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Results for “cross-validation”

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PubMed1986

[Regression analysis of clinical data for purposes of predicting the efficacy of psychopharmacotherapy of episodes of schizophrenia].

Validity of a multidimensional statistics procedure for the prediction of the psychotropic drugs efficacy (PDE) was tested in a study on 60 schizophrenics showing the signs of an acute condition before treatment. Pretreatment ratings of 78 psychopathological symptoms underwent a computer analysis. A multiple stepwise regression equation was obtained which predicted PDE using ratings of 15 symptoms. A high correlation between the predicted and actual PDE was shown at cross-validation (r = +0.87), as well as a higher proportion of the PDE variance explained by the "regression" predictor rather than traditional "syndromal" one or the former's combination with the diagnosed type of the course (42%, 57.4% and 71.9%, respectively). Some methodological problems (homogeneity of patients and treatment conditions, the adequacy of the mathematical model applied) are discussed.

Computers↗

PubMed1985

Neuropsychologic detection of abnormal mental decline in older persons.

We conducted comprehensive neuropsychologic assessment in normal 60- to 88-year-old persons and in patients with dementia of various causes, matched for age and sex. Patients with dementia performed significantly poorer on tests of short-term memory, temporal orientation, visual perception, and language. Further data analysis, including multivariate classification procedures, identified a combination of three tests (Visual Retention, Controlled Oral Word Association, and Temporal Orientation) that in a cross-validation study correctly classified 89% of cases with a high degree of probability. Only 6.5% of cases were misclassified, while 4.5% were in a questionable, borderline category. The battery constituted by these three discriminating tests provides a brief, easily administered neuropsychologic screening instrument that may be used by a variety of health professionals for the detection of abnormal mental decline in older persons.

Aged↗

PubMed1985

Accuracy of residual volume prediction--effects on body composition estimation in pulmonary dysfunction.

The accuracy of predicting residual volume (RV) and the effect of employing such predictions in the assessment of body composition by hydrostatic weighing was examined. Prediction equations derived by Wilmore (Med. Sci. Sports, 1969) and Boren et al. (Am. J. Med., 1966) were cross-validated on 400 male subjects with varying degrees of pulmonary dysfunction. Statistical analysis included comparison of predicted vs measured RV and regression analysis of measured on predicted values. Neither equation met acceptable statistical criteria (p greater than .05). Underwater weights were calculated based upon the measured RV and an assumed standard body weight, body density, and percent body fat (i.e., 70 kg, 1.0647 g/cc and 15.0%). Predicted RV was then substituted in the calculation and the effect on standardized values examined, between the calculated and standardized percent fat value with both equations. Results suggest in the present subjects, RV cannot be accurately predicted and the use of such prediction equations introduces sizable errors in body composition estimation.

Adult↗

PubMed1985

Predicting basal metabolic rate, new standards and review of previous work.

After reviewing the literature on basal metabolism, this paper discusses and reviews recent attempts to predict BMR from age, sex and anthropometric measurements. Criticism is made of the scientific and statistical integrity of a widely used table of standard metabolic rates for weight. The statistical screening of data from the literature of the past 50 years is described and equations computed from these screened data are presented. In these equations, BMR is predicted simply from weight or from weight and height with sex and age taken into account. Information is given on error, and tables estimating error for predictions on new data both for individuals and for means of groups of subjects are included. A table of BMRs for weights from 3 to 84 kg for males and females separately is also included. Cross-validation techniques are used to estimate possible threats to validity from various sources including, for example, different procedures of early workers. It was found that in the data available subjects from developing countries not only were smaller and had lower metabolic rates (as was expected) but also had lower rates per unit body weight than European or North American subjects. It is argued that at an individual level the error of prediction must be high since the global operationalisation of BMR confounds separate effects known to participate in complex relations with sex, age and anthropometric indices. The work reported is aimed at meeting a practical need for equations which are simple to apply. However, it was found that little was gained by the use of more complex equations, although they remain of scientific interest.

Adolescent↗

PubMed1979

Individual temperament as a predictor of health or premature disease.

