Table 4.

Contingent group lotteries intervention: Diagnosis and Design

DIAGNOSIS PHASE		DESIGN PHASE
Identified Actionable bottlenecks	Behavioral economic rationale	Original intervention design elements	Implementation challenge	Revised design
Costs (time, lost wages, dislike of insecticide, distrust) are immediate and salient.	Lottery leverages present bias by making the intangible benefits of spraying more immediate [49, 50].	Contiguous households are assigned to lottery groups of 6. Lottery groups are randomly assigned a lottery number. In a lottery drawing following the attack phase of the campaign, households whose lottery group is selected and who participated in spraying will win a small prize such as a food basket.	The Ministry of Health preferred that lottery prizes be related to vector control. Agreed-upon prize (gift card to home repair store) could not be carried out when home store discontinued use of gift cards. Block structure did not always allow for lottery groups of size 6. Houses assigned to lottery groups using campaign maps were occasionally abandoned or had split into multiple households	A gift card to a large home repair store was selected as the lottery prize, to focus winners on purchasing supplies to improve home against vector infestation. A local hardware store agreed to accept vouchers developed by the research team. The hardware store recorded the content of purchases made with vouchers Lottery groups could range in size from 5 to 7 households, allowing for a group to lose or gain a household in the field.
Benefits are intangible, probabilistic, and far in the future.	Immediate feedback and rewards can increase desired behavior.	Lottery prizes are awarded to households as soon as possible after the participation decision.	Unpredictable timing of spray campaign made immediate notification of lottery prizes impossible.	Lottery groups were assigned a lottery date several weeks in the future. Study team visited winning households within a few weeks of lottery drawing.
No perceived cost to refusing participation.	Invoke anticipated regret, leveraging regret aversion [51, 52]	Lottery procedure notifies winning households and non-participating households who could have won.	Households and some field staff assumed the households only entered the lottery if they sprayed.	Ongoing training and fidelity checking of field staff needed.
Spraying perceived as signifying infestation	The lottery may mitigate any stigma associated with participation [53, 54]	Households can attribute spraying participation to lottery incentives.
Some neighborhoods report little awareness of neighbors’ participation decisions.	Making neighbor participation more salient through creation of lottery groups will increase each household’s motivation to participate. [55]	If all households in the selected group participated, each participating household also wins an inexpensive tablet computer.	The Ministry of Health preferred that lottery prizes be related to vector control.	Lottery prize if all households in the group participated was a voucher twice the value (USD 34) of the individual prize.