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At least 1,459 records · Page 81Linked to original sources
PubMed1995

Alternative pork carcass evaluation techniques: II. Statistical analysis of error attributable to sex, genotype, and weight.

Carcasses of 154 hogs representing seven genotypes with substantial variation in carcass composition and percentage of lean were completely dissected and analyzed. Measurements from a ruler, Hennessy probe, and electromagnetic scanner were each used to predict wholesale and lean boneless carcass value. Error, defined as dissected value minus predicted value, due to the omission of sex, genotype, weight, and their interactions was estimated for each model. The errors were significantly different from zero for the models using ruler and electromagnetic scanning measurements separately (P < .01). Errors due to sex, genotype, weight, and their interactions were greatest for the less lean barrows. A combination of probe and electromagnetic scanner measurements resulted in the least error. The value of barrows with low percentage of lean was consistently overpredicted, whereas the value of leaner gilts was underpredicted for the models using ruler and electromagnetic scanning separately (P < .001).

Analysis of Variance↗
PubMed1998

Modeling the effects of hydroxypropylcellulose in acetaminophen tablet formulation.

The objective of the research described here was to develop a set of predictive models that would be used to show the performance of hydroxypropylcellulose as a pharmaceutical tablet binder. A statistically designed set of experiments was used to relate tablet formulation to functionality. It was found that the binder level affected both hardness and dissolution time. Useful predictive models were generated for tablet hardness and dissolution time as a function of the binder or binder-drug ratio. The optimal formulation can be predicted from this study, and will depend upon the combination of desired hardness and the dissolution time for a particular drug.

Acetaminophen↗
PubMed1991

Outcomes of an AIDS prevention program for methadone patients.

Methadone maintenance patients are at risk of contracting or transmitting HIV through intravenous drug use and/or unsafe sexual practices. An outcome evaluation of a voluntary AIDS prevention program for methadone patients in three clinics (two experimental, one control) is reported. The prevention program included three components: didactic AIDS education, HIV antibody counseling/testing, and facilitated peer support groups. Participation in AIDS education was associated with increased knowledge of AIDS risks and with improved attitudes toward condoms. Peer group participation was associated with improved attitudes toward the use of condoms and with increased use of condoms. Learning of HIV seronegativity was related to increased self-efficacy and decreased intravenous drug use risk behaviors. Rates of participation in the prevention program were disappointing, but the program seemed beneficial for those patients who did become involved.

Acquired Immunodeficiency Syndrome↗
PubMed2000

A link function approach to model heterogeneity of residual variances over time in lactation curve analyses.

Several studies with test-day models for the lactation curve show heterogeneity of residual variance over time. The most common approach is to divide the lactation length into subclasses, assuming homogeneity within these classes and heterogeneity between them. The main drawbacks of this approach are that it can lead to many parameters being estimated and that classes have to be arbitrarily defined, whereas the residual variance changes continuously over time. A methodology that overcomes these drawbacks is proposed here. A structural model on the residual variance is assumed in which the covariates are parametric functions of time. In this model, only a few parameters need to be estimated, and the residual variance is then a continuous function of time. The analysis of a sample data set illustrates this methodology.

Analysis of Variance↗
PubMed2004

Technical note: Estimating parameters of nonlinear segmented models.

The objective of this technical note is to develop an applied technique to estimate parameters using the Statistical Analysis System's nonlinear procedure (SAS PROC NLIN) for segmented models that have a change point or lag as one of the parameters. The goal is to select good starting values for the parameters near the global minimum or at least near a lower local minimum compared with what might be achieved using traditional starting values. The model used was f1 (t) = B1 + B4 if t < or = B3 and f2(t) = B1*exp[-B2*(t - B3)] + B4 if t > B3, where B1, B2, B3, and B4 are the parameters that require estimates, B3 is the change point or lag, and t = time. This technical note illustrates the solution when a traditional grid search for starting values is used and demonstrates a modified technique where starting values are systemically determined by fixing B3 over a range of reasonable values and then using the parameters from the solution with the lowest residual sums of squares as the starting values for the final solution. The modified method resulted in a lower square root of mean square error compared with the traditional method. The estimates for B3 (lag) were 3.5 for the modified method compared with 4.5 for the traditional method. This technique works well when using the SAS PROC NLIN procedure but can be modified to work with other statistical packages.

Models, Statistical↗
PubMed2007

Herd-level risk factors for lameness in high-producing holstein cows housed in freestall barns.

