Experimental and fitted regression data using a nonsignificantly correlated VLU data set. Residuals are distributed less randomly about zero and are larger in magnitude, particularly at week #12 (2.27). Unusually large residuals are typically not attributable to regression variation, resulting in a poor model fit.
Cardinal et al. BMC Dermatology 2009 9:2 doi:10.1186/1471-5945-9-2