https://www.selleckchem.com/products/eflornithine-hydrochloride-hydrate.html Healthy versus diseased eyes could be classified in the test data-set with an agreement of 0.92 (Cohen's kappa). The exemplary incorrect learning algorithm and variable selection resulted in an MAE for visual acuity prediction of 0.229 LogMAR [0.150; 0.309] for the test data-set. The drastic overfitting became obvious on comparison of the MAE with the null model MAE (0.235 LogMAR [0.148; 0.322]). Selection of an unsuitable measure of the goodness-of-fit, inadequate validation, or withholding of anull or reference model can obscure the actual goodness-of-fit of AI models. The illustrated pitfalls can help clinicians to identify such shortcomings. Selection of an unsuitable measure of the goodness-of-fit, inadequate validation, or withholding of a null or reference model can obscure the actual goodness-of-fit of AI models. The illustrated pitfalls can help clinicians to identify such shortcomings. To explore the safety of multiple tract percutaneous nephrolithotomy (PNL) in terms of complication and draw a nomogram to predict the possibility of significant renal function decline (SRFD). Patients with complex renal calculi appropriate for PNL at our institution between August 2016 and February 2018 were included in the study. The outcome of single and multiple tract PNL was analyzed retrospectively. A nomogram was created to predict the probability of SRFD. 793 (88.4%) patients were treated with single tract PNL (Group 1) and 104 patients (11.6%) treated with multiple tract PNL (Group 2). Group 2 had a significantly greater hemoglobin reduction (16.0 ± 12.5 vs. 11.4 ± 11.8g/L, p < 0.001), higher rate of postoperative fever (19.2% vs. 11.9%, p = 0.034) and longer duration of the operation (110.6 ± 39.6 vs. 97.8 ± 34.5min, p < 0.001). A nomogram for predicting the probability of SRFD was constructed based on identified risk factors patients' age, positive urine culture (UC +), hemoglobin reducti