SEARCH · PubMed Health

Results for “Comparison”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources

PubMed1979

The class-inclusion task: question form and distributive comparisons.

The class-inclusion task is regarded by Piaget as a measure of the child's mastery of the structure of hierarchical classification. Class-inclusion was improved by changing the wording of the question to conform to standard English usage. A theoretical argument is offered that the child's difficulties with this task derive from confusion of collective comparisons, in which properties of classes are compared, and distributive comparisons, in which properties of elements are compared. A grammatical constraint on expression of distributive comparisons--an element of a class cannot be compared to an element of an included subclass--is hypothesized to be overgeneralized to expressions referring to collective comparisons such as the class-inclusion task. This hypothesis accounts for the improvement in class-inclusion performance with changes in wording of the question and for the finding that young children's response to class-inclusion questions and to ungrammatical requests for comparison of an element of a class and an element of an included subclass are similar: the children respond readily but understand wrongly that the comparison involves coordinate classes.

Child↗

PubMed2003

Temperature measurement in intensive care patients: comparison of urinary bladder, oesophageal, rectal, axillary, and inguinal methods versus pulmonary artery core method.

OBJECTIVE: Comparisons of urinary bladder, oesophageal, rectal, axillary, and inguinal temperatures versus pulmonary artery temperature. DESIGN: Prospective cohort study. SETTING: Intensive Care Unit of a University-Hospital. PATIENTS: Forty-two intensive care patients requiring a pulmonary artery catheter (PAC). INTERVENTION: Patients requiring PAC and without oesophageal, urinary bladder, and/or rectal disease or recent surgery were included in the study. Temperature was simultaneously monitored with PAC, urinary, oesophageal, and rectal electronic thermometers and with axillary and inguinal gallium-in-glass thermometers. Comparisons used a Bland and Altman method. MEASUREMENTS AND MAIN RESULTS: The pulmonary arterial temperature ranged from 33.7 degrees C to 40.2 degrees C. Urinary bladder temperature was assessed in the last 22 patients. A total of 529 temperature measurement comparisons were carried out (252 comparisons of esophageal, rectal, inguinal, axillary, and pulmonary artery temperature measurements in the first 20 patients, and 277 comparisons with overall methods in the last patients). Nine to 18 temperature measurement comparisons were carried out per patient (median = 13). The mean differences between pulmonary artery temperatures and those of the different methods studied were: oesophageal (0.11+/-0.30 degrees C), rectal (-0.07+/-0.40 degrees C), axillary (0.27+/-0.45 degrees C), inguinal (0.17+/-0.48 degrees C), urinary bladder (-0.21+/-0.20 degrees C). CONCLUSION: In critically ill patients, urinary bladder and oesophageal electronic thermometers are more reliable than the electronic rectal thermometer which is better than inguinal and axillary gallium-in-glass thermometers to measure core temperature.

Aged↗

PubMed2005

A comparison of three methods to collect submerged aquatic vegetation in a shallow lake.

Two boat-based and one in-water sampling method have been used to collect submerged aquatic vegetation (SAV) as part of a long-term monitoring program in Lake Okeechobee, Florida, USA. The boat-based methods consisted of collecting SAV with a ponar dredge, used only to collect Chara, and an oyster tongs-like rake apparatus, used to collect all SAV. The in-water method involved use of a 0.5 m2 PVC quadrat frame deployed by a diver. During summer 2002, SAV biomass samples were collected using all three methods at various sites in the lake to compare between-methods sampling precision. Sites used for these comparisons were selected based on plant type, plant density and sediment type. Statistical comparisons indicated that there were significant (p < or = 0.05) biomass differences in 8 of 15 possible pairwise comparisons between sampling method biomass means. In four of the eight comparisons, significantly higher biomass mean values were obtained using the quadrat frame. In three of the remaining four comparisons, significantly higher biomass mean values were obtained with the rake apparatus. For the fourth comparison, a significantly higher biomass mean value was obtained with the ponar dredge. Three of the four relationships between SAV biomass collected by the rake and the quadrat and the rake and the quadrat/ponar dredge were statistically significant, linear and explained between 67 and 78% of the biomass variability. There were no significant differences between regression coefficients or elevations for these relationships, therefore these regressions estimated the same population regression. The population regression coefficient was 0.95, suggesting that the quadrat and ponar over-sampled relative to the rake, but the amount of this over-sampling was very small. Since there was no consistent pattern in the sampling method which yielded the significantly different biomass values and there were no significant differences in sampling precision across a range of plant species, plant densities and two sediment types, the boat-based rake method appears to be a suitable replacement for the previously used ponar dredge and quadrat methods, when in-lake measurements are not practical.

