Two-way Random Effects Research Articles

Factors impacting airline efficiency in southern Africa: a data envelopment analysis

The airline industry in southern Africa has a notoriously high failure rate. The purpose of this study is to identify factors impacting airline efficiency in southern Africa. An extensive data collection using primary and secondary sources enabled the researcher to gather data from ten airlines in southern Africa, for the period 2012–2016, on a variety of parameters. A two-stage empirical analysis was carried out, which involved estimation of operational efficiencies during the first stage using data envelopment analysis, and determination of factors impacting efficiency during the second stage using a two-way random effects GLS regression and also a Tobit model. The findings reveal that, ‘aircraft size’, ‘seat load factor (SLF)’, ‘LCC business model’ and ‘revenue hours per aircraft’, significantly impacted (p < 0.05) positively on technical and cost efficiency of airlines. However, ‘aircraft families’ and ‘ownership’ negatively impacted on airline efficiencies. Since the market in southern Africa is too small to operate with a smaller aircraft efficiently, for airlines that operate with smaller aircraft to optimise SLF they should first identify niche markets where they can have a route monopoly. The findings could improve airline performances in southern Africa, and improve the regions’ potential for tourism growth and regional sustainability.

The airline industry in South Africa: drivers of operational efficiency and impacts

PurposeThe airline industry is structurally challenged by its very nature, because of high overhead and capital costs. This is further exacerbated by macro-predictability and micro-uncertainty, thereby making it difficult for airlines in South Africa to attain operational efficiency. The purpose of this study is to identify drivers of operational efficiency and their impacts on airline performances in South Africa.Design/methodology/approachAn extensive data collection using primary and secondary sources enabled the researchers to gather data on all the airlines operating in South Africa, for the period of 2012-2016, on a variety of parameters. A two-stage empirical analysis was carried out, which involved estimation of operational efficiencies during the first stage by using data envelopment analysis (DEA) and determination of performance drivers during the second stage by using a two-way random-effects generalised least squares regression and also a Tobit model.FindingsFrom the study, it is clear that two structural drivers, namely, “aircraft size” and “seat load factor”, and two executional drivers, namely, “low cost business model” and “revenue hours per aircraft”, significantly impacted (p < 0.05) positively on airline efficiencies in South Africa. To improve efficiency, management should first concentrate on the drivers that can be changed in the short-term (executional drivers) and later focus on the drivers that require long-term planning (structural drivers). However, among the structural drivers, only “aircraft families” had a negative impact on airline efficiencies, whilst among executional drivers, only “block hours” negatively impacted on airline efficiencies.Research limitations/implicationsDespite the importance of this study, it is not free of limitations. Firstly, because of the small size of the industry, fewer airlines and lack of detailed data, the study could not consider other important factors such as optimal routing and network structure. Secondly, although non-aeronautical revenues have become increasingly important in airline management, they were not included in this study. Further studies may investigate the impact of these factors on airline efficiency.Practical implicationsThe results have potential policy implications. Firstly, as the domestic airline market in South Africa is too small to operate with a smaller aircraft efficiently, airlines that intend to make use of smaller aircraft should first identify niche markets where they can have a route monopoly, such as SA Airlink. Secondly, as block time negatively affected airline efficiency, airlines can undertake schedule adjustments to reduce block time and thus improve technical efficiency.Originality/valueThis paper is a first attempt to identify drivers of operational efficiency in the airline industry in South Africa. The results indicate that DEA is a useful tool to identify factors impacting airline efficiency and could improve airline performances in South Africa.

Monitoring Energy Balance in Breast Cancer Survivors Using a Mobile App: Reliability Study.

