You must have COMPUT enabled. You must have run more than one test to calculate statistics. Press the M key. Use the up or down arrow keys to highlight STATS. Press the TDX key. Press the X key do not erase. Press the X key. The statistic values are displayed on the main screen. Press the MAX key until CPI is displayed in the lower right corner. Now press the M key. You will notice STATS are displayed as computed values.