This paper analyzes the effect of subgroup size on the x-bar chart characteristics using sample influx (SIF) into forensic science laboratory (FSL). The characteristics studied include changes in out-or-control points...This paper analyzes the effect of subgroup size on the x-bar chart characteristics using sample influx (SIF) into forensic science laboratory (FSL). The characteristics studied include changes in out-or-control points (OCP), upper control limit UCLx, and zonal demarcations. Multi-rules were used to identify the number of out-of-control-points, Nocp as violations using five control chart rules applied separately. A sensitivity analysis on the Nocp was applied for subgroup size, k, and number of sigma above the mean value to determine the upper control limit, UCLx. A computer code was implemented using a FORTRAN code to create x-bar control-charts and capture OCP and other control-chart characteristics with increasing k from 2 to 25. For each value of k, a complete series of average values, Q(p), of specific length, Nsg, was created from which statistical analysis was conducted and compared to the original SIF data, S(t). The variation of number of out-of-control points or violations, Nocp, for different control-charts rules with increasing k was determined to follow a decaying exponential function, Nocp = Ae–α, for which, the goodness of fit was established, and the R2 value approached unity for Rule #4 and #5 only. The goodness of fit was established to be the new criteria for rational subgroup-size range, for Rules #5 and #4 only, which involve a count of 6 consecutive points decreasing and 8 consecutive points above the selected control limit (σ/3 above the grand mean), respectively. Using this criterion, the rational subgroup range was established to be 4 ≤ k ≤ 20 for the two x-bar control chart rules.展开更多
X-ray fluoroscopy has been used not only for diagnoses but also for treatment, as in interventional radiology. The aim of this study is to assess the usefulness of the signal-to-noise ratio (SNR) using the subtraction...X-ray fluoroscopy has been used not only for diagnoses but also for treatment, as in interventional radiology. The aim of this study is to assess the usefulness of the signal-to-noise ratio (SNR) using the subtraction method, which is used in the quality assurance/quality control (QA/QC) of magnetic resonance imaging (MRI) equipment, and image visibility using the Howlett chart method in the fluoroscopic examination. The fluoroscopy unit has a detector with an image intensifier and a color liquid crystal display. A 2620 dosimeter and an ionization chamber were selected for the dose measurement. Fluoroscopic images for visual and physical evaluations were collected as dynamic data. The skin surface absorbed dose rates for each tube current were measured using a dosimeter. The SNR using the subtraction method and image visibility using the Howlett chart method were examined. The results from both indicate that as the SNR improves, visual evaluation increases, but the rate of increase gradually saturates. Therefore, physical and visual evaluations are possible with the SNR using the subtraction method and the image visibility using the Howlett chart method.展开更多
评估平均值—极差值质控图(X-Bar and R Charts)在临床检验室内质控中的应用价值。利用SPSS质控程序中的平均值—极差值质控图分析甘油三酯的模拟质控数据,生成X-Bar(平均值)和R(极差值)质控图,并产生多种能力指数和性能指数。平均值—...评估平均值—极差值质控图(X-Bar and R Charts)在临床检验室内质控中的应用价值。利用SPSS质控程序中的平均值—极差值质控图分析甘油三酯的模拟质控数据,生成X-Bar(平均值)和R(极差值)质控图,并产生多种能力指数和性能指数。平均值—极差值质控图正确显示了违反质控规则的质控点,并对此做出了详细的报告;能力指数和性能指数正确反映了质控过程维持在规格限内的能力。平均值—极差值质控图适合于分析临床检验定量项目的质控数据。展开更多
文摘This paper analyzes the effect of subgroup size on the x-bar chart characteristics using sample influx (SIF) into forensic science laboratory (FSL). The characteristics studied include changes in out-or-control points (OCP), upper control limit UCLx, and zonal demarcations. Multi-rules were used to identify the number of out-of-control-points, Nocp as violations using five control chart rules applied separately. A sensitivity analysis on the Nocp was applied for subgroup size, k, and number of sigma above the mean value to determine the upper control limit, UCLx. A computer code was implemented using a FORTRAN code to create x-bar control-charts and capture OCP and other control-chart characteristics with increasing k from 2 to 25. For each value of k, a complete series of average values, Q(p), of specific length, Nsg, was created from which statistical analysis was conducted and compared to the original SIF data, S(t). The variation of number of out-of-control points or violations, Nocp, for different control-charts rules with increasing k was determined to follow a decaying exponential function, Nocp = Ae–α, for which, the goodness of fit was established, and the R2 value approached unity for Rule #4 and #5 only. The goodness of fit was established to be the new criteria for rational subgroup-size range, for Rules #5 and #4 only, which involve a count of 6 consecutive points decreasing and 8 consecutive points above the selected control limit (σ/3 above the grand mean), respectively. Using this criterion, the rational subgroup range was established to be 4 ≤ k ≤ 20 for the two x-bar control chart rules.
文摘X-ray fluoroscopy has been used not only for diagnoses but also for treatment, as in interventional radiology. The aim of this study is to assess the usefulness of the signal-to-noise ratio (SNR) using the subtraction method, which is used in the quality assurance/quality control (QA/QC) of magnetic resonance imaging (MRI) equipment, and image visibility using the Howlett chart method in the fluoroscopic examination. The fluoroscopy unit has a detector with an image intensifier and a color liquid crystal display. A 2620 dosimeter and an ionization chamber were selected for the dose measurement. Fluoroscopic images for visual and physical evaluations were collected as dynamic data. The skin surface absorbed dose rates for each tube current were measured using a dosimeter. The SNR using the subtraction method and image visibility using the Howlett chart method were examined. The results from both indicate that as the SNR improves, visual evaluation increases, but the rate of increase gradually saturates. Therefore, physical and visual evaluations are possible with the SNR using the subtraction method and the image visibility using the Howlett chart method.
文摘评估平均值—极差值质控图(X-Bar and R Charts)在临床检验室内质控中的应用价值。利用SPSS质控程序中的平均值—极差值质控图分析甘油三酯的模拟质控数据,生成X-Bar(平均值)和R(极差值)质控图,并产生多种能力指数和性能指数。平均值—极差值质控图正确显示了违反质控规则的质控点,并对此做出了详细的报告;能力指数和性能指数正确反映了质控过程维持在规格限内的能力。平均值—极差值质控图适合于分析临床检验定量项目的质控数据。
