Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Data Analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,081 records · Page 60Linked to original sources
PubMed1985

Sound graphs: a numerical data analysis method for the blind.

A system for the creation of computer-generated sound patterns of two-dimensional line graphs is described. The objectives of the system are to provide the blind with a means of understanding line graphs in the holistic manner used by those with sight. A continuously varying pitch is used to represent motion in the x direction. To test the feasibility of using sound to represent graphs, a prototype system was developed and human factors experimenters were performed. Fourteen subjects were used to compare the tactile-graph methods normally used by the blind to these new sound graphs. It was discovered that mathematical concepts such as symmetry, monotonicity, and the slopes of lines could be determined quickly using sound. Even better performance may be expected with additional training. The flexibility, speed, cost-effectiveness, and greater measure of independence provided the blind or sight-impaired using these methods was demonstrated.

Adult↗
PubMed1995

Data analysis for dynamic contrast-enhanced MRI-based cerebral perfusion measurements: correcting for changing cortical CSF volumes.

The time evolution of the histogram (number of pixels versus signal intensity) is used to calculate delta R2 parameters from dynamic contrast-enhanced magnetic resonance (MR) imaging of the brain. This method partially corrects for partial volume effects and is an improvement over the approach using the signal intensity as a function of time when confounding factors such as changing cortical cerebrospinal fluid volumes are involved. The maximum value for delta R2 is found to correlate with relative cerebral blood flow as assessed by xenon inhalation and can be used to discriminate between vascular dementia and healthy volunteers. With this method, the normal range for delta R2 values is found to be the same for both young (19-40 years old) and elderly (65-85 years old) healthy volunteers.

Adult↗
PubMed2001

Use of longitudinal data analysis in the determination of a global score for total hip replacement indication in osteoarthritis patients.

BACKGROUND: A composite index would help in medical practice for considering total hip replacement (THR) in hip osteoarthritis. In association with other parameters, such as age or general status, this index could serve to objectively determine the time to THR surgery, and might be used as an outcome measure in therapeutic trials. The objective of this study was to propose such an index, taking into account symptomatic, structural and therapeutic variables, and impact on lifestyle. METHODS: A curve-fitting procedure and a marginal model were used to highlight the average change in the variables over time. A discrete Cox model, with time-dependent covariates. was then performed to study the association between the variables and hip surgery, leading to the construction of a composite index. RESULTS: The smoothing and fitting analysis suggested takes into account not only the variables, but also the changes in their values during the preceding year, when studying the association between variables and hip surgery. Five covariates were retained in the Cox model, among them only one concerns the changes during the preceding year, showing that the values of the covariates are more important that their changes during the preceding year for THR indication. The coefficients of the model were transformed into new coefficients, so that their sum provided a severity score with individual values 0-100. DISCUSSION: Based on the values of reliable variables recorded during the four last visits, this score can be regarded as a valid index able to objectively help with THR indications. This score might also be used as an outcome measure in therapeutic trials.

Aged↗
PubMed2004

Effects of censoring on parameter estimates and power in genetic modeling.

Genetic and environmental influences on variance in phenotypic traits may be estimated with normal theory Maximum Likelihood (ML). However, when the assumption of multivariate normality is not met, this method may result in biased parameter estimates and incorrect likelihood ratio tests. We simulated multivariate normal distributed twin data under the assumption of three different genetic models. Genetic model fitting was performed in six data sets: multivariate normal data, discrete uncensored data, censored data, square root transformed censored data, normal scores of censored data, and categorical data. Estimates were obtained with normal theory ML (data sets 1-5) and with categorical data analysis (data set 6). Statistical power was examined by fitting reduced models to the data. When fitting an ACE model to censored data, an unbiased estimate of the additive genetic effect was obtained. However, the common environmental effect was underestimated and the unique environmental effect was overestimated. Transformations did not remove this bias. When fitting an ADE model, the additive genetic effect was underestimated while the dominant and unique environmental effects were overestimated. In all models, the correct parameter estimates were recovered with categorical data analysis. However, with categorical data analysis, the statistical power decreased. The analysis of L-shaped distributed data with normal theory ML results in biased parameter estimates. Unbiased parameter estimates are obtained with categorical data analysis, but the power decreases.

Computer Simulation↗
PubMed1976

[On-line, high-speeded data analysis of cardiovascular function using hybrid systems (author's transl)].

