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At least 415 records · Page 23Linked to original sources
PubMed2005

Does data rounding-off influence reproducibility index estimates?

The intraclass correlation coefficient (ICC) is the reproducibility index commonly used to assess the reproducibility level of continuous data. Such data are collected with finite precision (i.e., a finite number of decimal digits corresponding to the level of data rounding-off error). We therefore investigated the consequences of having finite precision for data on ICC estimates, thus comparing ICC estimates in presence of rounding-off to those associated with data with infinite precision. As long as the rounding-off level is less than 0.3sigmaX (where sigmaX is the standard deviation of the outcome measured), there is no practical consequence on the ICC estimate. Therefore, in most practical situations the consequences of rounding-off data on the estimation of reproducibility levels can be ignored.

Data Collection↗
PubMed1988

How reproducible are flow cytometry data from paraffin-embedded blocks?

The purpose of this technical report is to determine the reproducibility of flow cytometry data for ploidy and cell cycle kinetics using paraffin-embedded blocks of breast cancer tissue. One block from each of 39 tumors was studied in this report with each block having multiple sections analyzed independently. All of these sections gave ploidy analyses, while only 34 gave cell kinetic values. The standard deviation for the DNA index value in the multiple analysis study was less than 0.1 in all but three cases. The cell kinetic values gave larger variability, and the actual values were dependent on the method of analysis. Comparison of the variability for each method of analysis could not predict which procedure was superior. These results would indicate that ploidy is a reproducible value, while cell kinetic parameters should only be used as an indicator of proliferative activity that has been normalized to the mean or median of a large set of observations processed and analyzed by the same procedure.

Breast Neoplasms↗
PubMed2004

Repeatability and reproducibility of high-concentration data in reversed-phase liquid chromatography. III. Isotherm reproducibility on Kromasil C18.

Single component equilibrium isotherms of six compounds (aniline, caffeine, ethylbenzene, phenol, propranolol, and theophylline) were determined by the inverse method on 10 Kromasil-C18 columns, using water-methanol solutions as the mobile phase. This method offers an economic and fast isotherm determination by means of the overloaded band profiles of the compounds. Five out of the ten columns used in this test come from the same batch whilst the other five columns represent five additional batches. Statistical evaluation was used to assess the reproducibility of the isotherm parameters. We found that the column-to-column reproducibility of the isotherm parameters is of the same magnitude as the batch-to-batch reproducibility (with the exception of one outlier column). In most of the cases, the reproducibilities of the saturation capacities and that of the retention factors are excellent, they are typically between 1.2 and 3%, and very often below 2%. Within the limits of the experimental precision, these results agree with those obtained earlier, using a conventional method of isotherm determination.

Adsorption↗
PubMed1989

Stereological estimates of nuclear volume in primary lung cancer.

The aim of this study is to provide unbiased, objective and reproducible morphometric data on primary lung carcinomas by using the stereological principle of estimating volume weighed mean volume of particles of arbitrary shape. The study includes 30 lung specimens; 10 from small cell carcinoma, 10 from squamous cell carcinoma, and 10 from adenocarcinoma. After standard fixation, embedding, sectioning and hematoxylin eosin staining, the mean nuclear volume was estimated using the formula: v upsilon = pi/3 . l0(3), where l0 is the length of the intercept through a test point hitting a nucleus measured in a random direction through the test point. The collection of the data took less than 10 min per specimen. The mean nuclear volume of small cell carcinomas varied from 109 to 238 microns 3 (group mean 152 microns 3), in squamous cell carcinomas from 407 to 826 microns 3, and in adenocarcinomas from 411 to 1046 microns 3 (group mean 736 microns 3). This simple and rapid method seems to provide unbiased, objective and reproducible data useful in the description and separation of primary lung carcinomas.

Adenocarcinoma↗
PubMed2002

Evaluation of the MicroFoss system for enumeration of total viable count, Escherichia coli and coliforms in ground beef.

