Time series design is one of the types of quasi-experimental designs. In this design, the measurements of similar variables are considered at different points. It can be used effectively in collaboration with official data. Throughout a programmed intervention, the successive observations are comprised by the design and the features of the change process are assessed by it. The effect of one or more treatments on a single case can be evaluated through this type of time-series design. In this design, the case may be related to any entity that forms the research unit, like, a family or a school.

Two relevant ethical considerations that must be considered when conducting single-subject experimental time-series research are: (a) requiring the informed consent of the participant, and (b) unique conditions involved within the structure of single-subject design for research must be discussed with potential participants.

For informed consent, the information related to all of the aspects of the research, like, data collection, confidentiality, measurement, and purpose must be provided. The possibility of premature withdrawal of treatment and the need for repeated baseline measurements are two conditions unique to single-subject design research.  

In group counseling research, the sample size is one of the main hurdles faced. By using single-subject experimental time-series designs, this issue of a sample size could be circumvented by researchers in the counseling profession. In family and group research, the group can be studied as an entity by the researcher through time-series designs and without lining up a huge number of subjects, the real client groups can be used. In addition to this, extraneous confounds are minimized, measurement is standardized and the change over time in a particular context is understood by time-series designs.