data=read.csv("Desktop/HWW.csv")
model=lm(BIO~SAL+pH+K+Na+Zn,data=data)
summary(model)
##
## Call:
## lm(formula = BIO ~ SAL + pH + K + Na + Zn, data = data)
##
## Residuals:
## Min 1Q Median 3Q Max
## -748.24 -223.57 -85.13 139.83 1072.32
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 1.252e+03 1.235e+03 1.014 0.31664
## SAL -3.029e+01 2.403e+01 -1.260 0.21502
## pH 3.055e+02 8.788e+01 3.476 0.00126 **
## K -2.851e-01 3.484e-01 -0.818 0.41817
## Na -8.672e-03 1.593e-02 -0.544 0.58926
## Zn -2.068e+01 1.505e+01 -1.374 0.17737
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 398.3 on 39 degrees of freedom
## Multiple R-squared: 0.6773, Adjusted R-squared: 0.6359
## F-statistic: 16.37 on 5 and 39 DF, p-value: 1.082e-08
anova(model)
## Analysis of Variance Table
##
## Response: BIO
## Df Sum Sq Mean Sq F value Pr(>F)
## SAL 1 204048 204048 1.2864 0.26364
## pH 1 11363668 11363668 71.6413 2.3e-10 ***
## K 1 935178 935178 5.8958 0.01989 *
## Na 1 182599 182599 1.1512 0.28990
## Zn 1 299334 299334 1.8871 0.17737
## Residuals 39 6186137 158619
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
step(model,direction = "both",k=log(45))
## Start: AIC=555.24
## BIO ~ SAL + pH + K + Na + Zn
##
## Df Sum of Sq RSS AIC
## - Na 1 47010 6233148 551.78
## - K 1 106207 6292344 552.20
## - SAL 1 251975 6438112 553.23
## - Zn 1 299334 6485471 553.56
## <none> 6186137 555.24
## - pH 1 1916874 8103012 563.58
##
## Step: AIC=551.78
## BIO ~ SAL + pH + K + Zn
##
## Df Sum of Sq RSS AIC
## - Zn 1 434922 6668070 551.00
## - SAL 1 436545 6669693 551.02
## <none> 6233148 551.78
## - K 1 732563 6965711 552.97
## + Na 1 47010 6186137 555.24
## - pH 1 1885351 8118499 559.86
##
## Step: AIC=551
## BIO ~ SAL + pH + K
##
## Df Sum of Sq RSS AIC
## - SAL 1 88239 6756309 547.79
## <none> 6668070 551.00
## + Zn 1 434922 6233148 551.78
## - K 1 935178 7603247 553.10
## + Na 1 182599 6485471 553.56
## - pH 1 11478835 18146905 592.25
##
## Step: AIC=547.79
## BIO ~ pH + K
##
## Df Sum of Sq RSS AIC
## <none> 6756309 547.79
## - K 1 924266 7680575 549.75
## + Na 1 245075 6511234 549.93
## + SAL 1 88239 6668070 551.00
## + Zn 1 86617 6669693 551.02
## - pH 1 11611782 18368091 588.99
##
## Call:
## lm(formula = BIO ~ pH + K, data = data)
##
## Coefficients:
## (Intercept) pH K
## -506.9774 412.0395 -0.4871