Two-tailed Test Of Significance Research Articles

Two-tailed significance tests for 2 × 2 contingency tables: What is the alternative?

Two-tailed significance testing for 2 × 2 contingency tables has remained controversial. Within the medical literature, different tests are used in different papers and that choice may decide whether findings are adjudged to be significant or nonsignificant; a state of affairs that is clearly undesirable. In this paper, it is argued that a part of the controversy is due to a failure to recognise that there are two possible alternative hypotheses to the Null. It is further argued that, while one alternative hypothesis can lead to tests with greater power, the other choice is more applicable in medical research. That leads to the recommendation that, within medical research, 2 × 2 tables should be tested using double the one-tailed exact probability from Fisher's exact test or, as an approximation, the chi-squared test with Yates' correction for continuity.

The efficacy of stress reappraisal interventions on stress responsivity: A meta-analysis and systematic review of existing evidence.

BackgroundThe beliefs we hold about stress play an important role in coping with stressors. Various theoretical frameworks of stress point to the efficacy of reframing stress-related information through brief reappraisal interventions in order to promote adaptive coping.PurposeThe goal of the current meta-analysis and systematic review is to substantiate the efficacy of reappraisal interventions on stress responsivity compared to control conditions. Differences in experimental methodologies (e.g., type of stressor used, timing of reappraisal intervention, and content of intervention instructions) will be examined to further delineate their effects on intervention outcomes.MethodsThe literature searches were conducted on May 16, 2018 using PsycINFO, ProQuest Dissertations and Theses, and PILOTS databases with no date restriction. The search terms included stress, reframing, reappraisal, mindset and reconceptualising. A total of 14 articles with 36 independent samples were included in the meta-analysis, while 22 articles with 46 independent samples were included in the systematic review. Random-effects model was used to test the null hypothesis using two-tailed significance testing. Fisher’s Z value was reported for each corresponding test. Heterogeneity tests are reported via Cochran’s Q-statistics.ResultsFindings from both the meta-analysis and systematic review revealed that overall, reappraisal interventions are effective in attenuating subjective responsivity to stress. Standard differences in means across groups are 0.429 (SE = 0.185, 95% CI = 0.067 to 0.791; z = 2.320, p = .020). However, reappraisal intervention groups did not outperform control groups on measures of physiological stress, with standard differences of -0.084 (SE = 0.135, 95% CI = -0.349 to 0.180; z = -0.627, p = .531). Moderator analysis revealed heterogeneous effects suggesting large variability in findings.ConclusionsOn one hand, findings may suggest a promising avenue for the effective management of self-reported stress and optimization of stress responses. However, more research is needed to better elucidate the effects, if any, of reappraisal interventions on stress physiology. Implications for the use of reappraisal interventions on stress optimization are discussed in the context of theoretical frameworks and considerations for future studies.

IMPACT OF BMI AND FOOT ARCH HEIGHT ON PHYSICAL PERFORMANCES

Aims: The study aimed to determine the association between BMI, foot arch height and physical performances and also to ascertain the impact of BMI and foot arch height on physical performances. Methodology: This was a cross-sectional study conducted on 118 university students (59 males and 59 females) between the age group of 18 to 25 years by using convenience sampling method. Measurements of BMI and Normalized navicular height truncated (NNHt) for foot arch height (FAH) was taken for all subjects. Physical performance tests of 50-m sprint and vertical jump height (VJH) were performed with their comfortable sports shoes. Relations between all variables were analyzed by Pearson correlation coefficient test and multiple regression analysis. A 2-tailed test of significance of < 0.05 was considered statistically significant. Results: A two-tailed test of significance indicated that BMI was unrelated to 50-m sprint, rs (118) = -0.08, p > 0.05 and VJH, rs (118) = 0.072, p > 0.05. A two-tailed test of significance indicated that FAH was unrelated to 50-m sprint, rs (118) = -0.07, p > 0.05. But there was a weak or negligible negative relationship between FAH and VJH, rs (118) = -0.21, p < 0.05. The results of multiple linear regression analysis showed that BMI was not a significant predictor for both 50-m sprint and VJH physical performances. FAH was a significant predictor for VJH but not for the 50-m sprint. Conclusion: BMI is not related to 50-m sprint and VJH. FAH is not related to the 50-m sprint but there is a weak relationship between FAH and VJH. FAH was a significant predictor for VJH.

