CREATE TABLE table_327 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

How many episodes did David Jackson write and direct?
SELECT COUNT("Written by") FROM table_327 WHERE "Directed by" = 'David Jackson'
SELECT COUNT("Written by") FROM "table_327" WHERE "Directed by" = 'David Jackson'