CREATE TABLE table_37702 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" TEXT, "Result" TEXT)

When was republican incumbent Joseph McKenna first elected?
SELECT "First elected" FROM table_37702 WHERE "Party" = 'republican' AND "Incumbent" = 'joseph mckenna'
SELECT "First elected" FROM "table_37702" WHERE "Incumbent" = 'joseph mckenna' AND "Party" = 'republican'