7.2

Friedman (1991) introduced several benchmark data sets create by simulation. One of these simulations used the following nonlinear equation to create data:

\(y=10sin(\pi x_1x_2) + 20(x_3-0.5)^2+10x_4+5x_5+N(0,\sigma^2)\)

where the x values are random variables uniformly distributed between [0, 1] (there are also 5 other non-informative variables also created in the simulation). The package mlbench contains a function called mlbench.friedman1 that simulates these data:

library(mlbench)
set.seed(200)
trainingData <- mlbench.friedman1(200, sd = 1)
## We convert the 'x' data from a matrix to a data frame
## One reason is that this will give the columns names.
trainingData$x <- data.frame(trainingData$x)
## Look at the data using
featurePlot(trainingData$x, trainingData$y)

## or other methods.

## This creates a list with a vector 'y' and a matrix
## of predictors 'x'. Also simulate a large test set to
## estimate the true error rate with good precision:
testData <- mlbench.friedman1(5000, sd = 1)
testData$x <- data.frame(testData$x)

Tune several models on these data.

Which models appear to give the best performance? Does MARS select the informative predictors (those named X1–X5)?

nnetGrid <- expand.grid(.decay = c(0,0.01,.1),
                        .size = c(1:5),
                        .bag = FALSE)

nnetFit <- train(trainingData$x, trainingData$y,
                  method = 'avNNet',
                  tuneGrid = nnetGrid,
                  preProc = c('center','scale'),
                  linout = TRUE,
                  trace = FALSE,
                  MaxNWts = 5 * (ncol(trainingData$x) + 1 + 5 + 1),
                  maxit = 100
  
)
## Warning: executing %dopar% sequentially: no parallel backend registered
nnetFit
## Model Averaged Neural Network 
## 
## 200 samples
##  10 predictor
## 
## Pre-processing: centered (10), scaled (10) 
## Resampling: Bootstrapped (25 reps) 
## Summary of sample sizes: 200, 200, 200, 200, 200, 200, ... 
## Resampling results across tuning parameters:
## 
##   decay  size  RMSE      Rsquared   MAE     
##   0.00   1     2.473423  0.7539089  1.936474
##   0.00   2     2.507141  0.7476210  1.957269
##   0.00   3     2.346503  0.7779602  1.865790
##   0.00   4     2.434863  0.7625743  1.921202
##   0.00   5     2.709936  0.7215371  2.093228
##   0.01   1     2.465089  0.7523657  1.922437
##   0.01   2     2.506239  0.7461192  1.965544
##   0.01   3     2.360384  0.7758343  1.876507
##   0.01   4     2.390931  0.7706564  1.909652
##   0.01   5     2.547943  0.7454483  2.004900
##   0.10   1     2.446652  0.7563434  1.898926
##   0.10   2     2.500327  0.7477902  1.963910
##   0.10   3     2.283814  0.7878965  1.807668
##   0.10   4     2.322818  0.7847297  1.864023
##   0.10   5     2.362975  0.7752266  1.887780
## 
## Tuning parameter 'bag' was held constant at a value of FALSE
## RMSE was used to select the optimal model using the smallest value.
## The final values used for the model were size = 3, decay = 0.1 and bag = FALSE.
nnetPred <- predict(nnetFit, newdata = testData$x)
postResample(pred = nnetPred, obs = testData$y)
##      RMSE  Rsquared       MAE 
## 2.1852646 0.8101321 1.6309365

