Question 8.1

Recreate the simulated data from Exercise 7.2

Part A

Fit a random fores model to all the predictors, then estimate the variable importance scores:

Variable Overall
V1 8.7322354
V4 7.6151188
V2 6.4153694
V5 2.0235246
V3 0.7635918
V6 0.1651112
V7 -0.0059617
V10 -0.0749448
V9 -0.0952927
V8 -0.1663626

Did the random forest model significantly use the uninformative predictors (V6-V10)?

No. The scores are very close to zero indicating they are uninformative.

Part B

Now add an additional predictor that is highly correlated with one of the informative predictors. For example:

 0.9460206

Fit another random forest model to these data. Did the importance score for V1 change? What happens when you add another predictor that is also highly correlated with V1?

Variable Overall
V4 7.0475224
V2 6.0689606
V1 5.6911997
duplicate1 4.2833158
V5 1.8723844
V3 0.6297022
V6 0.1356906
V10 0.0289481
V9 0.0084044
V7 -0.0134564
V8 -0.0437056

The importance of v1 has decreased significantly since adding the additional correlated predictor. When adding the correlated predictor, both were included in the decision trees as significant predictors. This caused the overall significance to decrease.

Part C

Use the cforest function in the party package to fit a random forest model using conditional inference trees. The party package function varimp can calculate predictor importance. The conditional argument of that function toggles between the traditional importance measure and the modified version described in Stobl et al. (2007). Do these importance show the same pattern as the traditional random forest model?

Variable Overall
V4 6.0471707
V2 4.8021627
duplicate1 1.9703660
V1 1.8986240
V5 0.9850544
V3 0.0229993
V9 0.0004516
V10 -0.0074653
V7 -0.0104328
V8 -0.0104863
V6 -0.0119652

Part D

Repeat this process with different tree models, such as boosted trees and Cubist. Does the same pattern occur?

Boosted Tree

Training it without the duplicate predictor:

Variable Overall
V4 100.0000000
V1 94.3492687
V2 85.3573190
V5 37.3645989
V3 31.2757450
V6 3.2412743
V7 0.9391656
V9 0.5040653
V10 0.1698201
V8 0.0000000

The boosted tree did not pick up the uninformative predictors. Now let’s see what happens when I train it WITH the duplicate predictor:

Variable Overall
V4 100.000000
V2 81.847724
V1 54.988209
V5 43.118057
duplicate1 39.179131
V3 33.518028
V6 2.929334
V8 2.052144
V7 2.045898
V10 1.305226
V9 0.000000

This model exhibits the same pattern. The duplicate becomes one of the important variables and the importance of v1 decreases.

Cubist

Again training it without the duplicate predictor:

Variable Overall
V1 100.00000
V2 75.69444
V4 68.05556
V3 58.33333
V5 55.55556
V6 15.27778
V7 0.00000
V8 0.00000
V9 0.00000
V10 0.00000

Once again, the cubist model does not pick up the un-important variables. Let’s train it WITH the duplicate predictor and see what happens:

Variable Overall
V2 100.00000
V1 89.51613
V4 80.64516
V3 67.74194
duplicate1 59.67742
V5 50.00000
V6 25.00000
V7 0.00000
V8 0.00000
V9 0.00000
V10 0.00000

The cubist model also exhibits a similar behavior as the random forest model, but is not as pronounced.

Question 8.2

Use a simulation to show tree bias with different granularities.

I will create a simulated dataset generated by a non-linear function. I will then train the tree based models with varying levels of pruning. I will then look at the MSE on the training set and test set in relation to the complexity of the tree.

One can see that as the granularity of the tree model increases, the MSE on the training set decreases. However the MSE on the test set initially begins to decline then increases again as the model starts to overfit the training data.

Question 8.3

In stocastic gradient boosting the bagging fraction and learning rate will govern the construction of the trees as they are guided by the gradient. Although the optimal values of these parameters should be obtained through the tuning process, it is helpful to understand how the magnitudes of these parameters affect magnitudes of variable importance. Figure 8.24 provides the variable importance plots for boosting using two extreme values for the bagging fraction (0.1. and 0.9) and the learning rate (0.1 and 0.9) for the solubility data. The left-hand plot has both parameters set to 0.1, and the right-hand plot has both set to 0.9:

Fig 8.24

Fig 8.24

Part A

Why does the model on the right focus its importance on just the first few of predictors, whereas the model on the left spreads importance across more predictors?

Because the learning rate is set to 0.1, the importance get’s spread out over more predictors. The higher learning rate will focus the importance on a smaller set of variables.

Part B

Which model do you think would be more predictive of other samples?

The one on the left. It will generalize while the one on the right will overfit the training data. Always go for an ensemble of weak predictors.

Part C

How would increasing interaction depth affect the slope of predictor importance for either model in Fig. 8.24?

The predictor importance would get spread across more predictors as the interaction depth would increase. The slope would decrease.

Question 8.7

Refer to Exercises 6.3 and 7.5 which describe a chemical manufacturing process. Use the same data imputation, data splitting, and pre-processing steps as before and train several tree-based models:

Part A

Which tree-based regression model gives the optimal resampling and test set performance?

Partial Least Squares 

144 samples
 56 predictor

No pre-processing
Resampling: Cross-Validated (10 fold) 
Summary of sample sizes: 130, 129, 128, 129, 130, 129, ... 
Resampling results across tuning parameters:

  ncomp  RMSE       Rsquared   MAE      
   1     0.8824790  0.3779221  0.6711462
   2     1.1458456  0.4219806  0.7086431
   3     0.7363066  0.5244517  0.5688553
   4     0.8235294  0.5298005  0.5933120
   5     0.9670735  0.4846010  0.6371199
   6     0.9959036  0.4776684  0.6427478
   7     0.9119517  0.4986338  0.6200233
   8     0.9068621  0.5012144  0.6293371
   9     0.8517370  0.5220166  0.6163795
  10     0.8919356  0.5062912  0.6332243
  11     0.9173758  0.4934557  0.6463164
  12     0.9064125  0.4791526  0.6485663
  13     0.9255289  0.4542181  0.6620193
  14     1.0239913  0.4358371  0.6944056
  15     1.0754710  0.4365214  0.7077991
  16     1.1110579  0.4269065  0.7135684
  17     1.1492855  0.4210485  0.7222868
  18     1.1940639  0.4132534  0.7396357
  19     1.2271867  0.4079005  0.7494818
  20     1.2077102  0.4022859  0.7470327
  21     1.2082648  0.4026711  0.7452969
  22     1.2669285  0.3987044  0.7634170
  23     1.3663033  0.3970188  0.7957514
  24     1.4531634  0.3898475  0.8243034
  25     1.5624265  0.3820102  0.8612935

RMSE was used to select the optimal model using the smallest value.
The final value used for the model was ncomp = 3.

