{"id":17843,"date":"2025-07-18T07:39:38","date_gmt":"2025-07-18T07:39:38","guid":{"rendered":"https:\/\/multiqos.com\/blogs\/?p=17843"},"modified":"2025-08-01T06:50:15","modified_gmt":"2025-08-01T06:50:15","slug":"overfitting-and-underfitting-in-machine-learning","status":"publish","type":"post","link":"https:\/\/multiqos.com\/blogs\/overfitting-and-underfitting-in-machine-learning\/","title":{"rendered":"Understanding Overfitting and Underfitting in Machine Learning Models"},"content":{"rendered":"<h2 id=\"id0\"><b>Introduction<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">Ever built a machine learning model that performs perfectly during training, but completely misses the mark when tested on new data? It\u2019s frustrating, and usually comes down to one of two things: overfitting or underfitting.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">This usually boils down to two problems: overfitting or underfitting. They may sound technical, but the idea is simple. Overfitting means that the model is trying hard to memorize the training data, including all small details that really do not matter. During Underfitting? When it doesn&#8217;t try enough, it misses the pattern completely.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Understanding both is key if you want your model to actually work in the real world. In this post, we\u2019ll explain what each one really means, why they occur, and what you can do to handle them.<\/span><\/p>\n<h2 id=\"id1\"><b>What is Overfitting and Underfitting in Machine Learning?<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">In machine learning, model accuracy is not just about obtaining the right answer during training &#8211; it is about providing accurate predictions of new, unveiled data, and this is the place where overfitting and underfitting in machine learning come into play.\u00a0<\/span><\/p>\n<p><b>Overfitting <\/b><span style=\"font-weight: 400;\">occurs when a model learns training data well, including random noise and fewer details. As a result, it works well during training but is poor on test data because it lacks generalization.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">On the other hand, <\/span><b>underfitting <\/b><span style=\"font-weight: 400;\">occurs when a model is so easy to understand the pattern in the data. It performs poorly in both training and testing of datasets, as it has not learned enough.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Both are common problems that developers encounter when they build models, and know how to avoid them, especially with the increase of more complex algorithms in today&#8217;s <\/span><a href=\"https:\/\/multiqos.com\/blogs\/top-machine-learning-trends\/\"><span style=\"font-weight: 400;\">top machine learning trends<\/span><\/a><span style=\"font-weight: 400;\">.<\/span><\/p>\n<p><a href=\"https:\/\/multiqos.com\/contact-us\/\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-17845\" src=\"https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/looking-to-optimize-your-machine-learning-models.webp\" alt=\"looking to optimize your machine learning models\" width=\"700\" height=\"209\" srcset=\"https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/looking-to-optimize-your-machine-learning-models.webp 700w, https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/looking-to-optimize-your-machine-learning-models-430x128.webp 430w, https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/looking-to-optimize-your-machine-learning-models-150x45.webp 150w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/p>\n<h2 id=\"id2\"><b>Bias and Variance in Machine Learning<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">Bias and variance are the two main concepts that affect how well the machine-learning model works-specifically when it comes to normalizing new data.<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\"><strong>Bias,<\/strong> refers to errors that come from highly simplified assumptions in the learning algorithm. A high-bias model adds very little attention to training data and remembers the pattern in question. This often leads to underfitting, where the model performs poorly on both training and test data.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Variance<\/b><span style=\"font-weight: 400;\">, on the other hand, is the model&#8217;s sensitivity to small fluctuations in the training set. A high-variance model reacts a lot to training data and catching noise as it is a real pattern. This is usually the result of overfitting, where the model performs well on training data, but poorly on new or unseen data.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Finding the correct balance between bias and variance is known as the variance tradeoff. It is one of the most important parts of building a reliable and effective ML model. Too much leads to errors; the goal is to find a sweet spot where the model is complicated enough to learn the data, but not so complex that it misses it.