Performance of Social Enterprises in the Czech Republic

The paper investigates how Czech social economy has currently been performing. In the text, the authors mainly focus on an analysis of various financial indicators of social enterprises in the Czech Republic as well as on different relations between these indicators. The performed analysis comprises descriptive statistics, correlation matrix using Pearson correlation with a two-tailed test of significance for dependent and independent variables, and multiple regressions for significantly dependent variables. The main outcome of the research reveals that a high variance is present between the given SEs in productivity and debt-to-equity ratio.

A Simulation-based Approach to Measuring Team Situational Awareness in Emergency Medicine: A Multicenter, Observational Study.

Team situational awareness (TSA) is critical for effective teamwork and supports dynamic decision making in unpredictable, time-pressured situations. Simulation provides a platform for developing and assessing TSA, but these efforts are limited by suboptimal measurement approaches. The objective of this study was to develop and evaluate a novel approach to TSA measurement in interprofessional emergency medicine (EM) teams. We performed a multicenter, prospective, simulation-based observational study to evaluate an approach to TSA measurement. Interprofessional emergency medical teams, consisting of EM resident physicians, nurses, and medical students, were recruited from the University of Washington (Seattle, WA) and Wayne State University (Detroit, MI). Each team completed a simulated emergency resuscitation scenario. Immediately following the simulation, team members completed a TSA measure, a team perception of shared understanding measure, and a team leader effectiveness measure. Subject matter expert reviews and pilot testing of the TSA measure provided evidence of content and response process validity. Simulations were recorded and independently coded for team performance using a previously validated measure. The relationships between the TSA measure and other variables (team clinical performance, team perception of shared understanding, team leader effectiveness, and team experience) were explored. The TSA agreement metric was indexed by averaging the pairwise agreement for each dyad on a team and then averaging across dyads to yield agreement at the team level. For the team perception of shared understanding and team leadership effectiveness measures, individual team member scores were aggregated within a team to create a single team score. We computed descriptive statistics for all outcomes. We calculated Pearson's product-moment correlations to determine bivariate correlations between outcome variables with two-tailed significance testing (p < 0.05). A total of 123 participants were recruited and formed three-person teams (n = 41 teams). All teams completed the assessment scenario and postsimulation measures. TSA agreement ranged from 0.19 to 0.9 and had a mean (±SD) of 0.61 (±0.17). TSA correlated with team clinical performance (p < 0.05) but did not correlate with team perception of shared understanding, team leader effectiveness, or team experience. Team situational awareness supports adaptive teams and is critical for high reliability organizations such as healthcare systems. Simulation can provide a platform for research aimed at understanding and measuring TSA. This study provides a feasible method for simulation-based assessment of TSA in interdisciplinary teams that addresses prior measure limitations and is appropriate for use in highly dynamic, uncertain situations commonly encountered in emergency department systems. Future research is needed to understand the development of and interactions between individual-, team-, and system (distributed)-level cognitive processes.

A Moderated Mediation Model of HIV-Related Stigma, Depression, and Social Support on Health-Related Quality of Life among Incarcerated Malaysian Men with HIV and Opioid Dependence.

Although it is well established that HIV-related stigma, depression, and lack of social support are negatively associated with health-related quality of life (HRQoL) among people living with HIV (PLH), no studies to date have examined how these psychosocial factors interact with each other and affect HRQoL among incarcerated PLH. We, therefore, incorporated a moderated mediation model (MMM) to explore whether depression mediates the effect of HIV-related stigma on HRQoL as a function of the underlying level of social support. Incarcerated HIV-infected men with opioid dependence (N=301) were recruited from the HIV units in Kajang prison in Malaysia. Participants completed surveys assessing demographic characteristics, HIV-related stigma, depression, social support, and HRQoL. Results showed that the effect of HIV-related stigma on HRQoL was mediated via depression (a1:β=0.1463, p<0.001; b1:β=-0.8392, p<0.001), as demonstrated by the two-tailed significance test (Sobel z=-3.8762, p<0.001). Furthermore, the association between social support and HRQoL was positive (β=0.4352, p=0.0433), whereas the interaction between HIV-related stigma and depression was negatively associated with HRQOL (β=-0.0317, p=0.0133). This indicated that the predicted influence of HIV-related stigma on HRQoL via depression had negative effect on HRQoL for individuals with low social support. The results suggest that social support can buffer the negative impact of depression on HRQoL and highlights the need for future interventions to target these psychosocial factors in order to improve HRQoL among incarcerated PLH.