This study was conducted to evaluate the performance of the MicroFoss system (Biosys, Ann Arbor, MI) for enumeration of total viable organisms, Escherichia coli and coliforms in ground beef. The system performance was compared to that of the USDA Bacteriological Analytical Method (BAM) reference culture methods. The correlation coefficients for the regression lines comparing the MicroFoss system detection times to the results of plate count methods for the total viable counts, coliform counts and the most probable number (MPN) method for E. coli were -0.95, -0.96 and -0.97, respectively. Tests comparing the reproducibility of data generated independently by two technicians on the same batch of samples showed no significant differences (P>0.05) in the MicroFoss detection times and culture results. The plate count methods for the total viable counts and coliform counts, and the MPN method for E. coli required 10, 11 and 22 times, respectively, the amount of time to complete tests compared to the length of time required to perform these tests using the MicroFoss system. The MicroFoss system produced reproducible data and provided a rapid and cost-efficient alternative method for enumeration of TVC, coliforms and E. coli in ground beef.

Animals↗
PubMed1976

The reproducibility of dietary intake data in a prospective study of gastrointestinal cancer.

To test the reproducibility of the dietary questionnaire used in the Japan-Hawaii Cancer Study and to measure the consistency of dietary patterns over time, 109 men were reinterviewed with the same questionnaire after a 6-month interval and 111 men were reinterviewed after a 2-year interval. The responses for intake of the 33 food items in the questionnaire were fairly reproducible. Food items with substantial correlation coefficients in both groups of men tended to be consumed on a more habitual basis. This finding suggests that if habitually consumed foods are linked to specific cancers, it is less likely that such associations occur by chance. This is of particular importance because when many food items are considered in a dietary study, chance association between a specific food and cancer is not an infrequent event.

Aged↗
PubMed1981

Point by Point Examination of the equilibrium gated radionuclide left ventricular time activity curve; validation by biplane angiography.

Examination of the time course of left ventricular ejection has been found useful in several clinical applications. Equilibrium gated radionuclide angiography provides non-invasive means to obtain the ventricular ejection curve. To evaluate the accuracy of the equilibrium gated radionuclide left ventricular volume curve we compared equilibrium gated radionuclide date with biplane cine-angiography in 16 patients examining each set of data on a point by point basis. The cine-angiographic data consisted of 60 frame per second biplane cineangiograms and the radionuclide data consisted of 28 points spanning the cardiac cycle. All data was normalized for the patient's heart rate and stroke volume. The equilibrium gated radionuclide angiographic data accurately reproduced the contrast angiographic data at each point on the curve. This result justifies using the equilibrium gated radionuclide time activity curve to evaluate parameters such as early systolic ejection rates or rates of maximum ventricular ejection.

Cardiac Output↗
PubMed2006

Phase equilibria in carbon dioxide expanded solvents: Experiments and molecular simulations.

We present complementary molecular simulations and experimental results of phase equilibria for carbon dioxide expanded acetonitrile, methanol, ethanol, acetone, acetic acid, toluene, and 1-octene. The volume expansion measurements were done using a high-pressure Jerguson view cell. Molecular simulations were performed using the Gibbs ensemble Monte Carlo method. Calculations in the canonical ensemble (NVT) were performed to determine the coexistence curve of the pure solvent systems. Binary mixtures were simulated in the isobaric-isothermal distribution (NPT). Predictions of vapor-liquid equilibria of the pure components agree well with experimental data. The simulations accurately reproduced experimental data on saturated liquid and vapor densities for carbon dioxide, methanol, ethanol, acetone, acetic acid, toluene, and 1-octene. In all carbon dioxide expanded liquids (CXL's) studied, the molecular simulation results for the volume expansion of these binary mixtures were found to be as good as, and in many cases superior to, predictions based on the Peng-Robinson equation of state, demonstrating the utility of molecular simulation in the prediction of CXL phase equilibria.

Carbon Dioxide↗
PubMed1997

An assessment, and reproducibility of food frequency data provided by hospital controls.

