The bridge between design and analysis

The overall purpose of the ‘Statistical Points and Pitfalls’ series is to help readers and researchers alike increase awareness of how to use statistics and why/how we fall into inappropriate choices or interpretations. We hope to help readers understand common misconceptions and give clear guidance on how to avoid common pitfalls by offering simple tips to improve your reporting of quantitative research findings. Each entry discusses a commonly encountered inappropriate practice and alternatives from a pragmatic perspective with minimal mathematics involved. We encourage readers to share comments on or suggestions for this section on Twitter, using the hashtag: #mededstats

Problematic internet use (PIU): Associations with the impulsive-compulsive spectrum. An application of machine learning in psychiatry.

Problematic internet use is common, functionally impairing, and in need of further study. Its relationship with obsessive-compulsive and impulsive disorders is unclear. Our objective was to evaluate whether problematic internet use can be predicted from recognised forms of impulsive and compulsive traits and symptomatology. We recruited volunteers aged 18 and older using media advertisements at two sites (Chicago USA, and Stellenbosch, South Africa) to complete an extensive online survey. State-of-the-art out-of-sample evaluation of machine learning predictive models was used, which included Logistic Regression, Random Forests and Naïve Bayes. Problematic internet use was identified using the Internet Addiction Test (IAT). 2006 complete cases were analysed, of whom 181 (9.0%) had moderate/severe problematic internet use. Using Logistic Regression and Naïve Bayes we produced a classification prediction with a receiver operating characteristic area under the curve (ROC-AUC) of 0.83 (SD 0.03) whereas using a Random Forests algorithm the prediction ROC-AUC was 0.84 (SD 0.03) [all three models superior to baseline models p < 0.0001]. The models showed robust transfer between the study sites in all validation sets [p < 0.0001]. Prediction of problematic internet use was possible using specific measures of impulsivity and compulsivity in a population of volunteers. Moreover, this study offers proof-of-concept in support of using machine learning in psychiatry to demonstrate replicability of results across geographically and culturally distinct settings.This research received internal departmental funds of the Department of Psychiatry at the University of Chicago.This is the final version of the article. It first appeared from Elsevier at http://dx.doi.org/10.1016/j.jpsychires.2016.08.010

Communication skills training and the conceptual structure of empathy among medical students

Introduction: Medical and healthcare professionals’ empathy for patients is crucially important for patient care. Some studies have suggested that a significant decline in empathy occurs during clinical training years in medical school as documented by self-assessed empathy scales. Moreover, a recent study provided qualitative evidence that communication skills training in an examination context, such as in an objective structured clinical examination, might stimulate perspective taking but inhibit the development of compassionate care. Therefore, the current study examined how perspective taking and compassionate care relate to medical students’ willingness to show empathic behaviour and how these relations may change with communication skills training. Methods: A total of 295 fourth-year Japanese medical students from three universities completed the Jefferson Empathy Scale and a newly developed set of items on willingness to show empathic behaviour twice after communication skills training, pertaining to post-training and retrospectively for pre-training. Results: The findings indicate that students’ willingness to show empathic behaviour is much more correlated with perspective taking than with compassionate care. Qualitative descriptive analysis of open-ended question responses revealed a difficulty of feeling compassion despite showing empathic behaviour. Discussion: These findings shed light on the conceptual structure of empathy among medical students and generate a number of hypotheses for future intervention and longitudinal studies on the relation between communication skills training and empathy

The Evolution of Cognitive Load Theory and the Measurement of Its Intrinsic, Extraneous and Germane Loads: A Review

Cognitive Load Theory has been conceived for supporting instructional design through the use of the construct of cognitive load. This is believed to be built upon three types of load: intrinsic, extraneous and germane. Although Cognitive Load Theory and its assumptions are clear and well-known, its three types of load have been going through a continuous investigation and re-definition. Additionally, it is still not clear whether these are independent and can be added to each other towards an overall measure of load. The purpose of this research is to inform the reader about the theoretical evolution of Cognitive Load Theory as well as the measurement techniques and measures emerged for its cognitive load types. It also synthesises the main critiques of scholars and the scientific value of the theory from a rationalist and structuralist perspective

EurA1c: the European HbA1c Trial to Investigate the Performance of HbA1c Assays in 2166 Laboratories across 17 Countries and 24 Manufacturers by Use of the IFCC Model for Quality Targets

