## What is Root Mean Squared Error (RMSE) :

Root Mean Squared Error (RMSE) is a measure of the difference between the predicted value and the actual value of a quantity. It is used in a variety of fields, including statistics, machine learning, and engineering, to evaluate the performance of predictive models.

The RMSE is calculated as the square root of the mean squared error (MSE), which is defined as the average of the squared differences between the predicted values and the actual values. The MSE is calculated by taking the sum of the squared differences between the predicted and actual values, dividing it by the number of samples, and then taking the square root of the result.

The RMSE is a commonly used metric for evaluating the performance of a model, as it provides a clear and interpretable measure of the model’s accuracy. It is often used in conjunction with other metrics, such as mean absolute error (MAE) and R-squared, to provide a more complete evaluation of a model’s performance.

Here are two examples to illustrate the concept of RMSE:

Example 1:

Suppose we have a predictive model that is used to predict the price of a house based on its size, location, and other features. We have a dataset of 100 houses, and we use our model to predict the price of each house. The actual prices of the houses are recorded in the dataset.

After making the predictions, we calculate the RMSE to evaluate the model’s performance. The RMSE is calculated as follows:

RMSE = sqrt(mean((predicted_prices – actual_prices)^2))

If the RMSE is low, it means that the model is able to accurately predict the prices of the houses. On the other hand, if the RMSE is high, it means that the model is not very accurate and there is a large difference between the predicted and actual prices.

Example 2:

Suppose we have a predictive model that is used to predict the number of customers that will visit a store on a given day. We have a dataset of 100 days, and we use our model to predict the number of customers that will visit the store on each day. The actual number of customers that visited the store on each day is recorded in the dataset.

After making the predictions, we calculate the RMSE to evaluate the model’s performance. The RMSE is calculated as follows:

RMSE = sqrt(mean((predicted_customer_count – actual_customer_count)^2))

If the RMSE is low, it means that the model is able to accurately predict the number of customers that will visit the store. On the other hand, if the RMSE is high, it means that the model is not very accurate and there is a large difference between the predicted and actual number of customers.

In both of these examples, a low RMSE indicates that the model is able to accurately predict the values of the quantity that it is trying to predict. A high RMSE, on the other hand, indicates that the model is not very accurate and there is a large difference between the predicted and actual values.