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PubMed1988

Selecting ozone exposure statistics for determining crop yield loss from air pollutants.

Numerous ozone exposure statistics were calculated using hourly ozone data from crop yield loss experiments previously conducted for alfalfa, fresh market and processing tomatoes, cotton, and dry beans in an ambient ozone gradient near Los Angeles, California. Exposure statistics examined included peak (maximum daily hourly) and mean concentrations above specific threshold levels, and concentrations during specific time periods of the day. Peak and mean statistics weighted for ozone concentration and time period statistics weighted for hour of the day were also determined. Polynomial regression analysis was used to relate each of 163 ozone statistics to crop yield. Performance of the various statistics was rated by comparing residual mean square (RMS) values. The analyses demonstrated that no single statistic was best for all crop species. Ozone statistics with a threshold level performed well for most crops, but optimum threshold level was dependent upon crop species and varied with the particular statistics calculated. The data indicated that daily hours of exposure above a critical high-concentration threshold related well to crop yield for alfalfa, market tomatoes, and dry beans. The best statistic for cotton yield was an average of all daily peak ozone concentrations. Several different types of ozone statistics performed similarly for processing tomatoes. These analyses suggest that several ozone summary statistics should be examined in assessing the relationship of ambient ozone exposure to crop yield. Where no clear statistical preference is indicated among several statistics, those most biologically relevant should be selected.

Journal Article↗

PubMed2005

The use of the barbell cluster ANOVA design for the assessment of environmental pollution: a case study, Wigierski National Park, NE Poland.

This report presents an assessment of chemical variability in natural ecosystems of Wigierski National Park (NE Poland) derived from the calculation of geochemical baselines using a barbell cluster ANOVA design. This method enabled us to obtain statistically valid information with a minimum number of samples collected. Results of summary statistics are presented for elemental concentrations in the soil horizons-O (Ol + Ofh), -A and -B, 1- and 2-year old Pinus sylvestris L. (Scots pine) needles, pine bark and Hypogymnia physodes (L.) Nyl. (lichen) thalli, as well as pH and TOC. The scope of this study also encompassed S and C stable isotope determinations and SEM examinations on Scots pine needles. The variability for S and trace metals in soils and plant bioindicators is primarily governed by parent material lithology and to a lesser extent by anthropogenic factors. This fact enabled us to study concentrations that are close to regional background levels.

Analysis of Variance↗

PubMed1990

Statistical analysis of gamma-emitting radionuclide concentrations for three fields in southern Saskatchewan, Canada.

During 1988, the spatial variability of the natural gamma-emitting radionuclides (238U, 232Th, and 40K) and the artificial radionuclide 137Cs were studied in three near-level unfertilized fields in Saskatchewan, Canada. One field was used as a native (uneroded) control site; the other two sites have been cultivated, one since 1979 and the other since at least the 1940s. The two cultivated sites have been eroded by aeolian processes and tillage practices. Autocorrelation analysis indicated that most of the radionuclides were not serially correlated for the two depth increments sampled (0-15 cm and 15-30 cm). Autocorrelation is a necessary procedure when equally spaced transect sampling is employed, since sample independence cannot be assumed. Robust and nonrobust statistical summaries are presented for the selected gamma-emitting radionuclide concentrations. Robust statistical estimates of location and dispersion are favored when distributions are not normal or when the distribution is skewed. Median concentrations for the three fields indicated that 238U, 232Th, 40K, and 137Cs were similar to areas in the U.S. and to other areas in southern Saskatchewan. Median 238U activity concentrations were between 31.4 and 34.1 Bq kg-1; 232Th concentrations were between 29.6 and 31.2 Bq kg-1; 40K concentrations were between 471 and 502 Bq kg-1; and 137Cs concentrations were between 10.0 and 12.6 Bq kg-1. The variability of natural radionuclides in a given field for a specific depth increment was generally low, with coefficients of variation less than or equal to 10%. The variability of 137Cs concentrations was greater, ranging from 18% to 23%. Nonparametric tests indicated a significant decrease in 214Bi concentration (238U indicator corrected for 222Rn) with depth of the 1979 field, and an increase in 228 Ac (232Th) with depth in the 1940s field. Significant differences in concentration between fields were indicated for all radionuclides except for 228 Ac. The possible reasons for differences in depth and between fields are briefly discussed.

Cesium Radioisotopes↗

PubMed1994

The risks of "Putting the numbers in context": a cautionary tale.