I’m going to fit the data against a series of tree based models. I will use caret and try to match the same paramaters to guague th preformance against the similar PLS model.

Boosted Tree

Stochastic Gradient Boosting 

144 samples
 56 predictor

No pre-processing
Resampling: Cross-Validated (10 fold) 
Summary of sample sizes: 129, 129, 130, 129, 130, 130, ... 
Resampling results across tuning parameters:

  interaction.depth  n.trees  RMSE       Rsquared   MAE      
   1                   50     0.6529787  0.5702357  0.5102064
   1                  100     0.6259745  0.5906080  0.4846082
   1                  150     0.6099166  0.6047640  0.4860877
   1                  200     0.6008357  0.6159204  0.4746704
   1                  250     0.6007583  0.6168513  0.4745437
   1                  300     0.6032872  0.6139154  0.4803398
   1                  350     0.6054569  0.6124108  0.4810323
   1                  400     0.6042296  0.6141087  0.4831893
   1                  450     0.6044401  0.6176478  0.4809852
   1                  500     0.6054335  0.6184590  0.4809517
   1                  550     0.6061891  0.6193797  0.4796327
   1                  600     0.6056039  0.6199645  0.4771155
   1                  650     0.6083802  0.6177853  0.4796680
   1                  700     0.6112744  0.6142575  0.4820985
   1                  750     0.6150272  0.6119709  0.4849456
   1                  800     0.6132495  0.6140022  0.4824066
   1                  850     0.6129022  0.6147128  0.4805281
   1                  900     0.6125136  0.6163699  0.4799557
   1                  950     0.6146513  0.6141389  0.4791453
   1                 1000     0.6158677  0.6136756  0.4810977
   1                 1050     0.6168063  0.6135476  0.4807789
   1                 1100     0.6190710  0.6114224  0.4824817
   1                 1150     0.6178899  0.6133618  0.4805481
   1                 1200     0.6182632  0.6126484  0.4816822
   1                 1250     0.6190874  0.6120263  0.4828504
   2                   50     0.6094282  0.6099501  0.4849066
   2                  100     0.5829629  0.6335127  0.4565230
   2                  150     0.5838239  0.6333416  0.4594031
   2                  200     0.5794192  0.6416762  0.4522288
   2                  250     0.5703484  0.6522903  0.4427181
   2                  300     0.5704290  0.6539219  0.4424843
   2                  350     0.5688872  0.6558810  0.4446840
   2                  400     0.5691133  0.6553808  0.4440911
   2                  450     0.5693332  0.6558510  0.4436964
   2                  500     0.5675464  0.6582781  0.4421581
   2                  550     0.5658889  0.6603078  0.4396887
   2                  600     0.5660413  0.6600440  0.4397280
   2                  650     0.5670866  0.6590858  0.4400525
   2                  700     0.5668798  0.6595438  0.4396349
   2                  750     0.5666876  0.6596874  0.4395221
   2                  800     0.5668211  0.6596993  0.4396469
   2                  850     0.5665125  0.6601553  0.4395041
   2                  900     0.5667711  0.6598908  0.4398854
   2                  950     0.5669461  0.6596749  0.4398769
   2                 1000     0.5668896  0.6597418  0.4397258
   2                 1050     0.5668324  0.6599450  0.4398214
   2                 1100     0.5665139  0.6602574  0.4396333
   2                 1150     0.5666514  0.6601821  0.4397815
   2                 1200     0.5668290  0.6600264  0.4399304
   2                 1250     0.5668629  0.6599759  0.4400462
   3                   50     0.5964119  0.6301569  0.4620894
   3                  100     0.5881904  0.6348098  0.4617679
   3                  150     0.5784579  0.6432397  0.4539545
   3                  200     0.5756343  0.6493645  0.4495719
   3                  250     0.5753652  0.6492650  0.4496511
   3                  300     0.5739679  0.6499200  0.4490757
   3                  350     0.5744236  0.6496053  0.4496752
   3                  400     0.5731088  0.6511659  0.4488762
   3                  450     0.5743237  0.6506949  0.4493729
   3                  500     0.5740582  0.6510667  0.4491126
   3                  550     0.5737973  0.6513584  0.4490028
   3                  600     0.5736313  0.6516578  0.4486977
   3                  650     0.5734303  0.6520309  0.4486500
   3                  700     0.5734154  0.6521713  0.4487097
   3                  750     0.5734448  0.6521538  0.4486533
   3                  800     0.5733412  0.6523101  0.4485162
   3                  850     0.5734461  0.6522107  0.4486230
   3                  900     0.5733855  0.6522783  0.4486340
   3                  950     0.5734464  0.6522402  0.4487534
   3                 1000     0.5734346  0.6522662  0.4487900
   3                 1050     0.5734458  0.6522690  0.4488393
   3                 1100     0.5735230  0.6521787  0.4489117
   3                 1150     0.5734965  0.6522345  0.4488955
   3                 1200     0.5734652  0.6522657  0.4489010
   3                 1250     0.5734822  0.6522470  0.4489104
   4                   50     0.6090419  0.6106657  0.4697679
   4                  100     0.5954252  0.6226990  0.4637289
   4                  150     0.5938504  0.6285557  0.4636849
   4                  200     0.5913247  0.6319587  0.4642710
   4                  250     0.5900504  0.6333095  0.4639411
   4                  300     0.5896414  0.6341805  0.4634896
   4                  350     0.5895137  0.6345933  0.4633461
   4                  400     0.5895641  0.6348717  0.4637587
   4                  450     0.5897582  0.6347995  0.4642484
   4                  500     0.5898016  0.6348652  0.4640096
   4                  550     0.5901324  0.6345240  0.4644099
   4                  600     0.5903075  0.6345846  0.4645382
   4                  650     0.5906552  0.6344835  0.4647610
   4                  700     0.5906150  0.6345581  0.4646932
   4                  750     0.5904937  0.6347022  0.4646343
   4                  800     0.5903896  0.6348218  0.4647111
   4                  850     0.5904498  0.6348500  0.4648654
   4                  900     0.5903898  0.6348947  0.4648645
   4                  950     0.5905029  0.6348003  0.4649357
   4                 1000     0.5904679  0.6348542  0.4649824
   4                 1050     0.5905540  0.6348192  0.4650847
   4                 1100     0.5904812  0.6348914  0.4651039
   4                 1150     0.5905393  0.6348489  0.4651573
   4                 1200     0.5905692  0.6348523  0.4652096
   4                 1250     0.5905788  0.6348482  0.4652295
   5                   50     0.6019146  0.6193173  0.4631369
   5                  100     0.5718941  0.6522686  0.4417011
   5                  150     0.5652677  0.6602092  0.4392289
   5                  200     0.5615494  0.6644658  0.4390921
   5                  250     0.5617600  0.6643786  0.4400462
   5                  300     0.5596646  0.6653772  0.4374645
   5                  350     0.5600163  0.6651947  0.4374533
   5                  400     0.5594723  0.6657756  0.4364679
   5                  450     0.5583903  0.6671558  0.4358012
   5                  500     0.5582863  0.6672867  0.4358657
   5                  550     0.5585848  0.6668710  0.4361121
   5                  600     0.5586374  0.6668762  0.4362419
   5                  650     0.5588214  0.6666570  0.4364302
   5                  700     0.5590060  0.6664883  0.4365978
   5                  750     0.5589198  0.6665628  0.4366476
   5                  800     0.5589112  0.6665959  0.4367284
   5                  850     0.5588357  0.6666270  0.4366683
   5                  900     0.5588534  0.6666288  0.4366668
   5                  950     0.5588659  0.6666386  0.4366916