MARS model

#creating tune grid
marsGrid <- expand.grid(.degree = 1:2, .nprune = 2:28)
set.seed(100)
marsTuned <- train(trainingData$x, trainingData$y,
                   method = 'earth',
                   tuneGrid = marsGrid,
                   trControl = trainControl(method = 'cv'))

marsTuned
## Multivariate Adaptive Regression Spline 
## 
## 200 samples
##  10 predictor
## 
## No pre-processing
## Resampling: Cross-Validated (10 fold) 
## Summary of sample sizes: 180, 180, 180, 180, 180, 180, ... 
## Resampling results across tuning parameters:
## 
##   degree  nprune  RMSE      Rsquared   MAE     
##   1        2      4.327937  0.2544880  3.600474
##   1        3      3.572450  0.4912720  2.895811
##   1        4      2.596841  0.7183600  2.106341
##   1        5      2.370161  0.7659777  1.918669
##   1        6      2.276141  0.7881481  1.810001
##   1        7      1.766728  0.8751831  1.390215
##   1        8      1.780946  0.8723243  1.401345
##   1        9      1.665091  0.8819775  1.325515
##   1       10      1.663804  0.8821283  1.327657
##   1       11      1.657738  0.8822967  1.331730
##   1       12      1.653784  0.8827903  1.331504
##   1       13      1.648496  0.8823663  1.316407
##   1       14      1.639073  0.8841742  1.312833
##   1       15      1.639073  0.8841742  1.312833
##   1       16      1.639073  0.8841742  1.312833
##   1       17      1.639073  0.8841742  1.312833
##   1       18      1.639073  0.8841742  1.312833
##   1       19      1.639073  0.8841742  1.312833
##   1       20      1.639073  0.8841742  1.312833
##   1       21      1.639073  0.8841742  1.312833
##   1       22      1.639073  0.8841742  1.312833
##   1       23      1.639073  0.8841742  1.312833
##   1       24      1.639073  0.8841742  1.312833
##   1       25      1.639073  0.8841742  1.312833
##   1       26      1.639073  0.8841742  1.312833
##   1       27      1.639073  0.8841742  1.312833
##   1       28      1.639073  0.8841742  1.312833
##   2        2      4.327937  0.2544880  3.600474
##   2        3      3.572450  0.4912720  2.895811
##   2        4      2.661826  0.7070510  2.173471
##   2        5      2.404015  0.7578971  1.975387
##   2        6      2.243927  0.7914805  1.783072
##   2        7      1.856336  0.8605482  1.435682
##   2        8      1.754607  0.8763186  1.396841
##   2        9      1.603578  0.8938666  1.261361
##   2       10      1.492421  0.9084998  1.168700
##   2       11      1.317350  0.9292504  1.033926
##   2       12      1.304327  0.9320133  1.019108
##   2       13      1.277510  0.9323681  1.002927
##   2       14      1.269626  0.9350024  1.003346
##   2       15      1.266217  0.9359400  1.013893
##   2       16      1.268470  0.9354868  1.011414
##   2       17      1.268470  0.9354868  1.011414
##   2       18      1.268470  0.9354868  1.011414
##   2       19      1.268470  0.9354868  1.011414
##   2       20      1.268470  0.9354868  1.011414
##   2       21      1.268470  0.9354868  1.011414
##   2       22      1.268470  0.9354868  1.011414
##   2       23      1.268470  0.9354868  1.011414
##   2       24      1.268470  0.9354868  1.011414
##   2       25      1.268470  0.9354868  1.011414
##   2       26      1.268470  0.9354868  1.011414
##   2       27      1.268470  0.9354868  1.011414
##   2       28      1.268470  0.9354868  1.011414
## 
## RMSE was used to select the optimal model using the smallest value.
## The final values used for the model were nprune = 15 and degree = 2.
varImp(marsTuned)
## earth variable importance
## 
##    Overall
## X1  100.00
## X4   75.24
## X2   48.73
## X5   15.52
## X3    0.00
marsPred <- predict(marsTuned, newdata = testData$x)
postResample(pred = marsPred, obs = testData$y)
##      RMSE  Rsquared       MAE 
## 1.1589948 0.9460418 0.9250230