Stock price fluctuations in periods of corporate acquisition and control: A new outlook for the board of directors

This paper rummages the stock price fluctuations in periods of corporate acquisition and control. The paper became pertinent to provide information to the corporate board of directors and investors to improve decision making by understanding the inherent fluctuations and the concomitant uncertainties during periods of corporate acquisitions and control negotiations. The main aim of the paper is to examine if there is a significant difference in stock price fluctuation before and during periods of corporate acquisition. The methodological approach is quantitative and used the statistical T-test of difference in mean stock price differences before and during periods of SABMiller acquisition. It also applied the cointegration analysis to establish a correlation in stock price between the acquiring company and the company under acquisition. The analysis was tested at an alpha of 0.05 and results from the statistical analysis disclosed a significant difference to the degree of P&lt;0.001 on two-tailed significance test and showed that stock price fluctuation was higher during the acquisition period than before. Similarly, the cointegration test showed a significant correlation in stock price movement between the purchasing company and the company under acquisition at a P&lt;0.001. The Granger causality test was applied to determine the direction of causality, and the analysis showed that the AB Inbev stock price trend influenced the stock price movement in SABMiller during the period of acquisition with a P=0.008. The paper concludes that at least within the case examination, the news of corporate acquisition may trigger investment uncertainties, which may reverberate on stock price fluctuations. The paper brings insight to the corporate board of directors toward improved negotiation of acquisition or merger prices and compensations given the price fluctuations that acquisition news may trigger on the merging companies’ stocks.

Intracerebral hypoglycemia and its clinical relevance as a prognostic indicator in severe traumatic brain injury: A cerebral microdialysis study from India.

Traumatic brain injury (TBI) remains a major cause of morbidity and mortality worldwide. Largely, the prognosis is dependent on the nonmodifiable factors such as severity of the initial injury, Glasgow coma scale score, pupillary response, age, and presence of additional physiological derangements such as hypoxia or hypotension. However, secondary insults continue to take place after the initial injury and resuscitation. The study hypothesis in the present research article was that hypoglycemia is an independent outcome prognosticator in severe traumatic brain injury. The study aimed to assess the role of glucose monitoring in the brain parenchyma as an independent outcome prognosticator and also to study its association with plasma glucose levels. The aim of the study was to analyze the relationship of intracerebral glucose measured by intraparenchymal cerebral microdialysis (CMD), and also to study its relationship with blood glucose levels. We also evaluated the relationship of these values to the outcome of patients. Prospective nonrandomized study conducted at a tertiary care trauma center in India. Twenty-five patients with severe TBI, who underwent decompressive craniectomy, were prospectively monitored with CMD catheters. Twenty cases had unilateral catheters placed intraparenchymally (20 mm inside the brain parenchyma to accommodate 10 mm of the semipermeable catheter tip and another 10 mm of extra catheter length). Frontotemporal contusions were noted in 21 cases and an acute subdural hematoma (with/without associated contusions) were noted in 15 cases in the present series. Bilateral CMD catheters were placed during bifrontal decompressive craniectomies in five patients (two patients had peri-contusional catheters placement; these patients had bilateral frontal contusions); while, the remaining 3 patients had a contralateral catheter placement in the normal brain parenchyma [Table 1]. The position of the catheters was confirmed on postoperative computerized tomographic scan carried out in these subjects. However, bilateral catheter placement to compare the difference in cerebral biochemical values of glucose in the penumbric zone as well as the normal brain could not be done in all cases due to cost restraints. The relation between plasma glucose and CMD-measured interstitial brain glucose concentrations, as well as the temporal pattern of CMD glucose was studied for 3-5 days following a decompressive craniectomy using a CMD analyzer at the patient's bedside at 1 hourly intervals. All data were tabulated in Microsoft Excel 2011 and analyzed using SPSS version 21. To calculate the correlation between plasma and CMD glucose, Pearson's correlation was used with a two-tailed test of significance. Student's t-test was used to calculate the difference in means between the two groups. Significance was assumed at P ≤ 0.05. Fifteen patients (60%) had a good outcome in terms of the Glasgow Outcome Scale (GOS) at 3 months while the rest (10 patients) had a poor GOS at 3 months. There was a significant difference in the incidence of hyperglycemia (random blood sugar >10 mmol/L) between the two groups (P < 0.0001). The difference between the two groups while comparing episodes of hypoglycemia was also significant (P = 0.0026). The good outcome group had fewer episodes of brain hypoglycemia during the presence of systemic hypoglycemia (P = 0.0026). Neither the mean blood glucose values nor the mean cerebral glucose values predicted the outcome at 3 months. After decompressive craniectomy in severe TBI, there was a poor correlation between the plasma and CMD glucose concentration. A higher degree of variation was seen in the correlations for individual patients. Neither the mean blood glucose values nor the mean cerebral glucose values predicted the outcome at 3 months. The good outcome group had fewer episodes of both hyperglycemia and hypoglycemia.

