<u>Table 6: Ad recall at endline</u>

||All resp|ondents|Solid|house|Non-s|olid house|
|---|---|---|---|---|---|---|
||(1)|(2)|(3)|(4)|(5)|(6)|
|T|0.030<sup>_∗∗_</sup>|0.033<sup>_∗∗_</sup>|0.049<sup>_∗∗_</sup>|0.049<sup>_∗∗_</sup>|0.011|0.009|
||(0.014)|(0.013)|(0.024)|(0.023)|(0.023)|(0.023)|
|Individual controls||✓||✓||✓|
|Cluster controls||✓||✓||✓|
|Observations|1492|1492|728|728|764|764|
|Adj. R-squared|0.000|0.002|0.003|0.004|-0.001|0.001|
|Mean in control|0.114|0.114|0.101|0.101|0.126|0.126|

Each observation is an individual. Responses collected in the endline survey between December 15, 2020 and January 31, 201 are included. T is the treatment indicator. Solid house is a binary indicator equal to 1 if the individual lives in a dwelling made of stones, bricks, cement or concrete. State fixed-effects are included in all specifications. Individual controls include gender, age, household size, caste, education, distance to the medical center, employment and student status, religion, presence of pregnant woman in the house, ownership of bednet and air conditioner, and 5-year malaria incidence at baseline. Cluster controls are reported in Table 1. Standard errors are clustered at the district level.<sup>_∗_</sup> _p <_ 0 _._ 1,<sup>_∗∗_</sup> _p <_ 0 _._ 05,<sup>_∗∗∗_</sup> _p <_ 0 _._ 01 theoretically more likely to be exposed to and remember the campaign.<sup>36</sup> While the table confirms both hypotheses, the effect is only evident for respondents living in solid dwellings. Among them, ad recall significantly increased only for individuals under 26 (by 16 p.p.) and for those expressing at least some concern about malaria (by 9 p.p.). By contrast, among residents of non-solid dwellings, the coefficients for both younger respondents and those more concerned about malaria were close to zero and statistically insignificant. This lack of recall effect, including those theoretically more receptive to the campaign, suggests the ad content may not have effectively reached this population. To substantiate this hypothesis, we conducted the following _feed_ experiment.

# **6.2 Individual-level** **_Feed_ Experiment**

To differentiate between limited ad effectiveness and limited reach of the ad campaign, in April 2021 we nested an individual-level study at the end of the cross-sectional survey (January-March 2021, see timeline 4.3). This study ensured that the campaign ads were distributed equally to both solid and non-solid dwellers (balancing also across gender, caste, education, as well as the treatment assignment of their district in the MNM ad campaign). In other words, by maintaining exposure to the campaign ads constant, this experiment offers a direct assessment of ad effectiveness on both types of households.

Specifically, after completing the cross-sectional survey of the broader trial, respondents were asked if they would be open to being contacted again within 1 to 3 months. To enhance statistical power, we also recruited a new group of participants using the same Facebook Ads and methodology of the longitudinal and cross-sectional samples. Those who agreed to take part in this study were randomly placed into either a treatment or control group, ensuring that each dwelling type was equally represented in each group. We used Facebook remarketing tool to show ads in the Facebook

> 36We expect ad recall to be larger among younger respondents, since they spend more time on social media and thus have more exposure to ads. We also expect larger recall rates among respondents with higher levels of concern about getting malaria, since they would pay more attention to malaria-related ads if these appeared on their feeds.

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