Two studies of temperament as a possible predictor of continuing good health or premature disease are reported. In earlier work to determine youthful precursors of premature disease, a number of separate characteristics distinguishing medical students who remain healthy from those with premature disorders have been identified. Characterization by temperament, an expression of innate biological endowment, provides a more global portrayal of an organism that can an aggregate of separate characteristics alone. Criteria for designating three temperament types, termed Alpha, Beta and Gamma, are presented. In 1948, 45 subjects were assigned to one of these types on the basis of youthful characteristics. The subjects in the three temperament groups had different health outcomes 30 years later, significant at the p less than 0.01 level. Gamma type had the most disorders and deaths, Beta type the fewest. A cross-validation study on 127 subjects had similar results at the p less than 0.05 level. Temperament appears to be a variable of predictive potential of individual stamina, or of vulnerability to premature disease and death.

Adult↗

PubMed1979

Prediction of maximal oxygen uptake in boys, ages 7-15 years.

Predictions of Vo2max (1 min-1 and ml kg-1 min-1) were obtained via multiple regression procedures from a sample of 100 boys, ages 6.7-14.8 years. Prediction equations for Vo2max (1 min-1) were obtained from the subjects' height, and the Vo2 (1 min-1) and heart rate observed during the third min of a treadmill walk (R = 0.95; CV = +/- 9.3%). A similar prediction was obtained when the subjects' age, height and weight were used (R = -0.94; CV = +/- 9.7%). Vo2max (ml kg-1 min-1) was predicted with similar accuracy (CV = +/- 8.4%) from age, and heart rate, VCO2(1 min-1), Vo2 (ml kg min-1), or from simply age, height and weight (CV = +/- 9.2%). Cross-validation of the equations with another sample of 39 boys demonstrated that the prediction equations based on laboratory data were quite stable, % errors approximately 1-2 +/- 9%. However, the equations based on age, height and weight underestimated the Vo2max slightly, both in 1 min (X = -0.091 min) and ml kg min (X = -2.2 ml kg min, P less than 0.05). The results indicate that reasonably reliable and accurate estimates of Vo2max for children may be obtained from either laboratory data, or simply from their age, height and weight.

Adolescent↗

PubMed1979

Alcoholism-related content in the MMPI: item analysis of alcoholics vs. normal and general psychiatric populations.

An analysis of alcoholism-related content in the MMPI was undertaken using an alcoholic population, a psychiatric population and two normal populations. The alcoholic and psychiatric groups were drawn from facilities in the Minneapolis-St. Paul area, and the normal populations were the Hathaway Adult Group and the Mayo Clinic nonpsychiatric patient group. A derivation study and a cross-validation resulted in the identification of three item pools: 1) that discriminate alcoholics from both normals and psychiatric patients, 2) items that discriminate alcoholics from normals only, 3) items that discriminate alcoholics from psychiatric patients only. Only seven items discriminate both male and female alcoholics from both normals and psychiatric patients. These items have substantial face validity. As the core of alcoholism-related content in the MMPI, they can serve as a stem for the development of scales with more specialized purposes.

Alcoholism↗

PubMed1984

Prediction of chronicity in acute low back pain.

Forty-eight patients seeking treatment for low back pain were assessed in the acute stage to see if they exhibited characteristics that would predict response to medical treatment. It was hoped that, if there were personality and demographic differences between patients who did and those who did not respond to standard medical treatment, potential chronic pain patients could be identified and targeted for special treatment. Stepwise discriminant analysis yielded a prediction equation that correctly identified 41 of the 48 cases (85.4%). Acute patients who became chronic complained of pain over a wider area of the body; had deeper, more central pain; were highly anxious; and had a lower activity level. Although cross-validation studies are needed, identification of potentially chronic pain patients may be feasible, making appropriate early intervention possible.

Back Pain↗

PubMed1984

Research design and analysis of data procedures for predicting body density.

Statistical methods used to develop body composition prediction equations were examined. Equations published in the 1960s and early 1970s have been called "population-specific" equations because they were developed on homogeneous samples. A major limitation of population-specific equations was a low ratio of subjects per variable, which reduces validity. The more recent method has been to develop "generalized" equations with large samples varying greatly in age and body fatness. The statistical models used for generalized equations were nonlinear regression analysis to account for the quadratic relation between body density and skinfold fat. Age was used as an independent variable to adjust for aging. Generalized equations exhibit accuracy consistent with population-specific equations and increase the generalizability of prediction. Future body composition research should focus on the cross-validation of published equations to define the limits of equation accuracy.