Background: A major objective of the IFCC Committee on Education and Use of Biomarkers in Diabetes is to generate awareness and improvement of HbA1c assays through evaluation of the performance by countries and manufacturers. Methods: Fresh whole blood and lyophilized hemolysate specimens manufactured from the same pool were used by 17 external quality assessment organizers to evaluate analytical performance of 2166 laboratories. Results were evaluated per country, per manufacturer, and per manufacturer and country combined according to criteria of the IFCC model for quality targets. Results: At the country level with fresh whole blood specimens, 6 countries met the IFCC criterion, 2 did not, and 2 were borderline. With lyophilized hemolysates, 5 countries met the criterion, 2 did not, and 3 were borderline. At the manufacturer level using fresh whole blood specimens, 13 manufacturers met the criterion, 8 did not, and 3 were borderline. Using lyophilized hemolysates, 7 manufacturers met the criterion, 6 did not, and 3 were borderline. In both country and manufacturer groups, the major contribution to total error derived from between-laboratory variation. There were no substantial differences in performance between groups using fresh whole blood or lyophilized hemolysate samples. Conclusions: The state of the art is that 1 of 20 laboratories does not meet the IFCC criterion, but there are substantial differences between country and between manufacturer groups. Efforts to further improve quality should focus on reducing between-laboratory variation. With some limitations, fresh whole blood and well-defined lyophilized specimens are suitable for purpose

Mechanism of IL-12 mediated alterations in tumour blood vessel morphology: analysis using whole-tissue mounts

Angiogenesis is a multistep process that is limited and carefully regulated in normal adult tissue, but in tumours this regulation is disrupted and the process remains ‘switched on’ (Hanahan and Folkman, 1996). Ample experimental data support the fact that tumour growth requires access to blood vessels and subsequent expansion of host vessels to provide nutrients for the growing tumour mass (Folkman, 1995a). Furthermore, many studies in a variety of tumour types have reported a correlation between the extent of tumour vasculature and poor prognosis or increased metastases (Weidner et al, 1991; Folkman, 1995b; Weidner and Folkman, 1996). Thus, accurate assessment of the vasculature of tumours could provide valuable information regarding treatment outcomes and the likelihood of metastatic spread to other sites. Angiogenesis can be regulated by a variety of factors. Several cytokines produced by immune cells also have been shown to affect the process of angiogenesis. One of the most noteworthy is interleukin (IL)-12, which is produced by antigen presenting cells (APC), such as macrophages and dendritic cells (DC) in response to bacterial stimuli or other inflammatory cytokines. Thus, IL-12 plays an important role in both the innate and adaptive immune responses (Trinchieri, 1998). Owing to its central role in stimulating immunity, it has been examined for possible therapeutic effects in the treatment of tumours. In addition to its effects on the immune system, IL-12 has also been shown to inhibit angiogenesis (Voest et al, 1995; Sgadari et al, 1996). Despite studies in both experimental models and in patients (reviewed in Trinchieri and Scott, 1999), and clear demonstrations of therapeutic efficacy, relatively little is known about how it alters vessel formation within tumours. In part, this is due to the difficulty in assessing the three-dimensional structure of vessels and other cellular components within the tumour. Assessment of tumour vessels is generally based on immunohistochemistry of tumour sections. Although use of this technique has led to a great deal of important information, these procedures are extremely time consuming and provide only a limited two-dimensional view of the vessels. This makes it very difficult to visualise the structure of the microvasculature and identify differences among different tumour types or changes following treatment regimens. To more easily and accurately visualise vessels within tumours, we developed a whole-tissue mount technique that provides a three-dimensional view of the tumour vasculature relative to other components of the tumour tissue. This technique was first validated by studying vessels from transgenic mice that express green fluorescent protein (GFP) (Wu et al, 2000), and then used to investigate the mechanism by which IL-12 influences the vessel architecture within B16 tumours

How to combine collaboration scripts and heuristic worked examples to foster mathematical argumentation – when working memory matters

Mathematical argumentation skills (MAS) are considered an important outcome of mathematics learning, particularly in secondary and tertiary education. As MAS are complex, an effective way of supporting their acquisition may require combining different scaffolds. However, how to combine different scaffolds is a delicate issue, as providing learners with more than one scaffold may be overwhelming, especially when these scaffolds are presented at the same time in the learning process and when learners’ individual learning prerequisites are suboptimal. The present study therefore investigated the effects of the presentation sequence of introducing two scaffolds (collaboration script first vs. heuristic worked examples first) and the fading of the primarily presented scaffold (fading vs. no fading) on the acquisition of dialogic and dialectic MAS of participants of a preparatory mathematics course at university. In addition, we explored how prior knowledge and working memory capacity moderated the effects. Overall, 108 university freshmen worked in dyads on mathematical proof tasks in four treatment sessions. Results showed no effects of the presentation sequence of the collaboration script and heuristic worked examples on dialogic and dialectic MAS. Yet, fading of the initially introduced scaffold had a positive main effect on dialogic MAS. Concerning dialectic MAS, fading the collaboration script when it was presented first was most effective for learners with low working memory capacity. The collaboration script might be appropriate to initially support dialectic MAS, but might be overwhelming for learners with lower working memory capacity when combined with heuristic worked examples later on