The deployment of statistical models—such as those used in item response theory—necessitates the use of indices that are informative about the degree to which a given model is appropriate for a specific data context. We introduce the InterModel Vigorish (IMV) as an index that can be used to quantify accuracy for models of dichotomous item responses based on the improvement across two sets of predictions (i.e., predictions from two item response models or predictions from a single such model relative to prediction based on the mean). This index has a range of desirable features: It can be used for the comparison of non-nested models and its values are highly portable and generalizable. We use this fact to compare predictive performance across a variety of simulated data contexts and also demonstrate qualitative differences in behavior between the IMV and other common indices (e.g., the AIC and RMSEA). We also illustrate the utility of the IMV in empirical applications with data from 89 dichotomous item response datasets. These empirical applications help illustrate how the IMV can be used in practice and substantiate our claims regarding various aspects of model performance. These findings indicate that the IMV may be a useful indicator in psychometrics, especially as it allows for easy comparison of predictions across a variety of contexts.

This paper demonstrates that, after applying a simple modification to Li and Stout’s (Psychometrika 61(4):647–677, 1996) CSIBTEST statistic, an improved variant of the statistic could be realized. It is shown that this modified version of CSIBTEST has a more direct association with the SIBTEST statistic presented by Shealy and Stout (Psychometrika 58(2):159–194, 1993). In particular, the asymptotic sampling distributions and general interpretation of the effect size estimates are the same for SIBTEST and the new CSIBTEST. Given the more natural connection to SIBTEST, it is shown that Li and Stout’s hypothesis testing approach is insufficient for CSIBTEST; thus, an improved hypothesis testing procedure is required. Based on the presented arguments, a new chi-squared-based hypothesis testing approach is proposed for the modified CSIBTEST statistic. Positive results from a modest Monte Carlo simulation study strongly suggest the original CSIBTEST procedure and randomization hypothesis testing approach should be replaced by the modified statistic and hypothesis testing method.

This paper proposes a model-based family of detection and quantification statistics to evaluate response bias in item bundles of any size. Compensatory (CDRF) and non-compensatory (NCDRF) response bias measures are proposed, along with their sample realizations and large-sample variability when models are fitted using multiple-group estimation. Based on the underlying connection to item response theory estimation methodology, it is argued that these new statistics provide a powerful and flexible approach to studying response bias for categorical response data over and above methods that have previously appeared in the literature. To evaluate their practical utility, CDRF and NCDRF are compared to the closely related SIBTEST family of statistics and likelihood-based detection methods through a series of Monte Carlo simulations. Results indicate that the new statistics are more optimal effect size estimates of marginal response bias than the SIBTEST family, are competitive with a selection of likelihood-based methods when studying item-level bias, and are the most optimal when studying differential bundle and test bias.

In June 2015, an outbreak of cryptosporidiosis with 35 cases (23 probable and 12 laboratory-confirmed) occurred among 191 attendees of a residential rehabilitation holiday for paediatric organ transplant patients (n = 49) and their families at a hotel in Somogy county, Hungary. The overall attack rate was 18%. Most of the cases were transplanted children who experienced severe acute disease and required adjustment to their tacrolimus immunosuppression. A retrospective case-control study suggested an association between recreational water exposures and illness: cases were seven times more likely than controls to have swum in the children's pool (odds ratio 7.17; 95% confidence interval 2.9–17.2; P < 0.0001) and five times more likely to have used the jetted whirlpool (odds ratio 5.25; 95% confidence interval 2.1–13.1; P < 0.0001). This was the first outbreak of cryptosporidiosis in Hungary and it is especially unfortunate that it affected vulnerable children who experienced severe symptoms. Cryptosporidium presents specific infection control difficulties in treated recreational water venues; the link to a whirlpool is unusual and highlights the importance of the age-appropriate use of these facilities and reminding users not to immerse their heads or swallow the water. Cryptosporidiosis is more commonly linked to children’ pools where improved bather hygiene and promoting exclusion of diarrhoea cases could help to avoid similar outbreaks.