Despite the warnings of risk communication specialists, members of the technical community often urge that technological risks should be "put in context" by comparisons against risks that are more familiar. Little quantitative evidence is available on the actual behavioral consequences of such risk comparison efforts. In the present study, subjects were presented with two types of information about a hazardous waste incinerator--a simplified statistical summary and a comparison of incinerator risks against the risks of smoking. Statistical information led to a modest increase in the reported willingness to vote in favor of the incinerator in a community referendum, but the comparison against cigarettes led to a slight decrease in support; the difference between the two messages is statistically significant (p < .001). In combination with other results, this study's findings suggest that an implicit assumption of risk comparisons is in error: Opposition to controversial technologies may have little to do with citizens' levels of information about technology, having more to do with citizens' levels of trust in governmental and industrial actors.

Attitude to Health↗

PubMed2006

Web-based data collection: detailed methods of a questionnaire and data gathering tool.

There have been dramatic advances in the development of web-based data collection instruments. This paper outlines a systematic web-based approach to facilitate this process through locally developed code and to describe the results of using this process after two years of data collection. We provide a detailed example of a web-based method that we developed for a study in Starr County, Texas, assessing high school students' work and health status. This web-based application includes data instrument design, data entry and management, and data tables needed to store the results that attempt to maximize the advantages of this data collection method. The software also efficiently produces a coding manual, web-based statistical summary and crosstab reports, as well as input templates for use by statistical packages.Overall, web-based data entry using a dynamic approach proved to be a very efficient and effective data collection system. This data collection method expedited data processing and analysis and eliminated the need for cumbersome and expensive transfer and tracking of forms, data entry, and verification. The code has been made available for non-profit use only to the public health research community as a free download..

Journal Article↗

PubMed2006

Intraoperative knee anthropometrics: correlation with cartilage wear.

Accurate knee morphology is of value in determining the correct sizing of prosthetic implants. Intraoperative measurement of key linear dimensional variables was carried out on 196 Caucasian knees (osteoarthritic patients: 68 male and 128 female). Of the 196 knees measured, 70 had extensive cartilage degeneration. Statistical analysis was carried out on this large sample size of data. Summary statistics and correlation coefficients between variables were determined and compared between subgroups. Male knees were on average larger than female knees. Higher correlation was found between variables for males than between variables for females. Overall, the patellar dimensions were seen to correlate least well with other anatomical variables. High correlation between femoral variables supports current femoral sizing procedure, although routine patellar resection practices are called into question. Average values for the 70 knees with extensive cartilage degeneration were significantly smaller (P < 0.01) than their counterparts for the other 126 knees. For a measurement not containing cartilage, such as femoral epicondylar width, this difference cannot be accounted for by the loss of cartilage owing to wear. This suggests that, for similar height and weight, a naturally narrower femoral epicondylar width may be associated with severe osteoarthritis.

Aged↗

PubMed1995

The geographical accessibility of hospitals to the aged: a geographic information systems analysis within Illinois.

OBJECTIVE: This article uses geographic information systems and their related tools to empirically measure and display the geographic accessibility of the aged population to hospital facilities within Illinois. DATA SOURCES AND STUDY SETTING: Geographic accessibility of Illinois' aged population is measured from each of the state's 10,796 census block groups to the state's 214 hospital facilities. Block group demographic compositions and centroids are obtained from 1990 census files. Hospital coordinates are obtained by the authors. STUDY DESIGN: Of five alternative measures of accessibility considered, empirical estimates are obtained for two: choice set and minimum distance. Access to both general hospitals and the subset having specialized geriatric facilities is measured with special attention to differences in accessibility between the aged within metropolitan statistical areas (MSAs) and those outside MSAs. Cumulative accessibility distributions and their summary statistics provide a basis of comparison among subgroups. DATA COLLECTION AND EXTRACTION: Geographic information systems (GIS) and their related tools are used as a means of efficiently capturing, organizing, storing, and retrieving the required data. Hospitals and census block groups are geocoded to specific locations in the database, and aspatial attributes are assigned to the hospitals and block groups. The GIS database is queried to produce shaded isarithm and point distribution maps that show the location of hospitals relative to surrounding aged populations. CONCLUSION: The vast majority of Illinois' aged population is within close proximity to hospital facilities. Eighty percent (1,147,504 persons) of the aged in Illinois are within 4.8 miles (7.7 km) of a hospital and 11.6 miles (18.7 km) of two hospitals. However, geographic accessibility differences between the aged living in MSAs and those living outside MSAs to hospitals offering geriatric services are substantial; but there is no evidence that the aged's geographical accessibility to hospitals is less favorable than that of the general population. Detailed accessibility measures permitted by geographic information system technology call into question the continued use of crude empirical accessibility measures.