In recent years application of computer techniques to various problems in biology has increased. In the field of anesthesia, where rapid changes appearing in a short time must be followed, the conventional, mannual methods are not applicable. So we have developed on-line computer analytical methods of cardiovascular function. Hybrid systems are the preferred methods in many biological problems, either because of efficiency and lower cost, or because of real time, on-line, closed-loop capabilities for direct use during experiments. As a computer output we used a graphic display computer and cathod ray tube devices. We applied these systems to analize and calculate cardiac work with other circulatory parameters. We got a ventricular function curve in visible form on CRT within 30 seconds after introducing the signals of left ventricular work and ventricular end-diastolic pressure into the analog computer. It was also useful to calculate vascular input impedence and myocardial maximal velocity of shortening. Finally causes of input errors in these analytical methods were discussed.

Animals↗
PubMed1975

Determination of plasma lipid profiles by automated gas chromatography and computerized data analysis.

Plasma or serum [ 0.1-1.0 ml] was digested with phospholipase C and total lipid extracts were prepared and silylated in the presence of tridecanoylglycerol as internal standard. The neutral lipid and free fatty acid profiles were determined by means of an automated GLC system equipped with an unheated on-column inlet, time actuated liquid injector, programmed heating, cooling and equilibration cycles, and an electronic peak area integrator. The separations were accomplished on a 50 cm x 2 mm i.d. steel column packed with 3% OV-1 on100-120 mesh Gas Chrom Q using nitrogen as a carrier gas in the temperature range 175-350 degrees C. The tube number, peak retention time and peak area were recorded on a punched paper tape, which was subsequently read into a computer via a time-share terminal. The composition of the sample was calculated in relation to the internal standard using a modification of a commercially available computer program and the results were expressed as mg or mole % and characteristic molar ratios of lipid classes. In addition to estimates for total cholesterol and triglyceride, the method provides a detailed account of individual or small groups of molecular species of various lipid classes, which is a major advantage over other automated methods of plasma lipid analyses.

Autoanalysis↗
PubMed1990

[A study of seat-taking in seminar classes: data analysis of three seminar classes in a women's university].

The purpose of this study was to examine the conditions under which human territoriality (self/other boundary-regulation mechanism) appears in seat-taking behavior. Seat-taking in a social psychology seminar class of twelve students at a women's university was observed during the 1983, 1984 and 1985 academic years by female part-time lecturer (the author herself). At the beginning of each class, the lecturer drew the figure of the students' seating arrangement at a rectangular table, while calling each student's name. Questionnaires were also administered to the students at the end of the observation in the period 1983 and 1985 academic years. The results obtained were: 1) each student was more attached to one seating area and seating side than the others, 2) this fact reflected her seating preference to some extent, 3) no student monopolize the special seats to which she was most attached, 4) extra spaces were left between the lecturer's and the student's seat. The third finding was considered to be due to homogeneity of the student with respect to major, grade and sex and their temporal relationships within the seminar group. Also the fourth result was due to the status difference between the lecturer and the students, which led to the recognition that the seating places were mutually exclusive for both sides of them.

Adult↗
PubMed1989

[Clinical study on sweep-frequency tympanometry--data analysis using principal component analysis].

A sweep-frequency tympanometer has been developed to diagnose auditory ossicular lesions more precisely. This device measures acoustic middle ear features by changing the probe tone frequency continuously. The oscillator sweeps frequency of the probe tone from 200 to 2,500Hz 1.5 seconds. A microphone picks up the changes in the acoustic pressure and the phase in the external auditory meatus during the frequency change of the probe tone. These measurements are performed under pressures at -200 and 0 dapa, and differences of both the acoustic pressure and the phase between these two pressures are graphically displayed using a microcomputer. This device can also measure and digitally display the frequency (BHz) and the sound pressure (BdB) at the minimum point (B) of the sound pressure curve, the frequency (ZHz) at 0 crossing point (Z) of the sound pressure curve, and the frequency (PHz) and the phase difference (Pdeg) at the maximum point (P) of the phase curve. Normal ranges of these five values were obtained to establish diagnostic criteria from 200 normal ears. The normal values were as follows: BHz, 480 to 1,070Hz; BdB, -6.0 to -1.8dB; ZHz, 1,100 to 1,860Hz; PHz, 910 to 1,820Hz; and Pdeg, 16.3 to 47.9 degrees. Eight cases of ossicular dislocation and 14 cases of ossicular fixation, all of which had normal external auditory meatus and tympanic membrane, were evaluated based on these values. All the cases with ossicular dislocation and 12 cases out of 14 with ossicular fixation were correctly diagnosed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Impedance Tests↗
PubMed2006

Validation of the 2-DeltaDeltaCt calculation as an alternate method of data analysis for quantitative PCR of BCR-ABL P210 transcripts.