   5                 1000     0.5588004  0.6667090  0.4366808
   5                 1050     0.5588444  0.6666598  0.4367332
   5                 1100     0.5588288  0.6667027  0.4367230
   5                 1150     0.5587907  0.6667457  0.4366934
   5                 1200     0.5587934  0.6667445  0.4367111
   5                 1250     0.5587895  0.6667425  0.4367281
   6                   50     0.6018491  0.6113981  0.4716015
   6                  100     0.5860809  0.6279896  0.4539058
   6                  150     0.5789599  0.6340675  0.4501756
   6                  200     0.5715997  0.6426798  0.4421709
   6                  250     0.5711400  0.6437785  0.4446479
   6                  300     0.5722309  0.6432605  0.4457324
   6                  350     0.5728877  0.6433494  0.4461208
   6                  400     0.5735122  0.6430660  0.4468629
   6                  450     0.5733378  0.6435084  0.4468686
   6                  500     0.5736811  0.6432701  0.4474261
   6                  550     0.5737036  0.6433590  0.4473096
   6                  600     0.5738540  0.6432025  0.4476653
   6                  650     0.5739788  0.6431127  0.4478362
   6                  700     0.5740895  0.6430439  0.4480447
   6                  750     0.5740191  0.6431101  0.4479443
   6                  800     0.5739330  0.6432375  0.4478419
   6                  850     0.5741192  0.6430959  0.4480611
   6                  900     0.5742059  0.6429815  0.4481779
   6                  950     0.5742488  0.6429632  0.4482300
   6                 1000     0.5742852  0.6429315  0.4482727
   6                 1050     0.5742550  0.6429979  0.4482394
   6                 1100     0.5743812  0.6428550  0.4483377
   6                 1150     0.5744985  0.6427302  0.4484260
   6                 1200     0.5745169  0.6427252  0.4484495
   6                 1250     0.5745410  0.6427004  0.4484620
   7                   50     0.6199541  0.5939358  0.4951611
   7                  100     0.5904056  0.6257145  0.4697978
   7                  150     0.5788458  0.6390945  0.4585648
   7                  200     0.5810272  0.6391831  0.4611296
   7                  250     0.5799441  0.6409543  0.4606679
   7                  300     0.5800624  0.6409086  0.4596577
   7                  350     0.5806014  0.6403463  0.4610040
   7                  400     0.5805843  0.6404279  0.4609606
   7                  450     0.5808030  0.6404105  0.4609477
   7                  500     0.5806460  0.6408355  0.4606353
   7                  550     0.5801929  0.6413834  0.4605745
   7                  600     0.5803194  0.6413844  0.4606553
   7                  650     0.5805963  0.6411193  0.4608334
   7                  700     0.5807950  0.6410027  0.4609297
   7                  750     0.5807957  0.6410385  0.4609906
   7                  800     0.5808788  0.6410234  0.4610401
   7                  850     0.5808231  0.6411133  0.4609822
   7                  900     0.5808365  0.6410813  0.4609990
   7                  950     0.5808931  0.6410494  0.4610153
   7                 1000     0.5809359  0.6410051  0.4610537
   7                 1050     0.5808882  0.6410698  0.4610093
   7                 1100     0.5809232  0.6410468  0.4610294
   7                 1150     0.5809114  0.6410602  0.4610554
   7                 1200     0.5808922  0.6410764  0.4610722
   7                 1250     0.5809613  0.6410143  0.4611178
   8                   50     0.5763016  0.6411581  0.4576852
   8                  100     0.5716689  0.6461974  0.4512790
   8                  150     0.5759381  0.6437704  0.4563453
   8                  200     0.5721415  0.6496414  0.4538074
   8                  250     0.5711192  0.6516050  0.4518189
   8                  300     0.5695114  0.6546120  0.4513573
   8                  350     0.5689287  0.6555732  0.4504089
   8                  400     0.5682439  0.6561605  0.4498706
   8                  450     0.5673344  0.6572600  0.4491474
   8                  500     0.5674381  0.6572173  0.4490904
   8                  550     0.5670931  0.6576854  0.4489108
   8                  600     0.5667498  0.6580690  0.4488511
   8                  650     0.5666761  0.6581715  0.4488999
   8                  700     0.5666796  0.6582255  0.4489354
   8                  750     0.5665660  0.6583684  0.4489615
   8                  800     0.5663936  0.6586085  0.4488358
   8                  850     0.5663429  0.6586493  0.4488768
   8                  900     0.5662484  0.6587890  0.4488474
   8                  950     0.5662163  0.6588234  0.4488634
   8                 1000     0.5662062  0.6588372  0.4488826
   8                 1050     0.5661932  0.6588655  0.4488774
   8                 1100     0.5661859  0.6588721  0.4489328
   8                 1150     0.5661797  0.6589055  0.4489740
   8                 1200     0.5661731  0.6589180  0.4489745
   8                 1250     0.5661145  0.6589825  0.4489516
   9                   50     0.6167604  0.5965443  0.4845607
   9                  100     0.6055422  0.6101877  0.4735896
   9                  150     0.6027718  0.6130671  0.4745875
   9                  200     0.6064713  0.6092537  0.4803259
   9                  250     0.6025144  0.6149249  0.4778493
   9                  300     0.6044546  0.6123663  0.4795388
   9                  350     0.6048698  0.6115446  0.4806716
   9                  400     0.6055499  0.6107397  0.4814121
   9                  450     0.6053731  0.6108421  0.4821199
   9                  500     0.6056554  0.6105514  0.4825302
   9                  550     0.6062967  0.6099543  0.4830778
   9                  600     0.6062888  0.6100437  0.4831844
   9                  650     0.6063035  0.6100249  0.4832666
   9                  700     0.6063524  0.6100332  0.4834070
   9                  750     0.6065921  0.6097913  0.4836381
   9                  800     0.6065971  0.6098266  0.4837327
   9                  850     0.6067575  0.6097239  0.4838410
   9                  900     0.6068762  0.6095239  0.4839607
   9                  950     0.6069309  0.6094834  0.4839398
   9                 1000     0.6070451  0.6093556  0.4840833
   9                 1050     0.6070858  0.6093011  0.4840669
   9                 1100     0.6071045  0.6092895  0.4841145
   9                 1150     0.6071044  0.6093033  0.4841501
   9                 1200     0.6071309  0.6092787  0.4841950
   9                 1250     0.6071436  0.6092698  0.4842299
  10                   50     0.5970134  0.6171065  0.4623301
  10                  100     0.5806102  0.6398879  0.4516936
  10                  150     0.5687076  0.6525233  0.4416021
  10                  200     0.5721478  0.6492513  0.4463209
  10                  250     0.5769418  0.6459730  0.4509770
  10                  300     0.5781494  0.6456177  0.4515166
  10                  350     0.5799840  0.6438356  0.4534752
  10                  400     0.5799262  0.6437909  0.4532906
  10                  450     0.5804882  0.6433379  0.4535657
  10                  500     0.5809207  0.6427982  0.4541454
  10                  550     0.5811243  0.6425842  0.4543062
  10                  600     0.5813681  0.6424302  0.4544117
  10                  650     0.5812722  0.6425518  0.4544515
  10                  700     0.5814412  0.6423282  0.4544904
  10                  750     0.5815164  0.6422026  0.4545465
  10                  800     0.5816406  0.6419893  0.4546413
  10                  850     0.5817970  0.6417711  0.4546952
  10                  900     0.5818765  0.6416974  0.4547529
  10                  950     0.5819495  0.6416149  0.4547905
  10                 1000     0.5819670  0.6416085  0.4547866