Aged↗

PubMed1993

A unified approach to study hypervariable polymorphisms: statistical considerations of determining relatedness and population distances.

Relatedness between individuals as well as evolutionary relationships between populations can be studied by comparing genotypic similarities between individuals. When hypervariable loci are used to describe genotypes, it is shown that both of these problems can be approached with a unified theory based on allele sharing between individuals. The distributions of the number of shared alleles between individuals indicate their kin relationships. Extending this, we obtain statistics for genetic distances between populations based on average number of alleles shared between individuals within and between two different populations. Traditional statistical inferential procedure can be used to establish specific kinship relationships between individuals. We derive estimates of the number of hypervariable loci needed for a specified reliability of such an inference. Evolutionary dynamics of genetic distance statistics based on allele sharing is also studied. It shows that such measures of genetic distances remain linear with the time of divergence for a period comparable to that of the gene frequency-based measures of genetic distances. Statistical properties of measures based on allele sharing establish that for using such summary statistics it is not necessary to know the full characteristics of all loci used. It is enough to know the degree of heterozygosity per locus and the number of loci. Therefore, in principle, this approach can also be used for DNA fingerprinting data in the studies of relatedness between individuals as well as between populations. The possible compromising features of multilocus DNA fingerprinting data are also discussed.

Alleles↗

PubMed1998

The relationship of HIV prevalence in pregnant women to that in women of reproductive age: a validated method for adjustment.

OBJECTIVE: To devise and validate a method for adjusting HIV seroprevalences in pregnant women to estimate population prevalences among all women in their child-bearing years. DESIGN: Birth and termination rates from women with known HIV infection in the United Kingdom were calculated according to the likely route of HIV infection and whether HIV infection was diagnosed. METHODS: Birth and termination rates were weighted and combined to produce summary statistics. Comparisons were then made with population birth and termination rates to derive summary relative inclusion ratios (RIRs), the relative probabilities of including HIV-infected and uninfected women in seroprevalence surveys of pregnant women. RESULTS: The derived RIRs for women having live births were close to unity: 1.03 [95% confidence intervals (CI) 0.90-1.17] for London and 0.80 (Cl, 0.71-0.89) for elsewhere in England and Wales. This indicates that currently observed overall seroprevalences among pregnant women having live births in London would be similar to those among all women of the same age, while elsewhere it would be slightly underestimated. Sensitivity analysis indicated that RIRs could, however, vary three-fold (0.47-1.56) according to the proportion of diagnosed maternal infections and the mix of maternal HIV-exposure categories. The method was validated by using it to predict the ratio of unlinked seroprevalences between women having terminations and live births in London. It predicted a ratio of 1.74: 1, which is close to the observed ratio of 2.07 : 1. CONCLUSIONS: Application of HIV seroprevalences from pregnant women to whole populations may need adjustment for fertility rates among HIV-infected women. A general method for this has been derived and validated. Gathering fertility data for HIV-infected women is a useful adjunct to serosurveillance.

Birth Rate↗

PubMed2026

DNA Methylation, SERPING1 Expression, and Immune-related Traits in Osteoporosis: A Mendelian Randomization Study And Supportive Ex Vivo Evidence.

INTRODUCTION: Osteoporosis (OP) is a major public health burden; however, the role of SERPIN family proteins remains incompletely understood. This study aimed to investigate genetically inferred associations between SERPINs and OP and to explore potential regulatory relationships. METHODS: Genome-wide association study (GWAS) summary statistics were used to perform two-sample Mendelian randomization (MR) and summary-data-based Mendelian randomization (SMR) analyses. Primary MR estimates were derived using inverse-variance-weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode methods. Cancellous bone tissue from the greater trochanter of the femur was collected from three patients with OP and three non-osteoporotic controls. qPCR and WB were used to analyze the whole bone homogenate, IHC was used to detect decalcified bone sections, and mediation analysis was used to explore potential regulatory associations. RESULTS: Among the proteins of the SERPIN family, only SERPING1 had an obvious positive correlation with the risk of osteoporosis (OR = 1.06, P = 0.0012). qPCR, WB, and IHC analyses demonstrated increased SERPING1 mRNA and protein expression in bone tissue from OP patients. Mediation analyses suggested that cg15918732 DNA methylation may serve as an upstream regulatory factor for SERPING1 expression. In addition, the downstream associations also consist of the alteration of immune cell conditions, like the decrease in the quantity of natural killer cells and T cells, and the rise in the level of mononuclear cells, and so forth. DISCUSSION: These findings provide genetic evidence for the possible role of SERPING1 in OP, which may be achieved through epigenetic regulation and immune pathways. Due to the corresponding characteristics of genetic inference and the small sample size, these results are hypothetical and generative. CONCLUSION: This study shows that DNA methylation of cg15918732 may be associated with SERPING1 expression in osteoporosis and immune-related traits. These findings provide new insights into potential epigenetic and immunological pathways in osteoporosis, which may contribute to future mechanistic and translational research.