Support Vector Machines

svmRTuned <- train(trainingData$x, trainingData$y,
                   method = 'svmRadial',
                   preProc = c('center','scale'),
                   tuneLength = 14,
                   trControl = trainControl(method = 'cv'))

svmRTuned
## Support Vector Machines with Radial Basis Function Kernel 
## 
## 200 samples
##  10 predictor
## 
## Pre-processing: centered (10), scaled (10) 
## Resampling: Cross-Validated (10 fold) 
## Summary of sample sizes: 180, 180, 180, 180, 180, 180, ... 
## Resampling results across tuning parameters:
## 
##   C        RMSE      Rsquared   MAE     
##      0.25  2.490737  0.8009120  1.982118
##      0.50  2.246868  0.8153042  1.774454
##      1.00  2.051872  0.8400992  1.614368
##      2.00  1.949707  0.8534618  1.524201
##      4.00  1.886125  0.8610205  1.465373
##      8.00  1.849240  0.8654699  1.436630
##     16.00  1.834604  0.8673639  1.429807
##     32.00  1.833221  0.8675754  1.428687
##     64.00  1.833221  0.8675754  1.428687
##    128.00  1.833221  0.8675754  1.428687
##    256.00  1.833221  0.8675754  1.428687
##    512.00  1.833221  0.8675754  1.428687
##   1024.00  1.833221  0.8675754  1.428687
##   2048.00  1.833221  0.8675754  1.428687
## 
## Tuning parameter 'sigma' was held constant at a value of 0.06315483
## RMSE was used to select the optimal model using the smallest value.
## The final values used for the model were sigma = 0.06315483 and C = 32.
svmPred <- predict(svmRTuned, newdata = testData$x)
postResample(pred = svmPred, obs = testData$y)
##      RMSE  Rsquared       MAE 
## 2.0741473 0.8255848 1.5755185

K - Nearest Neighbors

knnTune <- train(trainingData$x, trainingData$y,
                   method = 'knn',
                   preProc = c('center','scale'),
                   tuneGrid = data.frame(.k = 1:20),
                   trControl = trainControl(method = 'cv'))

knnTune
## k-Nearest Neighbors 
## 
## 200 samples
##  10 predictor
## 
## Pre-processing: centered (10), scaled (10) 
## Resampling: Cross-Validated (10 fold) 
## Summary of sample sizes: 180, 180, 180, 180, 180, 180, ... 
## Resampling results across tuning parameters:
## 
##   k   RMSE      Rsquared   MAE     
##    1  4.299219  0.3772830  3.525540
##    2  3.551955  0.5041055  2.975169
##    3  3.468087  0.5137546  2.847178
##    4  3.311858  0.5590615  2.696377
##    5  3.219196  0.5848916  2.625896
##    6  3.197284  0.6003245  2.576550
##    7  3.164256  0.6116347  2.565735
##    8  3.157394  0.6246817  2.557959
##    9  3.174966  0.6293168  2.557658
##   10  3.140138  0.6441006  2.528967
##   11  3.069367  0.6730751  2.457660
##   12  3.069337  0.6830170  2.477946
##   13  3.086832  0.6926565  2.488467
##   14  3.082621  0.7033583  2.492675
##   15  3.089916  0.7033831  2.491969
##   16  3.115603  0.7110773  2.510279
##   17  3.117067  0.7169598  2.522369
##   18  3.137995  0.7137976  2.542800
##   19  3.137240  0.7211267  2.542361
##   20  3.141507  0.7221221  2.532482
## 
## RMSE was used to select the optimal model using the smallest value.
## The final value used for the model was k = 12.
knnPred <- predict(knnTune, newdata = testData$x)
postResample(pred = knnPred, obs = testData$y)
##      RMSE  Rsquared       MAE 
## 3.1307150 0.6731293 2.5070032

The MARS model produces the best results with a Rsquared of 0.9460418 on the test set. The Mars model only uses the informative predictors, X1-X5.

