Amara conducted a field experiment to investigate whether shoppers in a busy retail park are more likely to sign a petition for a local green initiative depending on whether there is a large promotional placard next to the researcher. She used two conditions: in one condition, she stood next to a promotional placard, and in the other condition, she stood alone with no placard. Each shopper was only observed once, in one of the two conditions.

Table 1: Number of shoppers who signed or did not sign the petition