BackgroundThe majority of breast cancer survivors do not meet recommendations in terms of diet and physical activity. To address this problem, we developed a mobile health (mHealth) app for assessing and monitoring healthy lifestyles in breast cancer survivors, called the Energy Balance on Cancer (BENECA) mHealth system. The BENECA mHealth system is a novel and interactive mHealth app, which allows breast cancer survivors to engage themselves in their energy balance monitoring. BENECA was designed to facilitate adherence to healthy lifestyles in an easy and intuitive way.ObjectiveThe objective of the study was to assess the concurrent validity and test-retest reliability between the BENECA mHealth system and the gold standard assessment methods for diet and physical activity.MethodsA reliability study was conducted with 20 breast cancer survivors. In the study, tri-axial accelerometers (ActiGraphGT3X+) were used as gold standard for 8 consecutive days, in addition to 2, 24-hour dietary recalls, 4 dietary records, and sociodemographic questionnaires. Two-way random effect intraclass correlation coefficients, a linear regression-analysis, and a Passing-Bablok regression were calculated.ResultsThe reliability estimates were very high for all variables (alpha≥.90). The lowest reliability was found in fruit and vegetable intakes (alpha=.94). The reliability between the accelerometer and the dietary assessment instruments against the BENECA system was very high (intraclass correlation coefficient=.90). We found a mean match rate of 93.51% between instruments and a mean phantom rate of 3.35%. The Passing-Bablok regression analysis did not show considerable bias in fat percentage, portions of fruits and vegetables, or minutes of moderate to vigorous physical activity.ConclusionsThe BENECA mHealth app could be a new tool to measure energy balance in breast cancer survivors in a reliable and simple way. Our results support the use of this technology to not only to encourage changes in breast cancer survivors' lifestyles, but also to remotely monitor energy balance.Trial RegistrationClinicalTrials.gov NCT02817724; https://clinicaltrials.gov/ct2/show/NCT02817724 (Archived by WebCite at http://www.webcitation.org/6xVY1buCc)

Rating of perceived exertion is a stable and appropriate measure of workload in judo

ObjectivesHeart rate (HR), blood lactate concentration [La] and/or rating of perceived exertion (RPE) have been utilised to monitor judo training load in technical and randori (competition training) sessions, but are yet to be investigated in mixed sessions containing both elements. Therefore the purpose of this study was to: (1) determine the stability of these variables, and (2) to assess the efficacy of RPE as a load variable for mixed judo sessions. DesignCross-sectional study. MethodsTwenty-nine athletes attended two mixed training sessions at an international training camp. Bout and session characteristics, including RPE, physical and mental effort, heart rate (HR) and post-session [La] were recorded. A two-way random-effects intra-class correlation assessed variable stability. Multilevel mixed-effects ordered logistic regression investigated relationships between RPE and other variables for bouts and sessions. ResultsAverage and minimum HR across sessions correlated highly (ICC=0.95 and 0.94, respectively). Good correlations existed between [La], session-RPE and mental effort, and fair correlation of max HR and physical effort. No relationships existed between [La]/HR and session-RPE. A unit increase in bout-RPE resulted in a 2.09 unit increase in physical, or a 1.36 unit increase in mental, effort holding all other bout variables constant. Gender and competitive level did not influence statistical models. ConclusionsResults provide further evidence that RPE can be used across a range of competitive levels and genders to monitor workload of mixed sessions and individual randori in judo. Physical effort may play a larger role than mental effort when athletes reflect on exertion during training.

Detection accuracy of maxillary sinus floor septa in panoramic radiographs using CBCT as gold standard: a multi-observer receiver operating characteristic (ROC) study.

To investigate diagnostic accuracy of panoramic radiography in detecting maxillary sinus floor septa by means of a multi-observer receiver operating characteristic (ROC) analysis and a standardized protocol for reporting (STARD protocol; Clin Chem 49(1):1-6, 2003). From our database, 25 cone beam computed tomographies (CBCTs) were selected with one maxillary sinus floor septum (height ≥2.5 mm). For the same patient, a recent panoramic radiograph (PAN) had to be available in the database. As controls, 28 CBCTs plus corresponding PANs without evidence of a sinus septum were selected. Using the CBCTs as ground truth, 17 observers from our dental school on a five-point confidence scale rated both sinuses in all 53 PANs with respect to presence/absence of a sinus septum. Areas beneath ROC curves (Az-values), sensitivity/specificity (SNT/SPF), positive/negative predictive values (PPV, NPV), and positive/negative likelihood ratios (LR+, LR-) were computed for each observer and pooled over all observers. Inter-rater reproducibility was assessed by means of the intraclass coefficient (ICC) using a two-way random effects model. A pooled Az-value of 0.839 was observed (SNT 84.6%, SPF 73.5%). PPV ranged between 0.492 and 0.824 (median 0.627) and NPV between 0.838 and 0.976 (median 0.917). A median LR+ of 3.567 was computed (LR- median 0.193). Inter-rater reliability revealed an ICC of 0.55 (95% confidence interval 0.48 to 0.62). Our results indicate that PAN is a moderately accurate method for sinus elevation planning for the purpose of septum detection. Ruling out a septum by PAN seems to work more accurately than ruling in. For the purpose of maxillary sinus floor septa detection, panoramic radiography can be relatively safely advocated, particularly for judgment of a septum-free sinus.