Adult↗

PubMed1984

Relationship between physical, psychological, social, and environmental variables and subjective sleep quality.

In a survey study of patients of a general practitioner the relationship between sleep quality and a heterogeneous set of other variables was examined. The data file was divided randomly, and a two-staged multiple regression analysis was performed on each half. The two resulting regression equations were cross-validated on the data of the other data file. The variables mood, age, and use of medicine proved to have the most significant relationship to sleep quality.

Adult↗

PubMed1984

The influence of somatotype on anthropometric prediction of body composition in young women.

The influence of somatotype on the validity of anthropometric prediction of body density (Db) in young women (N = 92) was investigated. Three groups of predominantly endomorph (N = 27), mesomorph (N = 35), and ectomorph (N = 30) women were identified by the Heath-Carter and Sheldon somatotyping methods. Discriminant analysis revealed a 100% accuracy in somatotype group determination. Thirteen diameters, 26 girths, and 8 skinfolds were measured and used in a STEPWISE regression analysis to derive somatotype-specific regression equations to predict body density. Combining all the measures provided very good prediction accuracy in all three groups with multiple correlation coefficients (R) of 0.98, 0.90, and 0.90, and the standard error of estimate (SEE) of 0.003, 0.005, and 0.005 for Db (gm X cc-1) in the endomorphs, mesomorphs, and ectomorphs, respectively. A cross-validation study confirmed the accuracy of the somatotype-specific regression equations and demonstrated an inherent weakness in using some generalized equations on specific somatotypes. The use of non-somatotype-specific equations resulted in mean Db prediction errors ranging from -0.018 to +0.023 gm X cc-1 (8.5 to -10.7% Fat). Although all equations tested demonstrated specific weaknesses in one or more of the somatotype groups when predicting Db, the Jackson et al. (1980) equation performed better than most of the non-somatotype-specific prediction equations. These findings suggest that the anthropometric estimation of Db may not be sample specific in the same manner as had been previously thought and that greater accuracy may be achieved by using regression equations which have been generated on a previously somatotyped population sample.

Adolescent↗

PubMed1984

Predictors of performance on National Board Examinations Part II.

An effort was made to determine successful predictors of performance on National Board Examinations Part II. Preliminary results, using stepwise regression analysis, identified two predictor variables accounting for 65 percent of the variance in the criterion variable. Cross-validation regression analysis again identified the same two predictor variables accounting for 69 percent of the variance in the criterion variable. In both investigations, the correlation coefficients for the predicted National Board averages and the actual National Board averages are statistically significant. Implications of the studies are discussed.

Certification↗

PubMed1984

Neuropsychological impairment and associated intellectual functions in schizophrenic and other psychiatric patients.

As a routine admission procedure of an ongoing research program, the Halstead-Reitan Battery (HRB) and the Wechsler Adult Intelligence Scale (WAIS) were completed by 37 chronic schizophrenic patients, 3 patients with major affective disorders, and 2 with atypical psychoses. These admission data provided a basis for a retrospective investigation into the possibility of a relationship between impairment on the HRB and IQ. It was found that greater impairment on the HRB was associated with lower full-scale IQ (FSIQ) scores (r = -0.78, p less than .001). When the sample was separated into impaired and normal groups based on performance on the HRB, the coefficients of two discriminant functions, i.e., Verbal IQ and Picture Arrangement, classified the two groups with 100% accuracy. Cross-validation of the stepwise discriminant function analysis, using the jackknife procedure, resulted in a 98% hit rate. The results of the present study together with those of two other recent studies suggest that intellectual functions are critical interactive variables for interpreting the performance of chronic schizophrenic and other psychiatric groups on the HRB. Cautions to be observed in interpreting impaired and normal functioning in the context of intellectual functions are discussed.

Adult↗

PubMed1982

Steps toward the development of generalized equations for predicting body composition of adults.