Biomass↗

PubMed1991

A parallel computing approach to genetic sequence comparison: the master-worker paradigm with interworker communication.

We have implemented a parallel version of a dynamic programming biological sequence comparison algorithm to study the potential applicability of using parallel computers for genetic sequence comparisons. Our parallel program is built using C-Linda, a machine-independent parallel programming language, and was tested on both a 10 CPU Sequent Symmetry and a 64 CPU Intel Hypercube. C-Linda implements a shared associative memory model, "tuple space," through which multiple processes can communicate and coordinate control. In our master-worker (MW) parallel implementation, a master process creates several worker processes, extracts a test sequence and multiple library sequences from a database and stores them in tuple space. Each worker reads the test sequence and then repeatedly extracts library strings from tuple space, performs pairwise sequence comparison using a local comparison algorithm to generate a similarity score, and returns the similarity scores to tuple space. The master collects the scores from tuple space and identifies the best match over all library sequences. We also implemented a method of global interworker communication to reduce the total search time by stopping those string comparisons that had no chance of improving on the current best match. Comparisons of the total run time, speedup, and efficiency were made for parallel and sequential versions of a basic MW implementation as well as versions with the global abort threshold.

Algorithms↗

PubMed1989

A comparison of serial 49-lead precordial ECG maps and standard 6-lead precordial ECGs in patients with acute anterior Q wave myocardial infarction.

A comparison of 265 pairs of standard ECGs and 49-lead precordial maps in 20 patients with ST-segment elevations in anterior ECG leads on admission who eventually were diagnosed as having suffered an anterior Q wave myocardial infarction was carried out to investigate the diagnostic performance provided by the standard ECG in serial studies. Ten patients received intravenous methylprednisolone and 10 were given placebo on admission, and paired map-standard ECG studies were done. ST-segment elevations were taken as an index of ischemic injury and reduction of R wave amplitude or development of Q waves as a marker of developing necrosis. Methods of measurements and derivation of ECG parameters used in the analysis were the same for the standard ECGs and maps. Comparisons of percent change of five ECG-derived variables between 13 time points and admission, as assessed by the six precordial leads of the standard ECGs and the paired 49-lead maps, were made for the entire data base. A separate analysis to assess the performance of the standard ECG was carried out in a comparison of the methylprednisolone and placebo subgroups. In this latter assessment results of comparisons of the standard ECGs from the treatment and placebo cohorts were similar to the conclusions from the comparisons of the corresponding 49-lead maps. Comparisons for the entire 265 pairs of tracings by the two ECG systems demonstrated that the standard ECG is adequate to monitor quantitatively the ischemic injury and necrosis as reflected by the ECG in serial studies throughout the hospitalization and can be effectively employed in lieu of multilead precordial maps in the evaluation of therapeutic modalities for patients with anterior Q wave myocardial infarction.

Body Surface Area↗

PubMed1996

Cerebral activations during number multiplication and comparison: a PET study.

Positron emission tomography was used to examine the cerebral networks underlying number comparison and multiplication in eight normal volunteers. Cerebral blood flow was measured within anatomical regions of interest defined in each subject using magnetic resonance imaging. Three conditions were used: rest with eyes closed, mental multiplication of pairs of arabic digits and larger-smaller comparison of the same pairs. Both multiplication and comparison activated the left and right lateral occipital cortices, the left precentral gyrus, and the supplementary motor area. Beyond these common activations, multiplication activated also the left and right inferior parietal gyri, the left fusiform and lingual gyri, and the right cuneus. Relative to comparison, multiplication also yielded superior activity in the left lenticular nucleus and in Brodmann's area 8, and induced a hemispheric asymmetry in the activation of the precentral and inferior frontal gyri. Conversely, relative to multiplication, comparison yielded superior activity in the right superior temporal gyrus, the left and right middle temporal gyri, the right superior frontal gyrus, and the right inferior frontal gyrus. These results underline the role of bilateral inferior parietal regions in number processing and suggest that multiplication and comparison may rest on partially distinct networks.

Adult↗

PubMed2006

Radon activity concentration--a Euromet and BIPM supplementary comparison.

For the first time, a comparison of radon activity concentration in air has been performed within the scope of Euromet. In the project 657, 'Comparison of calibration facilities for the radon activity concentration,' 12 participants from 9 countries compared different radon reference atmospheres at 1, 3 and 10 k Bq m-3 via a transfer standard. The comparison was listed as BIPM supplementary comparison EUROMET.RI(II)-S1. The results of most participants are correlated due to common traceability to one single radon gas standard producer. This makes a careful correlation analysis necessary to achieve an appropriate comparison reference value. The results of the comparison as well as the complex analysis of the correlated set of data is presented and discussed.