Is frictional lichenoid dermatitis a minor variant of atopic dermatitis or a photodermatosis.

Context:Frictional lichenoid dermatitis.Background:Frictional lichenoid dermatitis (FLE) is an entity that is probably under diagnosed and has been variably associated with either friction and/or atopy with a distinctive seasonal variation.Aims and Objectives:To study correlation of FLE with UV index and to assess its association with atopic dermatitis.Materials and Methods:A cross sectional analysis of children with FLE was done, over a period of 6 years in two tertiary hospitals. A detailed history and examination was done to assess the features of atopic dermatitis. The number of cases seen per month was compared with the mean monthly UV index. Two-tailed significance tests using Pearson's coefficient of correlation and T-test were used to interpret the data. (P < 0.05).Results:One hundred seventy-four patients were studied using the UKC criterion 17.2% of the patients had AD while xerosis (40.3%) was the predominant cutaneous finding. The number of patients seen in summer was more than in winter (P < 0.05) but there was no statistical difference between the cases in winter and spring. There was a significant correlation of the number of cases per month with UV index (P = 0.019). Almost 42% of patients gave a history of recurrence.Conclusions:FLE is probably not associated with atopic dermatitis and is likely to be related to the ambient UV index though a larger cohort with meticulous follow up may be needed to draw a final conclusion.Statistical Analysis Used:The Pearson's coefficient of correlation was used for comparing the cases per month with the UV index. The tests of hypothesis used included the paired T-tests. F-test of variance, Welch test, Wilcoxon rank sum test and the Kolmogorov-Smirnov Test. P < 0.05 was considered significant.

Self-reported taste and smell alterations in patients under investigation for lung cancer

This study of patients under investigation for lung cancer (LC) aims to: 1) examine the prevalence of self-reported taste and smell alterations (TSAs) and their relationships with demographic and clinical characteristics; and 2) explore nutritional importance of TSAs by examining their associations with patient-reported weight loss, symptoms interfering with food intake, and changes in food intake.Methods. Patients were recruited consecutively during investigation for LC from one university hospital in Sweden. Patient-reported information on TSAs, demographics, six-month weight history, symptoms interfering with food intake, and changes in food intake was obtained. Relationships between TSAs and other variables were examined using two-tailed significance tests. In addition, putative explanatory factors for weight loss were explored in those patients diagnosed with LC, since a relationship between TSAs and weight loss was found in this group.Results. The final sample consisted of 215 patients, of which 117 were diagnosed with primary LC within four months of study inclusion and 98 did not receive a cancer diagnosis. The 38% prevalence of TSAs was identical in both groups, and were generally reported as mild and not interfering with food intake. However, a statistically significant relationship between TSAs and weight loss was found among patients with LC, with a median weight change of − 5.5% and a higher frequency of weight loss ≥ 10%. Patients with LC and weight loss ≥ 10%, had higher frequency of reporting TSAs, of decreased food intake and of ≥ 1 symptom interfering with food intake compared with those with less weight loss.Conclusion. TSAs, although relatively mild, were present in 38% of patients with and without LC. Relationships between TSAs and weight loss were found among patients with LC, but not fully explained by decreased food intake. This highlights the complexity of cancer-related weight loss.

