6 Types of Bias in Machine Learning

Akshata Gunapache
3 min readAug 5, 2023

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Machine learning is a transformative technology that holds immense potential to revolutionize various industries. It enables computers to learn from data and make predictions or decisions without explicit programming. However, like any other technology, machine learning is not without its flaws. One of the most significant challenges facing the field is bias. Bias in machine learning can lead to unfair or discriminatory outcomes, perpetuating societal inequalities.

In this article, we’ll delve into six types of bias that can affect machine learning systems and explore strategies to mitigate their impact.

  1. Historical Bias: Historical bias refers to the presence of bias in the data used to train a machine learning model due to past societal inequalities or flawed decision-making processes.
  2. Representation bias: Also known as data bias or sampling bias, is a type of bias that arises when the dataset used to train a machine learning model poorly represents the population it is intended to serve or make predictions for. In other words, the training data does not accurately reflect the diversity and distribution of the real-world instances that the model will encounter in its operational use.
  3. Measurement bias: It is a type of bias that occurs when the accuracy or quality of data varies across different groups in a dataset. This bias can arise when using proxy variables, which are substitute variables used when the direct measurement of a specific variable is challenging or unavailable.
  4. Aggregation bias: Also known as Simpson’s paradox or ecological fallacy, occurs when data from different groups or subpopulations are inappropriately combined, leading to misleading or biased conclusions when analyzing the data as a whole. This type of bias is particularly common in medical applications, where the effects of treatments or interventions may vary across different demographic groups or patient populations.
  5. Evaluation bias: It is a type of bias that occurs during the assessment or evaluation of a machine learning model’s performance. It arises when the benchmark or evaluation data used to compare the model to other models or to measure its effectiveness does not adequately represent the population that the model is intended to serve or make predictions for.
  6. Deployment bias: Also known as deployment shift or model-implementation mismatch, refers to a situation where the way a machine learning model is intended to be used (in the problem it is designed to solve) is different from how it is actually used in practice by end-users or in a real-world setting.

Bias in machine learning is a critical issue that demands attention and proactive solutions. As machine learning technologies continue to advance, it becomes increasingly crucial to develop models that are not only accurate but also fair and ethical. By understanding and addressing the various types of bias in machine learning, we can work towards creating more inclusive and equitable AI systems that benefit everyone in society. As data scientists and AI developers, it is our responsibility to foster transparency, accountability, and continuous improvement to build a better future with unbiased machine learning algorithms.

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