Factors impacting restaurant efficiency: a data envelopment analysis

PurposeRestaurants are characterised by predictable, seasonal factors and unpredictable, individual customer demand, which make it difficult for restaurateurs to attain efficiency. A combination of these two factors, macro-predictability and micro-uncertainty, produces economic risks, which make it difficult for restaurants to attain operational efficiency. The purpose of this study is to identify factors impacting restaurant efficiency in South Africa.Design/methodology/approachBy using primary and secondary sources, data were collected from 16 different types of restaurants in South Africa, for the period 2012-2016, on a variety of parameters. A two-stage empirical analysis was carried out, which involved the estimation of operational efficiencies during the first stage by using data envelopment analysis (DEA) and determination of factors impacting restaurant performance in South Africa during the second stage by using two-way random-effects generalised least squares and Tobit regression models.FindingsThe results clearly show that the ability of restaurants to succeed will not be determined by their size but by their type, location and revenue per available seat. While the study finds various factors impacting on operational efficiency, the survival of restaurants in South Africa seem to be determined by cost efficiency, which brings in better market performance through lowering cost of sales.Practical implicationsThe results have implications for restaurant managers in that if they want to improve cost efficiency, they must manage restaurant capacity and customer demand in a way that maximises revenue. To stimulate demand during periods of low demand, management could consider strategies that attract more customers or encourage upselling, whereas during periods of high demand, management may consider raising prices or reducing meal durations. The results indicate that DEA is a useful tool to identify factors impacting restaurant efficiency and could enhance the service data and revenue management with regards to restaurant efficiency in South Africa.Originality/valueTo the best of the author’s knowledge, this paper is the first that attempts to identify factors impacting restaurant efficiency in South Africa by using DEA. The findings could enhance the service data and revenue management with regards to restaurant efficiency in South Africa.

Validation of a Novel Scoring System for Changes in Skeletal Manifestations of Hypophosphatasia in Newborns, Infants, and Children: The Radiographic Global Impression of Change Scale.

Hypophosphatasia (HPP) is the heritable metabolic disease characterized by impaired skeletal mineralization due to low activity of the tissue-nonspecific isoenzyme of alkaline phosphatase. Although HPP during growth often manifests with distinctive radiographic skeletal features, no validated method was available to quantify them, including changes over time. We created the Radiographic Global Impression of Change (RGI-C) scale to assess changes in the skeletal burden of pediatric HPP. Site-specific pairs of radiographs of newborns, infants, and children with HPP from three clinical studies of asfotase alfa, an enzyme replacement therapy for HPP, were obtained at baseline and during treatment. Each pair was scored by three pediatric radiologists ("raters"), with nine raters across the three studies. Intrarater and interrater agreement was determined by weighted Kappa coefficients. Interrater reliability was assessed using intraclass correlation coefficients (ICCs) and by two-way random effects analysis of variance (ANOVA) and a mixed-model repeated measures ANOVA. Pearson correlation coefficients evaluated relationships of the RGI-C to the Rickets Severity Scale (RSS), Pediatric Outcomes Data Collection Instrument Global Function Parent Normative Score, Childhood Health Assessment Questionnaire Disability Index, 6-Minute Walk Test percent predicted, and Z-score for height in patients aged 6 to 12 years at baseline. Eighty-nine percent (8/9) of raters showed substantial or almost perfect intrarater agreement of sequential RGI-C scores (weighted Kappa coefficients, 0.72 to 0.93) and moderate or substantial interrater agreement (weighted Kappa coefficients, 0.53 to 0.71) in patients aged 0 to 12 years at baseline. Moderate-to-good interrater reliability was observed (ICC, 0.57 to 0.65). RGI-C scores were significantly (p ≤ 0.0065) correlated with the RSS and with measures of global function, disability, endurance, and growth in the patients aged 6 to 12 years at baseline. Thus, the RGI-C is valid and reliable for detecting clinically important changes in skeletal manifestations of severe HPP in newborns, infants, and children, including during asfotase alfa treatment. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Trade concentration and dynamics of the Norwegian imports: an application of R-MANOVA model

