Math 3070 § 1. Treibergs Debate Data: Tabulating Two-Way Tables Name: Example May 19, 2011 In this example, we consider a common data manipulation question, following Elliott’s Learning SAS in the Computer Lab, 2nd. ed., Brooks/Cole, 2000 Module 20. This data processing task used to be done fifty years ago by collating machines, the “I. B. M. Machines,” that made Big Blue big. Debate coach Ronda Nielson of Skyline High School wanted to know if Granger, Hunter, Kearns and Skyline differed in the effectiveness of debate classes in teaching valuable life skills, at least according to opinions of debaters. A survey asked debaters to rate how their debate class compares in teaching skills to other classes. They gave the ratings 1 =more effective, 2 =just as effective, 3 =less effective, which were stored in the variable Compared. The task of the analyst is to cut the data set down to the four high schools in question and to the variables School and Compared. The number of responses in each category are counted. Some respondents didn’t answer all the questions, so that missing values had to be omitted. Once frequencies are available, the differences in high schools can be tested using the χ2 -test for homogeneity. The high p-value indicates that the high schools were not significantly different in responses to the question comparing debate to other classes. We further illustrate how to assemble tables that give the frequency, percentages and expected values of cells, and to display them in a way similar to how the SAS frequency procedure arranges output. Data File Used in this Analysis: # Math 3070 - 1 Debate Data May 18, 2011 # Treibergs # # From Elliott, Learning SAS in the Computer Lab, 2nd ed, Brooks/Cole 2000 # # Data collected from Granite School District of Utah debate students survey # by Ronda Nielson of Skyline HS. Questions were on debate classes. # # Variables # # Number Survey number # School (1=Cottonwood, 2=Cyprus, 3=Granger, 4=Granite, 5=Hunter, 6=Kearns, # 7=Olympus, 8=Skyline, 9=Taylorsville) # Gender (1=male 2=female) # Compared How debate compares in teaching skills # (1=more effective, 2=just as effective, 3=less effective) # Argumentation Effectiveness of speech/debate in teaching # (1=very effective, 2=somewhat effective,3=not at all effective) # Research (same as Argumentation) # Reasoning (same as Argumentation) # Speaking (same as Argumentation) Number School Gender Compared Argumentation Research Reasoning Speaking 1 6 1 1 1 1 1 1 108 7 1 1 1 1 1 2 56 3 1 1 1 1 1 1 55 8 1 1 1 2 1 1 54 8 1 1 1 2 1 1 1 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 299 298 297 296 295 294 293 292 291 290 289 288 287 286 285 284 283 282 281 280 279 317 316 315 314 300 277 278 109 251 252 8 8 8 8 8 8 8 9 9 8 8 8 8 8 8 8 8 8 8 8 8 1 1 1 1 1 1 1 1 1 1 1 1 8 1 1 1 1 1 1 1 1 1 1 1 1 1 3 3 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1 1 1 1 1 1 2 1 1 1 1 2 1 1 . 1 1 2 2 . 1 1 2 1 2 2 1 1 1 1 1 1 1 1 1 1 1 . 1 1 1 . 1 1 3 1 1 1 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 2 1 1 . 2 1 2 1 . 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 . 2 1 1 . 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 . 1 1 2 1 . 1 1 2 1 1 1 1 1 1 1 1 2 1 1 1 1 1 . 1 1 1 . 1 1 2 3 2 1 2 1 1 1 1 . 1 1 1 1 1 1 1 2 1 2 1 1 6 66 65 64 63 62 61 60 59 58 57 123 122 121 120 119 118 117 116 115 114 113 112 111 110 107 106 105 104 103 102 101 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 6 6 5 . 6 6 6 5 6 6 7 7 7 7 7 7 7 . 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 7 7 5 5 5 5 5 5 5 5 5 5 5 . 