The estimation of body density from anthropometric variables is often used to measure body composition. The purpose of this report was to review the development of early published equations and follow the transition from population specific equations to generalized equations for adults. The accuracy of population specific equations were improved and refined with the addition of circumference and diameter measures in combination with skinfolds and the use of populations of varied ages and degrees of body fatness. The major weakness of the population specific equations was their inability to account for aging and the non linear relationship between subcutaneous fat and body density. Regression models using the quadratic sum of skinfolds and age have been developed to account for these sources of variation. Cross-validation research has shown that these generalized regression models are accurate for adult males and females varying greatly in age and body fatness.

Adolescent↗

PubMed1983

[Comparative studies of the psychopathology of bronchial asthma and cystic fibrosis].

Comparative examinations were performed on each N = 36 subjects, with bronchial asthma, cystic fibrosis and healthy controls, with regard to individual psychopathology, family functioning, and the relationship of clinical parameters to psychopathology. Children suffering from cystic fibrosis had the highest prevalence rate of psychiatric disorder. Findings of the psychiatric assessment in general were cross-validated by parent's and teacher's questionnaires. Data relating to family function were less differentiating between the groups. In both groups of diseases significant correlations between clinical parameters and psychopathology were detected.

Adolescent↗

PubMedDate not supplied

Measurement of the nurse organizational climate of neonatal intensive care units.

The concept of organizational climate is important for the study and understanding of work organizations. Researchers have not yet studied the organizational climate of hospital intensive care units, so it is not clear that the dimensions useful in description of other work settings will be appropriate for conceptualizing neonatal intensive care units (NICU's). This study investigated nurse perceptions of the organizational climate of NICU's in a sample of 18 hospitals. The Organizational Climate Description Questionnaire was modified for use in the NICU setting. A set of homogeneous climate scales was developed from the revised instrument. The six scales of the resulting instrument, the Nursing Organizational Climate Description Questionnaire, Form B (NOCDQ-B), demonstrated median internal-consistency reliability of .69 on cross-validation. Analysis of variance indicated that each of the six NOCDQ-B dimensions served to differentiate the NICU's in the study. Further, significant relationships were found at the unit mean level between three of the six NOCDQ-B scales and nurse satisfaction, as measured by the Minnesota Satisfaction Questionnaire.

Analysis of Variance↗

PubMed1978

Objective assessment of prior air traffic control-related experience through the use of an occupational knowledge test.

The Occupational Knowledge Test (OKT) 101-B was administered to 784 air traffic control trainees who entered the FAA Academy's 16-week training course in 1976. All trainees completed the nonradar laboratory portion of the training and, in addition, completed a preemployment questionnaire. Based on responses to the questionnaire, the trainees were assigned to one of three experience groups, corresponding to groups given credit for experience using Civil Service Commission (CSC) selection procedures. It was found that the OKT was highly correlated with experience (r = 0.64) and, in addition, had a higher correlation with successful completion of the nonradar lab than did experience (r = 0.25 vs. 0.12). It was determined that use of an OKT score of 75 or above to assign extra credit would result in a failure rate of 3.1% for those receiving credit, while use of the current experience scale would result in a failure rate of 7.6% for those receiving extra credit on the CSC selection battery. The results held up for a cross-validation sample of 432 trainees who entered the Academy during 1977. Based on the results, it is recommended that an OKT score of 75 or above be used to assign extra credit for experience in the selection of air traffic controllers.

Aviation↗

PubMedDate not supplied

Schooling, occupational motivation, and personality as related to success in paramedical training.

Measures of prior school experience, motivation for working in a health care job, and personality were evaluated as potential predictors of success in Navy paramedical training. When, by multiple regression procedures, years of school completed, numbers of suspensions or expulsions from school, occupational motivation, and Comrey personality scale scores were combined with an aptitude measure that is used for guiding recruits into paramedical training, the cross-validity for predicting training completion was significantly increased (P less than 0.001) from 0.40 to 0.50. Practical means for applying these measures to the screening of candidates for paramedical training were developed. Results of the evaluation suggest that guiding people into jobs that they neither prefer nor perceive as congruent with their abilities and interests can significantly reduce the chances for occupational success.

Achievement↗