A method of verifying the accuracy of the operation of an analyte monitoring device (M). The method comprises receiving control information from a test cartridge (100, 200, 200') with an analyte monitoring device, wherein the control information comprises a range of analyte concentration values for a control material (218), wherein the control material has a known and/or predetermined concentration of at least one analyte. The presence of the control material (218) is determined using the analyte monitoring device (M). The control material (218) is analysed to measure the concentration of the at least one analyte contained therein and the measured concentration of the at least one analyte is compared with the control information to determine if the measured concentration corresponds to the range of concentration values obtained from the control information. A pass or fail signal is provided to indicate whether the measured concentration falls within the range of analyte concentration values.