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Results for “data reproducibility”

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At least 19 recordsLinked to original sources
PubMed2003

Validity of a population-based cancer register in Sweden--an assessment of data reproducibility in the South-East Region Prostate Cancer Register.

BACKGROUND: With a population-based setting, high coverage and accurately recorded data, the validity of a register is guaranteed. The South-East Region Prostate Cancer relies on the National Cancer Register as a basic source of data, thereby ensuring a high coverage of the corresponding geographic area. To assess the reproducibility of the data recorded a random sample of the cases were reviewed a second time and compared to the original recording. MATERIAL AND METHODS: The South-East Region Prostate Cancer Register was started in 1987. In addition to the basic data acquired from the Swedish National Register, it also includes tumour stage, grade, treatment and, since 1992, PSA. In the first stage of quality assessment 10 cases for each of the years 1987-1996 from Linköping University Hospital were randomly selected for two independent recodings according to the same protocol as the original registration. In the second step 10 cases each for the same years from the remaining 8 hospitals in the region were selected for a single recoding. RESULTS: No systematic deviations were seen between the two independent recodings from Linköping, a single recoding was therefore considered sufficient for assessing the reproducibility of the data from the remaining hospitals in the region. The Kappa values for agreement between the original registration and the single recoding ranged from 0.589 to 0.869. CONCLUSION: The population-based setting and high coverage guarantees the external validity of the register. The internal validity is ensured by the high reproducibility shown in the present study.

Humans↗
PubMed2003

Data reproducibility in fluorescence image analysis.

Fluorescence image analysis provides quantitative data on fluorescence in situ hybridization signals (FISH), immunofluorescence labelings, Green Fluorescent Protein (GFP) expression and microarrays. It is a valuable tool for decision making in the fields of biology and medicine. The aim of this study was to evaluate the reproducibility of fluorescence intensity measurements and standardization when acquisitions are performed under various but well defined conditions. Fluorescent intensity of standard beads (Inspeck series, Molecular Probes) was repeatedly measured using an image analyzer and automated procedures. Images were acquired using several integration times and neutral filter sets. A standardization procedure was used for expressing the data in a same unit: data were multiplied by the light attenuation factor and were divided by the CCD integration times. Results show that 1) standardization is possible 2) accurate and reliable fluorescence measurements can be obtained and 3) specimens showing large differences in fluorescence intensity can be objectively compared. Moreover fluorescent test slides including fluorochrome solutions and altuglas slides were tested for shading correction and as overall test systems.

Calibration↗
PubMed2006

Reproducing data.

Explore the source record for details and available documents.

Peer Review↗
PubMed1996

Reproducibility of data collected by patient interview.

This study examined the reproducibility of data, not generally considered at risk for poor patient recall, obtained on two separate occasions. Our study used data collected for a register of heart attacks in the Lower Hunter Region of New South Wales, and included 1675 patients who were registered at least twice. Reporting inconsistencies between occasions were assessed for eight data items. We found that the sex of five patients had been recorded differently on the two occasions. Among patients interviewed on both occasions, between 0.5 per cent and 2.0 per cent of patients had inconsistent reports for marital status, country of birth, smoking status and height, 2.7 per cent for date of birth, 13 per cent for education level and between 1.6 per cent and 9.6 per cent for the history of various medical conditions. Patients not from an English-speaking background, over 60 years of age or without tertiary education tended to have higher rates of inconsistent reporting. Time between occasions, marital status and sex were not associated with increased rates of inconsistent reporting. We concluded that apparently straightforward data items, such as date of birth and education level, were not perfectly reproducible when obtained by patient interview on separate occasions. Our results provide a starting point for sensitivity analysis in other studies if the potential inaccuracies in reporting of such data should be of concern.

Data Collection↗
PubMed1992

Reproducibility of data obtained by a newly developed anterior eye segment analysis system, EAS-1000.

The reproducibility of data obtained from the recently developed anterior eye segment analysis system (EAS-1000) was evaluated. 40 normal eyes and 62 cataractous eyes were examined at Kanazawa Medical University Hospital or Yayoi Hospital. The radius of the corneal curvature, the corneal thickness, anterior chamber depth, whole lens thickness, anterior chamber angle and the scattering light intensity were all observed on a slit section of the lens, and the intrapupillary area of the cataractous shadow was measured from a retroillumination image. The measurements were made twice at an interval of 14.2 days. There were no significant differences between the data of the 1st and 2nd examination in either place.