5 5 5 5 5 2 1 2 1 1 1 2 1 2 2 2 1 2 2 2 1 1 . 2 2 2 2 2 2 1 2 2 2 2 1 2 2 1 1 1 2 1 2 1 1 2 1 1 1 2 1 1 1 1 2 . 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 1 1 1 2 1 2 1 1 1 1 2 2 1 1 1 1 1 2 1 1 1 1 1 1 1 1 2 1 1 1 1 2 1 1 1 1 1 1 2 1 1 1 1 . 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 3 2 2 3 3 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 1 1 2 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 1 1 1 7 78 77 76 75 74 73 72 71 70 69 5 5 5 6 5 5 5 6 6 6 1 1 1 2 1 2 2 1 1 2 1 1 1 1 2 2 1 1 1 1 2 1 1 1 1 1 1 1 1 1 2 1 1 2 2 2 1 1 1 1 2 2 1 1 1 1 1 1 1 1 2 1 1 1 2 1 1 1 1 1 R Session: R version 2.11.1 (2010-05-31) Copyright (C) 2010 The R Foundation for Statistical Computing ISBN 3-900051-07-0 R is free software and comes with ABSOLUTELY NO WARRANTY. You are welcome to redistribute it under certain conditions. Type ’license()’ or ’licence()’ for distribution details. Natural language support but running in an English locale R is a collaborative project with many contributors. Type ’contributors()’ for more information and ’citation()’ on how to cite R or R packages in publications. Type ’demo()’ for some demos, ’help()’ for on-line help, or ’help.start()’ for an HTML browser interface to help. Type ’q()’ to quit R. [R.app GUI 1.34 (5589) i386-apple-darwin9.8.0] > > > > # Read the data file. Note that this file uses the "." for missing data # instead of "NA" which is standard for R. tt <- read.table("M3074DebateData.txt",header=T,na.strings=".") tt Number School Gender Compared Argumentation Research Reasoning Speaking 1 1 6 1 1 1 1 1 1 2 108 7 1 1 1 1 1 2 3 56 3 1 1 1 1 1 1 4 55 8 1 1 1 2 1 1 5 54 8 1 1 1 2 1 1 6 53 8 1 1 1 1 1 1 7 52 8 1 1 1 1 1 1 8 51 8 1 2 1 1 1 1 9 50 8 1 1 1 2 1 2 10 49 8 1 1 1 1 1 1 11 48 8 1 1 2 2 2 1 12 47 8 1 1 1 1 1 1 13 46 9 2 1 1 2 1 1 14 45 9 2 2 1 2 1 1 8 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 44 43 42 41 40 39 38 37 36 35 34 33 299 298 297 296 295 294 293 292 291 290 289 288 287 286 285 284 283 282 281 280 279 317 316 315 314 300 277 278 109 251 252 253 254 255 258 319 256 257 259 260 8 8 8 8 8 8 8 8 8 8 8 8 1 1 1 1 1 1 1 1 1 1 1 1 8 1 1 1 1 1 1 1 1 1 1 1 1 1 3 3 7 7 7 7 7 7 7 3 7 7 7 7 2 1 1 1 NA 1 1 1 1 1 1 1 2 1 1 1 1 2 2 1 2 1 1 2 1 2 1 2 2 1 1 2 1 1 2 1 1 1 1 1 1 1 1 2 1 2 NA 1 2 2 1 2 2 1 1 1 1 2 1 1 1 1 2 2 1 NA 1 1 1 2 1 1 1 1 1 2 1 1 1 NA 1 1 2 1 1 1 2 1 1 1 1 1 1 1 1 1 2 1 1 1 2 1 1 NA 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 2 1 1 2 1 1 1 1 9 2 1 1 1 2 2 1 1 1 2 2 2 2 1 1 1 1 1 1 1 1 1 2 2 1 1 1 2 1 1 2 1 1 1 1 2 1 1 1 1 1 NA 1 2 1 1 2 1 1 1 2 2 1 1 1 1 1 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 263 264 265 266 267 268 269 270 271 272 273 274 275 276 261 262 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 32 31 30 29 28 27 26 25 24 23 22 21 20 12 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 3 3 3 3 9 9 9 9 3 3 3 3 3 3 3 3 3 3 7 7 7 7 7 2 2 2 2 2 2 2 2 2 2 2 2 2 1 1 2 2 1 1 2 2 2 2 1 2 2 1 1 1 1 2 1 1 2 1 1 2 1 2 1 1 1 2 1 1 2 1 1 1 2 1 1 2 2 1 2 1 1 2 1 2 1 2 1 2 1 1 1 1 1 1 1 1 2 2 1 1 2 2 2 2 1 1 1 1 1 2 1 2 2 2 2 2 2 1 1 1 1 1 1 1 2 3 2 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 1 1 1 1 2 2 1 1 2 1 1 2 1 1 1 1 1 1 2 3 1 2 1 1 1 2 1 1 1 1 1 2 1 1 2 1 2 1 1 1 1 1 1 1 1 1 2 1 10 2 1 1 1 1 2 1 1 1 1 2 1 2 1 3 2 2 1 1 2 1 1 1 1 1 2 1 3 2 1 1 1 1 2 1 1 1 3 2 1 1 1 1 2 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 2 2 2 1 1 1 1 1 1 1 2 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 2 2 1 1 1 1 1 1 2 1 1 2 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 