7.5

Exercise 6.3 describes data for a chemical manufacturing process. Use the same data imputation, data splitting, and pre-processing steps as before and train several nonlinear regression models.

library(AppliedPredictiveModeling)
data(ChemicalManufacturingProcess)
df <- ChemicalManufacturingProcess

init <- mice(df, maxit = 0)
predM <- init$predictorMatrix
set.seed(123)
imputed <- mice(df, method = 'pmm', predictorMatrix = predM, m=5)
## 
##  iter imp variable
##   1   1  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   1   2  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   1   3  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   1   4  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   1   5  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   2   1  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   2   2  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   2   3  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   2   4  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   2   5  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   3   1  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   3   2  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   3   3  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   3   4  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   3   5  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   4   1  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   4   2  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   4   3  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   4   4  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   4   5  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   5   1  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   5   2  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   5   3  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   5   4  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
##   5   5  ManufacturingProcess01  ManufacturingProcess02  ManufacturingProcess03  ManufacturingProcess04  ManufacturingProcess05  ManufacturingProcess06  ManufacturingProcess07  ManufacturingProcess08  ManufacturingProcess10  ManufacturingProcess11  ManufacturingProcess12  ManufacturingProcess14  ManufacturingProcess22  ManufacturingProcess23  ManufacturingProcess24  ManufacturingProcess25  ManufacturingProcess26  ManufacturingProcess27  ManufacturingProcess28  ManufacturingProcess29  ManufacturingProcess30  ManufacturingProcess31  ManufacturingProcess33  ManufacturingProcess34  ManufacturingProcess35  ManufacturingProcess36  ManufacturingProcess40  ManufacturingProcess41
## Warning: Number of logged events: 675
df <- complete(imputed)

set.seed(123)
trans_df <- preProcess(df,
    method = c('center', 'scale'))

df <- predict(trans_df, df)

sample <- sample.split(df$Yield, SplitRatio = 0.75)
X_train = subset(df[,-1], sample == TRUE)
X_test = subset(df[,-1], sample == FALSE)

y_train <- subset(df[,1], sample == TRUE)
y_test <- subset(df[,1], sample == FALSE)

enetGrid <- expand.grid(.lambda = c(0,0.01,0.1),
            .fraction = seq(0.05,1,length = 20))

