//Correlational Analysis Example //created by John M. Quick //http://www.johnmquick.com //October 27, 2009 > #read the data into an R variable > datavar <- read.csv("dataset_readingTests.csv") > #attach the data variable > attach(datavar) > #display all data in set > datavar Subject Group PRE1 PRE2 POST1 POST2 POST3 1 1 Basal 4 3 5 4 41 2 2 Basal 6 5 9 5 41 3 3 Basal 9 4 5 3 43 4 4 Basal 12 6 8 5 46 5 5 Basal 16 5 10 9 46 6 6 Basal 15 13 9 8 45 7 7 Basal 14 8 12 5 45 8 8 Basal 12 7 5 5 32 9 9 Basal 12 3 8 7 33 10 10 Basal 8 8 7 7 39 11 11 Basal 13 7 12 4 42 12 12 Basal 9 2 4 4 45 13 13 Basal 12 5 4 6 39 14 14 Basal 12 2 8 8 44 15 15 Basal 12 2 6 4 36 16 16 Basal 10 10 9 10 49 17 17 Basal 8 5 3 3 40 18 18 Basal 12 5 5 5 35 19 19 Basal 11 3 4 5 36 20 20 Basal 8 4 2 3 40 21 21 Basal 7 3 5 4 54 22 22 Basal 9 6 7 8 32 23 23 DRTA 7 2 7 6 31 24 24 DRTA 7 6 5 6 40 25 25 DRTA 12 4 13 3 48 26 26 DRTA 10 1 5 7 30 27 27 DRTA 16 8 14 7 42 28 28 DRTA 15 7 14 6 48 29 29 DRTA 9 6 10 9 49 30 30 DRTA 8 7 13 5 53 31 31 DRTA 13 7 12 7 48 32 32 DRTA 12 8 11 6 43 33 33 DRTA 7 6 8 5 55 34 34 DRTA 6 2 7 0 55 35 35 DRTA 8 4 10 6 57 36 36 DRTA 9 6 8 6 53 37 37 DRTA 9 4 8 7 37 38 38 DRTA 8 4 10 11 50 39 39 DRTA 9 5 12 6 54 40 40 DRTA 13 6 10 6 41 41 41 DRTA 10 2 11 6 49 42 42 DRTA 8 6 7 8 47 43 43 DRTA 8 5 8 8 49 44 44 DRTA 10 6 12 6 49 45 45 Strat 11 7 11 12 53 46 46 Strat 7 6 4 8 47 47 47 Strat 4 6 4 10 41 48 48 Strat 7 2 4 4 49 49 49 Strat 7 6 3 9 43 50 50 Strat 6 5 8 5 45 51 51 Strat 11 5 12 8 50 52 52 Strat 14 6 14 12 48 53 53 Strat 13 6 12 11 49 54 54 Strat 9 5 7 11 42 55 55 Strat 12 3 5 10 38 56 56 Strat 13 9 9 9 42 57 57 Strat 4 6 1 10 34 58 58 Strat 13 8 13 1 48 59 59 Strat 6 4 7 9 51 60 60 Strat 12 3 5 13 33 61 61 Strat 6 6 7 9 44 62 62 Strat 11 4 11 7 48 63 63 Strat 14 4 15 7 49 64 64 Strat 8 2 9 5 33 65 65 Strat 5 3 6 8 45 66 66 Strat 8 3 4 6 42 > #How is pretest 1 related to posttest 1? > #use cor(VAR1, VAR2) to get the correlation between variable 1 and variable 2 > cor(PRE1, POST1) [1] 0.5659026 > #How are all of the variables related to each other? > #use cor(DATAVAR) to get the correlations between all variables > cor(datavar) Subject Group PRE1 PRE2 POST1 POST2 POST3 Subject 1.0000000 NA -0.19209882 -0.1182547 0.10308079 0.40518032 0.19488006 Group NA 1 NA NA NA NA NA PRE1 -0.1920988 NA 1.00000000 0.3348806 0.56590255 0.08883615 -0.03740325 PRE2 -0.1182547 NA 0.33488057 1.0000000 0.34514482 0.20580036 0.18093653 POST1 0.1030808 NA 0.56590255 0.3451448 1.00000000 0.06439532 0.47008487 POST2 0.4051803 NA 0.08883615 0.2058004 0.06439532 1.00000000 -0.04191999 POST3 0.1948801 NA -0.03740325 0.1809365 0.47008487 -0.04191999 1.00000000