DiaSurg 2 trial - surgical vs. medical treatment of insulin-dependent type 2 diabetes mellitus in patients with a body mass index between 26 and 35 kg/m2: study protocol of a randomized controlled multicenter trial - DRKS00004550

BackgroundType 2 diabetes mellitus (T2DM) is a disease with high prevalence, associated with severe co-morbidities as well as being a huge burden on public health. It is known that glycemic control decreases long-term morbidity and mortality. The current standard therapy for T2DM is medical treatment. Several randomized controlled trials (RCTs) performed in obese patients showed remission of T2DM after bariatric surgery. Recent RCTs have shown bariatric procedures to produce a similar effect in non-morbidly and non-severely obese, insulin-dependent T2DM patients suggesting procedures currently used in bariatric surgery as new therapeutical approach in patients with T2DM. This study aims at investigating whether Roux-en-Y gastric bypass (RYGB) is an efficient treatment for non-severely obese T2DM patients in terms of preventing long-term complications and mortality.MethodsThe DiaSurg 2 trial is a multicenter, open randomized controlled trial comparing RYGB including standardized medical treatment if needed to exclusive standardized medical treatment of T2DM (control group). The primary endpoint is a composite time-to-event endpoint (cardiovascular death, myocardial infarction, coronary bypass, percutaneous coronary intervention, non-fatal stroke, amputation, surgery for peripheral atherosclerotic artery disease), with a follow-up period of 8 years. Insulin-dependent T2DM patients aged between 30 and 65 years will be included and randomly assigned to one of the two groups. The experimental group will receive RYGB and, if needed, standardized medical care, whereas the control group will receive exclusive standardized medical care, both according to the national treatment guidelines for T2DM. Statistical analysis is based on Cox proportional hazards regression for the intention-to-treat population. Assuming a loss to follow-up rate of 20%, 200 patients will be randomly allocated to the comparison groups. A total sample size of n = 400 is sufficient to ensure 80% power in a two-tailed significance test at alpha = 5%.DiscussionThe DiaSurg2 trial will yield long-term data (8 years) on diabetes-associated morbidity and mortality in patients with insulin-dependent T2DM receiving either RYGB or standardized medical care.Trial registrationThe trial protocol has been registered in the German Clinical Trials Register DRKS00004550.

Characterizing optimality among three-decision procedures for directional conclusions

Jones and Tukey (2000) proposed three-decision procedures for directional conclusions in statistical inference, considered as an alternative to the conventional usage of one- and two-tailed significance testing. Moreover, implicit in their suggestions was to consider a procedure to be optimal in case indefinite results were minimized among all procedures with a given control of error. First, we argue by example that this characterization of optimality is not very fruitful when formalized into the strong sense of uniform minimization. Next, imposing a further regularity condition on the comparative class of procedures, we relate the suggested characterization to optimality criteria from test theory (UMP unbiasedness). Similarly, we also consider characterizing optimality in terms of maximizing correct decision rates and minimizing incorrect decision rates. Finally, we demonstrate the applicability of the three considered characterizations with respect to exponential families of distributions.

Efficacy and safety of a nano-emulsion gel formulation of adapalene 0.1% and clindamycin 1% combination in acne vulgaris: A randomized, open label, active-controlled, multicentric, phase IV clinical trial

Acne vulgaris is a very common skin disease with a significant detrimental effect on the quality of life of the patients. To assess the comparative efficacy and safety of a nano-emulsion gel formulation of adapalene and clindamycin combination with its conventional formulation in the treatment of acne vulgaris of the face. It was a prospective, randomized, open label, active-controlled, multicentric, clinical trial. Eligible patients suffering from acne vulgaris of the face were randomized to receive once-daily treatment with a nano-emulsion gel or conventional gel formulation of adapalene 0.1% and clindamycin (as phosphate) 1% combination for 12 weeks. Total, inflammatory and noninflammatory lesion counts, with grading of acne severity were carried out on a monthly basis. Safety assessments were done to determine the comparative local and systemic tolerability. Two-tailed significance testing was carried out with appropriate statistical tests, and P-values < 0.05 were considered as significant. 209/212 patients enrolled in the study were eligible for efficacy and safety assessments in both nano-emulsion gel (118/119 patients) and conventional gel (91/93 patients) groups. Significantly better reductions in total (79.7% vs. 62.7%), inflammatory (88.7% vs. 71.4%) and noninflammatory (74.9% vs. 58.4%) lesions were reported with the nano-emulsion gel as compared to the conventional gel (P < 0.001 for all). Mean acne severity score also reduced significantly more with the nano-emulsion formulation (1.9 ± 0.9 vs. 1.4 ± 1.0; P < 0.001) than the comparator. Significantly lower incidence and lesser intensity of adverse events like local irritation (4.2% vs. 19.8%; P < 0.05) and erythema (0.8% vs. 9.9%; P < 0.05) were recorded with the nano-emulsion gel. The nano-emulsion gel formulation of adapalene and clindamycin combination appears to be more efficacious and better tolerated than the conventional formulation for the treatment of acne vulgaris in Indian patients. Further studies can elucidate the comparative treatment benefits of this nano-emulsion gel formulation.

