2. Description of experimental design The study is a combination of a group time-series quasi-experimental design and a a variation of a double randomised consent design. The study comprises four groups of households, three of which include patients on ARV treatment (Figure 1). The provision of ARV treatment represents a quasi- or field experiment, while the peer adherence support and nutritional interventions represent a randomised-control experiment executed in accordance with a Zelen-type double randomised consent design. This study design is deemed appropriate given the fact that: blinding is not practicable or possible; the use of classical randomisation and informed consent procedures significantly threatens internal validity; the interventions are highly attractive; the control group receives standard care; the study focuses on a clinically relevant objective(s) and offers important new insights (Kaptchuk, 2001; MacLehose et al, 2001; Rains & Penzien, 2005).