Humans↗

PubMed1990

Statistics: curse of the writing class.

Research projects and reports may fail because of investigators' misunderstandings about the principles underlying basic data analysis. Such errors may taint otherwise valid conclusions; related mistakes may serve to falsely support incorrect results. This article explains some of the principles underlying the use of statistical analysis for normally distributed interval data and explores the potential ramifications of misusing summary statistical tests on non-normal distributions. A discussion of the meaning of the statement of probability concerning hypothesis testing and a suggested attitude for researchers toward significance testing is also included.

Data Interpretation, Statistical↗

PubMed2006

Systematic review and meta-analysis: importance of CagA status for successful eradication of Helicobacter pylori infection.

BACKGROUND: Some, but not all studies have provided evidence that the CagA status of Helicobacter pylori strains is a predictive factor for the outcome of eradication therapy. AIM: To clarify the association between CagA status and eradication outcome. METHODS: We included studies reporting the numbers of successful and failed cases in H. pylori-eradication therapy according to the CagA status. Fourteen studies (1529 patients) were included of 325 articles identified in the search. The pooled risk ratio for H. pylori-eradication failure in CagA-negative relative to CagA-positive strains and the pooled risk difference in eradication success between the two groups were used as summary statistics. Meta-regression was used for examining the source of heterogeneity. RESULTS: The summary risk ratio for eradication failure in CagA-negative relative to CagA-positive was 2.0 (95% CI: 1.6-2.4, P < 0.001), corresponding with the summary risk difference for eradication success between the groups of 11% (95% CI: 3-19%, P = 0.011). Meta-regression analysis demonstrated that usage of polymerase chain reaction examination for CagA status and a high proportion of non-ulcer dyspepsia patients were factors for heterogeneity among studies. CONCLUSIONS: Our meta-analysis confirmed the importance of the presence of CagA as a predictor for successful eradication of H. pylori.

Antigens, Bacterial↗

PubMed2005

An automated, broad-based, near real-time public health surveillance system using presentations to hospital Emergency Departments in New South Wales, Australia.

BACKGROUND: In a climate of concern over bioterrorism threats and emergent diseases, public health authorities are trialling more timely surveillance systems. The 2003 Rugby World Cup (RWC) provided an opportunity to test the viability of a near real-time syndromic surveillance system in metropolitan Sydney, Australia. We describe the development and early results of this largely automated system that used data routinely collected in Emergency Departments (EDs). METHODS: Twelve of 49 EDs in the Sydney metropolitan area automatically transmitted surveillance data from their existing information systems to a central database in near real-time. Information captured for each ED visit included patient demographic details, presenting problem and nursing assessment entered as free-text at triage time, physician-assigned provisional diagnosis codes, and status at departure from the ED. Both diagnoses from the EDs and triage text were used to assign syndrome categories. The text information was automatically classified into one or more of 26 syndrome categories using automated "naïve Bayes" text categorisation techniques. Automated processes were used to analyse both diagnosis and free text-based syndrome data and to produce web-based statistical summaries for daily review. An adjusted cumulative sum (cusum) was used to assess the statistical significance of trends. RESULTS: During the RWC the system did not identify any major public health threats associated with the tournament, mass gatherings or the influx of visitors. This was consistent with evidence from other sources, although two known outbreaks were already in progress before the tournament. Limited baseline in early monitoring prevented the system from automatically identifying these ongoing outbreaks. Data capture was invisible to clinical staff in EDs and did not add to their workload. CONCLUSION: We have demonstrated the feasibility and potential utility of syndromic surveillance using routinely collected data from ED information systems. Key features of our system are its nil impact on clinical staff, and its use of statistical methods to assign syndrome categories based on clinical free text information. The system is ongoing, and has expanded to cover 30 EDs. Results of formal evaluations of both the technical efficiency and the public health impacts of the system will be described subsequently.

Anniversaries and Special Events↗

PubMed2005

Comparing automatic and manual image processing in FLARE assay analysis for colon carcinogenesis.

