Here we investigate to what extend the usual rules of thumb for selectivity are reflected in the reported selectivities in the literature. We found 14,240 and 663 inter-and intramolecular Pd-catalysed Heck reactions in Reaxys, using the search criteria described in SI. Out of the 14,240 intermolecular reactions, 628 and 13,041 give either α or β selectivity, respectively, while 571 give a mix of α and β. However, it should be kept in mind that studies sometimes only report the sought-after isomer. For example, we found two pairs of studies that report opposite selectivities for identical reactants and reaction conditions (Figure ). Bidentate Pd-ligands, along with either non-halogen aryl substitutents or halide scavengers, are usually taken as prerequisite for the cationic path. However, in many cases only the catalyst precursor, e.g. palladium(II) acetate (Pd(OAc) 2 ), is listed in Reaxys which do not necessarily mean that the reactions are carried out without Pd-ligands. We therefore focus on reactions that explicitly use a Pd catalyst with canonical monodentate (PPh 3 ) or bidentate (DPPP or DPPE) ligands, which are also the single most abundant ligands for reactions with α and β selectivities, respectively. This leaves us with 287 and 2,988 reactions with α and β selectivity, where the vast majority of ligands are bi-and monodentate, respectively. In addition there are 67 reactions that result in a mix of isomers, of which 46 use bidentate Pd-ligands. Next we determined the number of reactions that were performed using either triflate alkyl ligands or halide scavengers (Table ). These results show that out of the 287 reactions that are reported as α-selective, only 99 (34 %) were obtained with the reaction conditions that are generally thought necessary to produce α selectivity.