In order to assess the comparability and reproducibility of information from a questionnaire used in a case-control study on digestive tract cancers conducted in Italy, a total of 400 subjects were randomly selected from a large sample of hospital controls and contacted at home to repeat the interview. Of these, 294 (73%) subjects were re-interviewed. Mean values of intake were computed for the 400 subjects selected, and among the 294 responders for the first and second interview. These values were comparable, most of them being within a 10% range. Spectrum correlation coefficient (rs) values of consumption between the first and second interview were > 0.65 for consumption of pastries, pasta or rice, bread, fish, milk, green vegetables, eggs and apples; between 0.50 and 0.65 for meat, chicken, liver, ham, cold cuts, cheese, fruit, cabbage, carrots, tomatoes, peppers, salad, citrus fruit and melon; and lower than 0.50 for a few infrequently eaten foods. For all foods, the estimated average weekly intake in the second interview increased consistently and substantially with increasing tertile of the first interview. This study shows a satisfactory comparability of dietary information from subjects interviewed at home with that provided during their original interview in the hospital, and a good reproducibility of information collected in the two settings.

Case-Control Studies↗
PubMed1999

Reproducibility of maximal exercise test data in the HERITAGE family study.

PURPOSE: The reproducibility of responses to maximal cycle ergometer testing was determined using data from the HERITAGE Family study at four Clinical Centers in the United States and Canada. METHODS: Reproducibility was determined from maximal exercise test data obtained a) on 2 d in a sample of 390 subjects (198 men and 192 women), b) across 4 d in an Intracenter Quality Control (ICQC) substudy with 55 subjects who were not part of the main study, and c) across 2 wk in a Traveling Crew Quality Control (TCQC) substudy with the same eight subjects who were tested at each of the four centers. Reproducibility was evaluated using technical errors, coefficients of variation (CV) for repeated measures, and intraclass correlation coefficients (ICC) for selected variables obtained on the main cohort, as well as on the ICQC and TCQC substudies. RESULTS: With the exception of systolic and diastolic blood pressures and respiratory exchange ratio, all the other variables (heart rate, ventilation, VO2, and VCO2) were highly reproducible, with CV below 10% and ICC over 0.86. These results were similar to those previously reported on the same subjects at a submaximal power output associated with 60% VO2max. Results were consistent for the main cohort, the ICQC sample, the TCQC sample, and across all four Clinical Centers. CONCLUSIONS: Day-to-day variations are small and reproducibility is high for maximal values of heart rate, ventilation, VO2 and VCO2 at each of the four Clinical Centers of the HERITAGE Family Study.

Adolescent↗
PubMed2006

Reproducibility of intravascular ultrasound radiofrequency data analysis: implications for the design of longitudinal studies.

OBJECTIVES: The purpose of this study was to assess in vivo the reproducibility of tissue characterization using spectral analysis of intravascular ultrasound (IVUS) radiofrequency data (IVUS-VH). BACKGROUND: Despite the need for reproducibility data to design longitudinal studies, such information remains unexplored. METHODS AND RESULTS: IVUS-VH (Volcano Corp., Rancho Cordova, USA) was performed in patients referred for elective percutaneous intervention and in whom a non-intervened vessel was judged suitable for a safe IVUS interrogation. The IVUS catheters used were commercially available catheters (20 MHz, Volcano Corp., Rancho Cordova, USA). Following IVUS-VH acquisition, and after the disengagement and re-engagement of the guiding catheter, an additional acquisition was performed using a new IVUS catheter. Fifteen patients with 16 non-significant lesions were assessed by 2 independent observers. The relative inter-catheter differences regarding geometrical measurements were negligible for both observers. The inter-catheter relative difference in plaque cross-sectional area (CSA) was 3.2% for observer 1 and 0.5% for observer 2. The limits of agreement for (observer 1 measurements) lumen, vessel, plaque and plaque burden measurements were 0.82, -1.10 mm(2); 0.80, -0.66 mm(2); 1.08, -0.66 mm(2); and 5.83, -3.89%; respectively. Limits of agreement for calcium, fibrous, fibrolipidic and necrotic core CSA measurements were 0.22, -0.25 mm(2); 1.02, -0.71 mm(2); 0.61, -0.65 mm(2); and 0.43, -0.38 mm(2) respectively. Regarding the inter-observer agreement, the limits of agreement for lumen, vessel, plaque and plaque burden measurements were 2.61, -2.09 mm(2); 2.20-3.03 mm(2); 1.70, -3.04 mm(2); and 9.16, -16.41%; respectively, and for calcium, fibrous, fibrolipidic and necrotic core measurements of 0.08, -0.09 mm(2); 0.89, -1.28 mm(2); 0.74, -1.06 mm(2); and 0.16, -0.20 mm(2); respectively. CONCLUSIONS: The present study demonstrates that the geometrical and compositional output of IVUS-VH is acceptably reproducible.

