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At least 19 recordsLinked to original sources
PubMed1991

Influence of the test medium on azithromycin and erythromycin regression statistics.

Azithromycin and erythromycin disk test results were compared to MIC values obtained in six different media. One hundred isolates were tested in triplicate, and geometric mean MICs were plotted against arithmetic mean zone diameters and regression statistics calculated. The test media evaluated did not markedly influence MIC values, but incubation in 5-7% CO2 resulted in a two- to four-fold decrease in the activity of both drugs. For testing Haemophilus influenzae and other species that need to be tested in 5-7% CO2, interpretive breakpoints for the macrolides and azalides should be modified to compensate for the anticipated decrease in activity.

Azithromycin↗
PubMed1991

A brief introduction to influence diagnostics in regression.

Statistical analyses that involve regression methods often encounter data in which some observations have substantial influence. This article presents a nontechnical discussion of influence and of two techniques, based on leaving out each individual observation in turn, for diagnosing influential data. An example illustrates the techniques in an analysis of recurrence rates in endoscopic treatment of bleeding peptic ulcers.

Endoscopy↗
PubMed1990

Parallelism test on microcomputers for statistically comparing regression lines of bivariate data sets.

Biomedical research is frequently confronted with regression lines that directionally describe the trend of phenomena, each one represented by a set of correlated x and y data. There could be a need to verify whether the regressions lines of two (or more) phenomena are statistically comparable in their slopes and intercepts, in order to draw conclusions about the similarity or dissimilarity of the conditions under scrutiny. The parallelism test the principles and methodology of which are presented here addresses this problem. A program for microcomputers is supplied as a non-profit software that can be freely shared on the understanding that the copyright belongs to the authors of this article.

Analysis of Variance↗
PubMed1990

Risk factors of alcoholism in Taiwan Chinese: an epidemiological approach.

This study investigated the risk factors of alcohol abuse and alcohol dependence, as defined by DSM-III criteria, in 11,004 Chinese subjects in the Taiwan community. Risk factors were analyzed using chi-square and multivariate logistic regression statistics. The logistic regression shows that the risk factors of alcohol dependence include male, having had childhood or adulthood behavior problems; of alcohol abuse include male, having had childhood or adulthood behavior problems, non-metropolitan community, age cohort, job-holder. The etiological models proposed are biological for Chinese alcohol dependence and interactional for Chinese alcohol abuse.

Adult↗
PubMed1991

Risk factors of alcoholism among Taiwan aborigines: implications for etiological models and the nosology of alcoholism.

The objective of this study was to explore possible risk factors of alcohol abuse (AA) and dependence (AD), as defined by DSM-III criteria, in Taiwan aborigines. The risk factors in a sample of 1555 Taiwan aborigines were analyzed by using the chi-square test and multivariate logistic regression statistics. The logistic regression showed that the risk factors of AD are being male, having relatively little education, being involved in a problem marriage, being a laborer, being part of a couple with a drinking problem, and having a positive family history of alcoholism. AA has the risk factors of ethnic subgroups dwelling in the main Taiwan Island, male, poor education, working people, and a drinking problem for the couple. Etiological models are proposed as social origins for AA, with interactional model for AD, in this aboriginal sample. Data on Chinese alcoholism is discussed, and a generalized hypothesis constructed that, for the same phenotypical subtype of alcoholism in different ethnic groups, the etiological models are different.

Adult↗
PubMedDate not supplied

Comparison of a commercial method for total protein with a candidate reference method.

The biuret method for total protein has been compared on the Boehringer Mannheim Diagnostics (BMD) Hitachi 717 Analyzer with a candidate reference method in efforts to standardize the BMD method. The methods were compared using 115 paired serum specimens collected during morning rounds at the Roger Williams Hospital. Results from the test method were compared to the reference method using a statistical procedure for quantifying bias between analytical methods. Linear regression statistics were also calculated. The Hitachi 717 biuret method shows no bias when compared to the reference method (z = -0.90), and there is acceptable correlation between the two methods (y = 0.86, m = 0.86, r = 0.896). The Hitachi method is linear to 15.0 g per dL and demonstrates excellent precision (CV less than or equal to 2.14 percent, N = 140). The Hitachi 717 biuret method has been found to be excellent in all respects and its use is recommended as a convenient and accurate means of measuring total protein.

Blood Chemical Analysis↗
PubMed1976

A review of the satatistical considerations involved in the treatment of isotope dilution calibration data.

