The discussion post presented by Lona Bailey reflects a profound understanding of single-study designs and its differences from experimental designs. Lona begins by stating that simple single-subject experimental design is a study designed with participants being placed in both the treatment group and the control group as opposed to certain participants being in the treatment and certain others being in control and/or randomly assigned in a true experiment. It is essential to recognize that a single-case study is unique because an individual case serves as its own control in comparison to two or more conditions. A study by WRITER indicates that single-case designs are useful in evaluating the effectiveness of interventions, and hence are considered as research tools.
Lona provides the analysis of both reversal designs and multi-baseline designs. In reversal designs, Lona indicates that they contain baseline period, treatment period, and baseline period. Also, reversal designs take the form of ABA designs, where the initial design (A) is considered the baseline. The multi-baseline designs focus on behaviors being measured over time with manipulation presenting at various points during the study with change in behaviors noted subsequently.
In the single-subject study, internal validity is ensured by the researcher through repeated measurements during the baseline phase. Specifically, the threat to internal validity controlled through repeated measurement includes maturation, instrumentation, and testing. In experimental designs, both internal and external threats affect validity. However, in experimental designs, ensuring both external and internal validity takes different approaches in addressing threats. These approaches include randomization, random assignment, utilization of control groups, and use of double-blind study.