American Oil and Gas Reporter - April 2016 - 75

SpecialReport: Drilling Technology
Model Evaluation
One critical, but often overlooked, aspect of model selection is evaluating the
goodness-of-fit. One approach to evaluating a model fit is to generate a scatterplot of actual response values in a training
set against the predicted response using
the model. However, many models can
overfit the training data when certain
conditions are met, and in a multidimensional space, one cannot easily visualize
the prediction surface generated by the
model.
Overfitting is the result of placing too
much emphasis on reproducing the training
set. The resulting model likely contains
more degrees of freedom than are necessary to capture the underlying shape of
the curve producing the observations. In
essence, the model captures not only the
true underlying function, but also the
noise in the measurements, making it unlikely to produce good predictions.
To avoid overfitting, it is important to
move beyond using predictions on the
training data as the sole measure of model
quality. A simple solution is to use an independent test set, either a completely
new dataset (e.g., pilot data from a region
where the model is intended for use) or a
"held out" portion of the training dataset.
In either case, the model can be fit using
the training dataset, and then evaluated
with independent test observations.
Another method of model evaluation
is k-fold cross-validation. In this approach,
the training dataset is split randomly into
different k groups, or folds. Next, each
of the k groups is held out and the model
is trained on the remaining groups. That
model is used then to make predictions
on the group that was held out.
After cycling through all k groups,
there will be a single prediction for every
observation in the dataset. These crossvalidated predictions can be used to evaluate the quality of the model-fitting procedure, and can indicate whether problems
may be expected on future data collections.
It is important to note that models
trained during cross-validation are not
used for predictions; they are used only
for evaluation purposes, to provide a
better indicator on the robustness of the
single predictive model built using the
full training set.
The cross-validation procedure can be
extended by repeating the entire process
with a different random selection of k
groups. A repeated cross-validation using

multiple runs with random assignment of
the k groups will yield different predictions
on each observation. These can be averaged

to compute goodness-of-fit metrics, but
they also can give important information
about model prediction variability.

FIGURE 2
Predictive Model Results on Wolfcamp Well Dataset

APRIL 2016 75



American Oil and Gas Reporter - April 2016

Table of Contents for the Digital Edition of American Oil and Gas Reporter - April 2016

