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PubMed1980

Distribution of eyeblink amplitude recorded by an electrode hookup: re-examination.

The present experiment was run to re-examine the distributional properties of the eyeblink amplitude elicited by a burst of 110-dB white noise, recorded by an electrode hookup as recommended in our previous report (Yamada, Yamasaki, & Miyata, 1979). 103 volunteers, 54 males and 49 females, were tested. Analysis showed that the amplitudes were distributed normally when a logarithmic transformation was performed but not when the raw scores were used. We conclude that the amplitude of the startle eyeblink reflex has a log-normal distribution property.

Acoustic Stimulation↗
PubMed1987

[Hazard function and life table: an introduction to the failure time analysis].

Failure time analysis has become popular in demographic studies. It can be viewed as a part of regression analysis with limited dependent variables as well as a special case of event history analysis and multistate demography. The idea of hazard function and failure time analysis, however, has not been properly introduced to nor commonly discussed by demographers in Japan. The concept of hazard function in comparison with life tables is briefly described, where the force of mortality is interchangeable with the hazard rate. The basic idea of failure time analysis is summarized for the cases of exponential distribution, normal distribution, and proportional hazard models. The multiple decrement life table is also introduced as an example of lifetime data analysis with cause-specific hazard rates.

Demography↗
PubMed1985

Incidence of finger pattern types and pattern intensity in a Spanish population (Tierra de Campos).

The incidence of finger pattern types and the pattern intensity distribution in a Spanish sample (417 males and 416 females) drawn from the geographical area of Tierra de Campos have been studied. Sexual and bilateral differences for both dermatoglyphic traits were explored by means of chi 2-test and Mann-Whitney U-test, showing significant differences in all cases, excepting the sexual difference between left hands for pattern intensity. Kolmogorov test for distribution normality showed that pattern intensity was not normally distributed, being the distributions right skewed because of the low frequency of classes with fewer triradii. The results obtained in Tierra de Campos were compared with those observed in other Spanish and Portuguese populations, showing more heterogeneity in the pattern types than in pattern intensity. This could imply that arches account for the main source of variation between populations. Moreover, pattern type frequencies and pattern intensity in Tierra de Campos are, as expected, within the variation ranges of Southeuropean-Mediterranean populations and Caucasians as a whole, although the incidence of radial loops is located in the lower extremes of the corresponding variation ranges.

Dermatoglyphics↗
PubMed1994

[Computerized tomography measurement of torsion angle of the lower extremities].

The precise evaluation of post-traumatic deformities is indispensable when planning a corrective osteotomy. Torsional angles of the lower extremities of 186 patients were measured using CT. The mean age of the studied population was 34 years (18-80). It consisted of 131 men and 55 women. All patients had sustained a fracture of at least one of the leg's bony segments. The normal femoral (n = 293) inward torsion measured 23.47 degrees +/- 17.16 degrees (mean +/- 2 SD). Normal tibia (n = 263) outward torsion was 34.03 degrees +/- 17.22 degrees. The intraindividual torsional differences were not normally distributed. Normal femoral (n = 103) intraindividual torsional difference measured 11 degrees (95% percentile) and 15 degrees (99% percentile), with a median of 4 degrees. The tibiae (n = 76) showed a normal intraindividual torsional difference of 12 degrees (95% percentile) and 15 degrees (99% percentile). Right tibiae showed a statistically significant greater outward rotation when compared to their left counterpart (P < 0.001). No correlation to sex could be established. Preoperative planning of a corrective osteotomy should include the geometric evaluation of all four bony segments of the leg. Intraindividual torsional differences must be considered. A corrective osteotomy appears to be unnecessary with a torsional difference smaller than 15 degrees in the femora and smaller than 15 degrees in the tibiae.

Adolescent↗
PubMed1988

Models of hepatic elimination: comparison of stochastic models to describe residence time distributions and to predict the influence of drug distribution, enzyme heterogeneity, and systemic recycling on hepatic elimination.

The residence time distribution of noneliminated solutes in the liver can be represented by a variety of stochastic models. The dispersion model (closed and mixed boundary conditions), gamma distribution, log normal distribution and normal distribution models were used to describe output concentration-time profiles after bolus injections into the liver of labeled erythrocytes and albumin. The dispersion model and log normal distribution model provide the best representation of the data and give similar estimates of relative dispersion and availability for varying hepatocellular enzyme activity. The availability of solutes eliminated from the liver by first-order kinetics is determined by the residence time distribution of the solute in the liver and not on events occurring in the liver when a uniform enzyme distribution is assumed. Both enzyme heterogeneity (axial or transverse) and hepatocyte permeability may affect solute availability. A more complex model accounting for enzyme distribution and the micromixing of solute within the liver is required for solutes undergoing saturable kinetics.

