Error control techniques in the various digital data transmission systems can be divided into three classes, i.e., classes of forward error correction (FEC), automatic repeat request (ARQ), and FEC embedded within ARQ (Hybrid). We exactly analyze and compare the performances of these error control techniques in both independenterror and dependent-error channels. It is shown that among the various error control techniques the Go-Back-2 ARQ system offers the best performances over a wide range of the channel error rate, i.e.,

, regardless of the type of the channel. The various numerical results are shown graphically along with the discussions.