Air Pollutants, Radioactive↗

PubMed2006

Characterisation of stationary phases in subcritical fluid chromatography by the solvation parameter model. II. Comparison tools.

This study is an investigation of numerical and graphical tools for the comparison of the chromatographic stationary phases previously characterized with the solvation parameter model [C. West, E. Lesellier, J. Chromatogr. A, in press]. Numerous methods are presented and discussed: the coefficient ratio comparison, principal component analysis (PCA) and calculation of the distance. The coefficient ratio comparison allows to estimate the weight of a particular type of interaction relative to dispersive interactions, but is not practical when a lot of chromatographic systems need to be compared. The principal component analysis is mainly used to reduce the set of correlated variables, but is not useful for non correlated variables such as the solvation parameters. The distance calculation is an interesting tool to measure the differences between two systems but suffers from a confusion between two notions: the difference in the type of interactions involved in the chromatographic system and the intensity of these interactions. Finally, we chose to associate each stationary phase to a vector in a five-dimensional space, according to a method proposed by Ishihama and Asakawa [Y. Ishihama, N. Asakawa, J. Pharm. Sci., 88(12) (1999) 1305] for the comparison of lipophilicity scales. Thus, the angles between the different vectors are used to compare the selectivities of the stationary phases, and the lengths of the vectors are used to compare the relative intensities of the interactions. This method was applied to different alkyl phases characterized in subcritical fluid chromatography (SubFC). The angle values are well suited to the description of the differences in chromatographic behaviour. As expected, a small angle value is obtained between C8, C12 and C18, when a greater one is noticed between C4 and the longer chain length alkyl bonded phases, showing the different acidity and basicity of the C4 phase. Moreover, a satisfactory correlation is obtained between the length of the vectors and the carbon number of the alkyl chain. The differences between classical alkyl-bonded silica phases and polar-embedded alkyl-bonded phases or fluorinated phases are also conveniently evidenced. Finally, graphical tools are investigated and a new type of representation, based in part on a radar plot, is proposed. This plot allows the comparison of stationary phases without reducing the number of studied variables. The comparisons based on this method are consistent with the observed chromatographic behaviour of the phases compared.

Adsorption↗

PubMed2006

Comparison and the development of knowledge.

This paper considers the role of comparison in the development of knowledge. Results show that comparing similar objects makes them appear more similar. Comparing dissimilar objects, on the other hand does not make them appear more similar, and in some circumstances may make them appear less similar. The effect of comparison on similar items was especially striking since participants judged items to be more similar after comparison even if the comparison task was to list differences between the two items. Further, this effect appears specific to comparison and does not appear to be simply due to a "fleshing out" of object representations (listing properties of two objects without comparing the objects themselves served to increase the objects' similarity regardless of whether the objects were similar or dissimilar to start). This suggests that comparison may play a special role in partitioning bits of experience into categories, sharpening categorical boundaries, and otherwise helping us create conceptual structure above and beyond that offered by the world.

Cognition↗

PubMed2002

A note on the variance of paired comparisons estimates.

The method of paired comparisons to estimate treatment effectiveness was introduced by Evans (Evans L. Double pair comparison--a new method to determine how occupant characteristics affect fatality risk in traffic crashes. Accident Analysis and Prevention 1985;12:217-27). It is similar in form to other effectiveness estimates based on odds ratios using independent groups. Therefore, it has been generally assumed that the variance is computed in the same way. In this note, it is demonstrated. using a simple binomial model and linear approximation, that the variance is lower for paired comparisons estimates than for odds ratios estimates based on independent groups. In order to use odds ratios, there must be a treated group and an untreated group. Within each group there are occurrences of an event against which treatment effectiveness is being estimated and, also, occurrences of different event that is considered unamenable to the treatment. The treatment effectiveness, e, is estimated by 1-R where R is the ratio of amenable type events to unamenable ones in the treated group, divided by the same ratio for the untreated group. A distinction is made between 'real' paired comparisons and odds ratios based on independent data. An example of the independent case is. x is the number of fatalities in frontal crashes without air bags; y the number of fatalities in non-frontal crashes without air bags; s the number of fatalities in frontal crashes with air bags, and t the number of fatalities in non-frontal crashes with air bags. While fatalities in non-frontal crashes serve as denominators in R, a particular frontal crash is not paired with one particular non-frontal crash. In this case, in which all the data are independent, the variance of e is approximately R2(1/x + 1/y + 1/s + 1/t), a result which is consistent with well known results about the log odds ratio. For an example of real paired comparisons, we consider fatalities in cars that have a driver and exactly one unbelted right front seat passenger. Suppose there were x driver fatalities and y passenger fatalities in the cars in which the driver was also unbelted and s driver fatalities and t passenger fatalities in the cars in which the driver was belted. Since the fate of the passenger would not be amenable to 'treating' the driver, the same estimate of belt effectiveness based on these data. 1 - (s/t)/(x/y), is reasonable. In this case, x and y, and s and t are not independent. This is due to the fact that while the overall probability of fatality in a crash is very low, the conditional probability of fatality given that someone else in the car died is greater than the unconditional probability of fatality. Under these circumstances, the variance of the paired comparisons estimate is reduced. Published by Elsevier Science Ltd.