The use of linear regression analysis for the reduction of isotope dilution data is reviewed. The calculation of linear regression statistics is based upon four assumptions: zero variance in the independent variable, equal variance for all values of the dependent variable, linearity and continuity. Unfortunately, isotope dilution data often violate one or more of these assumptions, which results in the calculation of an inaccurate calibration line. The inaccuracies can be avoided through careful inspection of the data, including analyses of variance and linearity. Large differences in the variances of the dependent variable require the use of a weighted linear regression. Nonlinearity necessitates either discarding data in the nonlinear portion of the calibration or the calculation and use of atom % excess and dilution instead of the sample isotope ratios.

Mass Spectrometry↗
PubMed1991

Function learning: induction of continuous stimulus-response relations.

This research investigates how people learn to select particular response magnitudes along one physical dimension (duration) when given stimulus magnitudes from another dimension (spatial extent). Stimuli and correct responses were related by either a power function, a logarithmic function, or a linear function with a positive intercept. The power function was learned quickly and accurately. In contrast, systematic response biases occurred during the early phases of learning the logarithmic and linear functions. As practice progressed, however, the biases gradually disappeared. These results support an adaptive regression model. According to it, people learn functions through a subjective process analogous to statistical regression. There is assumed to be an initial constraint that treats stimulus-response pairs as if a power function characterizes them.

Female↗
PubMed1975

Characteristics of mentally-impaired aged profiting from individualized treatment.

This study investigated subjects' characteristics which related to improvements from individualized treatment of mentally impaired aged. Project variables (158) were reduced to 12 Q-type factors. The excess disability (ED) criteria were partialled into experimental/control influences (EDe/c) and residual ED variance. Statistical regressions were run on the EDe/c criteria vs. age and the 12 Q-factors. Age significantly predicted post-treatment ED functioning in both conditions. Younger subjects (ages 65-82) profited most in both groups. After the statistical removal of age in the regression, Factor Q-3 still retained a significant relationship to EDe/c for the experimentals. The correlations indicate the importance of social capabilities, irrespective of age level, with regard to improvements due to ED treatments. For the control subjects, Q-12 and Q-5 showed significant independent relationships to the criteria. Subjects' competence appeared most important for EDe/c gains made without treatment.

Activities of Daily Living↗
PubMed1991

[Croup and air pollutants: results of a two-year prospective longitudinal study].

The Reutlingen/Tübingen/Rottenburg region in Baden-Württemberg is characterized by medium and small sized towns and rural areas. In 1986/87 875 cases of croup were registered there by the treating physicians during a 24-months period. In consideration of meteorological and virological "disturbing variables" the influence of the measured air pollution by SO2, NO, NO2, CO, ozone and dust on croup frequency was computed by means of statistical regression methods. For the months September till March, the main manifestation period of croup, weak but statistically significant influences of the daily means of NO and NO2 were found, for the whole year influences of NO, NO2, and CO. During the winter months temperature correlates positively and velocity of wind negatively, both statistically with significance, to croup frequency. The essential conditions of croup are individual and familiar disposition on the one hand, virus infections on the other. Air pollution of a concentration like given in the investigated region was found to be a weak additional factor that favours the manifestation of croup.

Air Pollutants↗
PubMed1989

Models of spinal trabecular bone loss as determined by quantitative computed tomography.

Noninvasive bone densitometry techniques have significantly improved our understanding of the pattern and magnitude of bone loss over the life span. Quantitative computed tomography (QCT) is capable of selectively measuring highly labile trabecular bone in the central portion of the vertebrae. Trabecular bone mineral density (mg/ml) was determined in 538 healthy women ranging in age from 20 to 80 using GE CT/T scanners at 80 kVp. Various statistical regressions were performed for the entire population to describe the general pattern of bone loss from the spine; a cubic model (r = -0.69, SEE = 26.0 mg/ml) was found to be statistically superior (p less than 0.01) to linear, quadratic, or exponential models. An average bone loss was approximated from these regression analyses with a yearly absolute rate of -2.02 +/- 0.097 mg/ml per year (p less than 0.0001). The average rate of change for premenopausal women was -0.45 mg/ml per year (p less than 0.05), for perimenopausal women was -4.39 mg/ml per year (p less than 0.0001) and for postmenopausal women was -1.99 mg/ml per year (p less than 0.0001). QCT values were also stratified into 5 and 10 year age groups and analyzed separately for pre- and postmenopausal women. The 5 and 10 year interval stratification revealed no identifiable bone density decrements prior to midlife using analysis of variance statistical methods; significant losses of bone mineral density were noted to correspond with the usual time of menopause and to continue into old age. Various two-phase regressions were employed using age and menstrual status to improve the description of age- and menopause-related bone loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Pancreatic amylase measured in serum by use of a monoclonal antibody immunochemically immobilized to a solid phase.