Coronary Disease↗
PubMed1981

Reproducibility of gamma camera data.

The increasing use of quantification in the interpretation of nuclear medicine images requires a knowledge of the errors associated with the estimation of the activity in a volume of interest from the recorded count rate data. Using sources of known cross-sectional area from 1 to 25 cm2, errors caused by variations in the count rate, day of measurement, source position in the camera field of view, and source size are evaluated. The effect of source depth in tissue-equivalent (TE) medium on the reproducibility of the data is also investigated. For a given source size at a known depth, variations in camera response lead to an error (SD) of a least 6% that increases as either the source size or the depth of the source in TE medium is increased. Failure to estimate accurately the true depth of the organ can also be a major source of error. The use of two conventional types of flood correction technique ('count-skipping' and matrix division) is found to increase the error only in the case of the smallest source.

Models, Structural↗
PubMed1997

Nasal airway in cleft-palate patients: acoustic rhinometric data.

The objective of this study was to investigate an instrumental assessment technique for acquiring reproducible, metric data on the nasal airway in cleft-palate associated nasal dysplasia. A consecutive sample of 23 unilateral, 17 bilateral CLP patients and 15 controls with subjective normal nasal patency from a cleft-palate rehabilitation centre were studied. A series of transnasal acoustic measurements (pressure wave: 55 dB for 2 ms) of nasal volume were performed before and after topical decongestion with 2 x 0.3 mg of xylometazoline. A standardized regimen of acoustic parameters of the nasal valve and the adjacent segment of the nasal cavity were calculated. The cleft side yielded a significantly (40%) lower nasal volume than the non-cleft side. Considerably lower values were recorded for the isthmus of the cleft side (0.31 cm2) compared with the non-cleft side (0.52 cm2). Decongestion capacity was higher in the posterior segment, indicating cleft-side massive mucosal hypertrophy. In bilateral CLP, the isthmus measured 0.46 cm2. By decongestion, individual side differences were reduced in unilateral CLP patients but enhanced in bilateral clefts. The prevailing pattern of the cleft-side airway profile can be described as a 'descending W'. Acoustic rhinometry is a non-invasive, instrumental assessment technique for acquiring reproducible metric data of nasal dysplasia in cleft-palate patients. By identification of the location and amount of nasal obstruction, it provides topographic information about the individual airway profile. It is suitable for the longitudinal investigation of nasal-airway development, as well as the preparation and follow-up of corrective rhinosurgery.

Acoustics↗
PubMed1993

Intra-articular ultrasonic stimulation and intracutaneous electrical stimulation: evoked potential and visual analogue scale data.

The reproducibility of focussed ultrasound-induced intra-articular pain was compared with that of electrically induced cutaneous pain over a period of time by measuring both the evoked potential (EP) amplitude and visual analogue scale (VAS) score. The responses to ultrasound were more variable than those to electrical stimulation. A greater degree of accommodation occurred during electrical stimulation compared with ultrasound stimulation. A statistically significant correlation between the EP amplitude and the VAS score was found for each form of stimulation. Changes in EP amplitude correlated with changes in the perception of pain as measured by the VAS score, rather than stimulus intensity, which remained constant for each subject throughout the duration of the experiment. A single oral dose of pethidine produced a statistically significant decrease in the EP amplitude and the VAS score in each case.

