III. III. METHODOLOGY
This section reviews the major XAI methodologies with a
specific focus on model-agnostic and intrinsic explainability
techniques. We present, along with their strengths and
limitations, their applicability to different domains.
A. Model-Agnostic Methods
Model-agnostic methods are those developed to be
independent of any particular machine learning model.
These include LIME, or Local Interpretable Model-agnostic
Explanations, and SHAP, or SHapley Additive exPlanations.
1) LIME: By locally approximating the behavior of a
complex model, LIME generates explanations for any given
prediction. This is particularly helpful during image
classification, where one is allowed to highlight those
regions within the images that provide the key to a specific
class prediction [3]. In this light, LIME becomes useful for
diagnostic applications within healthcare. However, local
approaches in LIME may be sensitive to data variation,
which can easily result in inconsistent explanations across
similar predictions [3].
2) SHAP: SHAP explanation methods are based on
cooperative game theory. SHAP attributes feature
contributions to model predictions consistently and
theoretically sound. The dependence of SHAP on Shapley
values is ideal in situations where fair feature importance is
required, including loan approval decisions [3]. However,
high computational cost is always a drawback for its use in
real-time systems when the dimensions of the data in hand
are higher.
B. Intrinsic Explainability Techniques
Some models are inherently interpretable. For instance,
decision trees, linear models, generalized additive models
are transparent by nature, because one can comprehend the
process of their decisions.
1) Decision Trees and Rule-Based Systems: In their
core, decision trees and rule-based systems have the
advantage of straightforward visualization of decision
paths. Indeed, they may not perform as good in comparison
with deep learning when heavy tasks are involved [3].
However, for medical applications, simpler models can still
work well enough for a satisfactory result, when expert
knowledge is integrated into modelling [3].
2) Generalized Additive Models: GAMs generalize
linear models in that they enable the learning of nonlinear
transformations on the input features. The flexibility
combined with easiness of interpretability makes GAMs very
popular in healthcare, among others, where their outputs
are not only interpretable by clinicians, but nonlinear
relationships between symptoms and diagnoses are also
handled [2].
C. Case Study: Application in Autonomous Vehicles
In autonomous driving systems, explainability is paramount
for safety reasons and also for legal accountability. It uses
deep learning models to process sensory data and make
instantaneous decisions to navigate the road [3]. However,
interpreting this increasingly complex decision-making
process is difficult, particularly in cases where the reason a
vehicle performs any particular maneuver would need to be
ascertained and explained [3]. Techniques for XAI such as
SHAP have been used to interpret key features like road
markings, obstacles, and speed limits that influence
decisions [3]. This case study focused on how SHAP was
applied in the search for visual cues that influence braking
and acceleration, thereby demonstrating the value of
interpretability methods to developers and regulators as well
as to the end-user.
IV. RESULTS AND DISCUSSION
Our investigation showed the diverse advantages
and limitations inherent in different XAI methods. In the
following section, we analyze the performance of
interpretability techniques concerning accuracy, usability,
and practical application to critical fields.
A. Performance Evaluation
While model-agnostic methods like LIME and SHAP work
very well in controlled environments, they fail in dynamic
settings such as real-time diagnosis in medicine or driving
an autonomous car. Consistency and robustness are again in
doubt when these techniques are applied to complex
real-world applications.
B. Interpretability metrics
Quantification of interpretability is usually subjective with a
few quantitative benchmarks. A few researchers have,
therefore, developed interpretability metrics based on
fidelity-alignment between explanation and model-and
stability-consistency between explanations for similar
predictions. Our review hence indicates a need for
standardized benchmarks regarding the quality assessment
of the explanations, especially for regulated fields.
C. User Studies
Various studies reveal that the end-users would not make
any sense of such complex explanations; this is a critical
gap that is emerging in the user-centered design in
interpretability tools. Good XAI tools need to be developed
keeping in mind the cognitive abilities and decision-making
needs of the end-users; hence, collaboration between fields
like human-computer interaction and psychology is
required.
V. ETHICAL AND REGULATORY IMPLICATIONS
The explainability of AI remedies this very real
possibility of unintended consequences in high-stake
decision-making. Inequity in AI models can lead to biased
treatment with respect to certain individuals or groups, and
such biases are difficult to trace in an opaque system. This
revealing and mitigation of bias is particularly current in
sectors such as law enforcement or hiring, where the biased
decisions will have a strong bearing on society.