malaria <-
structure(list(treatment = structure(c(2L, 2L, 2L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = c("placebo", 
"vaccine"), class = "factor"), outcome = structure(c(1L, 1L, 
1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 
1L, 1L), .Label = c("infection", "no infection"), class = "factor")), row.names = c(NA, 
-20L), class = c("tbl_df", "tbl", "data.frame"))