The invention relates to a method and apparatus for improving the measurement of the timing of touches of a touch screen. In an embodiment a method of determining a time at which a user touched a touch screen of an electronic device comprises obtaining (101) a touch signal generated by the touch screen for a first time period, the touch signal indicating when the user touched the touch screen during the first time period; obtaining (103) a sensor signal generated by a first sensor for at least the first time period, the sensor signal comprising a first signal component corresponding to a measurement by the first sensor of the user making contact with the touch screen; using (105) the touch signal to identify a time window in the sensor signal containing the first signal component; and processing (107) the windowed sensor signal to determine the timing of the first signal component in the sensor signal.