This article proposes to analyse trade concentration and dynamics of the Norwegian import's expenditures by applying the two-way random effect MANOVA (R-MANOVA) model. The MANOVA model factors considered in this econometric analysis are origin continents or countries (spatial effects) and the business cycles (dynamic effects). The R-MANOVA model fit estimation results confirms that the Norwegian import trade is sustainable in both short and long run controlling for the effect of both origin continent and business cycles. More importantly, the expenditure and the share of Norwegian imports across the continents show considerable dynamics. The overall econometric estimation results suggest that across all continents the Norwegian import expenditure is increasing with time. However, the share of the Norwegian import expenditures across continents is relatively stable. The analysis confirms that European exporters will be the leading partners for Norwegian import expenditures in future trade patterns. The ranking of the remaining continents in descending order will be Asia and Oceania, North and Central America, South America and Africa.

Monitoring training load- The journey of an Elite Judoka

Heart rate (HR), blood lactate concentration [La] and/or rating of perceived exertion (RPE) have been utilised to monitor judo training load in technical and randori (competition training) sessions, but are yet to be investigated in mixed sessions containing both elements. Therefore the purpose of this study was to: (1) determine the stability of these variables, and (2) to assess the efficacy of RPE as a load variable for mixed judo sessions.Cross-sectional study.Twenty-nine athletes attended two mixed training sessions at an international training camp. Bout and session characteristics, including RPE, physical and mental effort, heart rate (HR) and post-session [La] were recorded. A two-way random-effects intra-class correlation assessed variable stability. Multilevel mixed-effects ordered logistic regression investigated relationships between RPE and other variables for bouts and sessions.Average and minimum HR across sessions correlated highly (ICC = 0.95 and 0.94, respectively). Good correlations existed between [La], session-RPE and mental effort, and fair correlation of max HR and physical effort. No relationships existed between [La]/HR and session-RPE. A unit increase in bout-RPE resulted in a 2.09 unit increase in physical, or a 1.36 unit increase in mental, effort holding all other bout variables constant. Gender and competitive level did not influence statistical models.Results provide further evidence that RPE can be used across a range of competitive levels and genders to monitor workload of mixed sessions and individual randori in judo. Physical effort may play a larger role than mental effort when athletes reflect on exertion during training.

Ergonomics Calibration Training Utilizing Photography for Dental Hygiene Faculty Members.

Dental and dental hygiene clinical faculty members often do not provide consistent instruction, especially since most procedures involve clinical judgment. Although instructional variations frequently translate into variations in student performance, the effect of inconsistent instruction is unknown, especially related to ergonomics. The aim of this study was to determine whether photography-assisted calibration training would improve interrater reliability among dental hygiene faculty members in ergonomics evaluation. The photography-assisted ergonomics calibration program incorporated features to improve accessibility and optimize the quality of the training. The study used a two-group repeated measures design with a convenience sample of 11 dental hygiene faculty members (eight full-time and three part-time) during the autumn 2016 term at one U.S. dental school. At weeks one and seven, all participants evaluated imaged postures of five dental students using a modified-dental operator posture assessment instrument. During weeks three and five, training group participants completed calibration training using independent and group review of imaged postures. All pre-training and post-training evaluations were evaluated for interrater reliability. Two-way random effects intraclass coefficient (ICC) values were calculated to measure the effects of the training on interrater reliability. The average measure of ICC of the training group improved from 0.694 with a 95% confidence interval (CI) of 0.001 to 0.965 (F(4,8)=3.465, p>0.05) to 0.766 with a 95% CI of 0.098 to 0.972 (F(4,8)=7.913, p<0.01). The average measure of ICC of the control group improved from 0.821 with a 95% CI of 0.480 to 0.978 (F(4,28)=7.702, p<0.01) to 0.846 with a 95% CI of 0.542 to 0.981 (F(4,28)=8.561, p<0.01). These results showed that the photography-assisted calibration training with the opportunity to reconcile different opinions resulted in improved agreement among these faculty members.