13 14 15 19 18 17 16 11 10 9 8 7 6 5 4 3 2 228 227 226 225 224 223 222 221 220 219 218 215 214 217 216 213 212 211 210 209 208 207 206 205 204 203 202 201 200 199 198 197 196 195 194 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 4 5 3 3 NA 3 3 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 2 1 2 2 2 1 1 1 1 1 1 1 1 1 2 1 2 1 2 NA 1 2 1 2 2 2 2 1 1 2 2 1 2 1 1 2 2 1 1 1 1 1 1 2 1 2 2 2 1 2 1 2 1 1 2 2 1 1 1 1 1 2 1 2 1 1 2 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 1 1 1 1 1 1 2 2 2 2 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 1 1 1 2 1 1 1 1 1 2 11 1 1 3 3 2 1 1 2 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 NA 1 2 1 2 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 2 1 1 2 1 1 1 1 1 2 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 NA 1 1 1 2 1 1 2 1 1 1 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 193 192 320 321 191 190 189 188 187 184 183 182 181 180 179 178 177 176 175 174 173 171 170 169 168 167 166 165 164 163 162 161 343 342 341 340 339 338 337 336 335 334 333 332 331 330 329 328 327 326 325 344 9 9 8 7 9 9 9 9 9 7 9 9 9 9 9 9 9 9 9 9 NA 9 NA 9 9 9 3 9 9 9 9 9 6 6 6 NA 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 1 1 1 2 2 2 2 1 1 1 1 2 1 2 1 2 1 2 1 2 2 1 1 2 2 1 2 1 1 1 1 2 1 2 2 1 2 2 1 1 1 1 2 2 2 1 2 2 1 1 1 1 2 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 2 2 1 1 1 1 2 1 1 1 1 2 1 1 1 2 1 2 1 1 1 1 2 1 2 1 1 1 1 2 2 1 1 1 2 1 1 2 1 1 1 1 2 2 1 1 2 1 1 2 2 1 NA 1 1 1 1 2 1 1 1 1 NA 1 1 1 2 2 1 1 2 1 1 NA 2 1 1 1 NA 1 1 2 12 2 1 1 1 2 2 1 2 2 1 1 2 NA 1 2 1 2 2 1 1 1 1 NA 1 1 2 1 1 2 1 1 1 NA 2 1 1 2 1 1 2 1 2 1 NA 1 1 2 2 NA 1 1 2 1 1 1 1 2 1 2 1 1 1 1 1 2 2 1 1 1 1 1 2 1 1 1 1 1 1 1 2 2 1 1 1 NA 1 1 1 2 1 1 1 1 1 1 NA 2 1 2 1 NA 1 1 1 1 1 1 1 3 2 1 1 1 1 1 1 2 2 1 1 2 1 1 2 1 1 1 1 1 1 1 1 NA 1 1 1 NA 1 1 1 1 1 1 1 1 1 1 NA 1 1 2 1 NA 1 1 2 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 324 322 323 160 345 159 158 157 156 155 154 153 152 143 142 151 150 149 148 147 146 145 144 141 140 139 138 137 136 135 134 133 132 131 130 129 128 127 126 125 124 68 67 66 65 64 63 62 61 60 59 58 6 6 6 7 6 7 9 9 9 8 8 8 8 7 7 8 8 8 8 8 9 9 9 7 7 7 7 7 7 7 7 NA NA NA 9 9 9 9 9 NA 7 6 6 6 6 5 NA 6 6 6 5 6 1 1 2 1 1 1 2 2 1 1 2 1 1 2 1 1 1 1 1 1 2 1 2 1 1 2 1 1 1 1 1 2 1 2 1 2 1 2 1 2 2 1 1 2 1 2 1 1 1 2 1 2 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 2 1 2 1 2 2 1 1 1 2 1 2 2 1 2 1 1 3 2 2 2 2 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 1 1 1 NA 1 1 2 2 2 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 13 1 2 2 1 1 1 1 1 1 1 1 1 1 1 NA 1 1 1 NA 1 1 3 1 1 1 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 2 1 1 NA 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 NA 1 1 1 NA 1 1 2 3 2 1 2 1 1 1 1 NA 1 1 1 1 1 1 1 2 1 2 1 1 1 1 2 1 1 1 1 1 1 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 57 123 122 121 120 119 118 117 116 115 114 113 112 111 110 107 106 105 104 103 102 101 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 6 7 7 7 7 7 7 7 NA 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 7 7 5 5 5 5 5 5 5 5 5 5 5 NA 5 5 5 5 5 5 5 5 6 5 5 5 6 6 2 2 1 2 2 2 1 1 NA 2 2 2 2 2 2 1 2 2 2 2 1 2 2 1 1 1 2 1 2 1 1 2 1 1 1 2 1 1 1 1 2 NA 2 1 1 1 2 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 1 1 1 1 1 1 1 1 1 1 1 2 1 2 1 1 1 1 2 2 1 1 1 2 1 1 1 1 1 1 1 1 14 1 1 2 1 1 1 1 2 1 1 1 1 1 1 2 1 1 1 1 NA 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 3 2 2 3 3 1 2 1 2 1 1 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 1 1 1 1 1 