Description: The Weighted Mean Squared Error (WMSE) is a metric used in the field of supervised learning to evaluate the accuracy of a prediction model. Unlike the standard mean squared error, which calculates the average of the squared errors of predictions against actual values, WMSE incorporates a weighting factor that allows for greater or lesser importance to be assigned to certain errors based on their relevance. This feature is particularly useful in situations where the data is imbalanced or when some observations are more critical than others. For example, in a classification model, certain types of errors may have more severe consequences, justifying a higher weight in the error calculation. WMSE is calculated by summing the squared errors, multiplied by their respective weights, and dividing the result by the sum of the weights. This metric not only provides a more nuanced view of model performance but also allows researchers and practitioners to adjust their models more effectively, prioritizing the reduction of errors in areas that are more significant for the specific context of the problem being addressed.