Total Error Values Research Articles

Validity of bioelectrical impedence equations for estimating fat-free weight in high school female gymnasts.

The present study examined the validity of bioelectrical impedence (BIA) equations for estimating fat-free weight (FFW) in female gymnasts by comparing the values to those obtained from underwater weighing (UWW). Ninety-seven female Caucasian high school gymnasts (mean age +/- SD = 15.7 +/- 1.1 yr) participated in the study. FFW from UWW was calculated from percent fat using the revised formula of Brozek et al. (mean FFW +/- SD = 43.8 +/- 4.5 kg) and the age-specific constants of Lohman (mean FFW +/- SD = 44.8 +/- 4.6 kg). Cross-validation analyses included examination of the constant error (CE), SEE, r, and total error (TE). The results indicated similar trends between equations when based on either the Brozek or Lohman conversions; however, the CE, SEE, and TE values were consistently lower for the majority of the equations using the revised formula of Brozek et al. Based upon the results of the cross-validation analyses, the equation of Houtkooper et al. and the interlaboratory equations of Van Loan et al. and Lohman, which resulted in identical TE values of 2.4 kg are recommended for use with young high school gymnasts.

VALIDITY OF NEAR-INFRARED INTERACTANCE AND BIOELECTRICAL IMPEDANCE FOR ESTIMATING PERCENT FAT IN FEMALE SWIMMERS 329

The purpose of the present study was to determine the validity of near-infrared interactance (NIR) and bioelectrical impedance (BIA) instruments for estimating percent body fat (%fat) in young female swimmers. Fifty-three female, age-group swimmers ([horizontal bar over]X age±SD=11.7 ± 3.0 yrs) volunteered to have their% fat estimated by underwater weighing(UWW), a Futrex-5000A NIR instrument, and an RJL Systems BIA-106 Spectrum analyzer. The cross-validation procedures used to compare estimated% fat values from NIR and BIA to criterion% fat from UWW included the constant error(CE), validity coefficient (r), standard error of estimate (SEE), and total error (TE). Table The findings from the present study indicated that the NIR (TE=6.6% fat), and BIA (TE=6.7% fat) instruments resulted in TE values that were too large to be of practical value. Thus, the NIR and BIA instruments used in the present study are not recommended for estimating% fat in young female swimmers.

Validity of bioelectrical impedance equations for estimating percent fat in males.

The present study examined the validity of selected bioelectrical impedance (BIA) equations for estimating percent fat (% fat) in males and compared their validity with that of a commonly used skinfold equation (Sum3). One-hundred twenty-two Caucasian males (X +/- SD = 12.5 +/- 5.8% fat, as determined by underwater weighing) served as subjects. Selection of the BIA equations was dependent upon meeting at least one of three criteria: 1) developed from a previous interlaboratory investigation, 2) derived on a large sample size (> 200), or 3) previously been shown to accurately estimate body composition when cross-validated against a criterion method. Cross-validation analyses included examination of the constant error, standard error of estimate (SEE), r, and total error (TE). The Sum3 equation which resulted in the lowest SEE and TE values (2.6% fat and 3.4% fat, respectively) and the highest validity coefficient (r = 0.90, P < 0.001), most accurately estimated % fat and, therefore, was recommended over BIA equations for estimating body composition in Caucasian males with lean to average body fatness. The fat-specific interlaboratory BIA equation of Segal et al. for males < or = 20% fat (N = 107) which resulted in a TE value of 3.6% fat and the generalized equation of Guo et al. (TE = 4.1% fat) may, however, be considered as acceptable alternatives.

Validity of skinfold equations for estimating body density in youth wrestlers

The present investigation examined the validity of 16 skinfold equations for predicting body density (BD) in youth wrestlers (mean age +/- SD = 11.0 +/- 1.3 yr) by comparing the values to those obtained from underwater weighing. Forty-eight members of youth wrestling clubs (mean BD +/- SD = 1.0634 +/- 0.0125 g.cm-3) volunteered to serve as subjects. The statistical analyses included examination of the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). The results of this investigation indicated that all of the equations resulted in TE values that were > or = 0.0106 g.cm-3 (range = 0.0106-0.0229 g.cm-3) which corresponded to > or = 4.9% body fat. The TE values were too large to provide accurate estimates of body composition in the present sample of youth wrestlers. Future studies should use the CE values from the present investigation to adjust the intercepts of the skinfold equations in the present study and cross-validate the modified equations on young male athletes.

