Giving Compass' Take:

• India Development Review explains why and how randomized controlled trials (RTCs) are used to prove (or disprove) hypotheses. 

• How can funders support and use RTC's to advance philanthropic work? 

• Read about the role of RTCs in social progress. 

What is an RCT and how does it work? 
An RCT is an evaluation technique that can be used to measure whether a particular programme is working: whether it has any impact, and how large that impact is. Essentially, it is an experiment designed to establish a cause-effect relationship, and isolate the influence that a particular intervention has on a certain outcome.

Participants in an RCT are randomly assigned to different groups—control groups and treatment groups. The concept of a control group and treatment group has roots in clinical trials, and the method of random assignment to these groups was developed through agricultural experiments in the 1920s.

The treatment group receives the programme or intervention being evaluated, while the control group does not. Statistically, both the control and treatment group are assumed not only to be representative of the larger group from which they are culled (and so what is discovered about them is arguably true about the larger group as well), but also equivalent to each other.

Before the programme or intervention is introduced, the two groups are thought to be the same. Proponents of RCTs believe that any difference that subsequently arises between them can then be attributed to the programme or intervention.

Control and treatment groups can be segregated at various levels: an individual level; or cluster levels—households, schools, villages, blocks, and so on—according to feasibility and ethicality, which will be discussed later.

However, it is important to note that RCTs do not always require a ‘no treatment’ control group. Randomisation can just as easily be used to compare different versions of the same programme, different interventions within a programme, or when resources are scarce—it can simply be a method of selecting who receives access to a particular intervention in a seemingly unbiased way. There are multiple ways of designing randomisation: lottery design, phase-in design, rotation design, encouragement design, and so on.

The RCT approach can be used across sectors and adapted to a number of different circumstances. In India, the first RCT was carried out with Seva Mandir in 1996, and today, RCTs are used in multiple sectors, including education, health, and agriculture.

Why are RCTs used? 
There are often various factors at play within development programmes, and narrowing in on which variables most significantly affect outcomes can be challenging. RCTs are therefore used to zero in on which aspects of the programme are affecting change and creating impact.

Measuring impact often involves comparisons: to what extent has the programme affected a group or community compared to if it had never been implemented in the first place? Because this is a question that is difficult to measure directly, the control group serves as an indicator of what the absence of the programme would reflect (referred to as the ‘counterfactual’).

Read the full article about randomized controlled trials at India Development Review.