> txtemp.mod1 <- lm(jantemp~lat+long+elev) > > summary(txtemp.mod1) Call: lm(formula = jantemp ~ lat + long + elev) Residuals: Min 1Q Median 3Q Max -1.65641 -0.32212 -0.01236 0.50637 1.10166 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 1.513e+02 2.513e+01 6.020 6.03e-05 *** lat -1.993e+00 1.364e-01 -14.614 5.23e-09 *** long -3.847e-01 2.286e-01 -1.683 0.118 elev -9.555e-04 5.676e-04 -1.683 0.118 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 0.7963 on 12 degrees of freedom Multiple R-squared: 0.9919, Adjusted R-squared: 0.9899 F-statistic: 491.1 on 3 and 12 DF, p-value: 8.124e-13 > anova(txtemp.mod1) Analysis of Variance Table Response: jantemp Df Sum Sq Mean Sq F value Pr(>F) lat 1 881.00 881.00 1389.322 8.928e-14 *** long 1 51.53 51.53 81.258 1.086e-06 *** elev 1 1.80 1.80 2.834 0.1181 Residuals 12 7.61 0.63 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > > txtemp.mod2 <- lm(jantemp~lat) > > summary(txtemp.mod2) Call: lm(formula = jantemp ~ lat) Residuals: Min 1Q Median 3Q Max -3.5086 -1.3762 0.1537 0.8452 3.4651 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 126.1297 5.4157 23.29 1.35e-12 *** lat -2.4724 0.1738 -14.23 1.02e-09 *** --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 2.086 on 14 degrees of freedom Multiple R-squared: 0.9353, Adjusted R-squared: 0.9307 F-statistic: 202.4 on 1 and 14 DF, p-value: 1.023e-09 > anova(txtemp.mod2) Analysis of Variance Table Response: jantemp Df Sum Sq Mean Sq F value Pr(>F) lat 1 881.00 881.00 202.41 1.023e-09 *** Residuals 14 60.93 4.35 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > > txtemp.mod3 <- lm(jantemp~lat+elev) > > summary(txtemp.mod3) Call: lm(formula = jantemp ~ lat + elev) Residuals: Min 1Q Median 3Q Max -2.1711 -0.3172 0.1458 0.5542 1.3548 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 1.093e+02 2.979e+00 36.682 1.64e-14 *** lat -1.832e+00 1.038e-01 -17.651 1.83e-10 *** elev -1.846e-03 2.188e-04 -8.439 1.24e-06 *** --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 0.8506 on 13 degrees of freedom Multiple R-squared: 0.99, Adjusted R-squared: 0.9885 F-statistic: 644.4 on 2 and 13 DF, p-value: 9.906e-14 > anova(txtemp.mod3) Analysis of Variance Table Response: jantemp Df Sum Sq Mean Sq F value Pr(>F) lat 1 881.00 881.00 1217.67 3.114e-14 *** elev 1 51.53 51.53 71.22 1.240e-06 *** Residuals 13 9.41 0.72 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > > txtemp.mod4 <- lm(jantemp~lat*elev) > > summary(txtemp.mod4) Call: lm(formula = jantemp ~ lat * elev) Residuals: Min 1Q Median 3Q Max -2.1517 -0.3326 0.0679 0.5816 1.3561 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 1.098e+02 3.860e+00 28.431 2.22e-12 *** lat -1.849e+00 1.328e-01 -13.919 9.11e-09 *** elev -2.286e-03 2.068e-03 -1.105 0.291 lat:elev 1.372e-05 6.420e-05 0.214 0.834 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 0.8836 on 12 degrees of freedom Multiple R-squared: 0.9901, Adjusted R-squared: 0.9876 F-statistic: 398.1 on 3 and 12 DF, p-value: 2.829e-12 > anova(txtemp.mod4) Analysis of Variance Table Response: jantemp Df Sum Sq Mean Sq F value Pr(>F) lat 1 881.00 881.00 1128.2835 3.078e-13 *** elev 1 51.53 51.53 65.9920 3.213e-06 *** lat:elev 1 0.04 0.04 0.0457 0.8344 Residuals 12 9.37 0.78 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1