Biological Transport↗
PubMed1998

Statistical Inference (part II): The Normal and Related Distributions.

The normal (or gaussian) is the most important probability distribution in the statistical inference process. By transforming the normal distribution to a standard distribution (z-distribution) it is possible to determine the probabilities where observations or values fall in certain intervals for variables with different means and standard deviations. Areas under the normal distribution may be represented in a table where the z is the number of standard deviations away from the mean. For example, the area under the normal distribution delimited by a z value of 1.96 to the left and 1.96 to the right of the mean corresponds to 95% of the total area of the normal distribution. Sampling distribution of estimates of population parameters may also be described by the normal distribution. It is important to note, however, that the estimation of a population mean based on the normal distribution is conditional to the assumption that the population standard deviation is a known parameter. The t distribution is used to infer about a population mean when the population standard deviation is estimated by the sample data. In statistical inference about proportions, the normal approximation of the binomial distribution may be used provided the data fit certain assumptions. Statistical methods that do not depend on the form of the distribution (distribution-free or nonparametric methods) and those based on the actual probability distribution, called exact methods, are often used in situations where the data do not comply with the assumption that the distribution of the estimate is approximately normal.

Journal Article↗
PubMed2003

Solutions to the Behrens-Fisher problem.

When testing the equality of the means from two independent normally distributed populations given that the variances of the two populations are unknown but assumed equal the classical Student's two sample t-test is recommended. If the underlying population distributions are normal with unequal and unknown variances, either Welch's t-statistic or Satterthwaite's Approximate F test is suggested. However, Welch's procedure is non-robust under most non-normal distributions. There is a variable tolerance level around the strict assumptions of data independence, homogeneity of variances, identically and normal distributions. Few textbooks offer alternatives when one or more of the underlying assumptions are not defensible. We have developed an executable FORTRAN code for producing the statistics suggested by Cressie and Whitford, Yuen and Dixon, and Yuen. An executable FORTRAN is available from the author on request (e-mail only).

Animals↗
PubMed2002

Cost effective policies for alternative distributions of stochastic water pollution.

This study investigates the role for cost effective coastal water management with regard to different assumptions of probability distributions (normal and lognormal) of pollutant transports to coastal waters. The analytical results indicate a difference in costs for a given probability of achieving a certain pollutant load target whether a normal or lognormal distribution is assumed. For low standard deviations and confidence intervals, the normal distribution implies a lower cost while the opposite is true for relatively high standard deviations and confidence intervals. The associated cost effective charges and permit prices are higher for lognormal distributions than for normal distributions at relatively high confidence intervals and probabilities of achieving the target. An application to Himmerfjärden--an estuary south of Stockholm, Sweden--shows that the minimum costs of achieving a 50 per cent reduction in nitrogen load to the coast varies more for a lognormal than normal probability distribution. At high coefficient of variation and chosen probability of achieving the target, the minimum cost under a lognormal assumption can be three times as high as for a normal distribution.

Cost-Benefit Analysis↗
PubMed1994

Non-normality of distribution of Glasgow Coma Scores and Revised Trauma Scores.

STUDY OBJECTIVE: Inferential and descriptive statistics continue to be used incorrectly when analyzing biomedical data. Glasgow Coma Score (GCS) and Revised Trauma Score (RTS) data have recently been described and analyzed using parametric statistical methods in several studies despite the ordinal nature of these data scales. The objective of this study was to determine whether GCS and RTS data are normally distributed, despite their ordinal nature. HYPOTHESIS: Neither GCS nor RTS data are normally distributed. DESIGN: A retrospective review of GCS and RTS data obtained at a medical school teaching and county hospital that is a Level I trauma center. PARTICIPANTS: Patients who met criteria for trauma team activation at the hospital. METHODS: GCS and RTS data distributions were compared to a standard normal distribution using the chi 2 goodness of fit test. RESULTS: GCS and RTS data distributions differed significantly from the normal distribution for all data sets examined. CONCLUSION: Parametric statistical descriptors and inferential methods are inappropriate for use with GCS and RTS data. Ordinal data should be tested for normality before statistical analysis with parametric statistical methods.

