On Wed, 9 Nov 2011, Daniel Nordlund wrote:
I would guess that there is something problematic with the how the data frame is structured relative to what lm() is expecting.
Dan, I was not comfortable with my explanation, but the formula (and data frame) was equivalent to those of the other 8 streams.
So, I would not give up looking for a solution just yet.
OK. I'm always up for learning more about R and its processes.
Can you show us the result of str() on the data frame that you attached?
Sure. I subset the original data frame to select only the 6 predictor variables and the response variable. Same lm() results. I'll provide the data frame, too. summary(lm(formula = TDS ~ Cond + Ca + Cl + Mg + Na + SO4, data = mod.stump.cast)) Call: lm(formula = TDS ~ Cond + Ca + Cl + Mg + Na + SO4, data = mod.stump.cast) Residuals: ALL 1 residuals are 0: no residual degrees of freedom! Coefficients: (6 not defined because of singularities) Estimate Std. Error t value Pr(>|t|) (Intercept) 125 NA NA NA Cond NA NA NA NA Ca NA NA NA NA Cl NA NA NA NA Mg NA NA NA NA Na NA NA NA NA SO4 NA NA NA NA Residual standard error: NaN on 0 degrees of freedom (63 observations deleted due to missingness) str(mod.stump.cast) 'data.frame': 64 obs. of 7 variables: $ Ca : num NA NA 24.4 NA 21.4 NA NA NA NA NA ... $ Cl : num 1.58 5.6 3 NA 1 5 1.2 4 4 8.4 ... $ Cond: num NA NA 190 187 184 NA NA NA NA NA ... $ Mg : num NA NA 10 NA 9.1 NA NA NA NA NA ... $ Na : num NA NA NA NA NA NA NA NA NA NA ... $ SO4 : num 9.4 6.5 9 NA 7 55 6.8 105 15.6 8.4 ... $ TDS : num 105 181 112 144 114 308 96 430 108 108 ... summary(mod.stump.cast) Ca Cl Cond Mg Na Min. : 0.60 Min. : 1.000 Min. : 2.2 Min. : 9.10 Min. : 4 1st Qu.:23.35 1st Qu.: 2.000 1st Qu.:214.8 1st Qu.:11.00 1st Qu.: 4 Median :28.35 Median : 4.000 Median :282.5 Median :17.40 Median : 4 Mean :32.77 Mean : 4.076 Mean :294.6 Mean :17.85 Mean : 4 3rd Qu.:40.55 3rd Qu.: 5.600 3rd Qu.:372.0 3rd Qu.:22.10 3rd Qu.: 4 Max. :64.30 Max. :13.000 Max. :636.0 Max. :32.40 Max. : 4 NA's :50.00 NA's :11.000 NA's : 42.0 NA's :51.00 NA's :62 SO4 TDS Min. : 4.00 Min. : 14.0 1st Qu.: 7.00 1st Qu.:131.2 Median : 9.40 Median :174.0 Mean : 16.31 Mean :176.9 3rd Qu.: 17.00 3rd Qu.:195.5 Max. :105.00 Max. :430.0 NA's : 3.00 NA's : 2.0 mod.stump.cast Ca Cl Cond Mg Na SO4 TDS 1 NA 1.58 NA NA NA 9.4 105 2 NA 5.60 NA NA NA 6.5 181 3 24.4 3.00 190.0 10.0 NA 9.0 112 4 NA NA 187.0 NA NA NA 144 5 21.4 1.00 184.0 9.1 NA 7.0 114 6 NA 5.00 NA NA NA 55.0 308 7 NA 1.20 NA NA NA 6.8 96 8 NA 4.00 NA NA NA 105.0 430 9 NA 4.00 NA NA NA 15.6 108 10 NA 8.40 NA NA NA 8.4 108 11 NA 1.00 NA NA NA 8.8 125 12 NA 1.40 NA NA NA 19.4 129 13 NA 4.90 NA NA NA 37.0 360 14 NA 1.70 NA NA NA 12.0 140 15 NA 2.00 NA NA NA 10.0 95 16 NA 1.60 NA NA NA 9.1 120 17 NA 3.30 NA NA NA 34.0 280 18 NA 2.20 NA NA NA 11.0 130 19 NA 9.00 NA NA NA 69.0 352 20 NA 1.00 NA NA NA 18.0 148 21 NA 2.00 NA NA NA 9.0 107 22 28.0 1.00 248.0 11.0 4 13.0 125 23 32.0 1.00 NA 12.0 4 9.0 139 24 NA 5.00 NA NA NA 7.0 188 25 NA 4.00 NA NA NA 6.0 201 26 NA 3.00 NA NA NA 5.0 178 27 NA 2.27 NA NA NA 7.8 197 28 NA 1.76 NA NA NA 7.8 187 29 NA 5.81 NA NA NA 7.5 182 30 NA 4.23 NA NA NA 6.0 165 31 NA 4.23 NA NA NA 7.3 186 32 NA 6.25 NA NA NA 7.0 191 33 NA 6.72 NA NA NA 7.5 190 34 34.7 4.00 304.0 17.4 NA 6.0 176 35 NA NA 354.0 NA NA 7.0 175 36 42.5 5.00 379.0 21.1 NA 7.0 220 37 NA 5.80 NA NA NA 5.6 163 38 26.0 5.80 300.0 24.0 NA 5.6 163 39 NA 2.20 NA NA NA 5.4 152 40 NA 5.40 NA NA NA 11.0 221 41 NA 5.40 NA NA NA 10.5 171 42 NA 4.80 NA NA NA 9.9 204 43 NA 8.00 NA NA NA 11.7 174 44 NA 1.00 NA NA NA 8.4 190 45 NA 4.80 NA NA NA 12.1 174 46 NA 5.90 NA NA NA 16.0 210 47 NA 5.90 NA NA NA 20.0 190 48 NA 13.00 NA NA NA 7.6 180 49 NA 5.60 NA NA NA 17.0 200 50 NA 1.20 NA NA NA 6.5 180 51 0.6 NA 2.2 NA NA NA NA 52 21.4 NA 187.0 9.5 NA 8.0 120 53 NA NA 285.0 NA NA 22.0 135 54 48.3 3.00 378.0 22.1 NA 24.0 228 55 63.5 7.00 533.0 29.9 NA 44.0 14 56 NA NA 207.0 NA NA NA NA 57 NA NA 262.0 NA NA 13.0 156 58 28.7 2.00 244.0 12.6 NA 13.0 140 59 NA NA 238.0 NA NA 12.0 128 60 NA NA 280.0 NA NA 18.0 160 61 NA NA 380.0 NA NA 23.0 215 62 NA NA 402.0 NA NA 23.0 230 63 64.3 7.00 636.0 32.4 NA 73.0 316 64 23.0 4.10 300.0 21.0 NA 4.0 163 Thanks, Rich ______________________________________________ R-help@r-project.org mailing list 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.