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Results for “Data Interpretation, Statistical”

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PubMed1992

Interpretation of BSE statistics.

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Animals↗

PubMed2007

Nuclear magnetic resonance metabonomics: methods for drug discovery and development.

Nuclear magnetic resonance (NMR)-based metabonomics is gaining popularity in drug discovery and development and in academia in a variety of settings, ranging from toxicology, preclinical, and clinical approaches to nutrition research, studies on microorganisms, and research on plants. This chapter focuses on the basic steps in a metabonomics study and emphasizes experience and lessons learned in our lab where we focused on metabonomic analyses of plant extracts, cell lines, and a variety of animal tissues and biofluids. We emphasize that a comprehensive and suitable study design is pivotal for a correct biological interpretation of the results, as well as highly controlled experimental conditions. Sample preparation and NMR protocols are detailed for a wide range of sample types. We discuss alternative data processing strategies and considerations for a general data analysis approach, paying particular attention to the statistical interpretation and validation of the results while also highlighting approaches to avoid possible pitfalls resulting from systematic and random errors. A tutorial written for the R statistical package and other small utilities are available from the authors upon request.

Animals↗

PubMed1994

Statistical significance of amino acid sequence similarity in type II DNA methyltransferases.

The statistical significance of amino acid sequence similarities previously observed in type II DNA methyltransferases has been investigated. It is shown: (1) that the intramolecular similarities observed among various type II Mtases are not statistically significant and thus can not be used to support a gene duplication model; (2) that the intermolecular similarities observed in a peptide in various type II adenine methylases are statistically confirmed; (3) that the similarities observed between MutH and these proteins for this peptide are not statistically significant and therefore cannot be used to propose a functional role in DNA recognition for this peptide.

Amino Acid Sequence↗

PubMed1991

Mental retardation and WAIS-R difference scores.

This article explores the psychometric properties (reliabilities, standard deviations and measurement errors) of Wechsler Adult Intelligence Scale--Revised (Wechsler, 1981) subtest difference scores. The sample consisted of 290 subjects with IQ less than 80. Results demonstrated less than satisfactory difference score reliability and disproportionate measurement error. Nevertheless, neither property was so inadequate as to render cautious profile interpretation impossible. The tabled values can help clinicians working with developmentally delayed clients interpret differences between subtest scores based on statistically reliable discrepancies.

Data Interpretation, Statistical↗

PubMed2004

Fundamentals of massive automatic pairwise alignments of protein sequences: theoretical significance of Z-value statistics.

MOTIVATION: Different automatic methods of sequence alignments are routinely used as a starting point for homology searches and function inference. Confidence in an alignment probability is one of the major fundamentals of massive automatic genome-scale pairwise comparisons, for clustering of putative orthologs and paralogs, sequenced genome annotation or multiple-genomic tree constructions. Extreme value distribution based on the Karlin-Altschul model, usually advised for large-scale comparisons are not always valid, particularly in the case of comparisons of non-biased with nucleotide-biased genomes (such that of Plasmodium falciparum). Z-values estimates based on Monte Carlo technics, can be calculated experimentally for any alignment output, whatever the method used. Empirically, a Z-value higher than approximately 8 is supposed reasonable to assess that an alignment score is significant, but this arbitrary figure was never theoretically justified. RESULTS: In this paper, we used the Bienaymé-Chebyshev inequality to demonstrate a theorem of the upper limit of an alignment score probability (or P-value). This theorem implies that a computed Z-value is a statistical test, a single-linkage clustering criterion and that 1/Z-value(2) is an upper limit to the probability of an alignment score whatever the actual probability law is. Therefore, this study provides the missing theoretical link between a Z-value cut-off used for an automatic clustering of putative orthologs and/or paralogs, and the corresponding statistical risk in such genome-scale comparisons (using non-biased or biased genomes).

Algorithms↗

PubMed2006

Systematic interpretation of microarray data using experiment annotations.

BACKGROUND: Up to now, microarray data are mostly assessed in context with only one or few parameters characterizing the experimental conditions under study. More explicit experiment annotations, however, are highly useful for interpreting microarray data, when available in a statistically accessible format. RESULTS: We provide means to preprocess these additional data, and to extract relevant traits corresponding to the transcription patterns under study. We found correspondence analysis particularly well-suited for mapping such extracted traits. It visualizes associations both among and between the traits, the hereby annotated experiments, and the genes, revealing how they are all interrelated. Here, we apply our methods to the systematic interpretation of radioactive (single channel) and two-channel data, stemming from model organisms such as yeast and drosophila up to complex human cancer samples. Inclusion of technical parameters allows for identification of artifacts and flaws in experimental design. CONCLUSION: Biological and clinical traits can act as landmarks in transcription space, systematically mapping the variance of large datasets from the predominant changes down toward intricate details.

Cluster Analysis↗

PubMed2006

Protein identification and expression analysis using mass spectrometry.

The identification and quantification of the proteins that a whole organism expresses under certain conditions is a main focus of high-throughput proteomics. Advanced proteomics approaches generate new biologically relevant data and potent hypotheses. A practical report of what proteome studies can and cannot accomplish in common laboratory settings is presented here. The review discusses the most popular tandem mass-spectrometry-based methods and focuses on how to produce reliable results. A step-by-step description of proteome experiments is given, including sample preparation, digestion, labeling, liquid chromatography, data processing, database searching and statistical analysis. The difficulties and bottlenecks of proteome analysis are addressed and the requirements for further improvements are discussed. Several diverse high-throughput proteomics-based studies of microorganisms are described.