Chi-Square Distribution↗
PubMed1988

Quantitative genetic analysis of bi-iliac breadth.

Bi-iliac breadth, the frontal maximum diameter between right and left iliac crests, was measured in 1,547 male and 2,085 female residents of a rural area in Japan. All subjects were over 14 years of age. The bi-iliac breadth showed an increase related to age but little sex difference. Modification of age and sex variations from the measured value was obtained by calculation of the score, represented by arithmetical means and standard deviations. Distribution of these scores appeared to be binomial, and since binomial distribution approaches normal distribution when n is large, it is presumed that this trait gains normal distribution. Thus variation of bi-iliac breadth in subjects 20-79 years of age enables us to analyze inheritance. No significant difference was found between husband and wife in the correlation coefficients or between father and daughter (0.13 +/- 0.08). Significant differences were found as follows: father-son (0.35 +/- 0.05) (P less than 0.001), mother-son (0.28 +/- 0.05) (P less than 0.001), and mother-daughter (0.28 +/- 0.06) (P less than 0.001). There was no indication of maternal or paternal effects, since no significant difference was found in father-child and mother-child correlation coefficients. It is concluded that bi-iliac breadth is a quantitative genetic trait under control of polygenes on autosomes. Regression coefficient of child on midparental value was 0.55 +/- 0.05, approximately twice the means of four pairs of correlation coefficients between parent-offspring. Narrowly, heritability was estimated as 0.54 approximately 0.55. Contribution of dominance to total variance was small (VD = 0.11), in contrast to the larger additive genetic variance (VA = 0.54).

Adolescent↗
PubMed1989

Role of bandpass filters in optimizing the value of the signal-averaged electrocardiogram as a predictor of the results of programmed stimulation.

Normal values for the signal-averaged electrocardiogram (SAECG) at 11 different high-pass filter settings were obtained from 100 normal subjects (group I). The filtered QRS duration and the duration of low amplitude signals less than 40 microV, but not the root mean square voltage of the last 40 ms (RMS40), showed normal distribution. A normal distribution for RMS40 could be obtained by transforming each value to its natural logarithm. The normal values were used in a systematic approach to optimize the accuracy of the SAECG to predict the results of programmed stimulation in 80 patients with spontaneous nonsustained ventricular tachycardia (VT). Fifty-two patients with no inducible VT (group II) and 28 patients with inducible sustained monomorphic VT (group III) were investigated. The 3 SAECG parameters at each high-pass filter in groups II and III were categorized as normal or abnormal and were evaluated singly or in combinations of 2 or 3. There was no combination that provided a sensitivity greater than 82% that could also be obtained by single determinations of low amplitude signals less than 40 microV at 25 to 40 Hz or RMS40 at 40 Hz. On the other hand, there were 267 different combinations that provided a maximal specificity of 98%. The best total predictive accuracy of a single parameter was 85%, provided by RMS40 at 40 or 60 Hz. The total predictive accuracy could be improved to 89% by 1 of 32 different combinations. The top combinations were mostly in triplets and included SAECG parameters recorded at different high-pass filter settings. The only 2 paired combinations with the best total predictive accuracy were RMS40 at 20 or 25 Hz paired with RMS40 at 40 Hz. Frequencies at both ends of the analyzed high-pass filter settings (less than 20 Hz and greater than 60 Hz) were not represented in the top predictive combinations. The SAECG parameters analyzed at 40 Hz were most frequently represented in the top predictive combinations, suggesting that the SAECG may have the best predictive accuracy at this filter setting. In summary, the combination of SAECG parameters analyzed at different filter settings can enhance the accuracy of the technique as a screening test for the results of programmed stimulation in patients with spontaneous nonsustained VT.

Adult↗
PubMed1986

Beta-cell dysfunction, rather than insulin insensitivity, is the primary defect in familial type 2 diabetes.

Continuous infusion of glucose with model assessment was used to measure glucose tolerance, beta-cell function, and insulin sensitivity in 154 first-degree relatives of 55 patients with type-2 diabetes. The plasma glucose achieved at 1 h was normally distributed in normal control subjects, but 31 (20%) of relatives of type-2 diabetics had values above the normal distribution mean +2 SD. Insulin secretion, assessed from the first or second phase plasma-C-peptide responses, was significantly lower in the glucose-intolerant relatives than in normoglycaemic relatives of similar sex, age, and obesity. beta-cell function, estimated by means of model analysis, was severely impaired in the glucose-intolerant relatives but was not impaired in the normoglycaemic relatives (geometric mean 41% and 109% of normal beta-cell response, respectively). Reduced beta-cell function was found with all degrees of glucose intolerance, whereas only the more severely hyperglycaemic relatives had impaired insulin sensitivity. This suggests that the primary defect in familial type-2 diabetes is beta-cell dysfunction.

