AI Products 

What do the Terms “Overfitting” and “under-fitting” Models Mean to You?

Nishit Agarwal
What do the Terms “Overfitting” and “under-fitting” Models Mean to You?

Let's pretend we're creating a machine learning model. If a model correctly generalizes any new input data from the issue domain, it is said to be a good machine learning model. This enables us to make predictions based on future data that the data model has never encountered before. Register for a data analyst course online to learn which is the finest. Let's say we want to see how well our machine learning model adapts to fresh data. Overfitting and underfitting are two factors that contribute to the poor performance of machine learning systems analytics. Before we go any further, it's vital to understand two key terms:

Bias: Bias is a type of prediction inaccuracy incorporated into a model because of oversimplifying machine learning techniques. Alternatively, it is the difference between the projected and actual numbers. You will gain more information by enrolling in a data science online course.

Variance: When you train your data on training data and get a low error, but then change the data and train the same previous model again, you get a high error, which is variance. Register for a data science online course to learn more about variance.

Signal: It refers to the data's genuine underlying pattern, which aids the machine learning model in learning from it.

Noise: - Noise is unimportant and irrelevant input that degrades the model's performance. Enroll in the best data science courses online to have a deeper knowledge.


When we train a statistical model with a large amount of data (much like fitting yourself into enormous clothing!), it is said to be overfitted. When a model is trained with a large amount of data, it begins to learn from the noise and inaccuracies in the data set. The model then fails to appropriately categorize the input due to too many details, relationship between variables and noise. In a nutshell, overfitting is characterized by a high variance and low bias. Non-parametric and non-linear approaches are the causes of overfitting since these types of machine learning algorithms have greater leeway it analyzes models based on the dataset and can thus create unrealistic models. If we have linear data, we can use a linear method to avoid overfitting, or we can use decision tree characteristics like the maximal depth to avoid overfitting.

Techniques for Avoiding Overfitting:

  • Increase the amount of data collected during training,
  • Reduce the number of variables in your model,
  • During the training phase, you should end sooner rather than later (have an eye over the loss over the training period as soon as loss begins to increase stop training),
  • Ridge Regularization and Lasso Regularization are two types of regularization and
  • To combat overfitting in neural networks, use dropout.


When a statistical model or machine learning method fails to capture the underlying trend of the data and its analytics, it is said to have underfitting. (It's like trying to fit into a pair of too-small jeans!) Our machine learning model's accuracy is destroyed by underfitting. It merely indicates that our analyzed model or method does not adequately fit the data. In a nutshell, underfitting is characterized by a high bias and low variance. It frequently occurs when there are insufficient data to form an appropriate model, as well as when attempting to build a linear model with insufficient non-linear data. In such instances, the machine learning model's rules are far too simple and flexible to be applied to such sparse data, relationship between variables, and the model is likely to make many incorrect predictions. Underfitting can be avoided by collecting more data and utilizing feature selection to reduce the number of features.

Techniques for reducing underfitting:

  • Increasing the complexity of the model,
  • Feature engineering is a technique for increasing the number of features,
  • Remove any unwanted noise from the data and
  • To improve your performance, increase the number of epochs or the duration of your training.


In contrast, underfitting refers to a model that has been trained insufficiently, for example, using a linear model to fit a quadratic function. Models that have under-fitted perform poorly when both training and testing is conducted. Enrolling in the best data science courses online will help you learn more.

The words overfitting and underfitting, which are opposite ends of the spectrum but both result in poor machine learning performance. In polynomial regression, overfitting occurs when a model is trained too much on the specifics and noises of the training data. A model that is overfitting will not perform well on new data. For a bright career take a data analyst course online.

Nishit Agarwal
Zupyak is the world’s largest content marketing community, with over 400 000 members and 3 million articles. Explore and get your content discovered.
Read more