Commence with allocating business values to four types of outcomes in commercial applications, which include true negatives, true positives, false negatives, and false positives. Optimizing the model you're utilizing can be achieved by multiplying the figures in each category with their corresponding business values.
Existing among the complexities of this model is the confidence values the system provides. The majority of machine learning platforms can be programmed to share their level of confidence in their output. A superior technique to use this data in the precision measurement is by multiplying it with the findings, effectively bestowing high credibility levels for correct predictions upon the model.
True Positive Rate and Business Value
The metric that ascertains the percentage of actual positives that are accurately identified is the true positive rate, also identified as sensitivity or recall in machine learning. However, there are also more sophisticated methods. For instance, if all low confidence predictions are expected to be manually verified, assigning the manual labor cost to them and subtracting their outcomes from the model's precision measurement provides a more precise estimation of the business value facilitated by the model.
Machine learning model results can be categorized as true or false predictions. These categories indicate whether the model is accurate or not. The real value of the data point is also crucial. The question that often arises is, "Why do we need a model that can predict values we already possess?" What we are honing in on here is the model's performance on the previously known training data.
The real values of the data points could either be the values we are seeking in our dataset (positives) or unrelated data (negatives). Consequently, the model can have one of four prediction outcomes: True positive, False positive, True negative, and False negative.
When focusing on accurately forecasting the instances in the true class, the positive rate becomes vital. Take, for instance, a test for a critical type of cancer. Our goal would be to identify accurately any instance where an individual actually has cancer. Thus, we remain primarily concerned with the positive rate.
To tabulate the true positive rate in machine learning, we divide the total true positives (TP) by the sum of total true positives and false negatives (FN):Recall/True Positive Rate = TP / (TP+FN)
In a scenario where recall is paramount, adjusting our decision threshold can help us predict more true cases more accurately. If the positive rate is our focus, we can lower the decision threshold to capture more of the true positive cases.
The Balance Between Sensitivity and Specificity
Notably, predicting every observation as positive to achieve a perfect 100% TPR might not always be ideal, especially when the cost of false positives is high. It becomes crucial to have a measure for tracking how well your model differentiates between true and false positives for heightened precision.
The Interplay of Rates in Model Evaluation
In the end, it's pivotal to note that a positive rate is interchangeably referred to like sensitivity or recall. The term specificity refers to the true negative rate. Normally, these two metrics stand in opposition to each other in any statistical measurement tool. However, certain dominating approaches in multiple statistical inferential methods allow achieving higher positive rates without correlatively increasing the false positive rate.
False negatives rate equals to 1 minus the false positive rate, whilst the false positive rate equals to 1 minus the positive rate.