  10                 1050     0.5820416  0.6415048  0.4548642
  10                 1100     0.5821291  0.6413995  0.4549316
  10                 1150     0.5821326  0.6413981  0.4549135
  10                 1200     0.5821708  0.6413569  0.4549586
  10                 1250     0.5821957  0.6413248  0.4549680
  11                   50     0.6007956  0.6191324  0.4784111
  11                  100     0.5796223  0.6436577  0.4611684
  11                  150     0.5734513  0.6497914  0.4595051
  11                  200     0.5760920  0.6478978  0.4603030
  11                  250     0.5764815  0.6483934  0.4592201
  11                  300     0.5770282  0.6479640  0.4592198
  11                  350     0.5763090  0.6487221  0.4583147
  11                  400     0.5758337  0.6494612  0.4581384
  11                  450     0.5758699  0.6496084  0.4581600
  11                  500     0.5754348  0.6501079  0.4575764
  11                  550     0.5753623  0.6503882  0.4575615
  11                  600     0.5751066  0.6507755  0.4575770
  11                  650     0.5750791  0.6508957  0.4575429
  11                  700     0.5751269  0.6508885  0.4574905
  11                  750     0.5750977  0.6508783  0.4575510
  11                  800     0.5751921  0.6507287  0.4576147
  11                  850     0.5752069  0.6507458  0.4576468
  11                  900     0.5752048  0.6507309  0.4576749
  11                  950     0.5751624  0.6507659  0.4575584
  11                 1000     0.5751346  0.6508012  0.4575377
  11                 1050     0.5751284  0.6508137  0.4575096
  11                 1100     0.5751163  0.6508334  0.4575075
  11                 1150     0.5751286  0.6508189  0.4575395
  11                 1200     0.5750890  0.6508693  0.4575222
  11                 1250     0.5750407  0.6509139  0.4574603
  12                   50     0.6131404  0.6008363  0.4788888
  12                  100     0.5936990  0.6206144  0.4563439
  12                  150     0.5917700  0.6239359  0.4570861
  12                  200     0.5894059  0.6276284  0.4536889
  12                  250     0.5896794  0.6286413  0.4545724
  12                  300     0.5884641  0.6307350  0.4541598
  12                  350     0.5885899  0.6311055  0.4538239
  12                  400     0.5878622  0.6319971  0.4533814
  12                  450     0.5876460  0.6325633  0.4531581
  12                  500     0.5873139  0.6327759  0.4527693
  12                  550     0.5872261  0.6329262  0.4530022
  12                  600     0.5875665  0.6325250  0.4532315
  12                  650     0.5876798  0.6324167  0.4532977
  12                  700     0.5876485  0.6325664  0.4532492
  12                  750     0.5876823  0.6325857  0.4532712
  12                  800     0.5879170  0.6323502  0.4534515
  12                  850     0.5879436  0.6323289  0.4534417
  12                  900     0.5880458  0.6322095  0.4534969
  12                  950     0.5880053  0.6322652  0.4534268
  12                 1000     0.5880199  0.6322607  0.4534472
  12                 1050     0.5880897  0.6321977  0.4535073
  12                 1100     0.5880935  0.6321941  0.4534805
  12                 1150     0.5880697  0.6322349  0.4534862
  12                 1200     0.5881165  0.6321864  0.4535333
  12                 1250     0.5881200  0.6321888  0.4535375
  13                   50     0.5973542  0.6314045  0.4668008
  13                  100     0.5777799  0.6451084  0.4518852
  13                  150     0.5764224  0.6467808  0.4476571
  13                  200     0.5730664  0.6505212  0.4451696
  13                  250     0.5743130  0.6495475  0.4462130
  13                  300     0.5760493  0.6476727  0.4459779
  13                  350     0.5766260  0.6469370  0.4465765
  13                  400     0.5770238  0.6468019  0.4468128
  13                  450     0.5776063  0.6459700  0.4475754
  13                  500     0.5779502  0.6456783  0.4478369
  13                  550     0.5779233  0.6457420  0.4477710
  13                  600     0.5781181  0.6454777  0.4481283
  13                  650     0.5782368  0.6453590  0.4482780
  13                  700     0.5783686  0.6452265  0.4484776
  13                  750     0.5784837  0.6450636  0.4487266
  13                  800     0.5785037  0.6450326  0.4487840
  13                  850     0.5786308  0.6449255  0.4489184
  13                  900     0.5786399  0.6448911  0.4490071
  13                  950     0.5786643  0.6448690  0.4490676
  13                 1000     0.5787736  0.6447447  0.4491924
  13                 1050     0.5787891  0.6447278  0.4491872
  13                 1100     0.5788049  0.6447156  0.4492184
  13                 1150     0.5788276  0.6446876  0.4492568
  13                 1200     0.5788448  0.6446723  0.4492837
  13                 1250     0.5788611  0.6446606  0.4493125
  14                   50     0.5968688  0.6288067  0.4721340
  14                  100     0.5788231  0.6442392  0.4626092
  14                  150     0.5772605  0.6493066  0.4581304
  14                  200     0.5767852  0.6504154  0.4555545
  14                  250     0.5763805  0.6510261  0.4554558
  14                  300     0.5773394  0.6501146  0.4569615
  14                  350     0.5771256  0.6504539  0.4561920
  14                  400     0.5774954  0.6500725  0.4563451
  14                  450     0.5778210  0.6498560  0.4567000
  14                  500     0.5773189  0.6507293  0.4564541
  14                  550     0.5774635  0.6506929  0.4566913
  14                  600     0.5772649  0.6509344  0.4564884
  14                  650     0.5769523  0.6513005  0.4562758
  14                  700     0.5768395  0.6514243  0.4561250
  14                  750     0.5767784  0.6515344  0.4562432
  14                  800     0.5767428  0.6516513  0.4561898
  14                  850     0.5767717  0.6516118  0.4562955
  14                  900     0.5767780  0.6516089  0.4563007
  14                  950     0.5767695  0.6515845  0.4563348
  14                 1000     0.5768071  0.6515531  0.4563581
  14                 1050     0.5767456  0.6516372  0.4563169
  14                 1100     0.5767604  0.6516236  0.4563322
  14                 1150     0.5767172  0.6516701  0.4562795
  14                 1200     0.5766858  0.6517006  0.4562711
  14                 1250     0.5766666  0.6517396  0.4562572
  15                   50     0.5984904  0.6144377  0.4802185
  15                  100     0.5843983  0.6293893  0.4687758
  15                  150     0.5763789  0.6365162  0.4607338
  15                  200     0.5742064  0.6397660  0.4613239
  15                  250     0.5734581  0.6414163  0.4627411
  15                  300     0.5732190  0.6423065  0.4629835
  15                  350     0.5725697  0.6433780  0.4630833
  15                  400     0.5718269  0.6444742  0.4627995
  15                  450     0.5718025  0.6447416  0.4631744
  15                  500     0.5718086  0.6446100  0.4633308
  15                  550     0.5719365  0.6446516  0.4634589
  15                  600     0.5718646  0.6447368  0.4634482
  15                  650     0.5715927  0.6451576  0.4633120
  15                  700     0.5714562  0.6453500  0.4633540
  15                  750     0.5714828  0.6453266  0.4634053
  15                  800     0.5716535  0.6452634  0.4636229
  15                  850     0.5716339  0.6453263  0.4636592
  15                  900     0.5715742  0.6454348  0.4636541
  15                  950     0.5715357  0.6455050  0.4637054
  15                 1000     0.5715801  0.6454600  0.4637473
  15                 1050     0.5715296  0.6455215  0.4636962
  15                 1100     0.5714731  0.6456070  0.4636752
