I got the message, " Coefficients: (1 not defined because of singularities)", in the returned result of lm(). What does it mean? And where should I start investigating why it happens?
thanks. /// Complete result of lm() Call: lm(formula = durationRatio ~ isHStar + isWordFinal + oneSyllToEOW + isInterNuclear + isIntonNuclear + isInterLP + isIntonLF + zeroSyllToNA + oneSyllToNA + zeroSyllToEOP + oneSyllToEOP + isInterNuclear:zeroSyllToEOP) Residuals: Min 1Q Median 3Q Max -3.031538 -0.126943 -0.002909 0.121606 4.322135 Coefficients: (1 not defined because of singularities) Estimate Std. Error t value Pr(>|t|) (Intercept) 1.044481 0.010694 97.669 < 2e-16 *** isHStar -0.055227 0.005748 -9.607 < 2e-16 *** isWordFinal -0.262071 0.009982 -26.254 < 2e-16 *** oneSyllToEOW -0.031313 0.009917 -3.158 0.00160 ** isInterNuclear 0.063470 0.015699 4.043 5.32e-05 *** isIntonNuclear 0.054570 0.011711 4.660 3.21e-06 *** isInterLP -0.262302 0.011868 -22.102 < 2e-16 *** isIntonLF -0.160018 0.012537 -12.764 < 2e-16 *** zeroSyllToNA -0.160767 0.011105 -14.477 < 2e-16 *** oneSyllToNA -0.012633 0.010779 -1.172 0.24123 zeroSyllToEOP -0.212474 0.011987 -17.726 < 2e-16 *** oneSyllToEOP -0.123324 0.010998 -11.214 < 2e-16 *** isInterNuclear:zeroSyllToEOP NA NA NA NA --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 0.2662 on 9650 degrees of freedom Multiple R-Squared: 0.3957, Adjusted R-squared: 0.395 F-statistic: 574.5 on 11 and 9650 DF, p-value: < 2.2e-16 ______________________________________________ R-help@stat.math.ethz.ch 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.