Accidents, Traffic↗

PubMed1983

The influence of editing on the performance of a computer program for serial comparison of electrocardiograms.

In this study, three tests of computer ECG analysis function were conducted: 1) interpretation of serial tracings using the single record analysis program, i.e. without serial comparisons; 2) interpretation of the same tracings using a computer-comparison program; and 3) interpretation of these tracings using not only a computer-comparison program but also an editing program which allows amending of each serial record and insertion of any corrections into the computer data base before the next comparison. There was an over-all reduction of 84% in the number of statement changes needed to produce a correct final report by using the combined comparison and editing program. When this combined program was used, 81% of all computer interpretations required no alteration, --a considerable saving of time in analyzing serial electrocardiographic tracings. Serial comparison was required in in 27--45% of all ECG's taken in four medical centers.

Arrhythmias, Cardiac↗

PubMed2003

Exploring the occurrence and nature of comparison of one's own perceived dietary fat intake to that of self-selected others.

Lack of awareness of personal dietary fat intake is associated with a low motivation to change to a diet lower in fat. An optimistic bias in the comparison of one's own fat intake to that of others is associated with this lack of awareness. Insight into the way people make interpersonal comparisons related to fat intake may contribute to a better understanding of dietary intake and its determinants. Such insight may provide suggestions for nutrition education interventions aimed at increasing awareness and intention to change. The present study explores interpersonal comparisons involved in evaluating personal dietary fat intake. One hundred and eighty-nine respondents participated in structured telephone interviews. The respondents reported that they use interpersonal comparison information related to fat intake to some extent and that they mostly compare themselves with close relatives and friends. Respondents who intended to change to a lower fat diet and the younger ones were more likely to compare themselves with others. Comparison targets were perceived to eat small, as well as large or average amounts of fat, which may indicate that people use positive as well as negative role models for making interpersonal comparisons in terms of dietary fat intake.

Adult↗

PubMed1993

Endotracheal tube selection in children: a comparison of four methods.

STUDY OBJECTIVE: To determine the accuracy of four methods of endotracheal tube size selection in the pediatric population. STUDY DESIGN: Prospective, blinded comparison. SETTING: The Children's Hospital of Philadelphia. PARTICIPANTS: Two hundred thirty-seven children aged 1 month to 9 years old undergoing elective surgery requiring endotracheal intubation. SELECTION PROCEDURES: Consecutive sample. INTERVENTIONS: Four methods of determining proper endotracheal tube size in children were compared. These methods included direct comparison with the width of the fifth finger, direct comparison with the diameter of the fifth finger using a ring-sizing device, direct comparison with the width of the fifth fingernail, and estimation using a formula ([age in years + 16]/4). In infants, a 3.0-mm (internal diameter) endotracheal tube was predicted for those 3 months of age and younger, and a 3.5-mm endotracheal tube was predicted for those from 3 to 9 months of age. The size of the endotracheal tube used in the operating room was recorded, as was the "air leak" around the tube. An appropriately sized endotracheal tube was determined by an air leak with ventilation pressures between 5 and 40 cm of water. MAIN RESULTS: Direct comparison using the width and the diameter of the fifth finger predicted an endotracheal tube between 1 mm smaller and 0.5 mm larger than that used by the anesthesiologists in 11% and 14% of patients, respectively. The age-based formula predicted an endotracheal tube size in this range in 97.5% of patients, and direct comparison with the width of the fifth fingernail predicted an endotracheal tube in this same range in 91% of patients. These findings were consistent within all age groups studied. CONCLUSION: Neither fifth finger width nor fifth finger diameter accurately predicts proper endotracheal tube size in most children. A more accurate estimation can be made using the age-based formula, but when the child's age is unknown or when calculation is awkward or impossible, an accurate estimate can be made using the width of the fifth fingernail.