Inter-rater reliability of a reflective rubric to assess pharmacy students’ reflective thinking

IntroductionMany health education programs aspire to foster reflective practices to enhance the reflective thinking of students during their study years and throughout their professional careers. Given the increasing attention paid to incorporating reflective practice activities into health education and evidence attributed to rater variability, it is important for educators to carefully consider the assessment criteria and reliability of assessment tools. A reflective rubric was developed to assess pharmacy students’ levels of reflection from a reflective writing task. This study investigates the inter-rater reliability (IRR) of a rubric as a tool to assess the levels of reflective thinking apparent in students’ written statements. MethodsThe research involved four raters from different disciplines utilizing a rubric to assess a random sample of the same forty-three reflective statements from a cohort of two hundred and sixty-four students. The IRR was measured using the intra-class correlation coefficient (ICC), using a two-way random effects model (ANOVA) with absolute agreement, to determine reliability of the assessment tool among the raters. ResultsResults showed measures between the raters for (i) overall reflective statement scores, and (ii) average scores for stages of reflection with an “almost perfect” agreement, ICC = 0.81 (95% CI 0.61–0.90), (F(42, 126) = 7.83, p < 0.01); and ICC = 0.89 (95% CI 0.83–0.93), (F(42, 840) = 12.49, p < 0.01) respectively. Discussion and conclusionsThe proposed rubric utilized by four raters showed high agreement with each other's scores, and is a tool for academic assessment of pharmacy students’ reflective thinking processes.

Smallest detectable change and test-retest reliability of a self-reported outcome measure: Results of the Center for Epidemiologic Studies Depression Scale, General Self-Efficacy Scale, and 12-item General Health Questionnaire.

This study aims to examine the smallest detectable change (SDC) and test-retest reliability of the Center for Epidemiologic Studies Depression Scale (CES-D), General Self-Efficacy Scale (GSES), and 12-item General Health Questionnaire (GHQ-12). We tested 154 young adults at baseline and 2weeks later. We calculated the intra-class correlation coefficients (ICCs) for test-retest reliability with a two-way random effects model for agreement. We then calculated the standard error of measurement (SEM) for agreement using the ICC formula. The SEM for agreement was used to calculate SDC values at the individual level (SDCind ) and group level (SDCgroup ). The study participants included 137 young adults. The ICCs for all self-reported outcome measurement scales exceeded 0.70. The SEM of CES-D was 3.64, leading to an SDCind of 10.10 points and SDCgroup of 0.86 points. The SEM of GSES was 1.56, leading to an SDCind of 4.33 points and SDCgroup of 0.37 points. The SEM of GHQ-12 with bimodal scoring was 1.47, leading to an SDCind of 4.06 points and SDCgroup of 0.35 points. The SEM of GHQ-12 with Likert scoring was 2.44, leading to an SDCind of 6.76 points and SDCgroup of 0.58 points. To confirm that the change was not a result of measurement error, a score of self-reported outcome measurement scales would need to change by an amount greater than these SDC values. This has important implications for clinicians and epidemiologists when assessing outcomes.

