CREATE TABLE table_18424435_3 (written_by VARCHAR, canadian_viewers__million_ VARCHAR)

Who wrote the episodes watched by 1.575 million people in Canada?
SELECT written_by FROM table_18424435_3 WHERE canadian_viewers__million_ = "1.575"
SELECT "written_by" FROM "table_18424435_3" WHERE "1.575" = "canadian_viewers__million_"