People who are given an intervention may feel as if their situation has improved (for example, they may feel that they were better able to respond to extreme weather events, if they were told that by changing their farming practices they would be less impacted by drought). This is because they believe they are getting a superior intervention and anticipate an improved situation. This can happen even if the intervention isn’t actually better than the comparison. It is called a “placebo effect”.
Knowing which intervention they got and having expectations about it can also change the way people behave. For example, a farmer who is told that a new variety is more pest resistant, may also check their crop for pests more frequently and deal with outbreaks more quickly, so they may have less pest damage because of their behaviour rather than the variety of crop.
One way of keeping this from happening is not to let the people who receive the interventions know which intervention they got (to “blind” them). Blinding is not always feasible for agricultural interventions due to their nature.
REMEMBER: Think about whether the farmers in the comparison groups knew which intervention they received and, if so, whether that may have changed how they felt or behaved.