Adolescent↗
PubMed1992

Reproducibility of data from a hand-held digital pulp tester used on teeth and oral soft tissue.

Controlled studies of the reproducibility of data from electronic pulp testing instruments are limited and contain few statistical analyses. The reproducibility of these readings is important if the instrument is to be used for determining differences in sensitivity. Twenty human subjects (16 male) were used in this study. One incisor, one premolar, one molar tooth with small or no restorations, and two gingival soft tissue positions from each upper and lower arch of each subject were stimulated with the Analytic Technology vitality scanner. This procedure was repeated twice with a 5-minute rest between each trial, for a total of three trials. Each subject was then seen again after a period of at least 3 days, at which time the trials were repeated. The collected data were grouped by trial, tooth position, and day. Paired t test analysis of both the absolute difference between any two trials on the same day and the average of the absolute differences between corresponding trials on days 1 and 2 showed no statistically significant differences (p greater than 0.05). Accommodation to the stimulus was evaluated by examining differences in the mean values between the three same-day trials. The Analytic Technology vitality scanner was found to be reproducible both for consecutive same-day trials and for corresponding trials on different days. No same-day trends in meter readings were noted.

Adult↗
PubMed1977

Reproducibility of data on steady-state gas exchange and indices of maldistribution of ventilation and blood flow.

The reproducibility of data on steady-state gas exchange and arterial blood gas levels was examined in 45 patients with similar pathophysiologic abnormalities (idiopathic scoliosis) by comparing the data obtained during two sequential periods breathing air. Comparison in all patients of 12 variables by paired t-test demonstrated statistically significant differences in the following three variables: the ratio of physiologic dead space to tidal volume (Vd/TV), the alveolar-arterial oxygen pressure difference (P[A-a]O2), and the arterial oxygen tension. By excluding four patients whose respiratory quotient was greater than two standard deviations from the mean value and one patient with a marked change in the pattern of ventilation, only the Vd/TV was significantly different (P less than 0.05). The range of the coefficients of variation was wide. The highest, which was for P(A-a)O2, was 18.8 percent; the majority were in range of 6 to 13 percent (minute ventilation, TV, frequency, oxygen consumption and carbon dioxide production, respiratory quotient, Vd/TV, dead space, and alveolar ventilation), and the coefficients of variation of partial pressure of oxygen and carbon dioxide in the arterial blood were, respectively, 3.6 and 3.4 percent.

Blood Gas Analysis↗
PubMed2002

RNA amplification results in reproducible microarray data with slight ratio bias.

Microarray expression analysis demands large amounts of RNA that are often not available. RNA amplification techniques have been developed to overcome this prcblem, but limited data are available regarding the reproducibility and maintenance of original transcript ratios. We optimized and validated two amplification techniques: a modified in vitro transcription for the linear amplification of 3 microg total RNA and a SMART PCR-based technique for the exponential amplification of 50 ng total RNA. To determine bias between transcript ratios, we compared the expression profiles in mouse testis versus spleen between the two amplification methods and a standard labeling protocol, using microarrays containing 4596 cDNAs spotted in duplicate. With each method, replicate hybridizations were highly reproducible. However, when comparing the amplification methods to standard labeling, correlation coefficients were lower. Twelve genes that exhibited inconsistent or contradictory expression ratios among the three methods were verified by quantitative RT-PCR. The amplification methods showed slightly more discrepancies in the expression ratios when compared to quantitative RT-PCR results but were more sensitive in terms of detecting expressed genes. In conclusion, although amplification methods introduce slight changes in the transcript ratios compared to standard labeling, they are highly reproducible. For small sample size, in vitro transcription is the preferred method, but one should never combine different labeling strategies within a single study.

Blotting, Southern↗
PubMedDate not supplied

Assessing reproducibility of data obtained with instruments based on continuous measurements.

