In a cross-cultural study conducted to determine whether the German concept of Sehnsucht could be generalized to the United States, four samples of American and German participants "rated their 2 most important life longings and completed measures of subjective well-being and health."[REF]
Also, in a study conducted in 2009, 168 middle-aged childless women were asked to rate their wish for children according to intensity and attainability.