  15                 1150     0.5714961  0.6455984  0.4637025
  15                 1200     0.5714283  0.6456968  0.4636602
  15                 1250     0.5714074  0.6457320  0.4636621
  16                   50     0.5845598  0.6367314  0.4522037
  16                  100     0.5744352  0.6415904  0.4402636
  16                  150     0.5712235  0.6450458  0.4374079
  16                  200     0.5706646  0.6461059  0.4395498
  16                  250     0.5743295  0.6426962  0.4431993
  16                  300     0.5732029  0.6443089  0.4421847
  16                  350     0.5740836  0.6434172  0.4426110
  16                  400     0.5733769  0.6441363  0.4427320
  16                  450     0.5731878  0.6440416  0.4426181
  16                  500     0.5733640  0.6440319  0.4428262
  16                  550     0.5734077  0.6440675  0.4428775
  16                  600     0.5733253  0.6442436  0.4429795
  16                  650     0.5731203  0.6444578  0.4429265
  16                  700     0.5732675  0.6444389  0.4430143
  16                  750     0.5731228  0.6445695  0.4428747
  16                  800     0.5732311  0.6445276  0.4431213
  16                  850     0.5732604  0.6445157  0.4432044
  16                  900     0.5732764  0.6444899  0.4432273
  16                  950     0.5731499  0.6446022  0.4431385
  16                 1000     0.5732311  0.6445054  0.4432125
  16                 1050     0.5732592  0.6445116  0.4432604
  16                 1100     0.5732651  0.6444995  0.4432389
  16                 1150     0.5732933  0.6444539  0.4433079
  16                 1200     0.5733533  0.6443725  0.4433261
  16                 1250     0.5733543  0.6443782  0.4433468
  17                   50     0.5895081  0.6221239  0.4584180
  17                  100     0.5598563  0.6545783  0.4403988
  17                  150     0.5588101  0.6549230  0.4345365
  17                  200     0.5585532  0.6557803  0.4346063
  17                  250     0.5560925  0.6593080  0.4346842
  17                  300     0.5583117  0.6567464  0.4355277
  17                  350     0.5589839  0.6564977  0.4365358
  17                  400     0.5585887  0.6567415  0.4358248
  17                  450     0.5579936  0.6581041  0.4363710
  17                  500     0.5576780  0.6586560  0.4363073
  17                  550     0.5580179  0.6583182  0.4369656
  17                  600     0.5576574  0.6586239  0.4365961
  17                  650     0.5573910  0.6588929  0.4364291
  17                  700     0.5572706  0.6591183  0.4364193
  17                  750     0.5572105  0.6592226  0.4363436
  17                  800     0.5572080  0.6592986  0.4364028
  17                  850     0.5571794  0.6593780  0.4364372
  17                  900     0.5572748  0.6592692  0.4364702
  17                  950     0.5572903  0.6592425  0.4365164
  17                 1000     0.5573969  0.6591232  0.4366330
  17                 1050     0.5573523  0.6592176  0.4366466
  17                 1100     0.5573181  0.6592760  0.4366223
  17                 1150     0.5572999  0.6593232  0.4366195
  17                 1200     0.5573417  0.6592814  0.4366678
  17                 1250     0.5573217  0.6593154  0.4366610
  18                   50     0.5947040  0.6238031  0.4720874
  18                  100     0.5618769  0.6575285  0.4478613
  18                  150     0.5582539  0.6634045  0.4444225
  18                  200     0.5585195  0.6646903  0.4463124
  18                  250     0.5632000  0.6587717  0.4503918
  18                  300     0.5628079  0.6600173  0.4498614
  18                  350     0.5627775  0.6601182  0.4500888
  18                  400     0.5624382  0.6605836  0.4498481
  18                  450     0.5630086  0.6602329  0.4503341
  18                  500     0.5625749  0.6607663  0.4500855
  18                  550     0.5625871  0.6610884  0.4501850
  18                  600     0.5627920  0.6609869  0.4503990
  18                  650     0.5627910  0.6610874  0.4501716
  18                  700     0.5629293  0.6609290  0.4501911
  18                  750     0.5629849  0.6608811  0.4504471
  18                  800     0.5631089  0.6607372  0.4505341
  18                  850     0.5632879  0.6605472  0.4507397
  18                  900     0.5634311  0.6604467  0.4508773
  18                  950     0.5635290  0.6603438  0.4509308
  18                 1000     0.5636527  0.6602004  0.4510463
  18                 1050     0.5637119  0.6601604  0.4510915
  18                 1100     0.5637187  0.6601415  0.4510943
  18                 1150     0.5637947  0.6600683  0.4511788
  18                 1200     0.5637589  0.6601116  0.4511481
  18                 1250     0.5638153  0.6600584  0.4511662
  19                   50     0.6044116  0.6084186  0.4816248
  19                  100     0.5884591  0.6259706  0.4666916
  19                  150     0.5827201  0.6350315  0.4611196
  19                  200     0.5796750  0.6394943  0.4593404
  19                  250     0.5791659  0.6405009  0.4592163
  19                  300     0.5789062  0.6406001  0.4594678
  19                  350     0.5792869  0.6402798  0.4606605
  19                  400     0.5798080  0.6398658  0.4610008
  19                  450     0.5798865  0.6398399  0.4611347
  19                  500     0.5796314  0.6402471  0.4607525
  19                  550     0.5799321  0.6402072  0.4611976
  19                  600     0.5798439  0.6403842  0.4609075
  19                  650     0.5798640  0.6404004  0.4609272
  19                  700     0.5799447  0.6403739  0.4610496
  19                  750     0.5801595  0.6401531  0.4611883
  19                  800     0.5800469  0.6402696  0.4610050
  19                  850     0.5801075  0.6402613  0.4611237
  19                  900     0.5801117  0.6402842  0.4610773
  19                  950     0.5800802  0.6403546  0.4611275
  19                 1000     0.5801482  0.6402883  0.4612403
  19                 1050     0.5800854  0.6403723  0.4612398
  19                 1100     0.5800651  0.6404008  0.4612760
  19                 1150     0.5800433  0.6404542  0.4612893
  19                 1200     0.5800546  0.6404666  0.4613544
  19                 1250     0.5800492  0.6404551  0.4613605
  20                   50     0.6228995  0.5928646  0.4924395
  20                  100     0.6009344  0.6133889  0.4698906
  20                  150     0.5921427  0.6222307  0.4687025
  20                  200     0.5883624  0.6284961  0.4663482
  20                  250     0.5858482  0.6313708  0.4644570
  20                  300     0.5854396  0.6320113  0.4637267
  20                  350     0.5850790  0.6320588  0.4644387
  20                  400     0.5844287  0.6334042  0.4640988
  20                  450     0.5848621  0.6327404  0.4649257
  20                  500     0.5849726  0.6328714  0.4651716
  20                  550     0.5848708  0.6330092  0.4652380
  20                  600     0.5851218  0.6326644  0.4654536
  20                  650     0.5853962  0.6324062  0.4658945
  20                  700     0.5854769  0.6323859  0.4659694
  20                  750     0.5854284  0.6324044  0.4659240
  20                  800     0.5856137  0.6322070  0.4661607
  20                  850     0.5858048  0.6320155  0.4663029
  20                  900     0.5857902  0.6321231  0.4662757
  20                  950     0.5858142  0.6320788  0.4662986
  20                 1000     0.5859219  0.6319654  0.4663609
  20                 1050     0.5859580  0.6319822  0.4663748
  20                 1100     0.5860260  0.6319045  0.4664469
  20                 1150     0.5861297  0.6317874  0.4665715