<\/span><\/p>\n<p><a href=\"https:\/\/multiqos.com\/blogs\/why-businesses-are-adopting-ai-ml-services\/\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-17846\" src=\"https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/why-businesses-are-adopting-AI-ML-services-faster.webp\" alt=\"why businesses are adopting AI ML services faster\" width=\"700\" height=\"209\" srcset=\"https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/why-businesses-are-adopting-AI-ML-services-faster.webp 700w, https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/why-businesses-are-adopting-AI-ML-services-faster-430x128.webp 430w, https:\/\/multiqos.com\/blogs\/wp-content\/uploads\/2025\/07\/why-businesses-are-adopting-AI-ML-services-faster-150x45.webp 150w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/p>\n<h2 id=\"id3\"><b>Key Differences Between Overfitting and Underfitting in Machine Learning Models<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">Here are the significant differences between overfitting and underfitting in machine learning. Check out how they affect the model performance.<\/span><\/p>\n<table>\n<tbody>\n<tr>\n<td><b>Aspect<\/b><\/td>\n<td><b>Overfitting<\/b><\/td>\n<td><b>Underfitting<\/b><\/td>\n<\/tr>\n<tr>\n<td><b>Definition<\/b><\/td>\n<td><span style=\"font-weight: 400;\">The model learns the training data too well, including noise and outliers<\/span><\/td>\n<td><span style=\"font-weight: 400;\">The model is too simple to capture the underlying structure of the data<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Model Complexity<\/b><\/td>\n<td><span style=\"font-weight: 400;\">Too complex<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Too simple<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Training Accuracy<\/b><\/td>\n<td><span style=\"font-weight: 400;\">High<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Low<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Validation\/Test Accuracy<\/b><\/td>\n<td><span style=\"font-weight: 400;\">Low (poor generalization)<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Low (poor learning)<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Bias<\/b><\/td>\n<td><span style=\"font-weight: 400;\">Low bias<\/span><\/td>\n<td><span style=\"font-weight: 400;\">High bias<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Variance<\/b><\/td>\n<td><span style=\"font-weight: 400;\">High variance<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Low variance<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Cause<\/b><\/td>\n<td><span style=\"font-weight: 400;\">Too many features, too long training, not enough regularization<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Model is not trained enough, or lacks complexity<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Example Scenario<\/b><\/td>\n<td><span style=\"font-weight: 400;\">A deep neural network memorizes every training point<\/span><\/td>\n<td><span style=\"font-weight: 400;\">A linear model trying to fit non-linear data<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Detection<\/b><\/td>\n<td><span style=\"font-weight: 400;\">Large gap between training and validation performance<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Both training and validation errors are high<\/span><\/td>\n<\/tr>\n<tr>\n<td><b>Solution<\/b><\/td>\n<td><span style=\"font-weight: 400;\">Regularization, pruning, simpler model, more data<\/span><\/td>\n<td><span style=\"font-weight: 400;\">Add features, increase model complexity, and train longer<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 id=\"id4\"><b>How to Detect Overfitting and Underfitting in Machine Learning?<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">To find out if a model is overfitting or underfitting usually comes down to seeing how it performs on training versus verification or test data.\u00a0<\/span><\/p>\n<h3><b>How to Reduce Underfitting?<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">If your model is underfitting, it means it doesn&#8217;t learn enough of the data. There are some ways to fix it, such as:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Use a more complex model: <\/b><span style=\"font-weight: 400;\">Try switching to a model that can handle more complexity.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Increase training time:<\/b><span style=\"font-weight: 400;\"> When it comes to learning effectively, some models might require multiple epochs or iterations<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Reduce Regularization:<\/b><span style=\"font-weight: 400;\"> If you use L1 or L2 regularization, you can limit the model too much.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Add more relevant features: <\/b><span style=\"font-weight: 400;\">More informative input models can help capture the catch pattern better.