set.seed(213)
enetTune <- train(X_train, y_train,
                  method = 'enet',
                  tuneGrid = enetGrid
                  )
enetTune
## Elasticnet 
## 
## 132 samples
##  57 predictor
## 
## No pre-processing
## Resampling: Bootstrapped (25 reps) 
## Summary of sample sizes: 132, 132, 132, 132, 132, 132, ... 
## Resampling results across tuning parameters:
## 
##   lambda  fraction  RMSE        Rsquared    MAE      
##   0.00    0.05       0.7270126  0.56132318  0.5629656
##   0.00    0.10       1.1259552  0.41659738  0.6744747
##   0.00    0.15       1.8955366  0.31904340  0.8499337
##   0.00    0.20       3.0144268  0.22447697  1.0705791
##   0.00    0.25       4.0516707  0.21514663  1.2564735
##   0.00    0.30       5.0180356  0.19349592  1.4396472
##   0.00    0.35       5.9864366  0.16262706  1.6117368
##   0.00    0.40       6.7661921  0.13050553  1.7596472
##   0.00    0.45       7.3886632  0.12020733  1.8803490
##   0.00    0.50       7.8721167  0.12096628  1.9739936
##   0.00    0.55       8.3264538  0.11484857  2.0605206
##   0.00    0.60       8.7285206  0.10703066  2.1449555
##   0.00    0.65       9.1484752  0.09959733  2.2333224
##   0.00    0.70       9.5106009  0.09423044  2.3072698
##   0.00    0.75       9.8946656  0.09136830  2.3868264
##   0.00    0.80      10.2920822  0.09056733  2.4655756
##   0.00    0.85      10.6911097  0.09031922  2.5419748
##   0.00    0.90      11.0311795  0.09057419  2.6037477
##   0.00    0.95      11.9174103  0.09069926  2.8770231
##   0.00    1.00      12.3285571  0.08941398  2.9562052
##   0.01    0.05       0.8415365  0.51958153  0.6824794
##   0.01    0.10       0.7292621  0.54190264  0.5913988
##   0.01    0.15       0.7395966  0.54138071  0.5659928
##   0.01    0.20       0.7489049  0.54744324  0.5628365
##   0.01    0.25       0.7875392  0.53512654  0.5709283
##   0.01    0.30       0.8667019  0.52140556  0.5921187
##   0.01    0.35       0.9431457  0.51335662  0.6125160
##   0.01    0.40       1.0802047  0.47259183  0.6476523
##   0.01    0.45       1.2088266  0.44330947  0.6826894
##   0.01    0.50       1.3289880  0.42612155  0.7138401
##   0.01    0.55       1.4549337  0.39679940  0.7485097
##   0.01    0.60       1.5864313  0.36831855  0.7812921
##   0.01    0.65       1.7126590  0.34755877  0.8130701
##   0.01    0.70       1.8479794  0.33197542  0.8452571
##   0.01    0.75       2.0049644  0.31222127  0.8840289
##   0.01    0.80       2.1771623  0.29141116  0.9246542
##   0.01    0.85       2.3768469  0.27059595  0.9683999
##   0.01    0.90       2.5894120  0.25282089  1.0119540
##   0.01    0.95       2.7828747  0.24269053  1.0501841
##   0.01    1.00       3.0226233  0.22078752  1.1065328
##   0.10    0.05       0.9358302  0.44646524  0.7544072
##   0.10    0.10       0.8306045  0.52549088  0.6735563
##   0.10    0.15       0.7550218  0.54448298  0.6159927
##   0.10    0.20       0.7283200  0.53960719  0.5840903
##   0.10    0.25       0.7320465  0.53798968  0.5701453
##   0.10    0.30       0.7447597  0.54066899  0.5651241
##   0.10    0.35       0.7392803  0.54525390  0.5636148
##   0.10    0.40       0.7433433  0.54529271  0.5657410
##   0.10    0.45       0.7712882  0.53747107  0.5726082
##   0.10    0.50       0.8030717  0.53640796  0.5799205
##   0.10    0.55       0.8384202  0.53638723  0.5882022
##   0.10    0.60       0.8877581  0.52533907  0.6007169
##   0.10    0.65       0.9401590  0.50779837  0.6175740
##   0.10    0.70       1.0102028  0.48376848  0.6384253
##   0.10    0.75       1.0914346  0.45646923  0.6619463
##   0.10    0.80       1.1877890  0.42705249  0.6878470
##   0.10    0.85       1.2830180  0.40204089  0.7123231
##   0.10    0.90       1.3732466  0.38258314  0.7345218
##   0.10    0.95       1.4570607  0.36674113  0.7552740
##   0.10    1.00       1.5738429  0.34139562  0.7907798
## 
## RMSE was used to select the optimal model using the smallest value.
## The final values used for the model were fraction = 0.05 and lambda = 0.
  1. Which nonlinear regression model gives the optimal resampling and test set performance?

Neural Network

nnetFit <- train(X_train, y_train,
                  method = 'avNNet',
                  tuneGrid = nnetGrid,
                  linout = TRUE,
                  trace = FALSE,
                  MaxNWts = 5 * (ncol(X_train) + 1 + 5 + 1),
                  maxit = 100
  
)