  20                 1200     0.5861911  0.6317411  0.4666073
  20                 1250     0.5861864  0.6317425  0.4666093
  21                   50     0.6164913  0.5907092  0.4901770
  21                  100     0.5954901  0.6129761  0.4706662
  21                  150     0.5863253  0.6208539  0.4555843
  21                  200     0.5880713  0.6212227  0.4594044
  21                  250     0.5878737  0.6214425  0.4575625
  21                  300     0.5863312  0.6232168  0.4574849
  21                  350     0.5874788  0.6219323  0.4588074
  21                  400     0.5879728  0.6216350  0.4597942
  21                  450     0.5875109  0.6219386  0.4597765
  21                  500     0.5874788  0.6220713  0.4599140
  21                  550     0.5875259  0.6220454  0.4600137
  21                  600     0.5878106  0.6216276  0.4602113
  21                  650     0.5880222  0.6214441  0.4604127
  21                  700     0.5881523  0.6212943  0.4605623
  21                  750     0.5882456  0.6212172  0.4608117
  21                  800     0.5883022  0.6211843  0.4609491
  21                  850     0.5883325  0.6211449  0.4610155
  21                  900     0.5884684  0.6210333  0.4611763
  21                  950     0.5884012  0.6211157  0.4612100
  21                 1000     0.5884770  0.6210339  0.4613186
  21                 1050     0.5885063  0.6210078  0.4613713
  21                 1100     0.5885325  0.6209880  0.4613699
  21                 1150     0.5885974  0.6209189  0.4614618
  21                 1200     0.5885644  0.6209809  0.4614654
  21                 1250     0.5885900  0.6209606  0.4615024
  22                   50     0.5793334  0.6434253  0.4720771
  22                  100     0.5531895  0.6722105  0.4488228
  22                  150     0.5488134  0.6781810  0.4432762
  22                  200     0.5528279  0.6739731  0.4470342
  22                  250     0.5495858  0.6780192  0.4443609
  22                  300     0.5493595  0.6789946  0.4426837
  22                  350     0.5502390  0.6779176  0.4441018
  22                  400     0.5515463  0.6764037  0.4447485
  22                  450     0.5512482  0.6765891  0.4447522
  22                  500     0.5507834  0.6775022  0.4440172
  22                  550     0.5508227  0.6774242  0.4439655
  22                  600     0.5512931  0.6770631  0.4443603
  22                  650     0.5514199  0.6769012  0.4444753
  22                  700     0.5513916  0.6769650  0.4444461
  22                  750     0.5512924  0.6771605  0.4443759
  22                  800     0.5514432  0.6769484  0.4444075
  22                  850     0.5515481  0.6768914  0.4445889
  22                  900     0.5516099  0.6768201  0.4446169
  22                  950     0.5516678  0.6767554  0.4446328
  22                 1000     0.5516392  0.6768049  0.4446332
  22                 1050     0.5516028  0.6768805  0.4446273
  22                 1100     0.5515640  0.6769180  0.4445721
  22                 1150     0.5515192  0.6769851  0.4445507
  22                 1200     0.5515205  0.6769964  0.4445526
  22                 1250     0.5515608  0.6769583  0.4445800
  23                   50     0.6177465  0.5985763  0.4831558
  23                  100     0.5937322  0.6267084  0.4623962
  23                  150     0.6002425  0.6181106  0.4665577
  23                  200     0.5959912  0.6256254  0.4651166
  23                  250     0.5976436  0.6234317  0.4671482
  23                  300     0.5983712  0.6239639  0.4676933
  23                  350     0.5969445  0.6255335  0.4662105
  23                  400     0.5972253  0.6253612  0.4668455
  23                  450     0.5973307  0.6254383  0.4672388
  23                  500     0.5972284  0.6255382  0.4674735
  23                  550     0.5969328  0.6258570  0.4674252
  23                  600     0.5968363  0.6260482  0.4676239
  23                  650     0.5971095  0.6257743  0.4679849
  23                  700     0.5971499  0.6257096  0.4681145
  23                  750     0.5972320  0.6256212  0.4682903
  23                  800     0.5973860  0.6254261  0.4684687
  23                  850     0.5974018  0.6254181  0.4685405
  23                  900     0.5974908  0.6253233  0.4686105
  23                  950     0.5975844  0.6252652  0.4687825
  23                 1000     0.5976395  0.6251821  0.4688300
  23                 1050     0.5976240  0.6251807  0.4688325
  23                 1100     0.5976592  0.6251428  0.4689031
  23                 1150     0.5976260  0.6251732  0.4689478
  23                 1200     0.5976233  0.6251752  0.4689585
  23                 1250     0.5976330  0.6251617  0.4689663
  24                   50     0.6308858  0.5776525  0.4972108
  24                  100     0.6046511  0.6104362  0.4799937
  24                  150     0.5995390  0.6177781  0.4799586
  24                  200     0.5978228  0.6194035  0.4813903
  24                  250     0.5976961  0.6207397  0.4819837
  24                  300     0.5980968  0.6207244  0.4820177
  24                  350     0.5978139  0.6210982  0.4823949
  24                  400     0.5976232  0.6215346  0.4820746
  24                  450     0.5987533  0.6205269  0.4830158
  24                  500     0.5986787  0.6208225  0.4832110
  24                  550     0.5988664  0.6206171  0.4833016
  24                  600     0.5987075  0.6208757  0.4833147
  24                  650     0.5988573  0.6207512  0.4835311
  24                  700     0.5989057  0.6207085  0.4837492
  24                  750     0.5989222  0.6207121  0.4837938
  24                  800     0.5988335  0.6208467  0.4838003
  24                  850     0.5989063  0.6208014  0.4838899
  24                  900     0.5988832  0.6208370  0.4839103
  24                  950     0.5988937  0.6208618  0.4839207
  24                 1000     0.5989267  0.6208511  0.4839856
  24                 1050     0.5989133  0.6208810  0.4839989
  24                 1100     0.5988945  0.6209149  0.4839993
  24                 1150     0.5989049  0.6209117  0.4840228
  24                 1200     0.5989236  0.6209006  0.4840094
  24                 1250     0.5988978  0.6209304  0.4840227
  25                   50     0.5967884  0.6181418  0.4722004
  25                  100     0.5761255  0.6368342  0.4559817
  25                  150     0.5671111  0.6485046  0.4470742
  25                  200     0.5646577  0.6522515  0.4440080
  25                  250     0.5639557  0.6540791  0.4446264
  25                  300     0.5643908  0.6541095  0.4458751
  25                  350     0.5645825  0.6548046  0.4472483
  25                  400     0.5646346  0.6549075  0.4471908
  25                  450     0.5657594  0.6538895  0.4484154
  25                  500     0.5667385  0.6529176  0.4492661
  25                  550     0.5667006  0.6530126  0.4490882
  25                  600     0.5669719  0.6528129  0.4495295
  25                  650     0.5668937  0.6530017  0.4495543
  25                  700     0.5670696  0.6529264  0.4496043
  25                  750     0.5671854  0.6528701  0.4498735
  25                  800     0.5671214  0.6529534  0.4498998
  25                  850     0.5671270  0.6529565  0.4498827
  25                  900     0.5671469  0.6529419  0.4498852
  25                  950     0.5671453  0.6529481  0.4499353
  25                 1000     0.5671302  0.6530179  0.4499500
  25                 1050     0.5671623  0.6529877  0.4499665
  25                 1100     0.5671858  0.6529748  0.4499741
  25                 1150     0.5672006  0.6529891  0.4499975
  25                 1200     0.5672042  0.6530004  0.4500351
  25                 1250     0.5672439  0.6529631  0.4500798