Contents
American Oil and Gas Reporter - April 2016 - Cover1
American Oil and Gas Reporter - April 2016 - Cover2
American Oil and Gas Reporter - April 2016 - 3
American Oil and Gas Reporter - April 2016 - Contents
American Oil and Gas Reporter - April 2016 - 5
American Oil and Gas Reporter - April 2016 - 6
American Oil and Gas Reporter - April 2016 - 7
American Oil and Gas Reporter - April 2016 - 8
American Oil and Gas Reporter - April 2016 - 9
American Oil and Gas Reporter - April 2016 - 10
American Oil and Gas Reporter - April 2016 - 11
American Oil and Gas Reporter - April 2016 - 12
American Oil and Gas Reporter - April 2016 - 13
American Oil and Gas Reporter - April 2016 - 14
American Oil and Gas Reporter - April 2016 - 15
American Oil and Gas Reporter - April 2016 - 16
American Oil and Gas Reporter - April 2016 - 17
American Oil and Gas Reporter - April 2016 - 18
American Oil and Gas Reporter - April 2016 - 19
American Oil and Gas Reporter - April 2016 - 20
American Oil and Gas Reporter - April 2016 - 21
American Oil and Gas Reporter - April 2016 - 22
American Oil and Gas Reporter - April 2016 - 23
American Oil and Gas Reporter - April 2016 - 24
American Oil and Gas Reporter - April 2016 - 25
American Oil and Gas Reporter - April 2016 - 26
American Oil and Gas Reporter - April 2016 - 27
American Oil and Gas Reporter - April 2016 - 28
American Oil and Gas Reporter - April 2016 - 29
American Oil and Gas Reporter - April 2016 - 30
American Oil and Gas Reporter - April 2016 - 31
American Oil and Gas Reporter - April 2016 - 32
American Oil and Gas Reporter - April 2016 - 33
American Oil and Gas Reporter - April 2016 - 34
American Oil and Gas Reporter - April 2016 - 35
American Oil and Gas Reporter - April 2016 - 36
American Oil and Gas Reporter - April 2016 - 37
American Oil and Gas Reporter - April 2016 - 38
American Oil and Gas Reporter - April 2016 - 39
American Oil and Gas Reporter - April 2016 - 40
American Oil and Gas Reporter - April 2016 - 41
American Oil and Gas Reporter - April 2016 - 42
American Oil and Gas Reporter - April 2016 - 43
American Oil and Gas Reporter - April 2016 - 44
American Oil and Gas Reporter - April 2016 - 45
American Oil and Gas Reporter - April 2016 - 46
American Oil and Gas Reporter - April 2016 - 47
American Oil and Gas Reporter - April 2016 - 48
American Oil and Gas Reporter - April 2016 - 49
American Oil and Gas Reporter - April 2016 - 50
American Oil and Gas Reporter - April 2016 - 51
American Oil and Gas Reporter - April 2016 - 52
American Oil and Gas Reporter - April 2016 - 53
American Oil and Gas Reporter - April 2016 - 54
American Oil and Gas Reporter - April 2016 - 55
American Oil and Gas Reporter - April 2016 - 56
American Oil and Gas Reporter - April 2016 - 57
American Oil and Gas Reporter - April 2016 - 58
American Oil and Gas Reporter - April 2016 - 59
American Oil and Gas Reporter - April 2016 - 60
American Oil and Gas Reporter - April 2016 - 61
American Oil and Gas Reporter - April 2016 - 62
American Oil and Gas Reporter - April 2016 - 63
American Oil and Gas Reporter - April 2016 - 64
American Oil and Gas Reporter - April 2016 - 65
American Oil and Gas Reporter - April 2016 - 66
American Oil and Gas Reporter - April 2016 - 67
American Oil and Gas Reporter - April 2016 - 68
American Oil and Gas Reporter - April 2016 - 69
American Oil and Gas Reporter - April 2016 - 70
American Oil and Gas Reporter - April 2016 - 71
American Oil and Gas Reporter - April 2016 - 72
American Oil and Gas Reporter - April 2016 - 73
American Oil and Gas Reporter - April 2016 - 74
American Oil and Gas Reporter - April 2016 - 75
American Oil and Gas Reporter - April 2016 - 76
American Oil and Gas Reporter - April 2016 - 77
American Oil and Gas Reporter - April 2016 - 78
American Oil and Gas Reporter - April 2016 - 79
American Oil and Gas Reporter - April 2016 - 80
American Oil and Gas Reporter - April 2016 - 81
American Oil and Gas Reporter - April 2016 - 82
American Oil and Gas Reporter - April 2016 - 83
American Oil and Gas Reporter - April 2016 - 84
American Oil and Gas Reporter - April 2016 - 85
American Oil and Gas Reporter - April 2016 - 86
American Oil and Gas Reporter - April 2016 - 87
American Oil and Gas Reporter - April 2016 - 88
American Oil and Gas Reporter - April 2016 - 89
American Oil and Gas Reporter - April 2016 - 90
American Oil and Gas Reporter - April 2016 - 91
American Oil and Gas Reporter - April 2016 - 92
American Oil and Gas Reporter - April 2016 - 93
American Oil and Gas Reporter - April 2016 - 94
American Oil and Gas Reporter - April 2016 - 95
American Oil and Gas Reporter - April 2016 - 96
American Oil and Gas Reporter - April 2016 - 97
American Oil and Gas Reporter - April 2016 - 98
American Oil and Gas Reporter - April 2016 - 99
American Oil and Gas Reporter - April 2016 - 100
American Oil and Gas Reporter - April 2016 - 101
American Oil and Gas Reporter - April 2016 - 102
American Oil and Gas Reporter - April 2016 - 103
American Oil and Gas Reporter - April 2016 - 104
American Oil and Gas Reporter - April 2016 - 105
American Oil and Gas Reporter - April 2016 - 106
American Oil and Gas Reporter - April 2016 - 107
American Oil and Gas Reporter - April 2016 - 108
American Oil and Gas Reporter - April 2016 - 109
American Oil and Gas Reporter - April 2016 - 110
American Oil and Gas Reporter - April 2016 - 111
American Oil and Gas Reporter - April 2016 - 112
American Oil and Gas Reporter - April 2016 - 113
American Oil and Gas Reporter - April 2016 - 114
American Oil and Gas Reporter - April 2016 - 115
American Oil and Gas Reporter - April 2016 - 116
American Oil and Gas Reporter - April 2016 - 117
American Oil and Gas Reporter - April 2016 - 118
American Oil and Gas Reporter - April 2016 - 119
American Oil and Gas Reporter - April 2016 - 120
American Oil and Gas Reporter - April 2016 - 121
American Oil and Gas Reporter - April 2016 - 122
American Oil and Gas Reporter - April 2016 - 123
American Oil and Gas Reporter - April 2016 - 124
American Oil and Gas Reporter - April 2016 - 125
American Oil and Gas Reporter - April 2016 - 126
American Oil and Gas Reporter - April 2016 - 127
American Oil and Gas Reporter - April 2016 - 128
American Oil and Gas Reporter - April 2016 - 129
American Oil and Gas Reporter - April 2016 - 130
American Oil and Gas Reporter - April 2016 - Cover3
American Oil and Gas Reporter - April 2016 - Cover4
http://staging.nxtbook.com/nxtbooks/aogr/201702/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201701/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201612/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201611/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201610/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/pbios2016_programguide/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201609/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201608/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201607/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201606/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201605/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201604/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201603/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201602/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201601/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201512/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201511/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201510/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201509/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201508/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201507/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201506/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201505/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201504/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201503/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201502/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201501/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201412/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201411/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201410/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201409/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/pbios2014_programguide/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201408/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201407/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201406/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201405/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201404/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201403/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201402/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201401/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201312/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201311/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201310/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201309/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201308/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201307/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201306/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201305/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201304/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201303/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201302/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201301/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201212/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201211/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201210/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201209/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/2012_pbios/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201208/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201207/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201206/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201205/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201204/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201203/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201202/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201201/stage.php
http://staging.nxtbook.com/nxtbooks/demo/aogr_clone/stage.php
http://staging.nxtbook.com/nxtbooks/aogr/201112/stage.php
https://www.nxtbookmedia.com