nnetFit
## Model Averaged Neural Network 
## 
## 132 samples
##  57 predictor
## 
## No pre-processing
## Resampling: Bootstrapped (25 reps) 
## Summary of sample sizes: 132, 132, 132, 132, 132, 132, ... 
## Resampling results across tuning parameters:
## 
##   decay  size  RMSE       Rsquared   MAE      
##   0.00   1     0.8243357  0.4377872  0.6509041
##   0.00   2     0.7504338  0.5211635  0.5929630
##   0.00   3     0.7827993  0.4986901  0.6288736
##   0.00   4     0.7880309  0.5050492  0.6168466
##   0.00   5     0.7868572  0.5046784  0.6242823
##   0.01   1     0.8524163  0.4366716  0.6756025
##   0.01   2     0.7954921  0.5013045  0.6250465
##   0.01   3     0.7669991  0.5287450  0.6049580
##   0.01   4     0.7563192  0.5355756  0.5973879
##   0.01   5     0.7693275  0.5267339  0.6083181
##   0.10   1     0.9054549  0.4292684  0.7213151
##   0.10   2     0.8222747  0.5022365  0.6457569
##   0.10   3     0.7727497  0.5369488  0.6154186
##   0.10   4     0.7536887  0.5464417  0.5996231
##   0.10   5     0.7496252  0.5442816  0.5957507
## 
## Tuning parameter 'bag' was held constant at a value of FALSE
## RMSE was used to select the optimal model using the smallest value.
## The final values used for the model were size = 5, decay = 0.1 and bag = FALSE.
nnetPred <- predict(nnetFit, newdata = X_test)
postResample(pred = nnetPred, obs = y_test)
##      RMSE  Rsquared       MAE 
## 0.5554940 0.6108372 0.4494205

MARS model

marsTuned <- train(X_train, y_train,
                   method = 'earth',
                   tuneGrid = marsGrid,
                   trControl = trainControl(method = 'cv'))

marsTuned
## Multivariate Adaptive Regression Spline 
## 
## 132 samples
##  57 predictor
## 
## No pre-processing
## Resampling: Cross-Validated (10 fold) 
## Summary of sample sizes: 119, 119, 120, 118, 118, 120, ... 
## Resampling results across tuning parameters:
## 
##   degree  nprune  RMSE        Rsquared   MAE       
##   1        2       0.7904048  0.4507351   0.6275043
##   1        3       0.6794020  0.6006938   0.5595096
##   1        4       0.6668748  0.6456619   0.5480074
##   1        5       0.6721475  0.6342758   0.5478607
##   1        6       0.6659013  0.6405694   0.5501379
##   1        7       0.6992911  0.6190223   0.5764416
##   1        8       0.7379095  0.5871325   0.6076607
##   1        9       0.7475117  0.5805781   0.6090211
##   1       10       0.7479548  0.5821133   0.6156703
##   1       11       0.7656027  0.5669601   0.6275956
##   1       12       0.7763067  0.5558621   0.6414700
##   1       13       0.7614792  0.5751865   0.6347228
##   1       14       0.7511342  0.5905119   0.6204779
##   1       15       0.7539206  0.5916118   0.6251120
##   1       16       0.7492616  0.5953842   0.6207587
##   1       17       0.7492616  0.5953842   0.6207587
##   1       18       0.7492616  0.5953842   0.6207587
##   1       19       0.7492616  0.5953842   0.6207587
##   1       20       0.7492616  0.5953842   0.6207587
##   1       21       0.7492616  0.5953842   0.6207587
##   1       22       0.7492616  0.5953842   0.6207587
##   1       23       0.7492616  0.5953842   0.6207587
##   1       24       0.7492616  0.5953842   0.6207587
##   1       25       0.7492616  0.5953842   0.6207587
##   1       26       0.7492616  0.5953842   0.6207587
##   1       27       0.7492616  0.5953842   0.6207587
##   1       28       0.7492616  0.5953842   0.6207587
##   2        2       0.7904048  0.4507351   0.6275043
##   2        3       0.6948443  0.5814909   0.5696606
##   2        4       0.6975476  0.5941590   0.5701798
##   2        5       0.7211229  0.5897593   0.5936467
##   2        6       0.7572959  0.5655344   0.6224076
##   2        7       0.7296402  0.5923496   0.6016324
##   2        8       0.7648427  0.5759890   0.5979807
##   2        9       0.7723891  0.5783378   0.5937947
##   2       10       0.7863662  0.5650889   0.6005829
##   2       11       0.7832637  0.5801301   0.6050668
##   2       12       0.7947543  0.5723002   0.6193604
##   2       13       0.8188549  0.5692406   0.6265319
##   2       14      34.9506631  0.4992262  10.5176534
##   2       15       0.9044488  0.5341156   0.6707949
##   2       16       0.9009244  0.5391817   0.6752735
##   2       17      38.2771710  0.4719446  11.5165907
##   2       18      38.2439523  0.4900186  11.5051393
##   2       19      38.2511792  0.4910174  11.4962234
##   2       20      38.2448459  0.4920223  11.4947142
##   2       21      38.2444561  0.4923313  11.4955496
##   2       22      38.2378403  0.4993308  11.4892405
##   2       23      38.2385832  0.5011157  11.4899425
##   2       24      38.2385832  0.5011157  11.4899425
##   2       25      38.2498546  0.4926230  11.4983649
##   2       26      38.2498546  0.4926230  11.4983649
##   2       27      38.2498546  0.4926230  11.4983649
##   2       28      38.2498546  0.4926230  11.4983649
## 
## RMSE was used to select the optimal model using the smallest value.
## The final values used for the model were nprune = 6 and degree = 1.
marsPred <- predict(marsTuned, newdata = X_test)
postResample(pred = marsPred, obs = y_test)
##      RMSE  Rsquared       MAE 
## 0.6084064 0.5203117 0.4713370