Adult↗
PubMed1993

Microautoradiographic analysis of the normal organ distribution of radioiodinated single-chain Fv and other immunoglobulin forms.

In previous studies, we have compared the immunochemical properties, the in vivo pharmacokinetics, and the tumor penetrance of a radioiodinated single-chain Fv (sFv) in comparison with other immunoglobulin (Ig) forms (intact IgG, F(ab')2, and Fab') (Cancer Res., 51: 6363-6371, 1991). Biodistribution studies demonstrated a higher percent injected dose/g in the liver and spleen for the intact IgG and F(ab')2. Renal uptake was observed with the Fab' and F(ab')2, whereas the sFv demonstrated no specific localization in either of these organs. The 125I-labeled sFv also demonstrated a more even distribution throughout the tumor xenografts as compared to the other Ig forms (Cancer Res., 52: 3402-3408, 1992). Subsequent studies utilizing the sFv conjugated with a radiometal (177Lu) demonstrated that the sFv was being metabolized by the kidney, and a significantly higher percent injected dose/g was obtained with a 177Lu-labeled sFv as compared to a 125I-labeled sFv (Cancer Res., 52: 6413-6417, 1992). These previous studies indicated the potential utility of radioiodinated sFv and other Ig fragments for use in radioimmunoguided surgery with a hand-held probe, diagnostic imaging, and possibly therapy. The present study compares the distribution in normal tissues of the 4 Ig forms of monoclonal antibody (MAb) CC49, which is directed against a pancarcinoma antigen (tumor-associated glycoprotein-72). 125I-labeled sFv, Fab', F(ab')2, and IgG of MAb CC49 were administered to athymic mice either bearing or not bearing the tumor-associated glycoprotein-72 positive human colon carcinoma xenograft (LS-174T). At various intervals following the i.v. injection of the Ig forms, the liver, spleen, kidneys, and lungs were removed for autoradiographic analyses. Dramatic differences were observed in the kidney; the IgG was found only in the renal vasculature, whereas the Fab', F(ab')2, and sFv showed a high density of grains in the cortical tubules. In the liver, the IgG and F(ab')2 were found in association with hepatocytes, Kupffer cells, and in the sinusoids; the Fab' and sFv were primarily associated with the Kupffer cells. In the spleen, the Ig forms localized to the marginal zones surrounding the lymphoid follicles. No specific accumulation of grains for any of the Ig forms was observed in the lung. In each of the tissues, the clearance rates were related to the size of the Ig form. The localization in the liver and spleen was determined to be antigen-mediated.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

[Spatial variability of soil nutrients in cultivated surface soil of Sujiatun District, Shenyang City].

The spatial variability of organic matter (OM), available nitrogen (AN), available phosphorus (AP), and available potassium (AK) in 0-20 cm horizon in cultivated soils of Sujiatun District, Shenyang City were investigated using geostatistics and geographic information system (GIS). Data of each variable fitted normal distribution or normal distribution after log transformation, and a spherical model for semivariogram fitted all the variables. Semivariograms indicated that OM content strongly spatially dependent with the ratio of nugget to sill of 24.11%. The contents of AN, AP and AK were moderately spatially dependent with the ratio of nugget to sill of 29.53%, 60.77% and 58.82%, respectively. The ranges of spatially dependent for OM, AN, AP and AK were 26.051, 28.293, 15.132 and 23.813 km, respectively. The spatial variability for OM and AN was fundamentally affected by structural factors such as soil formation factors, and that for AP and AK was by random factors such as fertilization. Kriging maps showed the spatial distributions of the four variables, which were useful in monitoring nutrient changes and providing quantitative support to decision and policy making for agriculture and environment management.

Geographic Information Systems↗
PubMed1991

[Individual and average weight requirements of pharmaceutical preparations].

