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PubMed1988

Empirical classification of infant-mother relationships from interactive behavior and crying during reunion.

Multiple discriminant function analysis (MDFA) was conducted with data from 255 Strange Situations conducted and scored by Ainsworth and her colleagues. Cross-validated discriminant functions and classification weights were obtained, allowing attachment classifications (A, B, C) to be assigned directly from scores on interactive behavior and crying during reunion episodes. In the past, classification agreement within laboratories has often been used as a training criterion. Unfortunately, this does not insure that classification criteria agreed upon within a laboratory are comparable across laboratories, nor does it insure that agreed upon criteria will yield the same classifications that would have been assigned by the researchers who developed the scoring system. The present results enable researchers who have mastered the scoring systems for reunion behavior and crying to obtain attachment classifications directly from scores on these variables. Alternatively, this procedure may be used to guide the training of, and validate classification decisions by, local judges.

Crying↗

PubMed1988

Discriminant analysis of laboratory tests in patients admitted to a coronary care unit.

Discriminant analysis of chemistry and hematology laboratory test results was used to classify patients with and without myocardial infarction in a coronary care unit. We studied 64 patients with myocardial infarction and 70 patients without infarction, using logistic regression, linear and quadratic discriminant analyses on untransformed and logarithmically transformed data. Serum aspartate aminotransferase (AST, EC 2.6.1.1), the best single discriminating test, classified 73% of patients correctly. Quadratic discriminant analysis on log-transformed data had a 98.5% classification accuracy when all variables were used in the discriminant function and had the highest classification accuracy and precision. All of the discriminant methods had acceptable cross-validation.

Adult↗

PubMed1988

Factor structure of the Arthritis Helplessness Index.

The factor structure of the Arthritis Helplessness Index (AHI) was examined using principal components factor analysis with varimax rotation. Data for the initial factor analysis came from a longitudinal study of 368 patients with rheumatoid arthritis (RA). Two slightly negatively correlated (r = -0.21) subscales emerged: internality and helplessness. This analysis was cross-validated twice. Findings reveal that the 2 subscales of the AHI are more reliable and valid than the total score. The 5 item helplessness subscale, in particular, appears to be a highly valid indicator of the degree to which patients with RA feel overwhelmed by their disease.

Arthritis↗

PubMed1988

Deconvolution of episodic hormone data: an analysis of the role of season on the onset of puberty in cows.

A new approach to the analysis of episodic hormone data is described. The method involves a stochastic model in which measured blood hormone concentration is represented as a convolution of individual pulses, each of which is thought of as the response to a burst of neural activity. Individual pulses are not constrained to occur in a fixed regular pattern in time. The methodology takes a series of blood hormone measurements and produces a spike train of pulse peak times together with a set of pulse shape parameters. This decomposition motivates some fresh approaches to the analysis of hormone data. For a given number of pulses the model is fit by minimizing a residual sum of squares criterion. This is a difficult combinatorial optimization problem. A randomized local adjustment algorithm is developed. Generalized cross-validation is used to select the number of pulses. The technique seems to produce reliable results on simulated data sets. The methodology is used to study some data concerned with the role of season of birth on the onset of puberty in bovine females. The analysis raises some interesting questions related to the maturation of the pituitary and hypothalamus.

Algorithms↗

PubMed1987

Assessment of PIC and MMPI scales in adolescent psychosis: a caution.

This study investigated the sensitivity of two frequently used multidimensional instruments--the Personality Inventory for Children (PIC) and the Minnesota Multiphasic Personality Inventory (MMPI)--in assessing psychotic states in adolescents. This issue arose as a result of the fact that the PSY scale on the PIC was constructed and cross-validated only on samples of children between the ages of 5 and 12 years. T-score comparisons between psychotic and nonpsychotic samples were performed, as well as Pearson correlations between PIC Psychosis (PSY) and MMPI Schizophrenia (Sc) scale T-scores. T-score comparisons indicated no significant differences between the groups on either PSY or Sc. A nonsignificant relationship between PSY and Sc scale elevations was also found. These results suggest the need for a profile-analytic approach to PIC and MMPI interpretation in identifying psychotic symptomatology in adolescents rather than PSY or Sc T-score elevation in isolation.

Adolescent↗

PubMed1987

Estimation of VO2max from a one-mile track walk, gender, age, and body weight.