Cartilage, Articular↗
PubMed2006

A mode coupling theory description of the short- and long-time dynamics of nematogens in the isotropic phase.

Optical heterodyne-detected optical Kerr effect (OHD-OKE) experimental data are pre-sented on nematogens 4-(trans-4-n-octylcyclohexyl)isothiocyanatobenzene (8-CHBT), and 4-(4-pentyl-cyclohexyl)-benzonitrile (5-PCH) in the isotropic phase. The 8-CHBT and 5-PCH data and previously published data on 4-pentyl-4-biphenylcarbonitrile (5-CB) are analyzed using a modification of a schematic mode coupling theory (MCT) that has been successful in describing the dynamics of supercooled liquids. At long time, the OHD-OKE data (orientational relaxation) are well described with the standard Landau-de Gennes (LdG) theory. The data decay as a single exponential. The decay time diverges as the isotropic to nematic phase transition is approached from above. Previously there has been no theory that can describe the complex dynamics that occur at times short compared to the LdG exponential decay. Earlier, it has been noted that the short-time nematogen dynamics, which consist of several power laws, have a functional form identical to that observed for the short time behavior of the orientational relaxation of supercooled liquids. The temperature-dependent orientational dynamics of supercooled liquids have recently been successfully described using a schematic mode coupling theory. The schematic MCT theory that fits the supercooled liquid data does not reproduce the nematogen data within experimental error. The similarities of the nematogen data to the supercooled liquid data are the motivation for applying a modification of the successful MCT theory to nematogen dynamics in the isotropic phase. The results presented below show that the new schematic MCT theory does an excellent job of reproducing the nematogen isotropic phase OHD-OKE data on all time scales and at all temperatures.

Journal Article↗
PubMedDate not supplied

Decelerated growth and longevity in men.

Severe dietary restriction delays the physical development of rodents and leads to adult animals of reduced body size but significantly increased life expectancy. We tried to find a similar relationship in human populations using demographical and statistical methods. We show for the total Spanish male population that the mean adult body height reliably reflects the regional living and nutritional conditions. This relation does not only hold for todays socioeconomic data but can also be reproduced using data on family income in the mid 19th century. We calculated the mean height of young men liable to the military service around 1860 and determined their longevity retrospectively using posterior census data. This was done separately for all the Spanish provinces. The linear regression between both parameters manifests a statistically highly significant relationship: the smaller the mean height at age 18 in a province, the higher the chance for people living there to reach high chronological ages. Migrational movements, selection, mortality due to epidemics or unreliability of the population censuses can be largely ruled out as explications for the described correlation. Furthermore, we determined the secular growth trend in Spain for the last 130 years. From 1860 to 1920 the mean height increased by 2.7 cm, from 1920 to 1987 by another 9.8 cm. Since 1950 the trend is above 2 cm per decade country-wide. From 1974 onwards it amounts to 2.89 +/- 0.17. Such high values were worldwide looked upon as isolated cases found only in geographically and socially isolated population subgroups during very limited periods.

Journal Article↗
PubMed1999

The effects of increasing heel height on forefoot peak pressure.

The purpose of this study was to determine the effect of increasing heel height on peak forefoot pressure. Thirty-five women were examined while wearing sneakers and shoes with 2-inch and 3-inch heels. An in-shoe pressure-measurement system was used to document the magnitude and location of plantar peak pressures. Pressure under the forefoot was found to increase significantly with increasing heel height. As the heel height increased, the peak pressure shifted toward the first metatarsal and the hallux. The reproducibility of data obtained with the in-shoe pressure-measurement system was tested in five subjects; the data were found to be reproducible to within approximately 3% of measured pressures.

Adult↗