Authors studied the weight deviations allowed by non-statistically constructed individual and average weight requirements of Pharmacopoeas under consideration of normal Gaussian distribution. Normality was examined on a given suppository product and has been established, that in this case theoretically the hypothesis of normal distribution is not valid. For this reason deviation characteristics calculated according to the severest and the lightest Pharmacopoean requirements have been presented, i.e. the lower limit (if the deviation is less than this limit, the preparation meets the requirements by all means), and the upper limit (if the deviation is larger than this limit, the preparation definitively does not meet the requirements) respectively. Moreover, deviation characteristics calculated for continuous Gaussian distribution and for discrete distribution with few elements (representing a good approximation of the former) are given in the paper. On the basis of these results authors suggested to modernize the requirements of Pharmacopoeas and to continue research work in this direction.

Dosage Forms↗
PubMed1988

Regional capillary and myocyte distribution in normal and exercise trained male and female rat hearts.

Adult Sprague-Dawley male and female rats were exercise trained for five months by either treadmill running or swimming. Significant differences in left ventricular regional capillary density and myocyte cross-sectional area were found. In control rats the epicardial regions had greater capillary density than endocardial regions. Endocardial myocyte cross-sectional areas were greater than those of epicardial myocytes in both sexes. Male rats had larger endocardial myocytes and larger hearts than females. After exercise training, myocyte size increased in the epicardial region but not in the endocardial region, while capillary density increased significantly only in the endocardial region. Similar changes were seen in both male and female rats with comparable degrees of exercise induced hypertrophy. These data suggest that exercise training "normalizes" the distribution of capillaries in the myocardium. Capillary density increased only in the regions where myocyte cross-sectional area did not increase. Further, the effects of exercise on male and female rat hearts is not different when the degree of exercise induced hypertrophy is similar.

Animals↗
PubMed1984

A study of body hair density and distribution in normal women.

The distribution and density of terminal hair growth have been studied in 19 different body regions in 100 normal women of fertile age and 25 normal postmenopausal women. In accordance with earlier investigations an age-dependent variation in hair growth pattern was observed. None of the women in either group had terminal hair growth on the cheek, and on the breast region hair was limited to a small circumareolar area. Whereas facial terminal hair growth appeared to be less common than that reported in earlier studies of women from other countries, the frequency of terminal hair in other regions was found to be significantly higher in the Norwegian women. No difference in hair growth pattern between blondes and brunettes could be detected.

Adolescent↗
PubMed1995

Calculation of trough:peak ratio of antihypertensive treatment from ambulatory blood pressure: methodological aspects.

OBJECTIVE: To address several methodological questions related to calculation of trough:peak ratio from 24 h ambulatory blood pressure (BP) recordings. METHODS: Data from patients with mild essential hypertension who were included in parallel group (n = 280) or cross-over studies (n = 39) were pooled. 24 h ambulatory BP recordings were available after 2- to 4-week washout from treatment and at the end of a 4- to 8-week period of treatment with calcium antagonists (n = 143), angiotensin converting enzyme inhibitors (n = 103) or placebo (73 patients from parallel group studies and 39 from a cross-over study). Each recording started between 0900 and 1000 h, immediately after the drug or placebo intake during the treatment phase. BP was measured at 15 min intervals during the day and at 15-20 min intervals during the night. Peak changes were calculated from systolic BP and diastolic BP 2-8 h after drug intake, and trough changes from readings taken during the last 4 h of the 24 h. RESULTS: Peak changes induced by drug treatment were progressively reduced when data were averaged over 1, 2, 4 and 6 h. BP reproducibility showed a concomitant increase and the best compromise between correct estimate of peak changes and reproducibility was the average of the adjacent 2 h with the maximal BP fall. Peak and trough (average of last 2 h) changes showed a normal distribution, whereas trough:peak ratios showed non-normal distributions, large scatters and many individual values with no pharmacodynamic significance (namely, much above unity and below zero). Selecting responders to treatment reduced the dispersion and made the trough:peak ratio distribution normal. There was no correlation between trough:peak ratios and changes in BP variability (standard deviation of 24 h mean) induced by treatment. Placebo administration caused no trough but a modest peak fall. Peak changes during placebo also showed a wide scatter and a non-normal distribution, which makes correction with respect to average peak placebo data inappropriate in parallel-group studies. However, placebo correction may be performed for each subject in cross-over studies, leading to a reduction in peak changes and an increase in trough:peak ratio values. CONCLUSIONS: When the trough:peak ratio is assessed from ambulatory BP, peak and trough changes should preferably be computed over a 2 h time window. To remove values with no pharmacodynamic significance, the analysis should preferably be conducted only in responders to treatment at peak. Although placebo is accompanied by some peak effect, placebo correction might be appropriate only for individual subjects in cross-over studies.

Antihypertensive Agents↗