Measurement of the amount of oxidative damage to DNA is one tool that can be used to estimate the beneficial effect of diet on the prevention of colon carcinogenesis. The FLARE assay is a modification of the single-cell gel electrophoresis (Comet) assay, and provides a measure of the 8OHdG adduct in the cells. In this paper, we present two innovations to the existing methods of analysis. The first one is related to the FLARE assay itself. We describe automated image analysis techniques that can be expected to measure oxidative damage faster, reproducibly, with less noise, and hence achieve greater statistical power. The proposed technique is compared to an existing technique, which was more manual and thus slower. The second innovation is our statistical analysis: we exploit the shape of FLARE intensity histograms, and show statistically significant diet effects in the duodenum. Previous analyses of this data concentrated on simple summary statistics, and found only marginally statistically significant diet effects. With the new imaging method and measure of oxidative damage, we show cells in the duodenum exposed to fish oil as having more oxidative damage than cells exposed to corn oil.

Journal Article↗

PubMed1999

Better late than never? Injecting statistical know-how into legislation on water quality.

Many of the Directives we use to control the risk of water pollution do not distinguish the statistical concepts of population and sample. They also fail to acknowledge the uncertainty in estimates of summary statistics. This leads to faulty assessments of performance, some of which have serious consequences. This paper explains how calculations of compliance should be done in duplicate. First, we must follow the stipulations in the Directives. Second we must make a proper statistical estimation. The results from the second assessment show where failure is statistically significant, and where the Directives' rules preclude a good decision on the need to act.

Confidence Intervals↗

PubMed2005

Human leukocyte antigen class II DQB10301, DRB11101 alleles and spontaneous clearance of hepatitis C virus infection: a meta-analysis.

AIM: To assess the associations of human leukocyte antigen (HLA) class II DQB1*0301 and/or DRB1*1101 allele with spontaneous hepatitis C virus (HCV) clearance by meta-analysis of individual dataset from all studies published till date. METHODS: To clarify the impact of HLA class II polymorphisms on viral clearance, we performed a meta-analysis of the published data from 11 studies comparing the frequencies of DQB1*0301 and DRB1*1101 alleles in individuals with spontaneous resolution to those with persistent infection. As we identified the heterogeneity between studies, summary statistical data were calculated based on a random-effect model. RESULTS: Meta-analyses yielded summary estimates-odds ratio (OR) of 2.36 [95%CI (1.62, 3.43), P<0.00001] and 2.02 [95%CI (1.56, 2.62), P<0.00001] for the effects of DQB1*0301 and DRB1*1101 alleles on spontaneous clearance of HCV, respectively. CONCLUSION: These results support the hypothesis that specific HLA class II alleles might influence the susceptibility or resistance to persistent HCV infection. Both DQB1*0301 and DRB1*1101 are protective alleles and present HCV epitopes more effectively to CD4(+)T lymphocytes than others, and subjects with these two alleles are at a lower risk of developing chronic HCV infection. Large, multi-ethnic confirmatory and well-designed studies are needed to determine the host genetic determinants of HCV infection.

Alleles↗

PubMed1988

Testing for linear trends in proportions using correlated otolaryngology or ophthalmology data.

This paper is concerned with the issue of testing for trend with correlated binary data. We consider the problem where one has either one or two ears (or eyes) available for analysis at baseline and one wishes to look at changes over time in a dichotomous outcome taking into account the correlation between responses from two ears. A reparameterization of Rosner's (1982, Biometrics 38, 105-114) correlated binary data model is presented and applied to a test for trend where the stratifying variable is age (or any other subject-specific variable). Observed and expected values are calculated for the trend statistic separately for both unilateral and bilateral cases and are then summed to obtain an overall summary statistic. The proposed method is illustrated by a reanalysis of data presented in a published study of the efficacy of antibiotics for the treatment of otitis media.

Amoxicillin↗

PubMed1989

Development and testing of a statistical and graphics-enhanced nutrient analysis program.

The authors have developed and tested a nutrient analysis program that will compute and present graphically summary statistics of population and population subgroup nutrient intakes. The program analyzes for 44 nutrients from 5,800 separate food items. Capabilities of the program include: storage of large numbers of diet records and evaluations of their nutrients; calculation of nutrient means and standard deviations; data sorting based on subject characteristics, such as age, sex, and supplement use; and generation of bar graphs and line plots for individual and/or group data. To test this computerized nutrient analysis program, two sets of 3-day diet records from 200 elderly individuals were analyzed. The program was then used to generate means, differences between means, and distribution frequencies of designated nutrients for various population subgroups (e.g., men greater than or equal to 65 years vs. men greater than or equal to 80 years) as well as comparisons with individual files (e.g., Mr. Smith vs. all men greater than or equal to 65 years). The statistical and graphics capabilities also function within the context of recipe analysis and menu planning, which enhances the application of this program in institutional and community nutrition settings.

Aged↗