1 1 NA 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 1 1 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NA 1 1 1 1 1 1 1 1 1 NA 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 1 1 1 2 1 1 1 2 1 1 1 1 327 69 6 2 1 1 1 1 1 > # we can check the variables available. > names(tt) [1] "Number" "School" "Gender" "Compared" "Argumentation" "Research" [7] "Reasoning" "Speaking" > > ############## CUT THE DATA FRAME TO FOUR HIGH SCHOOLS AND NO NA’S ############### > # We use the subsetting command. The logical condition includes the desired HS and > # excludes NA’s. select= picks the two desired columns "School" and "Compared". > > tt2 <- subset(tt,(School==3 | School==5 | School==6 | School==8 ) & + !(is.na(School) | is.na(Compared)),select=c(2,4)) > tt2 School Compared 1 6 1 3 3 1 4 8 1 5 8 1 6 8 1 7 8 1 8 8 2 9 8 1 10 8 1 11 8 1 12 8 1 15 8 2 16 8 1 17 8 1 18 8 1 19 8 1 20 8 2 21 8 1 22 8 1 23 8 1 24 8 1 25 8 2 26 8 2 39 8 1 53 3 1 54 3 1 62 3 1 83 3 1 84 3 1 85 3 1 86 3 1 91 3 2 92 3 2 93 3 2 94 3 2 95 3 2 96 3 1 97 3 1 15 98 99 100 135 136 137 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 160 161 162 163 164 165 173 197 203 204 205 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 3 3 3 5 3 3 3 3 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 3 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 2 1 2 1 1 1 1 2 1 2 1 1 1 1 16 222 223 224 225 227 232 233 234 235 238 239 240 241 242 264 265 266 267 268 270 271 272 273 274 275 293 294 295 296 297 298 301 302 303 304 305 306 307 308 309 310 311 313 314 315 316 317 318 319 320 321 322 6 6 6 6 6 8 8 8 8 8 8 8 8 8 6 6 6 6 5 6 6 6 5 6 6 8 8 8 8 8 8 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 6 5 2 1 1 1 1 1 1 2 1 1 1 1 2 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 17 323 5 2 324 5 1 325 6 1 326 6 1 327 6 1 > > # Now make the subset available locally. > attach(tt2) > > ############################ DO THE CELL COUNTS ############################# > > tb1 <- table(tt2) ; tb1 Compared School 1 2 3 17 6 5 22 3 6 30 7 8 55 7 > > # ROW TOTALS AND COLUMN TOTALS > > rowsum <- margin.table(tb1,1); rowsum School 3 5 6 8 23 25 37 62 > colsum <- margin.table(tb1,2); colsum Compared 1 2 124 23 > > # To add row and column sums to the table we can column-bind the vector of > # rowsums, sum the columns and row-bind it to the table. > > tb2 <- cbind(tb1,rowsum);tb2 1 2 rowsum 3 17 6 23 5 22 3 25 6 30 7 37 8 55 7 62 > columnsum <- margin.table(tb2,2) > rbind(tb2,columnsum) 1 2 rowsum 3 17 6 23 5 22 3 25 6 30 7 37 8 55 7 62 columnsum 124 23 147 18 > > > > > > > > > > > ######################### EXPECTED VALUE AND PERCENTAGES OF CELLS ################## # # # # Let total = sum of all celle = number of valid observations. If p[i] = sum row i / total and q[j] = sum col j / total are the row and column percentages then the expected number in the [i,j] cell is ex[i,j] = p[i] * q[j] * total = row[i] sum * col[j] sum / total. # A %o% B is "outer product" is the matrix whose [i,j] entry is A[i]B[j]. # It gives expected * total. ex <- ( rowsum %o% colsum )/ sum(tb1) ; ex Compared School 1 2 3 19.40136 3.598639 5 21.08844 3.911565 6 31.21088 5.789116 8 52.29932 9.700680 > > # Compute what the cell is as a percent of the whole table. > > pct <- 100* tb1 / sum(tb1) ; pct Compared School 1 2 3 11.564626 4.081633 5 14.965986 2.040816 6 20.408163 4.761905 8 37.414966 4.761905 > > # Compute what the cell is as a percent of its row. > > rowpct <- 100* prop.table(tb1,1) ; rowpct Compared School 1 2 3 73.91304 26.08696 5 88.00000 12.00000 