Tuning parameter 'shrinkage' was held constant at a value of 0.1

Tuning parameter 'n.minobsinnode' was held constant at a value of 10
RMSE was used to select the optimal model using the smallest value.
The final values used for the model were n.trees = 150, interaction.depth =
 22, shrinkage = 0.1 and n.minobsinnode = 10.

Random Forest

Random Forest 

144 samples
 56 predictor

No pre-processing
Resampling: Cross-Validated (10 fold) 
Summary of sample sizes: 129, 129, 130, 129, 130, 130, ... 
Resampling results across tuning parameters:

  mtry  splitrule   RMSE       Rsquared   MAE      
   2    variance    0.6497858  0.6438354  0.5345934
   2    extratrees  0.7107005  0.5913499  0.5896222
   4    variance    0.6171845  0.6644030  0.5076339
   4    extratrees  0.6635219  0.6303318  0.5515317
   6    variance    0.6040398  0.6653486  0.4934050
   6    extratrees  0.6438055  0.6420607  0.5349385
   8    variance    0.5955708  0.6700645  0.4806501
   8    extratrees  0.6262944  0.6656202  0.5207843
  11    variance    0.5898819  0.6693959  0.4744251
  11    extratrees  0.6146979  0.6750476  0.5068688
  13    variance    0.5903434  0.6629506  0.4755268
  13    extratrees  0.6078146  0.6769346  0.5042883
  15    variance    0.5875867  0.6652769  0.4701072
  15    extratrees  0.6046625  0.6756825  0.4957882
  17    variance    0.5840520  0.6641550  0.4649468
  17    extratrees  0.6063868  0.6668625  0.4976930
  20    variance    0.5890784  0.6532341  0.4674457
  20    extratrees  0.5946979  0.6841960  0.4852246
  22    variance    0.5879453  0.6542423  0.4622086
  22    extratrees  0.5963783  0.6790233  0.4886738
  24    variance    0.5858153  0.6551814  0.4636970
  24    extratrees  0.5971505  0.6726166  0.4875783
  26    variance    0.5880400  0.6496644  0.4626234
  26    extratrees  0.5981009  0.6718938  0.4871614
  29    variance    0.5895010  0.6475055  0.4643408
  29    extratrees  0.5967249  0.6668901  0.4851825
  31    variance    0.5951690  0.6376674  0.4677508
  31    extratrees  0.5976439  0.6635536  0.4847677
  33    variance    0.5928874  0.6411724  0.4669791
  33    extratrees  0.5924849  0.6768113  0.4838468
  35    variance    0.5867051  0.6489605  0.4611046
  35    extratrees  0.5929398  0.6699430  0.4837254
  38    variance    0.6004208  0.6315682  0.4740340
  38    extratrees  0.5968329  0.6645022  0.4862917
  40    variance    0.5964688  0.6348283  0.4651849
  40    extratrees  0.5939651  0.6651959  0.4825585
  42    variance    0.5923281  0.6392379  0.4630702
  42    extratrees  0.5927962  0.6625781  0.4817914
  44    variance    0.5956628  0.6331507  0.4641829
  44    extratrees  0.5925441  0.6628893  0.4776745
  47    variance    0.6043288  0.6220066  0.4688005
  47    extratrees  0.5964637  0.6564644  0.4838434
  49    variance    0.6009236  0.6281433  0.4683679
  49    extratrees  0.5942796  0.6633846  0.4830116
  51    variance    0.6009500  0.6258047  0.4727813
  51    extratrees  0.5895383  0.6664917  0.4784356
  53    variance    0.6023795  0.6254545  0.4713244
  53    extratrees  0.5917877  0.6623634  0.4786651
  56    variance    0.6031440  0.6269611  0.4686278
  56    extratrees  0.5920145  0.6621812  0.4794944

