What is the Negative Predictive Value? Given a negative prediction, the Negative Predictive Value (NPV) is the performance metric that tells you the probability that the true value is negative. It is closely related to the Positive Predictive Value, which is completely analogous. The complement of the Negative Predictive Value…
What is the Positive Likelihood Ratio? The Positive Likelihood Ratio (LR+, +LR, likelihood ratio positive or likelihood ratio for positive results) gives the change in odds of the true value being positive when the predicted value is positive. This is expressed as a ratio. An LR+ of 5 indicates a…
What is the Positive Predictive Value? Given a positive prediction, the Positive Predictive Value (PPV) is the performance metric that tells you the probability that the true value is positive. It is closely related to the Negative Predictive Value, which is completely analogous. The complement of the Positive Predictive Value…
What is the Fowlkes-Mallows Index? The Fowlkes-Mallows Index (FMI, Fowlkes-Mallows Score or G-Mean) is a performance metric to evaluate the similarity of clusters obtained through various clustering algorithms. It is typically used to evaluate the clustering performance of a specific algorithm by assuming that the cluster it is compared to is…
What is the True Negative Rate? The True Negative Rate (Specificity, Selectivity) is a performance metric that measures the probability that your model will predict negative when the true value is negative. It is closely related to the True Positive Rate, which is completely analogous. The False Positive Rate and the…
What is the True Positive Rate? The True Positive Rate (Sensitivity, Recall, Power) is a performance metric that measures the probability that your model will predict positive when the true value is positive. It is closely related to the True Negative Rate, which is completely analogous. The False Negative Rate and…
What is Youden’s Index? Youden’s Index (also known as Youden’s J Statistic or J) is a performance metric that evaluates the performance of a binary classification model. Its value ranges from 0 to 1. When the value is at its minimum of zero, the model is useless. When its value…
What is the prevalence? Prevalence is a measure of how common a phenomenon is present within a population at a specific time point or within a specified time period. The impact of the prevalence on the Accuracy, the Positive Predictive Value and the Negative Predictive Value cannot be understated. As…