The Parkland grading scale for cholecystitis

BackgroundGallbladders (GBs) with severe inflammation have longer operative times and an increased risk for complications. We propose a grading system using intraoperative images to better stratify GB inflammation. MethodsAfter reviewing the intraoperative images of GBs obtained during several hundred laparoscopic cholecystectomies, we developed a five-tiered grading system based on anatomy and inflammatory changes. Fifty intraoperative photographs were taken prior to dissection and then distributed to 11 surgeons who rated each GB's severity per the grading system. The two-way random effects Intraclass Correlation Coefficient (ICC) was used to assess the reliability among the raters. ResultsThe ICC among the raters of GB severity was 0.804 (95% CI: 0.733 to 0.867; p = 0.0001). Nineteen GB images had greater than 82% agreement and 16 were clustered around GBs with severe inflammation (grades 3–5). ConclusionThis study proposes a simple, reliable grading system that characterizes GB complexity based on inflammation and anatomy.

The Unsupported Upper Limb Exercise Test in People Without Disabilities: Assessing the Within-Day Test-Retest Reliability and the Effects of Age and Gender.

Purpose: To estimate the within-day test-retest reliability and standard error of measurement (SEM) of the unsupported upper limb exercise test (UULEX) in adults without disabilities and to determine the effects of age and gender on performance of the UULEX. Method: A cross-sectional study was conducted with 100 adults without disabilities (44 men, mean age 44.2 [SD 26] y; 56 women, mean age 38.1 [SD 24.1] y). Participants performed three UULEX tests to establish within-day reliability, measured using an intra-class correlation coefficient (ICC) model 2 (two-way random effects) with a single rater (ICC[2,1]) and SEM. The effects of age and gender were examined using two-factor mixed-design analysis of variance (ANOVA) and one-way repeated-measures ANOVA. For analysis purposes, four sub-groups were created: younger adults, older adults, men, and women. Results: Excellent within-day reliability and a small SEM were found in the four sub-groups (younger adults: ICC[2,1]=0.88; 95% CI: 0.82, 0.92; SEM∼40 s; older adults: ICC[2,1]=0.82; 95% CI: 0.72, 0.90; SEM∼50 s; men: ICC[2,1]=0.93; 95% CI: 0.88, 0.96; SEM∼30 s; women: ICC[2,1]=0.85; 95% CI: 0.78, 0.91; SEM∼45 s). Younger adults took, on average, 308.24 seconds longer than older adults to perform the test; older adults performed significantly better on the third test (p<0.0001; η2=0.096). Gender effects were not found (p>0.05). Conclusion: The within-day test-retest reliability and SEM values of the UULEX may be used to define the magnitude of the error obtained with repeated measures. One UULEX test seems to be adequate for younger adults to achieve reliable results, whereas three tests seem to be needed for older adults.

Workplace Sedentary Behavior Questionnaire

Self-report remains an important measurement method for physical activity and sedentary behaviors because it provides the contextual information needed in targeted behavioral interventions. PURPOSE: This study aimed to evaluate the validity and responsiveness to change of a workplace sedentary behavior questionnaire (SBQ) in assessing total sedentary behavior (1) at work and (2) outside of work during workdays, and during (3) non-workdays. METHODS: Participants (N= 359) were recruited from 16 worksites in the greater Minneapolis and Phoenix regions. Participants wore an activPAL3c accelerometer for 7 days at two timepoints (baseline and 12-week follow-up). They also completed a sedentary behavior questionnaire on the 7th day of each assessment timepoint. Time spent in each behavior from both measures was standardized to a 16-hour day on non-work days and 8-hours to both work hours and non-work hours on work days. The agreement between the two measures was assessed through single-measure with absolute definition ICC using a two-way random effects model. Bias estimates (mean difference [] and root of mean square error [RMSE= were used to compare reported behaviors to the activPAL values. Responsiveness to change following the intervention was assessed using the responsiveness statistic (RS). RESULTS: There was poor agreement between the SBQ and activPAL (ICC from 0.06 - 0.29) across all time periods. On average, participants over-reported their time spent sitting (Mean [95% CI]= 39.9 [31.1, 48.7] min/day, RMSE= 112.5) and moving (12.9 [9.39, 16.5] min/day, RMSE= 44.3), but under-reported standing (-52.9 [-60.5, -45.2) min/day, RMSE= 105.5) at work. Moreover, sitting time during their non-work hours was over-reported (51.7 [34.5, 68.8] min/day, RMSE= 211.8). Sitting on non-work days was underestimated (-87.2 [-111.6, -62.7] min/day, RMSE= 298.8). SBQ was similarly responsive to change compared to the activPAL except for sedentary time during non-work days (0.13 and 0.49 for SBQ and AP, respectively). CONCLUSION: Despite the poor absolute agreement between the SBQ and activPAL, overall bias estimates and responsiveness during work days were acceptable. Further studies are needed to explore ways to improve accuracy in sedentary behavior reporting during non-working days.

