CREATE TABLE table_18638 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

How many incumbents were first elected in 1930?
SELECT COUNT("Party") FROM table_18638 WHERE "First elected" = '1930'
SELECT COUNT("Party") FROM "table_18638" WHERE "First elected" = '1930'