What is Training Data? A Comprehensive Guide in 2021

Ajay Ohri


The thought of using a training dataset for machine learning programs can seem to be a simple concept; however, it is very elemental to the method applied by emerging technologies. The training data is a set of data that is initially used to train the program or algorithm for the technological applications, discover relationships, develop understanding, provide data structure training and decision-making capabilities, and give well-defined results. 

Data set Definition: Data set is a collection of various related sets of information that are incorporated with separate elements that can be manipulated and analyzed as a unit of the computer system. 

In this article let us look at:

  1. What is Training Data?
  2. What is a Test Set?
  3. How should you split up a Dataset into Test and Training Sets?
  4. How much Training Data is enough?
  5. What is the difference between Training Data and Big Data? 

1. What is Training data? 

It is the information through which the computer understands the method of how to process the information. It imitates the capabilities of the human brain to take several inputs, analyze them to produce activations in the human brain present in the brain cells. Artificial neurons recreate a significant part of this process with neural network and machine learning programs. Extremely detailed models are provided of the human thought process by these programs. 

Traning data can be identified in different ways. A set of raw or alphanumerical data is used for decision trees and algorithms. However, a training set of a vast amount of images is handled for convolutional neural networks that need image processing. 

The training data example consists of regular expressions and many lookup tables that give extra information to your training data. Collections of realistic data can also be a training dataset example. 

2. What is a test set?  

The test set is a set of data that is used to test the models after these models have already been trained. The training set and test set are separate from each other. Once the model is trained and validated using training and validation sets, the model can predict the output of the data in the test set. 

The test set is unique from the other two sets since the other two sets need to be labelled, whereas a test set is unlabeled. This enables us to observe the metrics provided during the training, such as loss in the accuracy from each epoch when the model is predicting on unlabeled data in test data. 

3. How should you split up a dataset into test and training sets?  

When we are working on the model development, we need to train it and test it on the same dataset. Since it is challenging to possess a vast number of data while the model is in the development phase, the most obvious answer is to split the data into two separate sets, out of which one will be for training and the other will be testing. 

A. Splitting the data set into a training set and test set:

The two conditions that need to be taken care of before proceeding with the splitting of the dataset:  

  • The test set needs to be large to give statistically essential outputs. 
  • The characteristics of the training set and test set should be similar.  

Therefore, after the satisfaction of the above two conditions, the ultimate goal should be to develop a model that can easily perform functions with the new dataset. 

B. Validation of the trained model over the test data. 

The model should not train over the test data. Many times good results on evaluation metrics is an indication that inadvertently, you are training on test data. 

4. How much training data is enough?  

The amount of data required for training the program depends upon the difficulty level of the problem and an algorithm. The inadequate data can affect the models’ prediction accuracy, and it can be difficult to manage the huge data though it can give the appropriate results. 

Therefore, initially, the amount of data depends upon the complexity of the problem. 

Many statistical heuristics methods help to calculate the appropriate sample size for training data. There are various components such as the number of input features, number of classes, and the number of model parameters that guide the selection of training data.

Even a study can also be designed to assess the model skills required as compared to the size of the training data.

Nonlinear algorithms are capable of analyzing the complex nonlinear relationships existing between the input and output variables. These are known as some of the most powerful machine learning algorithms. The predictions are directly proportional to the specific data used for training the models. 

However, one doesn’t have to wait for acquiring the correct amount of data. You can start with the amount of data you have and evaluate the effectiveness of the model.  Later on, more data can be acquired for further analysis and predictions. 

 5. What is the difference between training data and big data? 

Training data is an essential input to train the machine learning (ML) programs. It is crucial to have the appropriate quality and quantity of datasets. The huge size of data helps ML to acquainted with the diverse types of situations. 

Big Data is the upgraded version of the traditional data as it deals with various complex datasets. Big data training can perform with semi-structured, structured, and unstructured data. The five basic characteristics of big data are Velocity, Variety, Value, Volume, and Veracity. Big data refers to deriving significant data by interpreting a large number of complex data sets. Data integration in Big Data is difficult as it requires high configuration. 


For Scientists and Engineers, the perfect quality and quantity of data selection bear a huge significance. Therefore, training data assist in developing a robust model and in the future, its relevance will increase to a significant extent since it will become easier to develop an understanding of the amount of data required for model training and testing. 

There are no right or wrong ways of learning AI and ML technologies – the more, the better! These valuable resources can be the starting point for your journey on how to learn Artificial Intelligence and Machine Learning. Do pursuing AI and ML interest you? If you want to step into the world of emerging tech, you can accelerate your career with this Machine Learning And AI Courses by Jigsaw Academy.



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