Data obtained with any research tool must be reproducible, a concept referred to as reliability. Three techniques are often used to evaluate reliability of tools using continuous data in aging research: intraclass correlation coefficients (ICC), Pearson correlations, and paired t tests. These are often construed as equivalent when applied to reliability. This is not correct, and may lead researchers to select instruments based on statistics that may not reflect actual reliability. The purpose of this paper is to compare the reliability estimates produced by these three techniques and determine the preferable technique. A hypothetical dataset was produced to evaluate the reliability estimates obtained with ICC, Pearson correlations, and paired t tests in three different situations. For each situation two sets of 20 observations were created to simulate an intrarater or inter-rater paradigm, based on 20 participants with two observations per participant. Situations were designed to demonstrate good agreement, systematic bias, or substantial random measurement error. In the situation demonstrating good agreement, all three techniques supported the conclusion that the data were reliable. In the situation demonstrating systematic bias, the ICC and t test suggested the data were not reliable, whereas the Pearson correlation suggested high reliability despite the systematic discrepancy. In the situation representing substantial random measurement error where low reliability was expected, the ICC and Pearson coefficient accurately illustrated this. The t test suggested the data were reliable. The ICC is the preferred technique to measure reliability. Although there are some limitations associated with the use of this technique, they can be overcome.

Aging↗
PubMed2005

A critical appraisal of the performance, reporting, and interpretation of studies comparing carotid plaque imaging with histology.

BACKGROUND AND PURPOSE: Carotid plaque instability is an important determinant of stroke risk. There are now a number of different imaging techniques that provide information on carotid plaque morphology. However, it is unclear how they compare with one another or whether they can reliably assess plaque instability. Studies comparing imaging with pathology have shown highly variable results, even for similar imaging techniques. This may be because of variable pathology techniques rather than differences in imaging. METHODS: We performed a systematic review of studies that compared carotid imaging with histology of the excised plaque published between January 1995 and September 2004. We assessed the quality and comparability of these studies. In particular, we determined which histology methods were used and whether observer reproducibility of the histology assessment was reported. RESULTS: Among 73 eligible studies, histological methods were poorly reported and highly variable; 23% reported reproducibility data for imaging and only 12% reported reproducibility data for histology. Of 29 studies that reported quantitative results of blinded comparisons, there were methodological deficiencies and the results were highly variable. No study considered the extent to which the lack of reproducibility influenced the imaging-pathological correlations reported. CONCLUSIONS: Pathological correlation in studies of carotid plaque imaging cannot be reliably interpreted or compared because of incomparable and poorly reported histology methods. We make recommendations for the performance, reporting, and interpretation of imaging-pathological correlation studies and highlight the need for consensus guidelines.

Carotid Arteries↗
PubMed2006

Evaluation of image processing programs for accurate measurement of budding and fission yeast morphology.

To study the cellular functions of gene products, various yeast morphological mutants have been investigated. To describe yeast morphology objectively, we have developed image processing programs for budding and fission yeast. The programs, named CalMorph for budding yeast and F-CalMorph for fission yeast, directly process microscopic images and generate quantitative data about yeast cell shape, nuclear shape and location, and actin distribution. Using CalMorph, we can easily and quickly obtain various quantitative data reproducibly. To study the utility and reliability of CalMorph, we evaluated its data in three ways: (1) The programs extracted three-dimensional bud information from two-dimensional digital images with a low error rate (<1%). (2) The absolute values of the diameters of manufactured fluorescent beads calculated with CalMorph were very close to those given in the manufacturer's data sheet. (3) The programs generated reproducible data consistent with that obtained by hand. Based on these results, we determined that CalMorph could monitor yeast morphological changes accompanied by the progression of the cell cycle. We discuss the potential of the CalMorph series as a novel tool for the analysis of yeast cell morphology.

Cell Division↗
PubMed1997

Comparison of serum protein electrophoresis by agarose gel and capillary zone electrophoresis in a clinical setting.

