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Unveiling 7 Common Data Biases in Machine Learning

From:Nexdata Date:2023-09-19

Data bias in machine learning is an inherent issue where certain elements within a dataset carry more weight or prominence than others. Such bias can distort model outcomes, leading to skewed results, reduced accuracy, and analytical discrepancies.


Fundamentally, machine learning relies on training data that accurately mirrors real-world scenarios. Data bias can manifest in multiple forms, encompassing human reporting and selection bias, algorithmic bias, and interpretation bias. The graphic below illustrates various biases, many of which emerge during data collection and annotation stages.


Tackling data bias within machine learning projects hinges on initially identifying its presence. Only by pinpointing bias can necessary steps be taken to rectify it, whether through addressing gaps in data or refining the annotation process. Meticulous attention to data scope, quality, and processing is vital for mitigating bias's impact, which extends beyond model accuracy to encompass ethical, fairness, and inclusivity considerations.


This article serves as a guide to the seven prevalent forms of data bias in machine learning. It equips you with insights into recognizing and comprehending bias, along with strategies for its mitigation.


Common Types of Data Bias


While this compilation doesn't encompass every conceivable form of data bias, it offers insight into typical instances and their occurrences.


Example Bias: This bias arises when a dataset fails to faithfully reflect the real-world context where a model operates. For instance, some facial recognition systems heavily trained on white male faces exhibit reduced accuracy for women and individuals from diverse ethnic backgrounds. Another term for this bias is selection bias.


Exclusion Bias: This bias often occurs during data preprocessing. It emerges when data perceived as insignificant but valuable gets discarded or when certain information is systematically omitted. Consider a sales dataset covering Beijing and Shenzhen, where 98% of customers are from Beijing. Omitting location data due to perceived irrelevance means the model overlooks that Shenzhen's customer base has doubled.


Measurement Bias: Measurement bias emerges when the data collected and annotated for training diverges from real-world data or when measurement errors distort the dataset. A prime example is image recognition datasets, where training data originates from one camera type and production data from another. Measurement bias can also arise during AI data annotation due to inconsistent labeling.


Recall Bias: This form of measurement bias surfaces primarily during data annotation. It occurs when identical data isn't consistently labeled, leading to reduced accuracy. For instance, if one annotator labels an image as 'damaged' and a similar one as 'partially damaged,' the dataset becomes inconsistent.


Observer Bias: Also known as confirmation bias, observer bias manifests when researchers subjectively perceive the data according to their predispositions, whether consciously or unconsciously. This can result in data misinterpretation or the dismissal of alternative interpretations.


Dataset Shift Bias: Dataset shift bias occurs when a model is tested with a dataset different from its training data. This can lead to diminished accuracy or misleading outcomes. A common instance is testing a model trained on one population with another, causing discrepancies in results.


In summary, addressing data bias stands as a pivotal endeavor within machine learning projects. Familiarity with various forms of data bias and their occurrences enables proactive measures to reduce bias, ensuring the development of accurate, fair, and inclusive models.