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The study presents statistical procedures that monitor functioning of items over time. We propose generalized likelihood ratio tests that surveil multiple item parameters and implement with various sampling techniques to perform continuous or intermittent monitoring. The procedures examine stability of item parameters across time and inform compromise as soon as they identify significant parameter shift. The performance of the monitoring procedures was validated using simulated and real-assessment data. The empirical evaluation suggests that the proposed procedures perform adequately well in identifying the parameter drift. They showed satisfactory detection power and gave timely signals while regulating error rates reasonably low. The procedures also showed superior performance when compared with the existent methods. The empirical findings suggest that multivariate parametric monitoring can provide an efficient and powerful control tool for maintaining the quality of items. The procedures allow joint monitoring of multiple item parameters and achieve sufficient power using powerful likelihood-ratio tests. Based on the findings from the empirical experimentation, we suggest some practical strategies for performing online item monitoring. [ABSTRACT FROM AUTHOR]

Purpose: Laparoscopic totally extraperitoneal hernia repair (TEP) is a widely used treatment for inguinal hernia. Single-incision laparoscopic TEP (SILTEP) has attracted the attention of several surgeons, given its superior cosmetic results and patient satisfaction, as well as comparable outcomes to multiport surgery. Nonetheless, no relevant studies have evaluated the learning curve (LC) of SILTEP in terms of both operation time (OT) and surgical failure. Therefore, we aimed to investigate the LC of SILTEP for inguinal hernia. Methods: Medical records of 180 patients who underwent SILTEP performed by a single surgeon from a single institution between October 2012 and November 2017 were retrospectively reviewed. The LC was analyzed using the moving average method and cumulative sum control chart (CUSUM) for OT and surgical failure. Surgical failure was defined as the need for additional ports, open conversion, severe postoperative complications (Clavien–Dindo ≥ IIIa), and recurrence. Eight patients who underwent combined surgery or bilateral hernia repair were excluded from the OT analysis. Results: From CUSUM graphs, the study period was divided into three phases: OT-phases 1 (1st–32nd), 2 (33rd–83rd), and 3 (84th–172nd) for OT and failure-phases 1 (1st–29th), 2 (30th–58th), and 3 (59th–180th) for surgical failure. Mean OTs were statistically different in the three OT phases (64.6 vs. 50.8 vs. 35.2 min; p < 0.001). Open conversion (31.0% vs. 0% vs. 2.5%) and additional port insertion (6.9% vs. 24.1% vs. 2.5%) stabilized consecutively at failure-phases 2 and 3 (p < 0.001). Surgical failure rates decreased to 5.7% by failure-phase 3 (37.9% vs. 24.1% vs. 5.7%; p < 0.001). Conclusion: For an experienced laparoscopic surgeon, we estimated that approximately 60 cases are needed to overcome the LC for SILTEP in terms of both reducing OT and achieving a surgical failure rate < 10%. Further proficiency could be achieved after approximately 85 SILTEP procedures with a stable OT of approximately 35 min. [ABSTRACT FROM AUTHOR]

Cumulative sum (CUSUM) and change-point analysis (CPA) are two well-established statistical process control methods to detect changes in a sequence. Both have been used in psychometric research to detect aberrant responses in a response sequence, e.g., test speededness, inattentiveness, or cheating. However, the pros and cons of CUSUM and CPA in different testing settings still remain unclear. In this paper, we conduct a comprehensive comparison of the performance of twelve CUSUM-based statistics and three CPA-based procedures in detecting test speededness. Two speededness mechanisms are considered, namely the graduate change model (GCM) and the hybrid model (HM), to test the robustness and flexibility of the two methods. Simulation studies show that the performances of the statistics are affected by the underlying data generating model, the severity of speededness, and the test length. Generally, under HM some CUSUM statistics perform much better than the CPA-based statistics. Under the GCM, the performance of the CPA statistics is dramatically improved. Taken together, due to the unknown mechanism of speededness in real applications, two CUSUM-based statistics are recommended when the test length is long (e.g., 80 items), regardless of the underlying mechanism being HM or GCM. In a relatively short (e.g., 40 items) or medium-length (e.g., 60 items) test, no statistic always ends up in the top three under both HM and GCM. In those cases, either one of the two CUSUM-based statistics mentioned above can be a reasonable choice because of their good (though not necessarily the best) performance in a wide range of conditions. [ABSTRACT FROM AUTHOR]

In this research, we propose the new mixed control chart called the mixed Moving Average-Cumulative Sum (MA-CUSUM) control chart used for monitoring parameter changes in asymmetrical and symmetrical processes. Its efficiency was compared with that of the Shewhart, Cumulative Sum (CUSUM), Moving Average (MA), mixed Cumulative Sum-Moving Average (CUSUM-MA) and mixed Moving Average-Cumulative Sum (MA-CUSUM) control charts by using their average run lengths (ARLs), the standard deviation of the run length (SDRL), and median run length (MRL) via the Monte Carlo simulation (MC). The simulation results show that the MA-CUSUM control chart was more efficient than the other control charts for small-to-moderate parameter changes for all distributions tested. To compare their applicability to real-world situations, the control charts were applied to data for the River Nile flow from 1871–1930 and mine explosions in the UK from 1875–1951. It was found that the MACUSUM control chart could more quickly detect parameter changes than the other control charts. [ABSTRACT FROM AUTHOR]

Objective: To explore the training ability of pad to guide the balance of soft tissue by drawing cumulative sum (CUSUM) control chart total knee arthroplasty (TKA) sensor., Methods: The data of 73 knees of TKA assisted by electronic gasket initially completed by a senior physician were analyzed retrospectively. There were 8 males (8 knees) and 52 females (65 knees), with an average age of (67.5±5.9) years (57-82 years). The balance of the internal and external space of knee joint was measured at 0°, 45°, 90°, and 120°, in order to observe the pressure distribution of the medial and la-teral compartments, and CUSUM learning curve was drawn., Results: In 0° extension, the medial pressure was higher than the lateral ( P < 0.01), when flexion began, the medial and lateral pressures decreased, and became stable and approximately equal during 45°-120°. In the learning curve, by knee 34, CUSUM 0° curve crossed the acceptable control line from above, which showed that it was easy to grasp the soft tissue balance at 0° position through sensor learning. CUSUM 45° curve was above the unacceptable control line in the end, which meant that it was difficult to grasp the technique at the mid-flexion angle. CUSUM 90° and 120° crossed the acceptable control line from above by knee 68 and 57 respectively, which showed that the technique of balance could be improved with the aid of more cases., Conclusion: The electronic pressure sensor can effectively guide the soft tissue balance in TKA. The learning process is simple and does not increase the risk of complications. It can be used as a tool for learning TKA soft tissue balance technology to guide joint surgeons to further master or improve the soft tissue balance technology.