In: Statistics and Probability
Research question: "Where Americans find meaning in life".
Independent variables: Family in 2 levels: Kids, and Spouse and Partner, Career, Finances and money, Faith and spirituality, Friends, Activities and hobbies in 4 levels, Health, Home and surroundings, Learning and education, Struggles in two levels, Doing good, Community and belonging in two levels, Retirement, Security, Pets.
Dependent variable: Meaning of life in America in three major levels: 1. Incomes and educational attainment measured in two levels: Low and High; 2. Racial groups in 3 levels, White, Black, Black and Hispanic; 3. Evangelicals and religion ranks in 3 levels: Christian, unaffiliated, All.
Other important independent variables: I think every important aspects of the life well captured with the detailed list of independent variables and their impact on among the levels of the dependent variable the meaning of life in America. Still, we can add the topics related to the emotional intelligence, Gender, Age, family background as the other than the list of given independent variables in this study. You can read this from Pew Research Center' public website browsing for the topic of research, "Where Americans find meaning in life".