Table 4. 2018 yellow fever experiment results.
*P < 0.05, **P < .01, ***P < .005 (two-sided); OLS models with robust standard errors. Respondents are members of Survey Sampling International’s online panel in Brazil. For each outcome measure, higher values indicate greater belief in the claim or claims in question [measured on a Likert scale ranging from “not at all accurate” (1) to “very accurate” (4); see the Supplementary Materials for wording]. “Misperception belief” is a composite measure calculated as the mean of the three items listed. All misperception measures are false. “T” and “F” indicate true and false, respectively, for the other outcome measures.
| (A) Correction effects on targeted yellow fever misperceptions | |||||||||
|
Misperception beliefs (mean) |
Yellow fever vaccine ineffective |
Life-threatening side effects |
Propolis protects from yellow fever | ||||||
| Myths correction | −0.20*** | −0.03 | −0.20*** | −0.38*** | |||||
| (0.04) | (0.06) | (0.06) | (0.06) | ||||||
| Constant (placebo) | 1.98*** | 1.82*** | 2.00*** | 2.13*** | |||||
| (0.03) | (0.04) | (0.04) | (0.04) | ||||||
| n | 1063 | 1072 | 1072 | 1075 | |||||
| (B) Correction effects on other yellow fever beliefs | |||||||||
|
Spreads via mosquito bite (T) |
No effective vaccine (F) |
Same mosquito as Zika (T) |
Symptoms include fever, vomiting (T) |
Disease can be fatal (T) |
Government recommends vaccine (T) |
Yellow fever in cities (T) |
Vaccine causes immune damage (F) |
Hoax by drug companies (F) |
|
| Myths correction |
0.04 | 0.01 | 0.36*** | 0.02 | −0.07* | 0.11 | 0.03 | −0.14* | 0.03 |
| (0.04) | (0.05) | (0.06) | (0.04) | (0.04) | (0.06) | (0.04) | (0.06) | (0.05) | |
| Constant (placebo) |
3.77*** | 1.55*** | 3.10*** | 3.68*** | 3.82*** | 3.09*** | 3.51*** | 2.01*** | 1.45*** |
| (0.03) | (0.03) | (0.05) | (0.02) | (0.02) | (0.04) | (0.03) | (0.04) | (0.03) | |
| n | 1068 | 1077 | 1070 | 1075 | 1073 | 1073 | 1073 | 1074 | 1068 |