An apparatus comprising: an alternating current, AC, source; a pair of electrodes (214, 216); a reference load; a switching arrangement (261, 262) switchable between a first switch condition and a second switch condition; and measuring electronics, wherein in response to the switching arrangement (261, 262) being in the first switch condition, the AC source is applied across the reference load and the apparatus is configured to perform a first operation with respect to a resulting first voltage waveform across the reference load, wherein the first operation includes detecting when a peak voltage of the first voltage waveform occurs and determining a group delay of the measuring electronics based on when the detected peak voltage occurs; in response to the switching arrangement (261, 262) being in the second switch condition, the AC source is applied across the pair of electrodes (214, 216) and the apparatus is configured to perform a second operation with respect to a resulting second voltage waveform across the pair of electrodes (214, 216), wherein the second operation includes determining a calibrated second voltage waveform, the calibrated second voltage waveform being corrected for the group delay, wherein, when the pair of electrodes (214, 216) is in contact with a biological object, the apparatus is operable to determine a bioimpedance value of the biological object from the calibrated second voltage waveform. an alternating current, AC, source; a pair of electrodes (214, 216); a reference load; a switching arrangement (261, 262) switchable between a first switch condition and a second switch condition; and measuring electronics, wherein in response to the switching arrangement (261, 262) being in the first switch condition, the AC source is applied across the reference load and the apparatus is configured to perform a first operation with respect to a resulting first voltage waveform across the reference load, wherein the first operation includes detecting when a peak voltage of the first voltage waveform occurs and determining a group delay of the measuring electronics based on when the detected peak voltage occurs; in response to the switching arrangement (261, 262) being in the second switch condition, the AC source is applied across the pair of electrodes (214, 216) and the apparatus is configured to perform a second operation with respect to a resulting second voltage waveform across the pair of electrodes (214, 216), wherein the second operation includes determining a calibrated second voltage waveform, the calibrated second voltage waveform being corrected for the group delay, wherein, when the pair of electrodes (214, 216) is in contact with a biological object, the apparatus is operable to determine a bioimpedance value of the biological object from the calibrated second voltage waveform. in response to the switching arrangement (261, 262) being in the first switch condition, the AC source is applied across the reference load and the apparatus is configured to perform a first operation with respect to a resulting first voltage waveform across the reference load, wherein the first operation includes detecting when a peak voltage of the first voltage waveform occurs and determining a group delay of the measuring electronics based on when the detected peak voltage occurs; in response to the switching arrangement (261, 262) being in the second switch condition, the AC source is applied across the pair of electrodes (214, 216) and the apparatus is configured to perform a second operation with respect to a resulting second voltage waveform across the pair of electrodes (214, 216), wherein the second operation includes determining a calibrated second voltage waveform, the calibrated second voltage waveform being corrected for the group delay, wherein, when the pair of electrodes (214, 216) is in contact with a biological object, the apparatus is operable to determine a bioimpedance value of the biological object from the calibrated second voltage waveform.