CREATE TABLE table_73407 ("District" CLOB, "Vacator" CLOB, "Reason for change" CLOB, "Successor" CLOB, "Date successor seated" CLOB)

Name the reason for change pennsylvania 13th
SELECT "Reason for change" FROM table_73407 WHERE "District" = 'Pennsylvania 13th'
SELECT "Reason for change" FROM "table_73407" WHERE "District" = 'Pennsylvania 13th'