
Can anyone help explain to me why the two codes below have different result? I thought I can use log(time)~. to replace log(time)~dist+climb+timef.I am using CVlm from DAAG package. I think nihills is preloaded with the package. Thanks in advance.
> CVlm(df=nihills, form.lm=formula(log(time)~.),plotit="Observed",m=2)Analysis of Variance Table
Response: log(time)          Df Sum Sq Mean Sq F value  Pr(>F)    dist       1   6.34    6.34  384.31 4.6e-14 ***climb      1   0.12    0.12    7.24  0.0145 *  timef      1   0.19    0.19   11.29  0.0033 ** Residuals 19   0.31    0.02                    ---Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 


fold 1 Observations in test set: 11             Slieve Gullion McVeigh Classic Tollymore Mountain Moughanmore Hen & Cock Annalong Horseshoe  Rocky Meelbeg Meelmore Slieve Donard Seven Sevens Slieve GallionPredicted           -0.680          -0.538             -0.610      -0.786     -0.849           7.87e-01 -0.682        -6.20e-01     -2.98e-01     1.41e+00      -5.87e-01cvpred              -0.762          -0.614             -0.727      -0.769     -0.799           6.67e-01 -0.648        -7.89e-01     -5.30e-02     1.36e+00      -4.52e-01log(time)           -0.762          -0.614             -0.727      -0.769     -0.799           6.67e-01 -0.648        -7.89e-01     -5.30e-02     1.36e+00      -4.52e-01CV residual          0.000           0.000              0.000       0.000      0.000           1.11e-16  0.000         1.11e-16     -4.86e-17     4.44e-16      -5.55e-17
Sum of squares = 0    Mean square = 0    n = 11 
fold 2 Observations in test set: 12             Binevenagh Glenariff Mountain Donard & Commedagh Slieve Martin Monument Race Loughshannagh Horseshoe Donard Forest Flagstaff to Carling Slieve Bearnagh Lurig Challenge Scrabo Hill Race BARF Turkey TrotPredicted    -1.78e-01          -4.89e-01           2.78e-02        -0.577     -7.27e-01                  -0.623        -0.571             3.03e-01          -0.401       -7.20e-01           -0.889        -4.88e-01cvpred       -1.53e-01          -3.52e-01           3.79e-02        -0.597     -7.51e-01                  -0.435        -0.657             3.76e-01          -0.374       -8.33e-01           -1.125        -3.38e-01log(time)    -1.53e-01          -3.52e-01           3.79e-02        -0.597     -7.51e-01                  -0.435        -0.657             3.76e-01          -0.374       -8.33e-01           -1.125        -3.38e-01CV residual  -2.78e-17          -5.55e-17          -6.94e-18         0.000      1.11e-16                   0.000         0.000            -1.11e-16           0.000        1.11e-16            0.000        -5.55e-17
Sum of squares = 0    Mean square = 0    n = 12 
Overall (Sum over all 12 folds)       ms 1.18e-32 Warning messages:1: In predict.lm(subs.lm, newdata = df[rows.out, ]) :  prediction from a rank-deficient fit may be misleading2: In predict.lm(subs.lm, newdata = df[rows.out, ]) :  prediction from a rank-deficient fit may be misleading3: In CVlm(df = nihills, form.lm = formula(log(time) ~ .), plotit = "Observed",  :  
 As there is >1 explanatory variable, cross-validation predicted values for a fold are not a linear function of corresponding overall predicted values.  Lines that are shown for the different folds are approximate
> CVlm(df=nihills, form.lm=formula(log(time)~dist+climb+timef),plotit="Observed",m=2)Analysis of Variance Table
Response: log(time)          Df Sum Sq Mean Sq F value  Pr(>F)    dist       1   6.34    6.34  384.31 4.6e-14 ***climb      1   0.12    0.12    7.24  0.0145 *  timef      1   0.19    0.19   11.29  0.0033 ** Residuals 19   0.31    0.02                    ---Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 


fold 1 Observations in test set: 11             Slieve Gullion McVeigh Classic Tollymore Mountain Moughanmore Hen & Cock Annalong Horseshoe   Rocky Meelbeg Meelmore Slieve Donard Seven Sevens Slieve GallionPredicted          -0.6801        -0.53759             -0.610     -0.7857   -0.84929              0.787 -0.6824           -0.620        -0.298         1.41         -0.587cvpred             -0.7068        -0.60517             -0.680     -0.7501   -0.80507              1.053 -0.6856           -0.642        -0.185         2.81         -0.588log(time)          -0.7621        -0.61413             -0.727     -0.7687   -0.79913              0.667 -0.6481           -0.789        -0.053         1.36         -0.452CV residual        -0.0554        -0.00896             -0.047     -0.0186    0.00595             -0.386  0.0376           -0.147         0.132        -1.45          0.136
Sum of squares = 2.31    Mean square = 0.21    n = 11 
fold 2 Observations in test set: 12             Binevenagh Glenariff Mountain Donard & Commedagh Slieve Martin Monument Race Loughshannagh Horseshoe Donard Forest Flagstaff to Carling Slieve Bearnagh Lurig Challenge Scrabo Hill Race BARF Turkey TrotPredicted       -0.178             -0.489             0.0278       -0.5771      -0.72713                  -0.623        -0.571                0.303         -0.4008          -0.720           -0.889           -0.488cvpred          -0.308             -0.583             0.0268       -0.5822      -0.75753                  -0.614        -0.600                0.125         -0.3245          -0.751           -0.891           -0.558log(time)       -0.153             -0.352             0.0379       -0.5968      -0.75148                  -0.435        -0.657                0.376         -0.3743          -0.833           -1.125           -0.338CV residual      0.156              0.231             0.0111       -0.0147       0.00604                   0.178        -0.057                0.251         -0.0498          -0.082           -0.234            0.219
Sum of squares = 0.29    Mean square = 0.02    n = 12 
Overall (Sum over all 12 folds)    ms 0.113 Warning message:In CVlm(df = nihills, form.lm = formula(log(time) ~ dist + climb +  : 
 As there is >1 explanatory variable, cross-validation predicted values for a fold are not a linear function of corresponding overall predicted values.  Lines that are shown for the different folds are approximate
> head(nihills)
                   dist climb  time timefBinevenagh          7.5  1740 0.858 1.064Slieve Gullion      4.2  1110 0.467 0.623Glenariff Mountain  5.9  1210 0.703 0.887Donard & Commedagh  6.8  3300 1.039 1.214McVeigh Classic     5.0  1200 0.541 0.637Tollymore Mountain  4.8   950 0.483 0.589
 		 	   		  
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