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Improve functional technique: <\/b><span style=\"font-weight: 400;\">Changing existing features or creating new ones often helps the model learn more than data.<\/span><\/li>\n<\/ul>\n<h3><b>How to Reduce Overfitting?<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">If your model performs very well on training data but poorly on test data or validation, it is overfitting. How to address:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Use Regularization: <\/b><span style=\"font-weight: 400;\">Use L1 (Lasso) or L2 (Ridge) Regularization to punish very complex models.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Simple model: <\/b><span style=\"font-weight: 400;\">Reduce the number of layers, nodes, or parameters.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Prune Decision Three: <\/b><span style=\"font-weight: 400;\">For tree-based models, pruning can remove unnecessary branches to help make a better normal.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Use dropout (for neural networks): <\/b><span style=\"font-weight: 400;\">This leaves some compounds randomly during exercise to prevent dependence on specific routes.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Collect more training data: <\/b><span style=\"font-weight: 400;\">Helps multiple data models see a wide range of examples and reduces the possibility of remembering the noise.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Use Cross Validation: <\/b><span style=\"font-weight: 400;\">Technology such as k-fold cross-validation ensures that the model works continuously across different datasets.<\/span><\/li>\n<\/ul>\n<h2 id=\"id5\"><b>Conclusion<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">After reading this post, you must understand how important it is to keep the balance between overfitting and underfitting in machine learning when it comes to creating reliable and accurate models. Overfitting often leads to models that perform well on training data, but struggle with the actual landscape, while reducing performance in models that are unable to capture significant patterns from the beginning.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">For teams working on AI-operated solutions, partnering with a leading <\/span><a href=\"https:\/\/multiqos.com\/machine-learning-development\/\"><span style=\"font-weight: 400;\">machine learning development company<\/span><\/a><span style=\"font-weight: 400;\"> provides valuable guidance and technical expertise. Using the right techniques in the right development phase can help you create models that normalize and provide meaningful results. But let\u2019s say you want to scale your in-house team, it is significant to <\/span><a href=\"https:\/\/multiqos.com\/hire-machine-learning-developers\/\"><span style=\"font-weight: 400;\">hire ML developers<\/span><\/a><span style=\"font-weight: 400;\"> who are not only skilled in model building but also experienced in detecting and fixing these general problems.<\/span><br \/>\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [{\n    \"@type\": \"Question\",\n    \"name\": \"1. What causes a model to underfit?\",\n    \"acceptedAnswer\": {\n      \"@type\": \"Answer\",\n      \"text\": \"There are a few reasons why underfitting might happen. Maybe the model isn\u2019t complex enough. Maybe it didn\u2019t train long enough.\"\n    }\n  },{\n    \"@type\": \"Question\",\n    \"name\": \"2. How can I tell if my model is overfitting?\",\n    \"acceptedAnswer\": {\n      \"@type\": \"Answer\",\n      \"text\": \"A common sign is when your model performs really well on training data but does much worse on validation or test data. That gap is usually a giveaway.\"\n    }\n  },{\n    \"@type\": \"Question\",\n    \"name\": \"3. What can I do to avoid overfitting?\",\n    \"acceptedAnswer\": {\n      \"@type\": \"Answer\",\n      \"text\": \"There are several things you can try:<\/p>\n<p>Use simpler models\nAdd more training data if you can\nUse techniques like regularization or dropout\nStop training early if the model starts to get worse on validation data\"\n    }\n  },{\n    \"@type\": \"Question\",\n    \"name\": \"4. What helps fix underfitting?\",\n    \"acceptedAnswer\": {\n      \"@type\": \"Answer\",\n      \"text\": \"You might want to:<\/p>\n<p>Use a more complex model\nTrain it for longer\nChoose better features\nReduce any regularization that might be holding it back\"\n    }\n  }]\n}\n<\/script><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Introduction Ever built a machine learning model that performs perfectly during training, but completely misses the mark when tested on new data? It\u2019s frustrating, and usually comes down to one of two things: overfitting or underfitting. This usually boils down to two problems: overfitting or underfitting. They may sound technical, but the idea is simple. 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