Noble D, Smith D, Mathur R et al. Feasibility study of geospatial mapping of chronic disease risk to inform public health commissioning. BMJ Open 2012;2:e000711. In the section ‘Strengths of this study’ it was reported that only one data field (family history of diabetes) contained a significant proportion of missing data.  In fact, this variable is only recorded if positive and therefore it cannot be said whether or not it has a significant proportion of missing data.