This paper will be based on printed Latin texts from the late 15th and early 16th centuries that are based on the Arabic doctrine of the Great Conjunctions. This astrological theory was devised to predict the fortunes of religions and dynasties as well as other kinds of historical events, based primarily on the conjunctions of Saturn and Jupiter. Interestingly, many of these texts never provide the reader with systematic information on the entire set of astronomical data on which the predictions are based. For example, Paul of Middelburg, one of the foremost astronomers of the 15th century and successor of Regiomontanus at Padua, wrote an astrological prediction for the conjunction of Saturn and Jupiter in 1484 which runs, in the editio princeps, to 43 pages. The reader can only reconstruct the planetary alignment of the conjunction by collecting pieces of information that are scattered over the entire text. Another author, John of Lübeck (1474), active in the same university of Padua, applies a different method: He writes a prediction for the conjunction of 1504 in which he sets out providing systematic data regarding longitudes, latitudes and other parameters regarding the planetary alignment of the conjunction. My paper will investigate the ways how the authors of such texts generate, select and present the astronomical data. It will further try to provide explanations for the different strategies followed by the respective scientists.