AbstractThe author of the article“Error Ellipse”(Survey Review, Oct. 1971) is to be congratulated for reintroducing this topic which is becoming of every day interest to practising surveyors, who have access to a computer, and for whom the restrictions imposed by the tedium of unnecessary computation have been relaxed. A topic that was previously of academic interest is becoming commmonplace. The error ellipse is a clear visual device expressing the precision of adjusted quantities, in particular the precision of the points of a surveying network adjusted by the method of variation of coordinates. However, the data from which the error ellipses are constructed are more usually obtained as bi-products of the adjustment, rather than as speculated errors in observations, as the original article described. The purpose of this note is to augment the previous article to cater for this form of input.