Test-Retest Reliability of the King-Devick Test in an Adolescent Population.

The King-Devick (KD) test is a screening tool designed to assess cognitive visual impairments, namely saccadic rhythm, postconcussion. Test-retest reliability of the KD in a healthy adolescent population has not yet been established. To investigate the overall test-retest reliability of the KD among a sample of healthy adolescents. Additionally, we sought to determine if sex and age influenced reliability. Cross-sectional study. Secondary school. Sixty-eight healthy adolescents, 41 boys (age = 15.4 ± 1.9 years) and 27 girls (age = 15.4 ± 1.9 years). Participants completed the KD (version 1) at 3 testing sessions (days 1, 30, and 45) following standard instructions. We recorded total time to complete the reading of 3 cards for each participant during each testing session. Two-way random-effects intraclass correlation coefficients (ICCs) using single measurements repeated over time and repeatability coefficients were calculated. Linear mixed models were used to determine whether differences existed at each testing time and to examine whether changes that took place among visits were different by sex or age. Adolescents who completed the KD demonstrated acceptable reliability (ICC = 0.81; 95% confidence interval = 0.73, 0.87); however, the repeatability coefficient was large (±8.76 seconds). The sample demonstrated improvements between visits 1 and 2 (mean ± standard error = 4.3 ± 0.5 seconds, P < .001) and between visits 2 and 3 (2.4 ± 0.5 seconds, P < .001) for a total improvement of 6.9 seconds over 3 tests. No significant visit-by-sex or visit-by-age interactions were observed. Despite the ICC being clinically acceptable, providers using the KD test for serial assessment of concussion in adolescents should be cautious in interpreting the results due to a large learning effect. Incorporating multiple measures can ensure accurate detection of sport concussion.

Food Waste: The Role of Date Labels, Package Size, and Product Category

The presence of food waste, and ways to it, has generated significant debate among industry stakeholders, policy makers, and consumer groups around the world. Many have argued that the variety of date labels used by food manufacturers leads to confusion about food quality and food safety among consumers. Here, we develop a between-subject, laboratory experiment with different date label treatments (Best by, Fresh by, Sell by, and Use by) for products (ready-to-eat cereal, salad greens, and yogurt) of different sizes and dates. Our results show that, holding other observed factors constant, date labels influence the value of premeditated food waste of subjects, or willingness to waste (WTW). On average, the WTW is non-zero across all date labels. Ambiguity avoidance may prompt differential WTW. The WTW is greatest in the Use by treatment, the date label which may be the least ambiguous and suggestive of food safety. The WTW is the lowest for the Sell by treatment, which may be the most ambiguous date label about safety or quality for the consumer. Two-way ANOVA and random effects regression model results provide evidence that subjects respond differentially to date labels, product, date, and size. The WTW for cereal is most responsive to Fresh by, which is related to ideas of quality, but for salad and yogurt, the WTW is more responsive to Use by, which is more indicative of safety. Despite the limited information provided by the labels, date labels on average influence WTW, which may be indicative of future, actualized waste.

Validity and reliability of ankle morphological measurements on computerized tomography-synthesized planar radiographs.