Anthropometric estimation of thigh muscle cross-sectional area

The purpose of this investigation was to derive and validate circumference and skinfold equations for estimating the anatomical cross-sectional area (CSA) of the quadriceps, hamstrings, and total thigh muscles. Forty-three adult male (mean age +/- SD = 25 +/- 5 yr) volunteers underwent magnetic resonance imaging (MRI) to determine the CSA of the thigh muscles at the midfemur level as well as midthigh circumference and anterior thigh skinfold assessment. Multiple regression analyses were used to derive equations for predicting quadriceps, hamstrings, and total thigh muscle CSA of the dominant limb from the anthropometric dimensions on a random sample of 30 of the subjects. Cross-validation (CV) analyses were performed for each equation on: (a) the nondominant thigh of the derivation group (N = 30); (b) the dominant thigh of the CV group (N = 13); and (c) the nondominant thigh of the CV group (N = 13). The CV total error values for the quadriceps, hamstrings, and total thigh muscle CSA ranged from 5.4 to 14.4, 3.3 to 5.5, and 10.0 to 25.4 cm2, respectively. The anthropometric equations are recommended for one-time estimates of muscle CSA values in healthy, well-nourished young adult males when more sophisticated procedures are not available.

Validity of Bioelectrical Impedance Equations for Estimating Fat-free Mass in Japanese Males.

The present study validated the bioelectrical impedance analysis (BIA) method for estimating fat-free mass (FFM). Forty-five male university students served as subjects. Four equations that have been recently proposed for predicting FFM from resistance by BIA and anthropometrical indicators were compared with values obtained from underwater weighing. Cross validation analyses included examination of the constant error (CE), standard error of estimate, r, and total error (TE). The results indicated that the equations Deurenberg et al. (1991), which resulted in small TE and CE values, most accurately estimated FFM.

Validity of anthropometric techniques for estimating percentage body fat in obese females before and after sizable weight loss.

AbstractThe validity of selected generalized (n = 7) and obese population‐specific (n = 2) skinfold and girth based anthropometric equations (using hydrostatic weighing as the criterion measure) was evaluated in 19 obese women before and after a mean body weight loss of 19.4 kg (percent body fat was reduced from 45.3% to 35.4%). For the present study, evaluation criteria of mean differences in percent body fat (%BF) of &lt; 3%, r values &gt; 0.70, and total error (T.E.) values of &lt; 5% were selected. Only the equations that utilized girths as part of the prediction technique (Barrows and Snook, 1987; Jackson et al., 1980; Tran and Weltman, 1989; Weltman et al., 1988) resulted in mean differences in %BF of less than 3%, r values of &gt; 0.70 and T.E. values of less than 5% in obese women before weight loss. After 19.4 kg of weight loss, all but three of the equations resulted in mean differences in %BF of less than 3%, r values of &gt; 0.70 and T.E. values of less than 5%. The obese population‐specific equations of Barrows and Snook (1987) and Weltman et al. (1988) were not accurate predictors of body composition after weight loss as they resulted in mean differences of 4.5–7.0 %BF. Although some of the equations examined were valid predictors of %BF either before or after weight loss, only the Jackson et al. (1980) equations which utilized both skinfolds and hip girth, and the Tran and Weltman (1988) equation which utilized trunk girths, resulted in mean differences of &lt; 3 %BF, r values &gt; r = 0.70, and T.E. scores of &lt; ± 5 %BF both before and after weight loss. It was concluded that the prediction techniques of Jackson et al. (1980) and Tran and Weltman (1989), which utilize girth measures as part of the prediction technique, may have clinical utility for estimating changes in %BF in obese females before and after sizable weight loss. © 1993 Wiley‐Liss, Inc.

Validity of bioelectrical impedance equations for estimating fat-free weight in lean males

The present study examined the validity of bioelectrical impedance (BIA) equations for estimating fat-free weight (FFW) in lean males (± SD = 9.1 ± 2.2% fat) by comparing the estimates with values obtained from underwater weighing. Sixty-eight Caucasian male volunteers served as subjects. Cross-validation analyses included examination of the constant error (CE), standard error of the estimate (SEE), r, and total error (TE). The results indicated that the equations of Oppliger et al. (16), which resulted in small TE (1.70 kg) and CE (-0.02 kg) values, most accurately estimated FFW. Simple linear regression showed that FFW was more highly correlated with body weight (BW) (r = 0.98, P < 0.0001) and resulted in a lower SEE (1.68 kg) than cither height2/resistance (Ht2/R) (r = 0.81, P < 0.0001; SEE = 5.12 kg) or the independent variable (weight · resistance)/height2[WR/Ht2] utilized by the manufacturer of the BIA analyzer (r = 0.15, P > 0.05; SEE = 8.59 kg). Multiple regression showed that when WR/Ht2, Ht2/R, resistance, body mass index, Ht2, and/or Ht was added to the prediction equation, which utilized BW alone, they accounted for less than 1% additional variance and reduced the SEE by ≤ 0.16 kg. The results indicated that BW alone estimated FFW as accurately as any of the BIA equations in lean males.