Support Vector Machines

svmRTuned <- train(X_train, y_train,
                   method = 'svmRadial',
                   preProc = c('center','scale'),
                   tuneLength = 14,
                   trControl = trainControl(method = 'cv'))

svmRTuned
## Support Vector Machines with Radial Basis Function Kernel 
## 
## 132 samples
##  57 predictor
## 
## Pre-processing: centered (57), scaled (57) 
## Resampling: Cross-Validated (10 fold) 
## Summary of sample sizes: 119, 119, 119, 119, 117, 118, ... 
## Resampling results across tuning parameters:
## 
##   C        RMSE       Rsquared   MAE      
##      0.25  0.8003593  0.5875267  0.6509437
##      0.50  0.7106184  0.6278583  0.5860788
##      1.00  0.6486632  0.6649921  0.5316189
##      2.00  0.6174800  0.6862592  0.4981234
##      4.00  0.5959579  0.7008934  0.4751655
##      8.00  0.5808417  0.7129948  0.4650281
##     16.00  0.5750742  0.7165059  0.4612686
##     32.00  0.5750742  0.7165059  0.4612686
##     64.00  0.5750742  0.7165059  0.4612686
##    128.00  0.5750742  0.7165059  0.4612686
##    256.00  0.5750742  0.7165059  0.4612686
##    512.00  0.5750742  0.7165059  0.4612686
##   1024.00  0.5750742  0.7165059  0.4612686
##   2048.00  0.5750742  0.7165059  0.4612686
## 
## Tuning parameter 'sigma' was held constant at a value of 0.01108002
## RMSE was used to select the optimal model using the smallest value.
## The final values used for the model were sigma = 0.01108002 and C = 16.
svmPred <- predict(svmRTuned, newdata = X_test)
postResample(pred = marsPred, obs = y_test)
##      RMSE  Rsquared       MAE 
## 0.6084064 0.5203117 0.4713370

K - Nearest Neighbors

knnTune <- train(X_train, y_train,
                   method = 'knn',
                   preProc = c('center','scale'),
                   tuneGrid = data.frame(.k = 1:20),
                   trControl = trainControl(method = 'cv'))