Safety and efficacy of the HVTN 503/Phambili Study of a clade-B-based HIV-1 vaccine in South Africa: a double-blind, randomised, placebo-controlled test-of-concept phase 2b study

The MRKAd5 HIV-1 gag/pol/nef subtype B vaccine was designed to elicit T-cell-mediated immune responses capable of providing complete or partial protection from HIV-1 infection or a decrease in viral load after acquisition. We aim to assess the safety and efficacy of the vaccine in South Africa, where the major circulating clade is subtype C. We did a phase 2b double-blind, randomised test-of-concept study in sexually active HIV-1 seronegative participants at five sites in South Africa. Randomisation was by a computer-generated random number sequence. The vaccine and placebo were given by intramuscular injection on a 0, 1, 6 month schedule. Our coprimary endpoints were a vaccine-induced reduction in HIV-1 acquisition and viral-load setpoint. These endpoints were assessed independently in the modified intention-to-treat (MITT) cohort with two-tailed significance tests stratified by sex. We assessed immunogenicity by interferon-γ ELISPOT in peripheral-blood mononuclear cells. After the lack of efficacy of the MRKAd5 HIV-1 vaccine in the Step study, enrolment and vaccination in our study was halted, treatment allocations were unmasked, and follow-up continued. This study is registered with the South Africa National Health Research Database, number DOH-27-0207-1539, and ClinicalTrials.gov, number NCT00413725. 801 of a scheduled 3000 participants, of whom 360 (45%) were women, were randomly assigned to receive either vaccine or placebo. 445 participants (56%) had adenovirus serotype 5 (Ad5) titres greater than 200, and 129 men (29%) were circumcised. 34 MITT participants in the vaccine group were diagnosed with HIV-1 (incidence rate 4·54 per 100 person-years) and 28 in the placebo group (3·70 per 100 person-years). There was no evidence of vaccine efficacy; the hazard ratio adjusted for sex was 1·25 (95% CI 0·76-2·05). Vaccine efficacy did not differ by Ad5 titre, sex, age, herpes simplex virus type 2 status, or circumcision. The geometric mean viral-load setpoint was 20,483 copies per mL (n=33) in the vaccine group and 34,032 copies per mL (n=28) in the placebo group (p=0·39). The vaccine elicited interferon-γ-secreting T cells that recognised both clade B (89%) and C (77%) antigens. The MRKAd5 HIV-1 vaccine did not prevent HIV-1 infection or lower viral-load setpoint; however, stopping our trial early probably compromised our ability to draw conclusions. The high incidence rates noted in South Africa highlight the crucial need for intensified efforts to develop an efficacious vaccine. The US National Institute of Allergy and Infectious Disease and Merck and Co Inc.

Review of: Batchelor, Roy (2001), "How Useful are the Forecasts of Intergovernmental Agencies? The Imf And OECD Versus the Consensus"

Substantial resources are devoted to forecasting macroeconomic series by the International Monetary Fund (IMF) and the Organization for Economic Cooperation and Development (OECD). Forecasts for these series are also available from many private sources. For example, Consensus Economics, an English firm, combines forecasts from 10 to 30 private sector forecasts for each country. Batchelor asks whether the IMF and OECD, with their statistics and highly qualified analysts, might contribute to forecast accuracy beyond what is offered by private firms. Batchelor used a two-tailed significance test on whether these forecasts do better than the consensus. He examined forecasts for the G7 countries for seven years (1990-1996) using three starting points for each year for six variables. In all, there were comparisons for 1,200 forecasts. Using the Mean Absolute Errors, the consensus forecasts were superior to the OECD and IMF forecasts on 23 of 27 comparisons (summarized by variable by starting month). On average, the combined forecast error was 9.6% less than the IMF forecast and 8.1% less than the OECD forecast. These gains are in line with the estimate that combining will reduce the error by about 12% versus a single component forecast (Armstrong 2001). Batchelor then examined whether the Consensus Forecasts would be improved through the addition of the OECD and IMF forecasts. It was not, which is not surprising given the large number of forecasts included in the combined forecasts; the results for combining suggest that the gains in accuracy from adding forecasts become small after one has combined five forecasts (Armstrong 2001).

