Count the different affiliations of the authors of 'Data-driven algorithms for dimension reduction in causal inference'.
How many different affiliations do the authors of 'Data-driven algorithms for dimension reduction in causal inference' have?
SELECT (COUNT(DISTINCT ?answer) AS ?count) WHERE { <https://dblp.org/rec/journals/csda/PerssonHWL17> <https://dblp.org/rdf/schema#authoredBy> ?x . ?x <https://dblp.org/rdf/schema#primaryAffiliation> ?answer }
<https://dblp.org/rec/journals/csda/PerssonHWL17>