BackgroundClinical success of total ankle arthroplasty depends heavily on the available information on the morphology of the bones, often obtained from measurements on planar radiographs. The current study aimed to evaluate the intra-rater, inter-rater and inter-session reliability and the validity of radiograph-based measurements of ankle morphology, and to quantify the effects of examiner experience on these measurements.MethodsTwenty-four fresh frozen ankle specimens were CT scanned, data of which were used to reconstruct 3D volumetric bone models for synthesizing 2D radiographs. Two orthopaedic surgeons with different levels of clinical experience identified twenty landmarks five times on each of the synthesized sagittal and coronal radiographs and repeated the test on a subsequent day within 5 days. The landmarks were used to calculate fourteen morphological parameters. The two-way mixed-effects (ICC3,1), two-way random-effects (ICC2,k) and two-way random-effects (ICC3,k) models were used, respectively, to assess the intra-rater, inter-rater and inter-session reliability of measurements. The validity of the measurements for each examiner was assessed by comparing them with gold standard values obtained from the 2D radiographs projected from the 3D volumetric models using Pearson’s correlation analysis and Bland and Altman plots, and the differences were defined as the measurement errors.ResultsMost of the morphological parameters were of good to very good intra-rater, inter-session and inter-rater reliability for both examiners (ICC > 0.61). Experience appeared to affect the inter-rater and inter-session reliability, the senior examiner showing greater inter-session ICC values than the junior examiner. Most of the tibial parameters had moderate to excellent correlations with the corresponding gold standard values but were underestimated by both examiners, in contrast to most of the talar parameters that were overestimated and had only poor to fair correlations.ConclusionsMost of the morphological parameters of the ankle can be estimated from radiographs with good to very good intra-rater, inter-session and inter-rater reliability, for both clinically experienced and less experienced examiners. Clinical experience helped increase the reliability of repeated evaluations after a longer interval, such as in a follow-up assessment. It is suggested that critical clinical decisions based on repeated morphology measurements should be made by more experienced surgeons or after appropriate training.

Initial assessment of reliability of a self-administered web-based neuropsychological test battery

IntroductionWeb-based neuropsychological testing can be an important tool in meeting the increasing demands for neuropsychological assessment in the clinic and in large research studies. The primary aim of this study was to investigate practice effects and reliability of self-administered web-based neuropsychological tests in Memoro. Due to lack of consistent analysis and reporting of reliability in the literature, especially intraclass correlation coefficients (ICC), we highlight how using different ICC measures results in different estimates of reliability. Method61 (31 females) participants (mean age 53.3 years) completed the Memoro tests twice with a median of 14 days between testing. ResultsPractice effects were detected for all cognitive measures (d = 0.32–0.61), most pronounced for memory measures. Reliability estimated using two-way random effects single measure absolute agreement ICC(2,1) were between 0.55 and 0.74. Two-way mixed effects average measure consistency ICC(3,2), ranged from 0.79 to 0.89. Reliability was highest for the processing speed task and lower for the memory tasks. ConclusionsMemoro tests had test-retest reliability similar to that of traditional, computerized and web-based test batteries used clinically and in research. It is important to carefully choose and specify the ICC implemented, as ICC(2,1) and ICC(3,2) give different results and reflect reliability of different measures.

Drivers of operational efficiency and its impact on market performance in the Indian Airline industry

India is considered to be one of the toughest aviation markets in the world, due to high fuel prices, overcapacity and intense price competition. It is therefore important to identify critical drivers of performance, which enable the airlines to survive and succeed in this emerging market with huge growth potential. In the current empirical study, we investigate the linkages between various performance drivers, operational efficiencies and market performance. An extensive data collection using primary and secondary sources enabled us to gather data on all the airlines operating in India, both private and public, for the period 2005–2012, on a variety of important parameters. We carried out a two-stage empirical analysis, which involved estimation of operational efficiencies during the first stage using Data Envelopment Analysis, and determination of performance drivers during the second stage using a two-way random effects GLS regression and also a Tobit model. Our findings suggest that while some of the structural and regulatory factors have an undesirable impact on airline performance, the low cost carriers in India have managed to achieve significant operational efficiencies. In addition, we find that, while cost efficiency is driven by a variety of factors, it is the technical efficiency which brings in better market performance through pricing power in the Indian airline industry.