Prevalência de Cryptosporidium sp. em cães de instituições da cidade de São Paulo

Dogs play an important role as infection source of human cryptosporidiosis. The objective of the study was to determine the prevalence of Cryptosporidium sp. in dogs as well as to compare two techniques of fecal analysis. Four-hundred and fifty canine fecal samples from the city of São Paulo were analyzed between 2003 and 2004. Fecal samples were randomly selected from dogs housed in a university veterinary hospital (group 1, n=200) and private kennels (group 2, n=250). The detection of Cryptosporidium was performed using modified Ziehl-Neelsen staining and Polymerase Chain Reaction (PCR) technique. Statistical analysis was performed using the two-tailed test of significance at 5% confidence interval (z critical=+/-1.645). Only Cryptosporidium parvum oocysts were found. The prevalences found by light microscopy examination and PCR techniques were 8.8% and 9.5%, respectively. Young animals showed a lower frequency (5.5%) compared to adults (10.1%). There was no statistically significant difference in Cryptosporidium prevalence between males and females. The prevalence of C. parvum in the canine population studied was similar to that one found in the literature and affects equally males and females. The use of PCR allowed the detection of more positive cases than light microscopy.

Oral fluorescein angiography with the confocal scanning laser ophthalmoscope

Objective To evaluate the efficacy of oral fluorescein angiography with a confocal scanning laser ophthalmoscope (SLO) system. Design Comparative case series. Participants The authors used a confocal SLO (Heidelberg Retina Angiograph [HRA]) to perform oral fluorescein angiography in 47 patients, 13 of whom were without any retinal disease and 34 with a variety of retinal diseases including macular holes and pucker, inflammatory diseases, retinal vascular diseases, and age-related macular degeneration. The images were also compared to images taken with a fundus camera after intravenous fluorescein injections in patients on whom both studies were done. Intervention Color fundus photographs were taken of each eye (30° fundus camera) before drinking 4 ml of 25% sodium fluorescein mixed with 60 ml of orange juice. After oral fluorescein ingestion, images of each eye were taken with a fundus camera (TriX film) and the HRA (using 512- × 512-pixel resolution). The images were repeated at 0-, 2.5-, 5-, 7.5-, 10-, 12.5-, 15-, 20-, 25-, and 30-minute intervals. Twenty of the 47 patients underwent intravenous fluorescein angiography performed with the fundus camera. Main outcome measure Images were analyzed by a masked reader, and foveal avascular zone visualization, branch retinal vessel identification, and image quality were scored. Statistical analysis was performed with a t test for paired data with a two-tailed test of significance (alpha = 0.05). Results Foveal avascular zone was 100% as seen in 16 eyes (47%) in the HRA machine versus 1 eye (2%) in the conventional fundus camera ( P < 0.0001). The third-order branch retinal vessels were identified in 59% of eyes in the HRA versus 26% in the fundus camera group ( P < 0.0001), and the image quality was considered comparable to an intravenous angiogram in 47% with the HRA versus 9% with the conventional fundus camera ( P < 0.0001). Conclusions Oral fluorescein angiography using the HRA produces sufficiently detailed images to diagnose, treat, and follow many types of retinal pathology.

Program Corfree: A Program for Freeman's Family of Ordinal Correlation Coefficients

This paper describes a computer program, CORFREE, which computes the ordinal correlations discussed by Freeman. The correlation coefficients are calculated for the sample data, and the population values are estimated by a combination of the jackknife with robust/resistant methods. The sampling variance of each correlation coefficient is estimated by robust/resistant methods. The program computes one- and two-tailed significance tests of the null hypothesis by randomization methods. The program is useful for calculating the descriptive family of ordinal correlation coefficients described by Freeman, and for finding their significance levels. The program uses computer intensive methods to reduce errors or biases in estimating the population coefficients or their sampling variances. Program outputs can be further analyzed by other programs.

The Procedures and Justification of a Two-Tailed Directional Test of Significance

The procedures and justification of a directional two-tailed test of significance are presented along with some suggested advantages of the conception.