Data and methods
We use the Swedish Longitudinal Immigrant (SLI) database, hosted and administered at the Centre for Economic Demography, Lund University, Sweden. The SLI contains data from several administrative registers, providing longitudinal socio-demographic, economic, and health-related information on about 500,000 unique individuals, continuously observed over the time period 1968-2001. The database was originally developed to examine research questions focused on immigrant-native differences in socioeconomic and demographic outcomes and therefore contains an oversampling of the sixteen largest immigrant nationalities living in Sweden during the time period in question. Despite this oversampling of the foreign born, the nationally representative sample of natives represents by far the largest group in the data. As a result, the dataset is appropriate also for research without an explicit immigrant focus.
Since this study examines astrological predictions of relationship compatibility, the primary outcome of interest is divorce of those in ple to Nordic born index individuals in heterosexual unions with Nordic born spouses. This provides a study population with a largely similar cultural background and thereby more similar views on marriage and divorce as well as a similar propensity to believe in, and consult, astrology. With the study population additionally restricted to individuals between the ages of 18 and 70, the number of ount to roughly 66,000. Our analysis also examines the determinants of legal divorce with an additional sample restriction being that all examined unions were observed from the beginning of the marital union, since this is necessary to accurately measure time at risk of dissolution. Censoring in the data occurs when (i) either spouse dies or emigrates or (ii) the index individual turns 70 years of age. As a result, the number of unions examined in the divorce analysis drops to about 46,000, with 15,000 ending in divorce during the follow-up period.
Using information on date of birth, we determine the zodiac signs of both the index individual and their spouse, yielding 144 zodiac-sign combinations Footnote 1 . A potential source of criticism of this method is that more detailed information containing the precise place of birth (latitude and longitude) as well as the precise time of day that the individual was born, is required in order for a more exact horoscope to be read. The majority of horoscopes consumed by the general public in magazines, online, and in newspapers is, however, based solely on the date of birth. Consequently, it would follow that our ability to assess zodiac signs only based on the date of birth does not represent an insurmountable disadvantage, but rather reflects the way these signs are constructed in daily use.
While we are using data on couples in Sweden, the majority of the relationship classifications tested in this article was provided in English, due to the dearth of source material in Swedish. We do not have any information on whether sample individuals actually believe in astrology, something that we claim should not matter, as astrological theory would suggest that individuals are influenced regardless of whether they have any knowledge of astrology.
The measurements of relationship compatibility based on zodiac sign combinations that are examined in the analysis are summarized in Table 1
Among sources whose primary subject matter is astrology, we selected those that offered information on relationship compatibility based on partners’ zodiac signs free of charge. The information furthermore had to unambiguously define varying degrees of compatibility between zodiac signs, enabling an operationalization for quantitative analysis that did not rely on researcher interpretation. As evident from the table, the facebook dating reviews classifications employ different methods to distinguish between relationship compatibility, with all but one (#3), appropriate for a categorical operationalization. The following column shows the share of possible zodiac sign combinations that are allocated to each respective compatibility category, while the last column shows the visitor volume of each site. To illustrate the importance of these sources, two of the sites used obtained over 15 million monthly visitors during the first 6 months of 2020. Also note that while classifications 1-5 were provided in English, the final classification, #6, is provided in Swedish.