Why does the S:x1 column disappear (presumably S:x1 goes into ID but I dont know why)? S is a factor, x1 is a covariate and ID is a factor.
rich.side<-aov(y~S*x1+ID) summary(rich.side) Below is the model frame model.frame(~S*x1+ID) S x1 ID 1 1 12 A 2 1 12 A 3 1 12 A 4 1 12 A 5 1 0 B 6 1 0 B 7 1 0 B 8 1 0 B 9 1 0 C 10 1 0 C 11 1 0 C 12 1 0 C 13 1 0 D 14 1 0 D 15 1 0 D 16 1 0 D 17 1 0 E 18 1 0 E 19 1 0 E 20 1 0 E 21 1 0 F 22 1 0 F 23 1 0 F 24 1 0 F 25 2 6 AB 26 2 6 AB 27 2 6 AB 28 2 6 AB 29 2 6 AC 30 2 6 AC 31 2 6 AC 32 2 6 AC 33 2 6 AD 34 2 6 AD 35 2 6 AD 36 2 6 AD 37 2 6 AE 38 2 6 AE 39 2 6 AE 40 2 6 AE 41 2 6 AF 42 2 6 AF 43 2 6 AF 44 2 6 AF 45 2 0 BC 46 2 0 BC 47 2 0 BC 48 2 0 BC 49 2 0 BD 50 2 0 BD 51 2 0 BD 52 2 0 BD 53 2 0 BE 54 2 0 BE 55 2 0 BE 56 2 0 BE 57 2 0 BF 58 2 0 BF 59 2 0 BF 60 2 0 BF 61 2 0 CD 62 2 0 CD 63 2 0 CD 64 2 0 CD 65 2 0 CE 66 2 0 CE 67 2 0 CE 68 2 0 CE 69 2 0 CF 70 2 0 CF 71 2 0 CF 72 2 0 CF 73 2 0 DE 74 2 0 DE 75 2 0 DE 76 2 0 DE 77 2 0 DF 78 2 0 DF 79 2 0 DF 80 2 0 DF 81 2 0 EF 82 2 0 EF 83 2 0 EF 84 2 0 EF 85 3 4 ABC 86 3 4 ABC 87 3 4 ABC 88 3 4 ABC 89 3 4 ABD 90 3 4 ABD 91 3 4 ABD 92 3 4 ABD 93 3 4 ABE 94 3 4 ABE 95 3 4 ABE 96 3 4 ABE 97 3 4 ABF 98 3 4 ABF 99 3 4 ABF 100 3 4 ABF 101 3 4 ACD 102 3 4 ACD 103 3 4 ACD 104 3 4 ACD 105 3 4 ACE 106 3 4 ACE 107 3 4 ACE 108 3 4 ACE 109 3 4 ACF 110 3 4 ACF 111 3 4 ACF 112 3 4 ACF 113 3 4 ADE 114 3 4 ADE 115 3 4 ADE 116 3 4 ADE 117 3 4 ADF 118 3 4 ADF 119 3 4 ADF 120 3 4 ADF 121 3 4 AEF 122 3 4 AEF 123 3 4 AEF 124 3 4 AEF 125 3 0 BCD 126 3 0 BCD 127 3 0 BCD 128 3 0 BCD 129 3 0 BCE 130 3 0 BCE 131 3 0 BCE 132 3 0 BCE 133 3 0 BCF 134 3 0 BCF 135 3 0 BCF 136 3 0 BCF 137 3 0 BDE 138 3 0 BDE 139 3 0 BDE 140 3 0 BDE 141 3 0 BDF 142 3 0 BDF 143 3 0 BDF 144 3 0 BDF 145 3 0 BEF 146 3 0 BEF 147 3 0 BEF 148 3 0 BEF 149 3 0 CDE 150 3 0 CDE 151 3 0 CDE 152 3 0 CDE 153 3 0 CDF 154 3 0 CDF 155 3 0 CDF 156 3 0 CDF 157 3 0 CEF 158 3 0 CEF 159 3 0 CEF 160 3 0 CEF 161 3 0 DEF 162 3 0 DEF 163 3 0 DEF 164 3 0 DEF -- Yours sincerely, Justin *I check my email at 9AM and 4PM everyday* *If you have an EMERGENCY, contact me at +447938674419(UK) or +60125056192(Malaysia)* [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.