Amino Acid Sequence↗

PubMed1998

Independence and statistical inference in clinical trial designs: a tutorial review.

The requirements for statistical approaches to the design, analysis, and interpretation of experimental data are now accepted by the scientific community. This is of particular importance in medical studies where public health consequences are of concern. Investigators in the clinical sciences should be cognizant of statistical principles in general, but should always be wary of the pursuing their own analyses and engage statisticians for data analysis whenever possible. Examples of circumstances that require statistical evaluation not found in textbooks and not always obvious to the lay person are pervasive. Incorrect statistical evaluation and analyses in such situations will result in erroneous and potentially serious misleading interpretation of clinical data. Although a statistician may not be responsible for any misinterpretations in such unfortunate circumstances, the quote often cited about statisticians and "damned liars" may appear to be more truth than fable. This article is a tutorial review and describes a common misuse of clinical data resulting in an apparently large sample size derived from a small number of patients. This mistake is a consequence of ignoring the dependency of results, treating multiple observations from a single patient as independent observations.

Data Interpretation, Statistical↗

PubMed1994

Issues in analyzing data: experiences with three data bases.

Analytic issues in stroke data base research are reviewed, drawing upon relevant experiences in the analyses of three observational data bases from a variety of clinical fields. The specifics of the data base construct, statistical issues and variations in possible interpretations of results are discussed. Responsible analyses of and conservative inferences from observational data bases are stressed.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Activity-based sleep-wake identification: an empirical test of methodological issues.

The effects of actigraph placement and device sensitivity on actigraphic automatic sleep-wake scoring were assessed using concomitant polysomnographic and wrist actigraphic data from dominant and nondominant hands of 20 adults and 16 adolescents during 1 laboratory night. Although activity levels differed between dominant and nondominant wrists during periods of sleep (F = 4.57; p < 0.05) and wake (F = 15.5; p < 0.0005), resulting sleep-wake scoring algorithms were essentially the same and were equally explanatory (R2 = 0.64; p < 0.0001). When the sleep-wake scoring algorithm derived from the nondominant hand was used to score the nondominant data for sleep-wake, overall agreement rates with polysomnography scoring ranged between 91 and 93% for the calibration and validation samples. Results obtained with the same algorithm for the dominant-wrist data were within the same range. Agreement for sleep scoring was consistently higher than for wake scoring. Statistical manipulation of activity levels before applying the scoring algorithm indicated that this algorithm is quite robust toward moderate changes in activity level. Use of "twin-wrist actigraphy" enables identification of artifacts that may result from breathing-related motions.

Adolescent↗

PubMed1993

[Chemical and thermal eye burns in the residential area of RWTH Aachen. Analysis of accidents in 1 year using a new automated documentation of findings].

BACKGROUND: Until now there were no statistical data on the incidence and the prevalence of eye burns. Therefore we studied all patients coming to our hospital from the area of Aachen with eye burns during the time from September 1990 until August 1991. PATIENTS AND METHODS: All patients underwent a standardized examination including special history of the burning agent, industrial medical aspects and the employers liability insurance association. The documentation of the anterior eye segment pathology was scored separately for each eye encoded by location and special items. This documentation was worked up by the aid of a database (Filemaker II). 171 patients with eye burns were documented during one year. 65 patients had both eyes burned resulting in 236 documented records. RESULTS: The 171 accidents can be divided in 104 (61%) industrial accidents and 64 (37%) housework accidents. 3 accidents were of unknown origin. Classification of burns was scored according to Reim 1991. 208 (88%) eyes showed score I burns, 27 (11.5%) score II and only one patient showed a score III eye burn. We saw 121 (70%) male patients, 39 (23%) female patients and 11 children (7%). The main age group ranged from 16-45 years. 28% (n = 30) of all accidents happened in machine factories, which have thereby in our study the highest incidence of industrial accidents. CONCLUSION: By means of a one-year statistic we found that over 60% of all eye burns were industrial accidents, 28 in machine factories and 20% in service industries. 37% houseworks accidents are very difficult to prevent because of a deficit of safety rules.

Accidents, Home↗

PubMed1996

[A documentation procedure for community social psychiatry services--a pilot project in Bielefeld and Minden].

The status of health reporting (on community levels) has improved considerably during recent years. It is being increasingly used as an instrument for planning, controlling and evaluating political processes. In addition to individual studies the statistics within the departments of the health authorities are an important factor for meaningful health reporting on a local level. The IDIS (from Jan. 1st, 1995 LOGD) and the social psychiatric services on the Minden-Lübbecke district and the city of Bielefeld have developed a programme for automation-aided management of the statistics for social psychiatric services on a local level. Details on the personal situation and illnesses of the clients as well as on the activities of the services staff are recorded and analysed. Based on the WHO programme EPI-info 6.01 the documentation programme SPD-STAT was developed. This programme is menudriven and, in addition to the functions for the statistical data input and retrieval of fixed table sets, also offers the possibility of processing data with the full functionality of the ANALYSIS-module of EPI-Info. Thus interactive ad-hoc evaluations for current questions are made possible. Using SPD-STAT in as many local regions in NRW as possible may be a big step forward for health reporting on local levels as well as for health reporting on a state level.

Community Health Planning↗

PubMed1989