Dear R users, This works as expected: ? plot(density(c(1,2, 3, 4, 5, NA), na.rm=TRUE)) This raises an error ? plot(density(c(1,2, 3, 4, 5, NA), na.rm=TRUE, weights=c(1, 1, 1, 1, 1, 1))) ? plot(density(c(1,2, 3, 4, 5, NA), na.rm=TRUE, weights=c(1, 1, 1, 1, 1, NA))) This seems to work (it triggers a warning that the weights don?t add up to 1, which makes sense*): ? plot(density(c(1,2, 3, 4, 5, NA), na.rm=TRUE, weights=c(1, 1, 1, 1, 1))) Questions ? But shouldn?t the na.rm filter also filter the corresponding weights? ? Extra question: In case the na.rm filter is changed to filter the weights, the check for sum(weights) == 1 might trigger false positive warnings since the weights might not add up to 1 anymore Best wishes, Matthias [[alternative HTML version deleted]]