knnTune
## k-Nearest Neighbors 
## 
## 132 samples
##  57 predictor
## 
## Pre-processing: centered (57), scaled (57) 
## Resampling: Cross-Validated (10 fold) 
## Summary of sample sizes: 119, 120, 118, 118, 118, 119, ... 
## Resampling results across tuning parameters:
## 
##   k   RMSE       Rsquared   MAE      
##    1  0.8629536  0.4299310  0.6889696
##    2  0.7347385  0.5161024  0.5795412
##    3  0.7106262  0.5413118  0.5743603
##    4  0.7254470  0.5389945  0.5889178
##    5  0.7480052  0.4987857  0.6166085
##    6  0.7641720  0.4844230  0.6372895
##    7  0.7518329  0.5167120  0.6303624
##    8  0.7598386  0.5149700  0.6295734
##    9  0.7582677  0.5208215  0.6260547
##   10  0.7524152  0.5388093  0.6223745
##   11  0.7613537  0.5248970  0.6312540
##   12  0.7763461  0.5075823  0.6431757
##   13  0.7769667  0.5077997  0.6465760
##   14  0.7810270  0.5117965  0.6502142
##   15  0.7802343  0.5090971  0.6446063
##   16  0.7871757  0.5065479  0.6524623
##   17  0.7839005  0.5179838  0.6481946
##   18  0.7879388  0.5220966  0.6476796
##   19  0.7941630  0.5115538  0.6513305
##   20  0.8050150  0.5051792  0.6571662
## 
## RMSE was used to select the optimal model using the smallest value.
## The final value used for the model was k = 3.
knnPred <- predict(knnTune, newdata = X_test)
postResample(pred = knnPred, obs = y_test)
##      RMSE  Rsquared       MAE 
## 0.6479240 0.4326222 0.5183313

The neural network model produces the best performance on the test data set with an \(R^2\) value of 0.6173072.

  1. Which predictors are most important in the optimal nonlinear regression model? Do either the biological or process variables dominate the list? How do the top ten important predictors compare to the top ten predictors from the optimal linear model?

The process variables dominate the importance variables, similarly to the optimal linear model.

varImp(nnetFit, 10)
## loess r-squared variable importance
## 
##   only 20 most important variables shown (out of 57)
## 
##                        Overall
## ManufacturingProcess32  100.00
## ManufacturingProcess13   99.45
## ManufacturingProcess17   84.45
## BiologicalMaterial06     76.83
## ManufacturingProcess09   76.23
## BiologicalMaterial03     76.20
## ManufacturingProcess36   74.99
## ManufacturingProcess06   74.25
## BiologicalMaterial12     60.54
## BiologicalMaterial02     59.04
## BiologicalMaterial11     49.98
## ManufacturingProcess31   48.75
## ManufacturingProcess29   41.56
## ManufacturingProcess11   40.96
## BiologicalMaterial04     40.87
## ManufacturingProcess33   39.55
## ManufacturingProcess30   38.79
## BiologicalMaterial08     38.66
## BiologicalMaterial01     33.78
## ManufacturingProcess12   33.39
varImp(enetTune, 10)
## loess r-squared variable importance
## 
##   only 20 most important variables shown (out of 57)
## 
##                        Overall
## ManufacturingProcess32  100.00
## ManufacturingProcess13   99.45
## ManufacturingProcess17   84.45
## BiologicalMaterial06     76.83
## ManufacturingProcess09   76.23
## BiologicalMaterial03     76.20
## ManufacturingProcess36   74.99
## ManufacturingProcess06   74.25
## BiologicalMaterial12     60.54
## BiologicalMaterial02     59.04
## BiologicalMaterial11     49.98
## ManufacturingProcess31   48.75
## ManufacturingProcess29   41.56
## ManufacturingProcess11   40.96
## BiologicalMaterial04     40.87
## ManufacturingProcess33   39.55
## ManufacturingProcess30   38.79
## BiologicalMaterial08     38.66
## BiologicalMaterial01     33.78
## ManufacturingProcess12   33.39
  1. Explore the relationships between the top predictors and the response for the predictors that are unique to the optimal nonlinear regression model. Do these plots reveal intuition about the biological or process predictors and their relationship with yield?

The predictors seem to have a relatively strong correlation to the response variable.

vars <- varImp(nnetFit)$importance %>%
  arrange(desc(Overall)) %>%
  as.data.frame() %>%
  head(10)

vars <- rownames(vars)

plotX <- df[,vars]
plotY <- df[,1]

featurePlot(plotX, plotY)