Secrets of Sex & Marriage is based on data from the Marriage Intimacy Project (MIP), a three-year research study (January 2020 – January 2023) of more than 5,300 subjects. The MIP includes four primary surveys, two of which were nationally representative of the demographics of the United States (across age, racial background, religious background, geography, and so on). This includes the largest known nationally-representative matched-pair study of married couples on the topic of sex.

Links to the research data and methodology documents can be found in this section.

Secrets of Sex & Marriage Methodology

The Marriage Intimacy Project (MIP) is a research study conducted by Shaunti and Jeff Feldhahn and Michael Sytsma, PhD. The first phase of the research and analysis extended from February 2020 to February 2023. The next phase of research and analysis is ongoing. This is the Methodology Appendix promised in the book.

Additional Research from Shaunti Feldhahn

Shaunti Feldhahn has done extensive research in the areas of marriage, relationships, the inner lives of men and women, the workplace, and much more. Some was referenced in Secrets of Sex and Marriage. Explore her research here.