Zum Einfluss von Nachfrageverteilungen auf das Verhalten von Lagerhaltungsstrategien

Lagerhaltungsstrategien beinhalten Anweisungen zur Berechnung von Lagerbeständen und Bestellmengen. In diesem Artikel wird der Effekt von Nachfrageverteilungen auf das Ergebnis von verschiedenen bekannten Strategien untersucht und ein Vergleich bezüglich erreichter Servicegrade durchgeführt. Als eine Folgerung aus diesem Vergleich wird ein nicht parametrisches Nachfragemodell als Basis für Lagerhaltungsstrategien vorgeschlagen

The effect of demand distributions on the performance of inventory policies

Inventory policies provide instructions on how to calculate stock levels and order quantities. This paper examines the effect of the demand distribution on the performance of several well-known policies. Their performance is compared in terms of achieved service levels. As a conclusion from these comparisons, a nonparametric demand model is proposed to be used in inventory policies

Effective study selection using text mining or a single-screening approach: a study protocol

Abstract Background Systematic information retrieval generally requires a two-step selection process for studies, which is conducted by two persons independently of one another (double-screening approach). To increase efficiency, two methods seem promising, which will be tested in the planned study: the use of text mining to prioritize search results as well as the involvement of only one person in the study selection process (single-screening approach). The aim of the present study is to examine the following questions related to the process of study selection: Can the use of the Rayyan or EPPI Reviewer tools to prioritize the results of study selection increase efficiency? How accurately does a single-screening approach identify relevant studies? Which advantages or disadvantages (e.g., shortened screening time or increase in the number of full texts ordered) does a single-screening versus a double-screening approach have? Methods Our study is a prospective analysis of study selection processes based on benefit assessments of drug and non-drug interventions. It consists of two parts: firstly, the evaluation of a single-screening approach based on a sample size calculation (11 study selection processes, including 33 single screenings) and involving different screening tools and, secondly, the evaluation of the conventional double-screening approach based on five conventional study selection processes. In addition, the advantages and disadvantages of the single-screening versus the double-screening approach with regard to the outcomes “number of full texts ordered” and “time required for study selection” are analyzed. The previous work experience of the screeners is considered as a potential effect modifier. Discussion No study comparing the features of prioritization tools is currently available. Our study can thus contribute to filling this evidence gap. This study is also the first to investigate a range of questions surrounding the screening process and to include an a priori sample size calculation, thus enabling statistical conclusions. In addition, the impact of missing studies on the conclusion of a benefit assessment is calculated. Systematic review registration Not applicabl

Additional file 1: of Benefits and harms of screening for and treatment of asymptomatic bacteriuria in pregnancy: a systematic review

Search strategy. The file contains the full description of the search strategy. (PDF 18 kb

Screening for sickle cell disease in newborns: a systematic review

Background!#!Sickle cell disease (SCD) is an inherited autosomal recessive disorder caused by the replacement of normal haemoglobin (HbA) by mutant Hb (sickle Hb, HbS). The sickle-shaped red blood cells lead to haemolysis and vaso-occlusion. Especially in the first years of life, patients with SCD are at high risk of life-threatening complications. SCD prevalence shows large regional variations; the disease predominantly occurs in sub-Saharan Africa. We aimed to systematically assess the evidence on the benefit of newborn screening for SCD followed by an earlier treatment start.!##!Methods!#!We systematically searched bibliographic databases (MEDLINE, EMBASE, Cochrane Databases, and the Health Technology Assessment Database), trial registries, and other sources to identify systematic reviews and randomised controlled trials (RCTs) or non-randomised trials on newborn screening for SCD. The last search was in 07/2020. Two reviewers independently reviewed abstracts and full-text articles and assessed the risk of bias of the studies included. Data were extracted by one person and checked by another. As meta-analyses were not possible, a qualitative summary of results was performed.!##!Results!#!We identified 1 eligible study with direct evidence: a Jamaican retrospective study evaluating newborn screening for SCD followed by preventive measures (prevention of infections and education of parents). The study included 500 patients with SCD (intervention group, 395; historical control group, 105). Although the results showed a high risk of bias, the difference between the intervention and the control group was very large: mortality in children decreased by a factor of about 10 in the first 5 years of life (0.02% in the intervention group vs. 0.19% in the control group, odds ratio 0.09; 95% confidence interval [0.04; 0.22], p < 0.001).!##!Conclusion!#!The results are based on a single retrospective study including historical controls. However, the decrease of mortality by a factor of 10 is unlikely to be explained by bias alone. Therefore, in terms of mortality, data from this single retrospective study included in our systematic review suggest a benefit of newborn screening for SCD (followed by preventive measures) versus no newborn screening for SCD (weak certainty of conclusions)

Increasing the efficiency of study selection for systematic reviews using prioritization tools and a single-screening approach

Abstract Background Systematic literature screening is a key component in systematic reviews. However, this approach is resource intensive as generally two persons independently of each other (double screening) screen a vast number of search results. To develop approaches for increasing efficiency, we tested the use of text mining to prioritize search results as well as the involvement of only one person (single screening) in the study selection process. Method Our study is based on health technology assessments (HTAs) of drug and non-drug interventions. Using a sample size calculation, we consecutively included 11 searches resulting in 33 study selection processes. Of the three screeners for each search, two used screening tools with prioritization (Rayyan, EPPI Reviewer) and one a tool without prioritization. For each prioritization tool, we investigated the proportion of citations classified as relevant at three cut-offs or STOP criteria (after screening 25%, 50% and 75% of the citation set). For each STOP criterion, we measured sensitivity (number of correctly identified relevant studies divided by the total number of relevant studies in the study pool). In addition, we determined the number of relevant studies identified per single screening round and investigated whether missed studies were relevant to the HTA conclusion. Results Overall, EPPI Reviewer performed better than Rayyan and identified the vast majority (88%, Rayyan 66%) of relevant citations after screening half of the citation set. As long as additional information sources were screened, it was sufficient to apply a single-screening approach to identify all studies relevant to the HTA conclusion. Although many relevant publications (n = 63) and studies (n = 29) were incorrectly excluded, ultimately only 5 studies could not be identified at all in 2 of the 11 searches (1x 1 study, 1x 4 studies). However, their omission did not change the overall conclusion in any HTA. Conclusions EPPI Reviewer helped to identify relevant citations earlier in the screening process than Rayyan. Single screening would have been sufficient to identify all studies relevant to the HTA conclusion. However, this requires screening of further information sources. It also needs to be considered that the credibility of an HTA may be questioned if studies are missing, even if they are not relevant to the HTA conclusion

Additional file 1 of Systemic therapy in children and adolescents with mental disorders: a systematic review and meta-analysis

Supplementary file 1: Additional file 1. PRISMA 2020 Checklist. Additional file 2. Search strategies. Additional file 3. Study pool of included RCTs. Additional file 4. Characteristics of included RCTs. Additional file 5. Risk-of-bias assessment. Additional file 6. All results