The validity of visual estimations of percent body fat in lean males

The present study compared the validity of visual estimations of percent fat (% fat) in lean males (mean +/- SD = 9.6 +/- 2.3 % fat) to the validity of bioelectrical impedance analysis (BIA) and skinfold equations. Thirty-five Caucasian male volunteers (mean +/- SD = 23 +/- 5 yr; range = 19-40) served as subjects. Visual estimations of % fat were performed by two experienced male raters. The validity (compared to underwater weighing) for each procedure was determined by examining the constant error (CE), standard error of the estimate (SEE), r, and total error (TE). The results indicated that rater 1 (TE = 2.3% fat) could visually estimate % fat as accurately as the skinfold equations (TE = 2.4% fat). However, based on low TE, SEE, and CE values as well as considerable variability (mean difference = 2.7% fat) between the % fat estimates of the two raters, skinfold equations are recommended over visual inspection and BIA (TE = 5.0% fat) for estimating % fat in lean males.

The accuracy of coaches?? estimates of minimal wrestling weight

The purpose of this study was to compare estimations of minimal wrestling weight (MWW) from experienced high school wrestling coaches and anthropometric equations with those from underwater weighing. Eighty-two wrestlers (X age +/- SD = 16.54 +/- 1.05 yr) volunteered to be assessed via anthropometry and underwater weighing, with percent body fat calculated from body density (BD) using both the conversion constants of Lohman [percent body fat = [5.03/BD) - 4.59) x 100] and Brozek [percent body fat = [4.57/BD) - 4.142) x 100]. In addition, five head coaches, who had between 5 and 24 yr of experience, were asked to estimate within 1 lb the MWW for each of their athletes. The validity of four selected anthropometric equations and the coaches' estimates were compared with the actual MWW from underwater weighing by examining the constant error (CE), r, SEE, and total error (TE) values. The results indicated that the skinfold equation (EQ1) of Lohman provided the most accurate estimates of MWW (TE = 1.90-2.09 kg) and is therefore recommended over the subjective estimates of high school coaches.

Validity of Anthropometric Estimations of Body Composition in High School Wrestlers

The purpose of this study was to determine the validity of 23 anthropometric equations for estimating body composition and minimal wrestling weight in high school wrestlers. A total of 409 high school wrestlers (M age +/- SD = 16.42 +/- 1.03 yrs) volunteered for this study. Twenty-three anthropometric measures including eight skinfolds, nine circumferences, and six diameters were obtained from each subject. The mean body density, determined from underwater weighing, was 1.0748 +/- 0.0100 g.cm-3. The crossvalidation analyses indicated that the quadratic skinfold equation of Lohman resulted in the most accurate estimation of body density. The total error, constant error, standard error of estimate, and r for this equation were 0.0077 g.cm-3, -0.0003 g.cm-3, 0.0076 g.cm-3 and .65, respectively. Furthermore, the results of this investigation indicated that the minimal wrestling weight equations of Tcheng and Tipton resulted in total error values (5.54 to 6.06 kg) which were too large to be of practical use for high school wrestlers.

Estimation of minimal wrestling weight using measures of body build and body composition.

This study evaluated field methods for establishing minimal body weight in wrestlers based upon estimates of fat-free body weight (FFB): 239 high school wrestlers were measured for height, weight, 13 diameters, 24 circumferences, and 7 skinfolds, as well as for underwater weight to determine body density and resultant FFB. To estimate FFB, anthropometric models were used which were based upon diameters, circumferences, and/or skinfolds. Correlations between actual and predicted FFB were high, ranging from r = 0.89 to 0.92 for the models employing diameters and r = 0.96 for those employing circumferences, which respectively increased to r = 0.96 and r = 0.97 when body weight was included in theses models. The skinfold-based and mixed model estimates of FFB were r = 0.97 and r = 0.91 to 0.97, respectively. The corresponding total error (TE) in these estimates for the diameter-based models ranged from 6.54 to 3.80 kg (inclusion of body weight further reduced TE to 2.77 kg). Among the circumference models, TE ranged from 2.50 to 2.33 kg, with inclusion of body weight accounting for the lower value. Skinfold-based estimates of FFB demonstrated a TE level ranging from 2.48 to 2.33 kg. The lowest TE (2.32 kg) was demonstrated by a mixed model which included skinfolds, diameter, height, and body weight. Cross-validation of these new equations revealed the lowest TE values (less than 2.2 kg) for the skinfold and the mixed model equations, thereby identifying highly valid field techniques for determining the present level of FFB, which can serve as the basis upon which minimal body weight estimates can be made.

