This paper presents a comparison between two transmit diversity schemes, namely space-time coding and time-switched transmit diversity (TSTD) over block-fading and time-varying multi-input single-output (MISO) channels with various channel parameters. The schemes are concatenated with outer channel codes in order to achieve spatio-temporal diversity. The analytical results are derived for the error performances of the systems and simulation results as well as outage probabilities are provided. It is demonstrated using the analytical and simulation results that TSTD may have a comparable error performance with the space-time coding techniques and it even outperforms the space-time codes in some scenarios. Our results indicate that TSTD can be suggested as an alternative to space-time codes in some time-varying channels especially due to its implementation simplicity.