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disorder that is characterized by the presence of a reciprocal translocation between chromosomes 9 and 22 and results in the formation of the Philadelphia (Ph1) chromosome and is present in most of CML patients. The Ph1 chromosome forms a chimeric gene that encodes an abnormal P210 mRNA transcript in most CML patients. Surveillance for minimal residual disease by detection of BCR/ABL transcripts is currently done mostly by quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). Quantitation of BCR/ABL transcripts can monitor tumor load and the outcome of therapy. Absolute quantification determines the input copy number of the transcript of interest, usually by plotting the amount of PCR product onto a standard curve based on serial dilutions of the same product cloned in plasmids. Relative quantification describes the change in expression of the target gene in the patient sample relative to that of a control transcript by using the 2-DeltaDeltaCt calculation. The results of real-time RT-PCR for BCR/ABL transcripts are often analyzed by using plasmid DNA standard curves. In the present study, 79 BCR/ABL transcript-positive samples from CML patients who were being monitored for minimal residual disease by real-time quantitative RT-PCR were studied to determine whether the 2-DeltaDeltaCt approach was equivalent to the plasmid standard curve method. BCR/ABL P210 transcripts were quantitated using both the plasmid standard curve method and the 2-DeltaDeltaCt calculation. The comparison of both methods revealed a highly significant and linear correlation between the plasmid standard curve method and the 2-DeltaDeltaCt calculation (R2=0.98, P<0.0001). Furthermore, there was a reduction of preparation time, contamination risk, and reagent usage. The 2-DeltaDeltaCt calculation is a convenient alternative method to derive accurate quantitative information from real time PCR assays.

Data Interpretation, Statistical↗
PubMed1998

Evidence for cerebellar-frontal subsystem changes in children treated with intrathecal chemotherapy for leukemia: enhanced data analysis using an effect size model.

BACKGROUND: Following brain insult in early childhood, the later maturing neocerebellum and frontal lobes frequently show abnormalities. OBJECTIVE: To investigate the morphologic characteristics and function of a proposed cerebellar-frontal subsystem in children treated for acute lymphoblastic leukemia (ALL) with intrathecal methotrexate using quantitative magnetic resonance imaging, neuropsychological measures, nonlinear multiple regression analysis, and a statistical effect size model that augments interpretive validity of nonsignificant statistical findings, particularly from small sample size studies. DESIGN: Comparison and relationship of magnetic resonance imaging morphometry of cerebellar lobuli I-V and VI-VII and prefrontal cortices, and performance on 5 neuropsychological tests assessing visual-spatial attention, short-term memory, and visuomotor organization and coordination between childhood survivors of ALL and a matched control group. PARTICIPANTS: Ten childhood survivors of ALL treated between 1982 and 1989 with standard 3-year intrathecal chemotherapy, and matched control subjects. MAIN OUTCOME MEASURES: Morphometric results of cerebellar lobuli I-V and VI-VII and prefrontal cortices, and results of Trail-Making Tests, Rey-Osterreith Complex Figure Test, WISC-III Coding. RESULTS: Significant effect size model values for outcome measures in the ALL group support deficits in lobuli VI-VII and prefrontal cortices, and neuropsychological performance. Multiple regression analysis results were consistent with hypothesized involvement of a cerebellar-frontal brain subsystem. CONCLUSION: Treatment of children with ALL with intrathecal methotrexate before 5 years of age has structural and functional effects on the developing neocerebellar-frontal subsystem.

Adolescent↗
PubMed1997

Strategies for managing group A streptococcal pharyngitis. A survey of board-certified pediatricians.