Body composition in paraplegic male athletes

The body composition and anthropometric characteristics of male paraplegic athletes (PARA, N = 22) were contrasted to an able-bodied ectomorphic (N = 22) and mesomorphic (N = 31) comparison group of moderately and highly trained male subjects. The validity of 12 body composition [density (Db)] prediction equations reported in the literature, 4 generalized, were determined (tested) on this special group of athletes (PARA). On the whole, the prediction equations over-predicted Db in PARA by 0.0039 to 0.0166 g.cm3 (under-predicted relative fat by 1.8 to 7.4%). Five diameter, 11 circumference, and 7 skinfold measures were used in a SAS-STEPWISE multiple regression procedure with hydrostatically determined Db to develop several suitable Db prediction equations for the paraplegic athlete. Diameters were poor predictors (r = 0.60, SEE = 0.0164), while skinfolds, circumferences, or a combination of measures were acceptable, with the combined equation being best (r = 0.95, SEE = 0.0064). The findings of this study suggest that even generalized equations do not adequately predict Db in PARA and that paraplegic specific equations are presently best suited for predicting Db in paraplegic athletes. The results further indicate that although these equations meet many of the criteria of Lohman, the SEE and total error values are unusually high and make prediction of body composition using anthropometry in a heterogeneous group of PARA athletes slightly unreliable.

BODY COMPOSITION IN PARAPLEGIC MALE ATHLETES

The body composition and anthropometric characteristics of male paraplegic athletes (PARA, N = 22) were contrasted to an able-bodied ectomorphic (N = 22) and mesomorphic (N = 31) comparison group of moderately and highly trained male subjects. The validity of 12 body composition [density (Db)] prediction equations reported in the literature, 4 generalized, were determined (tested) on this special group of athletes (PARA). On the whole, the prediction equations over-predicted Db in PARA by 0.0039 to 0.0166 g X cm-3 (under-predicted relative fat by 1.8 to 7.4%). Five diameter, 11 circumference, and 7 skinfold measures were used in a SAS-STEPWISE multiple regression procedure with hydrostatically determined Db to develop several suitable Db prediction equations for the paraplegic athlete. Diameters were poor predictors (r = 0.60, SEE = 0.0164), while skinfolds, circumferences, or a combination of measures were acceptable, with the combined equation being best (r = 0.95, SEE = 0.0064). The findings of this study suggest that even generalized equations do not adequately predict Db in PARA and that paraplegic specific equations are presently best suited for predicting Db in paraplegic athletes. The results further indicate that although these equations meet many of the criteria of Lohman, the SEE and total error values are unusually high and make prediction of body composition using anthropometry in a heterogeneous group of PARA athletes slightly unreliable.

Measurement Errors in Field Calibration of in Situ Leaf Psychrometers1

Development of techniques for in situ field measurement of leaf water potential using thermocouple psychrometers highlight the need for an accurate analysis of the errors associated with such measurements. The major sources of error arise from random calibration errors, the temperature dependence of the calibration relationship, temperature differences between the leaf and the psychrometer sensing junction and the error in reading the psychrometer output voltage. In an analysis of such errors, using insulated field‐calibrated psychrometers, the major source of error was found to be in the calibration relationship, particularly as temperature decreased and approached the value of the calibration intercept. This resulted in total relative error values of 8 to 10% of the measured water potential at 0°C, whereas the error was less than 4% for temperatures greater than 20°C (for a potential of —1250 kPa).

A quality assurance programme for quantitative urine analyses

Eighty-six Australasian laboratories participated in an interlaboratory quality assurance programme for 10 urine analytes. Twelve liquid samples were prepared from commercial lyophilized urine control material and distributed in 3 batches of 4. Use of pre-set acceptability limits for total laboratory error and target values facilitated timely feedback in graphic form. The samples had concentrations which were linearly related; this allowed simple calculation of overall imprecision and bias, graphic feedback of all submitted results, and comparison of performance between laboratories. A number of unsuitable and poor methods were identified. Particular attention must be paid, in future, to more widespread use of appropriate calibration and quality control materials, to avoidance of transcription and calculation errors, and to analysis of urine samples with elevated levels of analyte. Current laboratory performance can meet analytical goals for analyses of urine creatinine, phosphate, urate, and glucose but analysis of urine sodium, potassium, urea, calcium, osmolality, and proteins require a significant improvement.

A computer program for focal mechanism determination combining P and S wave data

abstract A computer program has been developed to find the orientation of a double couple source model for the mechanism of an earthquake which best satisfies the data from P and S waves. The relationship between the two axes of the solution given by the equations for the polarization angle of S is used in order to rapidly find the orientation of the source model for which a total error value involving the error of S and P data is a minimum. The program gives best results for data from homogeneous instruments of similar period range. Solutions for three earthquakes, selected because of the orientation of the source, are presented and the reliability of their solutions under ideal conditions is discussed.