The purpose of this investigation was to explore an alternative field test to estimate maximal oxygen consumption (VO2max) using a one-mile walk test. VO2max was determined in 343 healthy adult (males = 165, females = 178) subjects 30 to 69 yr using a treadmill protocol (mean +/- SD: VO2max = 37.0 +/- 10.7 ml X kg-1 X min-1). Each subject performed a minimum of two, one-mile track walks as fast as possible. The two fastest walks (T1, T2) with elapsed times within 30 s were used for subsequent analyses. Heart rates were monitored continuously and recorded every one-quarter mile. Multiple regression analysis (best sub-sets) to estimate VO2max (l X min-1) yielded the following predictor variables: track walk-1 time (T1); fourth quarter heart rate for track walk-1 (HR 1-4); age (yr); weight (lb); and sex (1 = male, 0 = female). The best equation (N = 174) was: VO2max = 6.9652 + (0.0091*WT) - (0.0257*AGE) + (0.5955*SEX) - (0.2240*T1) - (0.0115*HR1-4); r = 0.93, SEE = 0.325 l X min-1. Comparing observed and estimated VO2max values in a cross-validation group (N = 169) resulted in r = 0.92, SEE = 0.355 l X min-1. Generalized and sex-specific equations to estimate VO2max (ml X kg-1 X min-1) were also generated. The accuracy of estimation as expressed by SEE was similar among the equations. The results indicate that this one-mile walk test protocol provides a valid sub-maximum assessment for VO2max estimation.

Adult↗

PubMed1987

The use of the logistic model in space motion sickness prediction.

The one-equation and the two-equation logistic models were used to predict tested subjects' susceptibility to motion sickness in KC-135 parabolic flights using data from other ground-based motion sickness tests. A data set containing data from 6 provocative tests, 2 vestibular function tests, and 1 motion sickness experience questionnaire from 162 subjects was used in this study. The prediction results from the logistic models were compared with those from the previously-used Bayes linear discriminant analysis procedures. The results based on this data set show that the logistic models correctly predicted substantially more cases (an average of 13%) in the data subset used for model building. In the data subset used for model cross-validation, the logistic models correctly predicted 4% and 5% more cases in the prediction of vomit or nonvomit, and of degree of susceptibility, respectively. Overall, the logistic models ranged from 53 to 65% predictions of the three endpoint parameters, whereas the Bayes linear discriminant procedure ranged from 48 to 65% correct for the cross validation sample.

Adult↗

PubMed1987

Logistic risk model for the unique effects of inherent aerobic capacity on +Gz tolerance before and after simulated weightlessness.

Small sample size (n less than 10) and inappropriate analysis of multivariate data have hindered previous attempts to describe which physiologic and demographic variables are most important in determining how long humans can tolerate acceleration. Data from previous centrifuge studies conducted at NASA/Ames Research Center, utilizing a 7-14 d bed rest protocol to simulate weightlessness, were included in the current investigation. After review, data on 25 women and 22 men were available for analysis. Study variables included gender, age, weight, height, percent body fat, resting heart rate, mean arterial pressure, VO2max, and plasma volume. Since the dependent variable was time to greyout (failure), two contemporary biostatistical modeling procedures (proportional hazard and logistic discriminant function) were used to estimate risk, given a particular subject's profile. After adjusting for pre-bed-rest tolerance time, none of the profile variables remained in the risk equation for post-bed-rest tolerance greyout. However, prior to bed rest, risk of greyout could be predicted with 91% accuracy. All of the profile variables except weight, MAP, and those related to inherent aerobic capacity (VO2max, percent body fat, resting heart rate) entered the risk equation for pre-bed-rest greyout. A cross-validation using 24 new subjects indicated a very stable model for risk prediction, accurate within 5% of the original equation. The result for the inherent fitness variables is significant in that a consensus as to whether an increased aerobic capacity is beneficial or detrimental has not been satisfactorily established. We conclude that tolerance to +Gz acceleration before and after simulated weightlessness is independent of inherent aerobic fitness.

Acceleration↗

PubMed1985

Behavioral airsickness management program for student pilots.

The management of recurrent airsickness in student pilots has traditionally involved positive reinforcement of motivation and limited use of medication. The Behavioral Airsickness Management (BAM) program seeks to establish an effective behavioral and cognitive intervention format for managing airsickness symptoms. There were 37 student pilots experiencing recurrent airsickness who were exposed to an assessment and rehabilitation program designed to develop diaphragmatic breathing skills while rapidly reducing physiological tension via cue-evoked relaxation strategies. Cognitive modification techniques were also included in the treatment protocol. Of the 37 students, 35 were returned to their flying training program with no recurrences of the airsickness problems. Cross-validation evidence is offered, as well as hypotheses for the program's success.

Adult↗

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↗