Ground truth is never perfect, with errors in measurements and human annotations, raising concerns on evaluating models using imperfect labels.Exploring methods to estimate a model's 'true' accuracy when labels are noisy is essential.Errors in both model predictions and ground truth labels can mislead accuracy measurements.The true accuracy of a model can vary based on error correlations between the model and ground truth labels.Indications show that the model's true accuracy depends on the overlap of errors with ground truth errors.If errors are uncorrelated, a probabilistic estimate formula can help derive a more precise true accuracy.In practices where errors may be correlated, the true accuracy tends to lean towards the lower bound.Understanding the difference between measured and true accuracy is crucial for accurate model evaluation.Targeted error analysis and multiple independent annotations are recommended for handling noisy labels in model evaluation.In summary, the range of true accuracy depends on ground truth error rates, with considerations for error correlations in real-world scenarios.