Child↗

PubMed2000

Indirect comparison in evaluating relative efficacy illustrated by antimicrobial prophylaxis in colorectal surgery.

This paper aims to explore the potential usefulness and limitations of indirect comparisons in evaluating the relative efficacy of interventions. From a systematic review of antimicrobial prophylaxis in colorectal surgery, we identified 11 sets of randomized trials that can be used to compare antibiotics both directly and indirectly. The discrepancy between the direct and the indirect comparison is defined as the absolute value of difference in log odds ratio. The adjusted indirect comparison has the advantages that the prognostic factors of participants in different trials can be partially taken into account and more uncertainty be incorporated into its result by providing a wider confidence interval. However, considerable discrepancies exist between the direct and the adjusted indirect comparisons. When there is no direct comparison, the adjusted indirect method may be used to obtain some evidence about the relative efficacy of competing interventions, although such indirect results should be interpreted with great caution. Further empirical and methodologic research is needed to explore the validity and generalizability of the adjusted indirect comparison for evaluating different interventions.

Antibiotic Prophylaxis↗

PubMed2002

Social comparison and patient information: what do cancer patients want?

The present study focuses on social comparison processes among cancer patients. The sample consisted of 60 (ex-) cancer patients who participated in a course "coping with cancer". This study examined several aspects of social comparison: the need for comparison, the preferred direction of comparison and the influence of mode (information or contact seeking) and dimension (illness severity or coping) of social comparison as well as indicators of low well-being. The results show that the need for comparison is particularly enhanced among those who evaluate their own health negatively. In addition, the results show that patients prefer to receive information about others who are better off, but also want contact with others who are better off. In addition, they are specifically interested in receiving information about others who are coping better. Practical implications are discussed.

Adaptation, Psychological↗

PubMed2004

Quantitative information on pore size distribution from the tangents of comparison plots.

The comparison plot obtained from the nitrogen adsorption data has a similar shape to that of the curve of accumulating pore volume of a solid. The intrinsic nature of this relation is discussed. It is known that the derivatives of the accumulating pore volume with respect to the pore size are the pore size distribution (PSD) of the solid. Thus, the tangent curve of the comparison plot can display, at least qualitatively, the PSD of a solid, over a wide range of pore sizes (from approximately 1 to 50 nm) because the comparison plot is applicable to both micropores and mesopores. Quantitative pore structure information can be derived from the comparison plots by establishing a relationship between the t value and the pore size from the samples with uniform pore structure and known pore sizes, such as MCM-41 and alumina pillared clay samples. A calculation procedure to derive quantitative PSD from the comparison plots is suggested, giving reasonable results. This study proposes concise and reliable methods based on the comparison plots to derive information on pore structure in porous solids.

Journal Article↗

PubMed1987

Attributional and social comparison processes in depression.

In this study we examined the consequences for depressed and nondepressed individuals of receiving comparison feedback regarding their causal understandings of an event. Specifically, the effects of similar, dissimilar, or no-comparison feedback on depressed and nondepressed subjects' evaluations of the comparison other and on their feelings about themselves were investigated. Because the reduction of uncertainty about one's conception of social reality is a major motive underlying social-comparison processes, we expected that depressed individuals, who are assumed to have experienced heightened uncertainty associated with frequent exposure to uncontrollable life events, would be more motivated to engage in social comparison and would be more sensitive to social-comparison feedback. Results generally were consistent with this reasoning. The implications of the results in terms of the development and maintenance of depression were discussed.

Depressive Disorder↗

PubMed1994

Strategies of social comparison among people with low self-esteem: self-protection and self-enhancement.

People with low self-esteem (LSE) seem to focus on self-protection; rather than trying to achieve gains for their self-esteem, they try to avoid losses. This research examined, in a social comparison context, the hypothesis that LSEs seek self-enhancement when they have an opportunity that is "safe," that is, carrying little risk of humiliation. Experiments 1 and 2 indicated that LSEs sought the most social comparisons after receiving success feedback, whereas high-self-esteem Ss (HSEs) sought the most comparisons after failure. Further results suggested that LSEs who succeeded were seizing a safe means of self-enhancement and that HSEs who failed were seeking to compensate for the failure. Also supporting this interpretation for LSEs was Experiment 3, in which LSEs who succeeded sought the most comparisons when such comparisons promised to be favorable. All three studies illustrate the value of a new measure of social comparison selection.

Adolescent↗