Tuning parameter 'min.node.size' was held constant at a value of 5
RMSE was used to select the optimal model using the smallest value.
The final values used for the model were mtry = 17, splitrule = variance
 and min.node.size = 5.

Conditional Inference Random Forest

Conditional Inference Random Forest 

144 samples
 56 predictor

No pre-processing
Resampling: Cross-Validated (10 fold) 
Summary of sample sizes: 129, 129, 130, 129, 130, 130, ... 
Resampling results across tuning parameters:

  mtry  RMSE       Rsquared   MAE      
   2    0.7898970  0.5184391  0.6525080
   4    0.7046135  0.5646303  0.5780069
   6    0.6725218  0.5887280  0.5500396
   8    0.6602660  0.5914750  0.5383059
  11    0.6542383  0.5867416  0.5291135
  13    0.6475067  0.5904548  0.5256915
  15    0.6498053  0.5834067  0.5264809
  17    0.6515475  0.5761058  0.5269520
  20    0.6511948  0.5722409  0.5237739
  22    0.6461205  0.5776471  0.5218458
  24    0.6476044  0.5719672  0.5225875
  26    0.6514498  0.5667591  0.5257020
  29    0.6503738  0.5666119  0.5229556
  31    0.6513746  0.5628461  0.5228537
  33    0.6531447  0.5604409  0.5239990
  35    0.6532619  0.5584804  0.5256739
  38    0.6564974  0.5523390  0.5270321
  40    0.6590074  0.5488009  0.5304481
  42    0.6557320  0.5530412  0.5254378
  44    0.6584156  0.5500981  0.5268187
  47    0.6578192  0.5469014  0.5257655
  49    0.6625088  0.5418367  0.5306678
  51    0.6614085  0.5431193  0.5296342
  53    0.6631957  0.5386486  0.5286492
  56    0.6677752  0.5318607  0.5336618

RMSE was used to select the optimal model using the smallest value.
The final value used for the model was mtry = 22.

Results

RMSE Rsquared MAE In Sample RMSE In Sample Rsquared In Sample MAE Model
0.6192577 0.6771122 0.5059984 0.7363066 0.5244517 0.5688553 PLS
0.6319866 0.7554852 0.4616119 0.5840520 0.6641550 0.4649468 Random Forest
0.6569218 0.6667230 0.4849000 0.5488134 0.6781810 0.4432762 Boosted Tree
0.6934245 0.6790718 0.5093532 0.6461205 0.5776471 0.5218458 Conditional Random Forest
0.7166524 0.6160449 0.5447146 0.7108683 0.4717657 0.5795483 Bagged Tree

All tree model’s fit the in sample data better than the PLS model. However they may have overfit the data as the RMSE on the test set is higher for the random forest and boosted tree. The boosted tree model is the only on that out preformed the PLS on the test set.

Part B

Which predictors are most important in the optimal tree-based regression model? Do either the biological or process variables dominate the list? How do the top 10 important predictors compare to the top 10 predictors for the optimal linear and nonlinear models?

Here’s the top ten predictors:

loess r-squared variable importance

  only 20 most important variables shown (out of 56)

                       Overall
ManufacturingProcess32  100.00
ManufacturingProcess13   93.82
ManufacturingProcess09   89.93
ManufacturingProcess17   88.20
BiologicalMaterial06     82.61
BiologicalMaterial03     79.44
ManufacturingProcess36   73.85
BiologicalMaterial12     72.36
ManufacturingProcess06   69.00
ManufacturingProcess11   62.34
ManufacturingProcess31   56.39
BiologicalMaterial02     50.34
BiologicalMaterial11     48.53
BiologicalMaterial09     44.76
ManufacturingProcess30   41.87
BiologicalMaterial08     40.24
ManufacturingProcess29   38.54
ManufacturingProcess33   38.16
BiologicalMaterial04     36.92
ManufacturingProcess25   36.83

The manufacturing process variables continue to dominate the list. The same variables are found in both lists (in different orders of importance)

pls variable importance

  only 20 most important variables shown (out of 56)

                       Overall
ManufacturingProcess32  100.00
ManufacturingProcess09   88.04
ManufacturingProcess36   82.20
ManufacturingProcess13   82.11
ManufacturingProcess17   80.25
ManufacturingProcess06   59.06
ManufacturingProcess11   55.93
BiologicalMaterial02     55.46
BiologicalMaterial06     54.64
BiologicalMaterial03     54.50
ManufacturingProcess33   53.91
ManufacturingProcess12   52.04
BiologicalMaterial08     49.76
BiologicalMaterial12     47.40
ManufacturingProcess34   45.47
BiologicalMaterial11     45.05
BiologicalMaterial01     44.18
BiologicalMaterial04     42.95
ManufacturingProcess04   39.94
ManufacturingProcess28   36.61

Part C

Plot the optimal single tree with the distribution of yield in the terminal nodes. Does this view of the data provide additional knowledge about the biological or process predictors and their relationship with yield?

This indicates that if you want to maximize yield, then the manufacturing process 32 must be greater than or equal to 0.19, process 13 < -0.85 and the Biological material 3 >= 0.49. This recipie will produce the greatest yield. Caution should be used however as this model is likely overfitting the training data.