Field, greenhouse, and laboratory studies were conducted to evaluate the performance of starch xanthide (SX), sludge polymer (SP), and coventional formulations (CF) of benefin [N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine], oxadiazon {3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H-one}, and prosulfalin {N-[[4-dipropylamino)-3,5-dinitrophenyl] sulfonyl]-5,5-dimethylsulfilimine} for the control of large crabgrass [Digitaria sanguinalis (L.) Scop. # DIGSA] in Kentucky bluegrass (Poa pratensis L.) turf. Turf injury was greatest with SP oxadiazon and prosulfalin formulations, while SX formulations of oxadiazon and prosulfalin caused decreased and /or delayed injury and provided control comparable to conventional formulations. Coarse SX granules containing prosulfalin caused less turf injury than fine granules, while the opposite effect sometimes occurred with SX oxadiazon. Differences in control were observed in the greenhouse when SX benefin formulations which varied in cross-linking agent and/or degree of substitution were compared to the conventional formulation on sandy and silt loam soils. Benefin SX formulations also demonstrated controlled-release properties, which improved large crabgrass control when compared to the conventional formulation in the greenhouse. This effect was short lived on silt loam but persisted on sand. SX granules cross-linked with Fe3+ extended benefin activity longer than H2O2 cross-linked materials on sandy soil only. Release of 14C-labeled benefin from SX matrices was altered by the extent of water imbibition, solvent characteristics, and granule size.

A case-control study was conducted to investigate an outbreak of 46 cases of cryptosporidiosis in visitors to a petting farm in England. Details of exposures on the farm were collected for 38 cases and 39 controls, recruited through snowball sampling. Multivariable logistic regression identified that cases were 5·5 times more likely than controls to have eaten without washing their hands [95% confidence interval (CI) 1·51–19·9, P = 0·01] and 10 times less likely to report being informed of risk of infection on arrival (odds ratio 0·10, 95% CI 0·01–0·71, P = 0·02). An uncommon Cryptosporidium parvum gp60 subtype (IIaA19G1R1) was identified in a lamb faecal sample and all subtyped cases (n = 22). We conclude that lack of verbal advice and non-compliance with hand washing are significantly associated with a risk of cryptosporidiosis on open farms. These findings highlight the public health importance of effectively communicating risk to petting farm visitors in order to prevent future outbreaks of zoonotic infections.

Water supply-associated cryptosporidiosis outbreaks have decreased in England since the application of risk reduction measures to public water supplies. We hypothesized that smaller outbreaks were occurring which could be better detected by enhanced surveillance. Rolling analysis of detailed questionnaire data was applied prospectively in a population of 2·2 million in the south of England in 2009 and 2010. Detection of spatiotemporal clusters using SaTScan was later undertaken retrospectively. Together these approaches identified eight outbreaks, compared to an expectation of less than one based on national surveillance data. These outbreaks were small and associated with swimming pool use or, less commonly, direct (e.g. petting-farm) contact with animals. These findings suggest that frequent small-scale transmission in swimming pools is an important contributor to disease burden. Identification of swimming pool-level risk factors may inform preventative measures. These findings and the approaches described may be applicable to many other populations and to some other diseases.

In September 2010, an outbreak of cryptosporidiosis affected members of a swimming club. A cohort study was undertaken to identify the number affected and risk factors for infection. Of 101 respondents, 48 met the case definition for probable cryptosporidiosis. Multivariate analysis demonstrated a strong and highly significant association between illness and attendance at a training session on 13 September 2010 (adjusted odds ratio 28, P < 0·0001). No faecal incidents were reported and pool monitoring parameters were satisfactory. The competitive nature of club swimming requires frequent training and participation in galas, potentially facilitating contamination into other pools and amplification of outbreaks among wider groups of swimmers. There was a lack of awareness of the 2-week exclusion rule among swimmers and coaches, and a high level of underreporting of illness. The study demonstrates the benefits of rapid field epidemiology in identifying the true burden of illness, the source of infection and limiting spread.

Asymptomatic carriage of gastrointestinal zoonoses is more common in people whose profession involves them working directly with domesticated animals. Subclinical infections (defined as an infection in which symptoms are either asymptomatic or sufficiently mild to escape diagnosis) are important within a community as unknowing (asymptomatic) carriers of pathogens do not change their behaviour to prevent the spread of disease; therefore the public health significance of asymptomatic human excretion of zoonoses should not be underestimated. However, optimal strategies for managing diseases where asymptomatic carriage instigates further infection remain unresolved, and the impact on disease management is unclear. In this review we consider the environmental pathways associated with prolonged antigenic exposure and critically assess the significance of asymptomatic carriage in disease outbreaks Although screening high-risk groups for occupationally acquired diseases would be logistically problematical, there may be an economic case for identifying and treating asymptomatic carriage if the costs of screening and treatment are less than the costs of identifying and treating those individuals infected by asymptomatic hosts.