OBJECTIVE: To assess the management strategies and knowledge of board-certified pediatricians regarding group A beta-hemolytic streptococcal (GABHS) pharyngitis. DESIGN: Survey of 1000 US pediatricians in 1991, chosen randomly from the membership of the American Academy of Pediatrics. The survey included questions related to 2 clinical scenarios, respondent demographics, and knowledge of streptococcal pharyngitis. SUBJECTS: Pediatricians who treated patients with pharyngitis. Of the 690 surveys that were returned, 510 pediatricians treated patients with pharyngitis and were included in the data analysis. DATA ANALYSIS: Data were analyzed using Chi 2 statistics for categorical data and the Student t test for continuous variables. RESULTS: Antigen detection tests (ADTs) were used by 64% of the pediatricians; 85% used throat cultures. Strategies for diagnosing streptococcal pharyngitis were throat culture alone (38%), consider positive ADTs definitive and use throat culture when ADTs are negative (42%), ADT alone (13%), ADT and throat culture for all patients with pharyngitis (5%), and no tests for GABHS performed (2%). Thirty-one percent usually or always treated with antibiotics before test results were available. Only 29% of these "early treaters" always discontinued antibiotics when tests did not confirm the presence of group A streptococci. The drug of choice for treatment was penicillin (73%); another 26% preferred a derivative of penicillin, particularly amoxicillin. Many pediatricians altered their management when a patient had recurrent streptococcal pharyngitis. Nearly half of the respondents would use a different antibiotic than they used for routine acute streptococcal pharyngitis. They most often changed to erythromycin (25%), cefadroxil (23%), or amoxicillin-clavulanate (20%). Follow-up throat culture was obtained by 51% of pediatricians after treatment of recurrent streptococcal pharyngitis. A patient with chronic carriage of GABHS and symptoms of pharyngitis would be treated with an antibiotic by 84%; most (62%) would use a penicillin. Other choices were cephalosporins (19%), erythromycin (12%), clindamycin (3%), or rifampin plus penicillin (3%). Tonsillectomy was recommended for symptomatic carriers by 31% of respondents. Carriers without symptoms were less likely to be treated with antibiotics (23%) or referred for tonsillectomy (21%). CONCLUSIONS: Most surveyed board-certified pediatricians managed acute GABHS pharyngitis appropriately, but 15% to 20% used diagnostic or treatment strategies that are not recommended. There was lack of a consensus about the management of recurrent GABHS pharyngitis and chronic carriage of GABHS.

Acute Disease↗
PubMed1999

Incorporation of metabolite prior knowledge for data analysis: biochemical implications of dynamic 31P NMR ex vivo pig liver studies.

A semi-automated, metabolite prior-knowledge-based, lineshape fitting analysis has been developed to assess the dynamic biochemical changes found in ex vivo 31P NMR pig liver preservation studies. Due to the inherent experimental limitations of the ex vivo study and the complexity of the composite phosphorus resonances, metabolite information obtained in vitro was incorporated into the ex vivo analysis. This approach has allowed complete metabolite analysis (phosphomonoesters, inorganic phosphate, phosphodiesters and nucleotide triphosphates) in over 2000 spectra in a fraction of the time compared with more conventional analysis methods. The developed analysis will enable complete and rapid assessment of the biochemical changes in ongoing cold preservation studies of the pig liver which will result in thousands of ex vivo 31P NMR spectra. It is also envisaged that comparative studies on human donor livers will be carried out, in which this type of analysis would be the method of choice. Moreover, this kind of analysis approach could be advantageous in many complex in vivo NMR spectroscopy applications.

Animals↗
PubMed1994

Intermediate-grade lymphomas treated with cyclophosphamide-doxorubicin- vincristine-prednisone-bleomycin alternated with cyclophosphamide-methotrexate-etoposide-dexamethasone. Application of prognostic models to data analysis.

BACKGROUND: Numerous treatment strategies have been tried with the aim of improving results for patients with intermediate-grade lymphomas (IGL) over those achieved with cyclophosphamide, doxorubicin, vincristine, prednisone, and bleomycin (CHOP-Bleo), and numerous prognostic models have been developed to identify and separate risk groups. This study reports on a new protocol for Ann Arbor Stages II-IV IGL that consists of CHOP-Bleo alternated with a new regimen of cyclophosphamide, methotrexate, etoposide, and dexamethasone (CMED) and radiation therapy and demonstrates the usefulness of prognostic models for identifying risk groups and comparing treatment programs. METHODS: One hundred seventy patients with Ann Arbor Stages II-IV IGL were treated with alternating cycles of CHOP-Bleo and CMED for a total of 12 cycles. Involved field radiation therapy was interspersed with courses of chemotherapy for patients with Stage II and Stage III disease. Results were analyzed and compared with those of the authors' previous study of CHOP-Bleo and radiation therapy using the Ann Arbor staging system, their earlier prognostic model, and the recently published International Index. RESULTS: A complete remission occurred in 78% of the patients. The overall 5-year survival rate was 67%. Survival was better for patients with Ann Arbor Stage II disease (80%) than for those with Stage III or Stage IV (67% and 58%, respectively). High tumor burden, above-normal levels of serum lactic dehydrogenase, serum beta 2-microglobulin, and Ann Arbor Stage IV disease were adverse factors. The International Index and the authors' earlier prognostic model separated four prognostic groups. CHOP-Bleo/CMED was generally well tolerated. Neutropenic fever was the major complication that occurred in 25 patients during treatment. Six of these patients died of sepsis. CONCLUSIONS: This study demonstrated that CHOP-Bleo/CMED is a well-tolerated regimen that produced better results than those reported for a former study that used CHOP-Bleo alone. Further, results for CHOP-Bleo/CMED compared favorably with those of other second- and third-generation regimens. The study also validated the usefulness of prognostic models and, in particular, the new International Index for identifying risk groups.

