Compare two different companies or compare one company vs ACME error before and Brand X error before and Hypothesized mean after maintenance after maintenance ACME ACME Brand X Brand X Altimeter Altimeter Altimeter Altimeter error before | error after error before error after Altimeter Altimeter Altimeter Altimeter Altimeter Altimeter |adjustment- adjustment- adjustment- adjustment- Brand A Brand B Brand C Brand D Brand E Brand F calibration calibration calibration calibration 42 38 16 47 42 39 41 9 14 0 38 32 35 6 4 7 11 8 5 0 29 4 18 12 6 32 4 33 4 4 26 31 22 38 25 4 33 9 30 36 28 10 12 42 25 9 26 29 20 21 22 3 32 1 32 45 32 25 25 42 38 4 5 19 32 5 29 10 10 9 44 10 40 45 32 19 7 17 4 11 29 5 14 34 31 9 13 23 3 31 37 27 23 30 11 34 39 13 20 27 38 36 26 15 48 42 1 31 25 6 15 14 33 45 29 10 2 36 43 43 34 19 14 14 11 11 10 22 8 49 18 12 26 9 11 1 38 10 4 20 49 23 2 29 9 20 26 36 32 25 42 5 32 43 43 46 47 17 3 43 3 19 46 3 23 36 44 5 5 26 19 0 17 10 12 47 10 12 32 *Note - Error (distance from zero) achieved by converting data to absolute values