Capillary zone electrophoresis (CZE) offers the potential for automating serum protein electrophoretic analysis traditionally performed on standard thin-layer agarose gels. The following describes the use of CZE compared to agarose gel electrophoresis (AGE) for the detection of dysproteinemia and paraproteinemia in a clinical study involving 240 patients. The study includes within-run and between-run reproducibility data on the Paragon CZE 2000 Clinical Capillary Electrophoresis System, in addition to concordance data between the two methodologies. Paraprotein quantitation studies comparing AGE versus CZE were also performed. Reproducibility for the automated CZE system was superior to the AGE system. Improved reproducibility for the CZE method is largely due to measuring protein absorbance directly at 214 nm versus the traditional AGE method that measures the amount of dye adsorbed to protein. Reproducibility data as percent coefficient of variance (% CV) for the five classic bands in a normal control serum for between-run precision ranged from 1.2 to 4.5% for CZE compared to AGE, which ranged from 3.8 to 8.0% CV. Concordance studies between AGE and CZE involving dysproteinemias including hypogammaglobulinemia, polyclonal and monoclonal gammopathies, acute and chronic inflammation, nephrosis, hepatodegenerative disease, cirrhosis, and iron deficiency anemia showed 96% agreement. Paraprotein classification, which compared the CZE immunosubtraction method to immunofixation electrophoresis (IFE) on agarose, showed 100% agreement. Certain dysproteinemias involving beta lipoprotein were in partial concordance due to the inability of the CZE procedure to detect this component. Detection limits for monoclonal gammopathies, providing they were not comigrating with other proteins, were IgG 50 mg/dL, IgM 75 mg/dL, and IgA 75 mg/dL. Paraprotein quantitative studies between the two methods showed less than a +/- 0.2 g/dL variation.

Blood Proteins↗
PubMed1994

The reproducibility of data from a Food Frequency Questionnaire among low-income Latina mothers and their children.

We examined the 3-month and 1-year reproducibility of mothers' and children's dietary intakes of calories and 11 nutrients derived from oral administrations of a food frequency questionnaire to 166 Latina women. One-year correlations generally ranged from 0.40 to 0.55 for both mothers and children. For most nutrients, roughly half the children in the highest (lowest) quartile of intake at baseline were also in the highest (lowest) quartile 1 year later. The food frequency questionnaire has great potential for measuring typical nutrient intakes in these populations.

Child↗
PubMed2000

[Measuring retinal circulation with the Heidelberg retinal flowmeter: reproducibility of data and no effect of metipranolol in normal probands].

PURPOSE: We wanted to know whether topical Metipranolol has any effect on ocular blood flow. Before starting this investigation using the Heidelberg Retina Flowmeter, we studied the reproducibility of this device. METHOD: Retinal blood flow was determined in 15 healthy volunteers. Altogether, each volunteer was measured 20 times (4 different days with 5 pictures each). Coefficients of variation were calculated for both, the short term fluctuation and the long term fluctuation. After that, the effect of metipranolol was tested in 14 of the 15 volunteers mentioned above. This was done in a randomized, placebo controlled, double masked and crossover designed study. RESULTS: The mean coefficients of variation were 21% for the short term fluctuation and 13% for the long term fluctuation. There was a significant effect of learning, i.e. coefficients of variation decreased with increasing experience of the investigator (MVR). Blood flow values did not differ significantly between metipranolol and placebo. CONCLUSIONS: 1. The reproducibility of blood flow values measured with the Heidelberg Retina flowmeter are sufficient, at least if the device is used in clinical studies. When performing those studies, the learning curve of the investigator should be taken into account. 2. The topical application of metipranolol does not alter the retinal blood flow in healthy volunteers.

Adult↗
PubMed2001

[Development of a standardized instrument for quantitative and reproducible rehabilitation data assessment after polytrauma (HASPOC)].

INTRODUCTION: Previous scoring systems for measurement of the quality of outcome are based on scores regarding injuries to individual body regions. Known scores which describe several organ regions are of no importance for trauma patients. Therefore a new rehabilitation outcome evaluation score was developed at our hospital. METHODS: Based on a prospective reinvestigation, a score system was developed that allows a quantitative appraisal of the subjective and objective outcome. A complete physical examination was performed, including ROM, neurologic examination and strength analysis. Part I (113 questions) is to be filled out by the patient; part II (191 questions) focusses on different body regions, physical examination and functional scoring. Included are the MFA, FIM, GCO and Frankel score. A final score (HASPOC) was developed to give a quantitative result of the outcome. RESULTS: The new score has a range from 5 to 411 points. One hundred and fifty patients were re-examined. The mean follow-up time was 2.2 +/- 0.1 years. The SF 12 indicated an outcome more than satisfactory in 63% of cases. The MFA demonstrated moderate or severe restrictions in 41%, in the case of injuries of the lower extremity in 52% of patients. The HASPOC indicated a mean of 44.5 points. CONCLUSION: This paper describes the development, structure, and the quantitative outcome of rehabilitation in polytrauma patients. This standardized rehabilitation instrument deals with a very heterogeneous patient population and shows the rehabilitation deficits accurately. Implemented recognized evaluations allow comparison of these results with those of other scoring systems.

Data Collection↗