Routine typing of 14 469 isolates from human cryptosporidiosis cases between 2000 and 2008 revealed that 7439 (51·4%) were Cryptosporidium (C.) hominis, 6372 (44·0%) C. parvum, 51 (0·4%) both C. hominis and C. parvum, 443 (3·1%) were not typable and 164 (1·1%) were other Cryptosporidium species or genotypes. Of the latter, 109 were C. meleagridis, 38 C. felis, 11 C. ubiquitum, one C. canis, two horse, two novel and one skunk genotype. C. hominis monkey genotype and C. cuniculus were identified in a separate study. Patients with unusual infections were older than those with C. hominis (P<0·01) or C. parvum (P<0·01) and were more likely to be immunocompromised (Fisher's exact P<0·01). Forty-one percent of unusual cases had travelled abroad, mainly to the Indian subcontinent. Significant risk factors in those with unusual species were travel abroad (C. meleagridis, P<0·01), being immunocompromised (C. felis, Fisher's exact P=0·02), and contact with cats (C. felis, Fisher's exact P=0·02).

Within Europe, Ireland has one of the highest reported infection rates with the diarrhoeal protozoan pathogen Cryptosporidium. In this study 249 Cryptosporidium parvum isolates collected from Irish patients between 2000 and 2009 were subtyped by sequence analysis of the GP60 locus. A subsample of 127 isolates was also typed at the MS1 and ML1 loci. GP60 subtype IIaA18G3R1 was the predominant subtype in every year and every season throughout the country. Over the 10-year period there was no evidence that host immunity to the predominant subtype caused a shift in its prevalence. Length frequency distributions of the GP60 TCA/TCG repeats compiled from published data, showed distinct patterns for countries with predominantly zoonotic or anthroponotic transmission cycles, respectively. Although considered to be mostly affected by zoonotic cryptosporidiosis, the GP60 fragment length of Irish C. parvum isolates mirrored that of countries with predominantly human-to-human transmission, indicating more complex routes of infection between livestock and humans. Due to their homogeneity, ML1 and MS1 were not considered useful loci for subtyping C. parvum strains in Ireland.

Background: A randomised study to investigate whether bilateral arm abduction is superior to unilateral abduction with respect to stability using shifts on treatment as the main outcome measure.

Material and Methods: 50 consecutive female patients were randomised to ipsilateral or bilateral arm abduction. Central lung depth (CLD) and cranial caudal depth (CCD) on the simulator image was compared with that featured on three Electronic Portal Images (EPI) captured during treatment for each patient. Systematic and random errors were analysed with respect to the average translational displacement and standard deviation per patient and per population between the planning image and the EPI.

Results: The CLD average translational displacement in the test group was −1.7 mm (95% CI = −5 to 1.6 mm) Σ pop = 2.3 mm, σ pop = 1.6 mm, and in the control group −1.9 mm (95% CI = −6 to 3 mm) Σ pop = 4 mm, σ pop = 2.1 mm. The average translational displacement of CCD in test group was 0 mm (95% CI = − 5.3 to 5.1 mm) Σ pop = 2.2 mm, σ pop = 2.6 mm. CCD translational displacement was greater in the unilateral arm abduction group at − 1.6 mm (95% CI = −6.7 to 3.4 mm) Σ pop = 3.6 mm, σ pop = 2.4mm.

Conclusion: The reduction in systematic error and inter-patient variability observed in the test group is evidence that bilateral arm abduction is a more stable and reproducible position than unilateral arm abduction. The CCD translational data indicates that patients treated with unilateral arm abduction were moving inferiorly on the breast board. These results support the adoption of bilateral arm abduction as a standard technique.

In order to monitor epidemiological trends, Cryptosporidium-positive samples (n=4509) from diarrhoeic patients were typed. Compared to the previous 4 years, the proportion of Cryptosporidium hominis cases in 2004–2006 increased to 57·3%, while 38·5% were C. parvum. The remaining 4·2% cases included mixed C. parvum and C. hominis infections, C. meleagridis, C. felis, C. ubiquitum and a novel genotype. When the typing results were combined with enhanced surveillance data to monitor risk exposures, C. hominis was linked to urban dwelling, previous diarrhoea in the household, any travel especially abroad, and using a swimming or paddling pool. C. parvum was linked to having a private water supply, contact with surface water, visiting or living on a farm, and contact with farm animal faeces. The proportion of laboratory-confirmed indigenous cases acquired from direct contact with farm animals was estimated to be 25% for C. parvum and 10% of all reported Cryptosporidium cases.