency of depressive symptoms, such as having little interest in activities, feeling down or hopeless, feeling bad about oneself, and having difficulty concentrating, etc. Responses are scored on a scale from 0 ("not at all") to 3 ("nearly every day").18 To determine depression status, the scores for all nine questions are summed, resulting in a total score ranging from 0 to 27, with scores categorized as follows: 0–4: Minimal depression, 5–9: Mild depression, 10–14: Moderate depression, 15–19: Moderately severe depression and 20–27: Severe depression. It is important to mention that individuals with a PHQ-9 score below 10 are classified as not having depression, while those with a score of 10 or higher are categorized as having depression.
Covariate Measures：Sociodemographic factors such as age, gender, race, education level will be assessed as covariates and moderator in the analyses. The moderator is gender (RIAGENDR), it is defined as male and female and is used to determine the moderation of depression effects due to smoking behaviour. Continuous variable age (RIDAGEYR), indicating participant’s age. From the quantitative responses, the age lies between 18 and 80 or older. NHANES codes the variable as 80 for all the participants that are aged 80 years and above to ensure that their identities are not revealed. Race is a categorical variable that will consist of Mexican American, Other Hispanic, Non-Hispanic White, Non-Hispanic Black, and Other. Education attainment level is a categorical variable that consists of “less than 9thgrade”, “9th-11thgrade”, “high school graduate”, “some college or AA degree”, and “college graduate or above”.
The analysis method, dataset, and codebook have been attached. Please use R to perform the statistical analysis and examine this thesis statement for me. Thank you for your help.
Exposure : SMQ020
Outcome: Depression status (binary or continuous PHQ-9 score).
Moderator: Gender (RIAGENDR).
Age (RIDAGEYR)
Education (DMDEDUC2),
Race/Ethnicity (RIDRETH3).