6 81.08108 18.91892 8 88.70968 11.29032 > > # Compute what the cell is as a percent of its column. > > colpct <- 100* prop.table(tb1,2) ; colpct Compared School 1 2 3 13.70968 26.08696 5 17.74194 13.04348 6 24.19355 30.43478 8 44.35484 30.43478 19 >################### MAKE A SAS STYLE TABLE INCLUDING EX AND PCTS #################### > > # One learns that anything is possible in R. The student just has to be tough enough > # to figure things out by themselves. There are several ways to so this. > # I concluded that it is easiest just to make a data frame with the numbers (val) > # viewed as a single vector and with School, Compared and vv (the statistic) as > # factors. I’m sure one of you will show me an easier way! > > compared <- factor(rep(rep(1:2,c(4,4)),5)); compared [1] 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 Levels: 1 2 > > school <- factor(rep(c(3,5,6,8),10)); school [1] 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 Levels: 3 5 6 8 > > vv <- factor(rep(1:5,rep(8,5))) ; vv [1] 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 Levels: 1 2 3 4 5 > > val <-c(tb1,ex,pct,rowpct,colpct) ; val [1] 17.000000 22.000000 30.000000 55.000000 6.000000 3.000000 7.000000 7.000000 [9] 19.401361 21.088435 31.210884 52.299320 3.598639 3.911565 5.789116 9.700680 [17] 11.564626 14.965986 20.408163 37.414966 4.081633 2.040816 4.761905 4.761905 [25] 73.913043 88.000000 81.081081 88.709677 26.086957 12.000000 18.918919 11.290323 [33] 13.709677 17.741935 24.193548 44.354839 26.086957 13.043478 30.434783 30.434783 > sast <- data.frame(school,compared,vv,val); sast school compared vv val 1 3 1 1 17.000000 2 5 1 1 22.000000 3 6 1 1 30.000000 4 8 1 1 55.000000 5 3 2 1 6.000000 6 5 2 1 3.000000 7 6 2 1 7.000000 8 8 2 1 7.000000 9 3 1 2 19.401361 10 5 1 2 21.088435 11 6 1 2 31.210884 12 8 1 2 52.299320 13 3 2 2 3.598639 14 5 2 2 3.911565 15 6 2 2 5.789116 16 8 2 2 9.700680 17 3 1 3 11.564626 18 5 1 3 14.965986 19 6 1 3 20.408163 20 8 1 3 37.414966 21 3 2 3 4.081633 22 5 2 3 2.040816 23 6 2 3 4.761905 24 8 2 3 4.761905 20 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 3 5 6 8 3 5 6 8 3 5 6 8 3 5 6 8 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 73.913043 88.000000 81.081081 88.709677 26.086957 12.000000 18.918919 11.290323 13.709677 17.741935 24.193548 44.354839 26.086957 13.043478 30.434783 30.434783 21 > > > > , # Give meaningful names to the statisics, the levels of factor vv. levels(vv) <- c("Frequency","Expected","Percent","Row Pct","Col Pct") xtabs(val ~ vv , school = 3 + compared + school) compared vv Frequency Expected Percent Row Pct Col Pct 1 2 17.000000 6.000000 19.401361 3.598639 11.564626 4.081633 73.913043 26.086957 13.709677 26.086957 , , school = 5 compared vv Frequency Expected Percent Row Pct Col Pct 1 2 22.000000 3.000000 21.088435 3.911565 14.965986 2.040816 88.000000 12.000000 17.741935 13.043478 , , school = 6 compared vv Frequency Expected Percent Row Pct Col Pct 1 2 30.000000 7.000000 31.210884 5.789116 20.408163 4.761905 81.081081 18.918919 24.193548 30.434783 , , school = 8 compared vv Frequency Expected Percent Row Pct Col Pct 1 2 55.000000 7.000000 52.299320 9.700680 37.414966 4.761905 88.709677 11.290323 44.354839 30.434783 22 >########################### CHI-SQUARED TEST FOR HOMOGENEITY ################# > > tb1 Compared School 1 2 3 17 6 5 22 3 6 30 7 8 55 7 > > > chisq.test(tb1) Pearson’s Chi-squared test data: tb1 X-squared = 3.3431, df = 3, p-value = 0.3417 Warning message: In chisq.test(tb1) : Chi-squared approximation may be incorrect > 23