They sent out a short survey to 1,000 married couples and asked several questions including the income and age of each member of the couple, as well as how much was spent on the engagement ring. Of the 1,000 surveys sent out, 114 were ones wherein the man had offered a ring as part of a surprise marriage proposal. As such, the final usable data did not include couples who purchased the ring jointly.
I begin by listing some of the key descriptive statistics of the sample as found by Cronk and Dunham. The minimal and maximal values for each of the variables are shown in parentheses.
Average Amount Spent on Ring: $3,531.72 ($0-20,000)
Men's Average Incomes: $41,858.20 ($0-500,000)
Women's Average Yearly Incomes: $28,667.48 ($0-80,000)
Men's Average Ages: 29.4 (18-90)
Women's Average 27.0 (16-82)
Note that based on the sample, a man spent 8.44% of his yearly salary on the engagement ring, a figure quite removed from the "expected" 25%!
Cronk and Dunham found that both men's and women's incomes were positively correlated to the amount spent on an engagement ring. These two findings are indicative of marriage customs found in other cultures such as bridewealth and dowries. Furthermore, the authors uncovered a negative correlation between the amount spent on a ring and the bride's age. In other words, the younger the bride, the larger the expenditure. Cronk and Dunham argue that their findings suggest that the amount spent on an engagement ring is linked to the mating "quality" of each of the two partners (as gauged in this case by the respective incomes of both sexes, as well as the age of the brides-to-be).