Table: congress_changes_13
Columns: state_class
vacator
reason_for_change
successor
date_of_successor_s_formal_installation

Question: Who is the vacator for the February 1, 1971 date of successor's formal installation?
SQL: SELECT "vacator" FROM congress_changes_13 WHERE "date_of_successor_s_formal_installation" = 'february 1, 1971'

Question: What is the state of the senator with a November 14, 1972 date of successor's formal installation?
SQL: SELECT "state_class" FROM congress_changes_13 WHERE "date_of_successor_s_formal_installation" = 'november 14, 1972'