Adolescent↗
PubMed2002

Metallic content of wines from the Canary Islands (Spain). Application of artificial neural networks to the data analysis.

Eleven elements, K, Na, Ca, Mg, Fe, Cu, Zn, Mn, Sr, Li and Rb, were determined in dry and sweet wines bearing the denominations of origin of El Hierro, La Palma and Lanzarote islands (Canary Islands, Spain). Analyses were performed by flame atomic absorption spectrophotometry, with the exceptions of Li and Rb for which flame atomic emission spectrophotometry was used. The content in copper and iron did not present risks of cases. All samples presented a copper and zinc content below the maximum amount recommended by the Office International de la Vigne et du Vin (OIV) for these elements. Significant differences in the metallic content were found among the different islands. Thus, Lanzarote presented the highest mean content in sodium and lithium and the lowest mean content in rubidium, and La Palma presented the highest mean content in strontium and rubidium. Sweet wines from La Palma, elaborated as naturally sweet with over-ripe grapes, presented mean contents significantly higher with regard to dry wines from the same island in the majority of the analysed elements. Cluster analysis and Kohonen self-organising maps showed differences in wines according to the island of origin and the ripening state of the grapes. Back-propagation artificial neural networks showed better prediction ability than stepwise linear discriminant analysis.

Atlantic Islands↗
PubMedDate not supplied

Body mass index growth in a sample of U.S. children: repeated measures data analysis of the Minneapolis Children's Blood Pressure Study.

Longitudinal assessments of the body mass index (BMI) in children and adolescents are limited. The purpose of the study was to describe the growth patterns of the BMI in children and young adults. Black and White children of Minneapolis Children's Blood Pressure Study (MCBPS) were 6 to 9 years old at entry and were followed for 12 years at 19 separate visits. Those with at least five visits (n = 1,302) were included for analysis, using non-linear mixed effects models in conjunction with the Gompertz curve. The growth patterns of four sex-ethnic groups were different at three levels: starting level (SL) (kg/m(2)), asymptote level (AL) (kg/m(2)), and peak growth age (PGA) (in years). In this context, SL is the average BMI level at age 6, AL is the average BMI level when growth diminishes, and PGA is the average age at which the rate of growth in the BMI peaks. The SL (16.3 +/- 0.1) for White males was significantly greater than SL in the other three sex-ethnic groups, among which there were no significant differences. There was a significant ethnic difference in AL between Black females (25.5 +/- 0.3) and White females (24.4 +/- 0.2) and a marginally significant difference in AL between Black females and Black males (24.4 +/- 0.3). For PGA, only sex differences were significant: Black females reached the peak at the earliest age at (11.5 +/- 0.1) years, followed by White females (11.7 +/- 0.1), Black males (12.6 +/- 0.1), and White males (12.8 +/- 0.1).

Adolescent↗
PubMed1983

Structured exploratory data analysis (SEDA) of finger ridge-count inheritance: II. Association arrays in parent-offspring and sib-sib pairs.

Familial similarity of the dermatoglyphic trait values of finger ridge-count scores and pattern intensity index is examined for 125 nuclear families from the Velanadu Brahmin population of Southern India by the method of association arrays. This methodology assesses parent-offspring and sibship similarity through a collection of measures of dependence that is sensitive to a variety of nonlinear trends and stochastic relationships between trait values. The method is used in conjunction with various weights to determine the relationship between family size and the level and form of dependence. These analyses reveal that siblings are most strongly associated for ridge-counts of the middle digit and less associated for the thumb and fifth digit ridge-counts. Further, sibship similarity for ridge-counts increases with family size for the thumb and fifth digit but remains relatively constant over all family sizes for the middle finger. Family size effects are also observed for total ridge-counts of the left hand, right hand, and both hands combined, and for the pattern intensity index. These effects of family size may be due to the most pronounced changes occurring in the amniotic environment between the first and second pregnancy, which are most strongly manifested in the sibship associations of smaller families.

Dermatoglyphics↗