The objective of this study was to investigate the association of some herd-level factors with the prevalence of lameness in 53 high-production groups of Holstein cows housed on 50 commercial dairy farms having freestall barns in Minnesota. Cows in the high-production group (n = 5,626) were scored for locomotion (score of 1 to 5, where 1 = normal and 5 = severely lame) to estimate prevalence of lameness (locomotion score >or=3) in the group. Herd-level variables were used to explain the variation in prevalence among groups. Among the variables tested, herd size, pen space per cow, type and size of milking parlor, total mixed ration content of crude protein and neutral detergent fiber, feeding frequency, linear feedbunk space per cow, type of feed barrier, and use of footbath did not show any association with the prevalence of lameness in the univariate analysis screening test and were not included in the multivariate model. Pen stocking density (cows per 100 stalls), total daily distance between pen and milking parlor, number of cows per full-time employee equivalent, cud chewing index, and pen type were eliminated from the multivariate model in the backwards stepwise procedure. Daily time away from the pen for milking was positively associated with the prevalence of lameness, whereas cow comfort quotient was negatively associated with prevalence of lameness. Prevalence of lameness was greater when farms performed hoof trimming only when the manager decided cows needed it because of hoof overgrowth or lameness compared with farms on which the feet of all cows were trimmed on a maintenance schedule once or twice annually. Brisket board height of more than 15.24 cm and presence of the area behind the brisket board filled with concrete were associated with greater prevalence of lameness. Most of these herd-level factors could be managed to reduce lameness prevalence in commercial dairy farms.

Animals↗
PubMed1997

Surgical reconstruction of the musculocutaneous nerve in traumatic brachial plexus injuries.

Over the last 16 years, 345 surgical reconstructions of the brachial plexus were performed using nerve grafting or neurotization techniques in the Neurosurgical Department at the Nordstadt Hospital, Hannover, Germany. Sixty-five patients underwent graft placement between the C-5 and C-6 root and the musculocutaneous nerve to restore the flexion of the arm. A retrospective study was conducted, including statistical evaluation of the following pre- and intraoperative parameters in 54 patients: 1) time interval between injury and surgery; 2) choice of the donor nerve (C-5 or C-6 root); and 3) length of the grafts used for repairs between the C-5 or C-6 root and the musculocutaneous nerve. The postoperative follow-up interval ranged from 9 months to 14.6 years, with a mean +/- standard deviation of 4.4 +/- 3 years. Reinnervation of the biceps muscle was found in 61% of the patients. Comparison of the different preoperative time intervals (1-6 months, 7-12 months, and > 12 months) showed a significantly better outcome in those patients with a preoperative delay of less than 7 months (p < 0.05). Reinnervation of the musculocutaneous nerve was demonstrated in 76% of the patients who underwent surgery within the first 6 months postinjury, in 60% of the patients with a delay of between 6 and 12 months, and in only 25% of the patients who underwent surgery after 12 months. Comparison of the final outcome according to the root (C-5 or C-6) that was used for grafting the musculocutaneous nerve showed no statistical difference. Furthermore, statistical analysis (regression test) of the length of the grafts between the donor (C-5 or C-6 root) nerve and the musculocutaneous nerve displayed an inverse relationship between the graft length and the postoperative outcome. Together, these results provide additional information to enhance the functional outcome of brachial plexus surgery.

Adolescent↗
PubMed2006

[Comparison of influential variables for smoking temptation between adolescent and adult smokers].

PURPOSE: This study attempted to identify influential variables on smoking temptation between groups: adolescent smokers and adult smokers. METHOD: A survey was conducted with 376 adolescent smokers in 4 high schools and 451 adult smokers in community settings in South Korea. Univariate statistics and regression were used for data analysis. RESULT: The most powerful predictor of smoking temptation for adolescent smokers was nicotine dependency. On the other hand, the most powerful predictor of smoking temptation for adult smokers was self-efficacy for smoking abstinence. In the high smoking temptation group, depression and nicotine dependency were the predictors for smoking temptation for adolescent smokers and nicotine dependency and pros for smoking were the predictors for smoking temptation for adult smokers. In the low smoking temptation group, cons for smoking and process of change for smoking abstinence were the predictors on smoking temptation for adolescent smokers and self-efficacy for smoking abstention and pros for smoking were the predictors on smoking temptation for adult smokers. CONCLUSION: There were different influential variables on smoking temptation according to age groups and level of smoking temptation. Smoking-cessation interventions should be tailored to the level of smoking temptation of the individual smokers.

Adolescent↗
PubMed2004

[The validity of the three dimensional model to classify coping behavior].