We studied a method for measuring the pancreatic isoenzyme of amylase (EC 3.2.1.1) by use of a mouse monoclonal antibody against human salivary-type amylase (Clin Chem 1985;31:1283) coupled indirectly to particles of polyvinylidene fluoride via polyclonal goat anti-mouse immunoglobulin. These particles, in 200 microL of a suspension, could remove salivary amylase (activity 2200 U/L) from an equal volume of serum in 5 min. Measurement of amylase activity in the supernatant fluids from treated sera thus provided an assay of pancreatic amylase. Precision studies at three activity concentrations yielded within-run CVs of 1.6% to 1.7% (n = 25) and total CVs of 2.2% to 5.1% (20 days). Salivary amylase added to each of 10 sera was completely (99.8%, SD 1.6%) removed. The new method (y) showed the following regression statistics when compared with an electrophoretic method (x): slope = 0.989 (SD 0.019), intercept = -0.220% (SD 1.48%), SEE 4.0%, n = 51. Similar respective regression values were found for urine samples: slope = 0.934 (SD 0.053), intercept = 2.3 U/L (SD 3.2), SEE 8.4 U/L, n = 26. The following respective values were found when the new method (y) was compared with the previously described immunoprecipitation assay (x): slope = 1.02 (SD 0.02), intercept = 2.2% (SD 1.4%), SEE 3.3%, n = 23 sera. Reference intervals for pancreatic amylase activity in serum were established for three different substrates: maltotetraose, maltopentaose, and p-nitrophenylheptaoside.

Acute Disease↗
PubMed1988

Regression analysis in biological research: sample size and statistical power.

Regression analysis is often used to demonstrate associations among variables believed to be biologically related. Failure to demonstrate a "significant" relationship may be due to two factors: 1) the variables are truly unrelated, or 2) a relationship exists but goes undetected due to inadequate statistical power. Investigators must consider the second possibility since failure to detect a statistically significant relationship is often taken as evidence for no biological relationship. These issues are addressed in the context of the interrelationship between four features common to all statistical methods: the size of effect or relationship worth detecting, the Type I (alpha) error, the sample size, and the Type II (beta) error. An example derived from published data relating morphological characteristics of muscle fiber type and isokinetic strength performance illustrates the practical significance of this dilemma.

Regression Analysis↗
PubMed1990

Estimating respiratory volumes from rib cage and abdominal displacements during ventilatory and speech activities.

This methodological study examined the predictive strength associated with modeling respiratory volumes from chest-wall movements during selected ventilatory and speech activities. A linearized magnetometry system transduced the anterior-posterior diameters of the rib cage and abdomen, supplying kinematic data that were used to estimate respiratory volumes. Kinematic and airflow measures were acquired during (a) tidal ventilation, (b) vital capacity maneuvers, (c) Rainbow Passage reading at customary loudness, (d) Rainbow Passage reading at twice-customary loudness, (e) extemporaneous speech, and (f) /a/ prolongation. Multiple-regression statistics were applied to the body surface and integrated airflow data to obtain (a) intercepts, (b) volume-motion coefficients for the rib cage and abdomen, and (c) coefficients of determination. Volumes estimated by applying regression-derived intercepts and volume-motion coefficients to the respiratory kinematic data were then compared to integrated airflow signals. Two magnetometer-based, volume-estimation strategies were contrasted for the speech tasks, one based on volume-motion coefficients derived from that particular speech activity and one based on volume-motion coefficients derived from tidal ventilation. Regression-derived intercepts and volume-motion coefficients for the abdomen varied significantly across subjects but not tasks. Volume-motion coefficients for the rib cage varied significantly across both subjects and tasks. Coefficients of determination for the magnetometer-based volume estimates were affected significantly by subjects and tasks but not by volume-estimation strategies. The calibration, use, and potential limitation of respiratory kinematic devices for speech research are discussed.

Abdomen↗
PubMed1988

Risk factors for cancer of the renal parenchyma.

A case-control study of cancer of the renal parenchyma (360 cases and 985 controls) investigated lifestyle and dietary risk factors by means of a questionnaire survey. A lifetime history concerning urological disease and consumption of analgesics, tobacco, and prescribed medicines, was obtained together with current dietary and demographic information. Estimates of relative risk were calculated using logistic regression. Statistically significant associations were found with phenacetin-containing analgesics, urological disease and increasing consumption of milk. No association was found with consumption of aspirin, paracetamol, prescribed medicines, tea, coffee or animal proteins other than milk, or with the type of fat or oil used for cooking or spreading. The association with tobacco just failed to reach significance.

Australia↗