The purpose of this study was to validate the three dimensional model of classifying coping behavior. The three are: Encounter-Avoidance, Problem-Emotion, Behavior-Cognition Dimension. A set of questionnaires on coping behavior and psychological stress responses were administered, and 1,604 undergraduates and 1,296 adults completed them. Analyses of covariance structure were performed, and results indicated that the three dimensional model, with eight coping style, showed the highest goodness-of-fit statistics. Multiple regression analyses also indicated that Problem-Emotion and Behavior-Cognition dimensions were useful for predicting the coping effects on psychological stress responses. Therefore, the two dimensional model of Problem-Emotion and Behavior-Cognition, with four coping style, would be helpful for further investigation of coping behavior that would buffer psychological stress responses.

Adaptation, Psychological↗
PubMed1992

Occupational exposure to sulfuric acid in southern Ontario, Canada, in association with laryngeal cancer.

A case-referent study, designed to test associations between asbestos, nickel, and the development of laryngeal cancer, was conducted in southern Ontario in 1977-1979. The cases were individually matched to neighborhood referents for gender and age. This constituted the primary study. Personal interviews had secured tobacco, alcohol, and detailed work histories. To 183 of the male pairs was added retrospective assessments of sulfuric acid exposure for each job, blind of disease status; this constituted the data base for an augmented secondary analysis. Logistic regression revealed statistically significant odds ratios when tobacco and alcohol were controlled. Exposure-response gradients were strongly positive with odds ratios in the range of 1.97 [95% confidence interval (95% CI) 0.63-6.13] for short duration-low level exposure through 6.91 [95% CI 2.20-21.74] for long duration-higher level exposure employing progressively more specific definitions of exposure. Asbestos as a confounder and the interaction terms examined were nonsignificant. These findings are corroborative of those of other studies.

Adult↗
PubMedDate not supplied

Equity in the diagnosis of chest pain: race and gender.

OBJECTIVE: To explore gender and racial equity in emergency room treatment of chest pain. METHODS: Three hundred seventy-nine patient records were analyzed, taking into account effects of age, clinic, comorbid status, and insurance status. RESULTS: Analysis of covariance and logistic regression revealed statistically significant differences between races but not between genders for time to first EKG and percent of patients receiving cardiac catheterization and echocardiography. Blacks waited longer than whites for an EKG and were less likely to receive cardiac catheterizations but more likely to receive echocardiography. CONCLUSION: This study demonstrates a lack of equity by race in treatment of chest pain emergencies.

Adult↗
PubMed2006

Can simple anthropometric and physical performance tests track training-induced changes in load-carriage ability?

The objective of this research was to determine whether tests of strength, endurance, and anthropometry could be used to assess training-induced changes (delta) in load-carriage performance. Eighty-four British Army recruits completed a 10-week training program. Strength, endurance, body composition, and 3.2-km load carriage with 15 kg and 25 kg were assessed before and after training. Training significantly increased load-carriage performance (7-16%), back extension and dynamic lifting strengths, endurance and fat-free mass, and reduced body fat. Statistically significant regression models (adjusted R2 of 0.063-0.797) were produced that predicted delta load-carriage performance. However, the 95% limits of agreement between observed and predicted delta load-carriage data showed margins of error (11-15%) comparable to the average training-induced gains in performance. Training-induced changes in load-carriage performance appear to be highly specific, which suggests that both training and testing procedures should also be specific to load-carriage performance.

Adolescent↗
PubMed1990

Hospital demand for physicians.

This article develops a derived demand for physicians that is general enough to encompass physician control, simple profit maximization and hospital utility maximization models of the hospital. The analysis focuses on three special aspects of physician affiliations: the price of adding a physician to the staff is unobserved; the physician holds appointments at multiple hospitals, and physicians are not homogeneous. Using 1983 American Hospital Association data, a system of specialty-specific demand equations is estimated. The results are consistent with the model and suggest that physicians should be concerned about reduced access to hospitals, particularly as the stock of hospitals declines.

Costs and Cost Analysis↗
PubMed1991

The impact of situational factors on health care preferences: exploring the prospect of situationally based segmentation.

Health care marketing research has examined the relationship between health care utilization and (1) client demographic characteristics and (2) service characteristics. The impact of situational factors on health care utilization has received limited attention. The authors find that the influence of situational factors in the health care market is substantial and suggest some preliminary situational segmentation strategies.

Community Participation↗
PubMed1992

Determinants of expenditures and use of services among elderly HMO enrollees.

This study examined determinants of expenditures and use of services by a group of elderly HMO enrollees. Study subjects were 895 elderly members of the Fallon Community Health Plan who enrolled between January 1, 1980 and December 31, 1983. We explored whether the determinants of expenditures and utilization varied across different types of services, specifically inpatient hospital care and ambulatory care. Having a heart problem, a mobility/disability, and arthritis were consistent predictors of high resource use. Having a mental health problem and a history of past hospitalization were also significant predictors across most models. The health policy implications of these data and their implications for quality assurance within the HMO setting are discussed.

Aged↗