The reliability and precision of measurement in sports medicine are of concern in both research and clinical practice. The validity of conclusions drawn from a research project and the rationale for decisions made about the care of an injured athlete are directly related to the precision of measurement. Through analysis of variance, estimates of reliability and precision of measurement can be quantified. The purpose of this manuscript is to introduce the concepts of intraclass correlation as an estimate of reliability and standard error of measurement as an estimate of precision. The need for a standardized set of formulas for intraclass correlation is demonstrated, and it is urged that the standard error of measurement be included when estimates of reliability are reported. In addition, three examples are provided to illustrate important concepts and familiarize the reader with the process of calculating these estimates of reliability and precision of measurement.
Background and Purpose. Several studies have demonstrated that patients with knee injury scored within a normal range during one-legged hop tests yet showed quadriceps femoris muscle weakness with non–weight-bearing isokinetic testing. This study evaluated lower-extremity kinetics while subjects performed a single-leg vertical jump (VJ) and a lateral step-up (LSU) in an attempt to explain this phenomenon. Subjects and Methods. Using a motion analysis and force platform system, hip, knee, and ankle extension moments of 20 subjects with anterior cruciate ligament (ACL) reconstructions and 20 matched subjects were measured while they performed an LSU and a VJ. Results. An analysis of variance revealed that the knee extension moment of the ACL-reconstructed extremity was lower than that of the uninjured and matched extremities during the LSU, VJ take-off, and VJ landing. However, there was no difference in summated extension moment (hip + knee + ankle) among extremities during the LSU and VJ take-off. The summated extension moment of the ACL-reconstructed extremity during VJ landing was less than that of the uninvolved and matched extremities. Conclusions and Discussion. These results suggest that the hip or ankle extensors may compensate for the knee extension moment deficit. The decrease in summated extension moment in the ACL-reconstructed extremity during VJ landing represents inadequate attenuation of landing forces, which may expose the skeleton and joint structures to injury.
Study Design: One-group discriminant analysis. Objective: To determine whether 1 MHz of continuous ultrasound can identify tibial stress fractures in subjects. Background: Stress fractures can lead to loss of function or to more serious nonunion fractures. Early diagnosis is important to reduce the risk of further injury and to assure a safe return to activity. Therapeutic ultrasound has been reported to be an accessible, less expensive alternative in diagnosing stress fractures compared with other diagnostic techniques. Methods and Measures: Twenty-six subjects (12 men, 20.33 2 1.37 years; 14 women, 20.78 2 3.8 years) with unilateral tibia pain for less than 2 weeks volunteered to participate in the study. Continuous, 1 MHz ultrasound was applied to the uninvolved and involved tibias at 7 increasing intensities for 30 seconds each. Subjects completed a visual analog scale after the application of each intensity to assess the pain response to ultrasound. Results from the visual analog scale were compared to magnetic resonance imaging (MRI) findings to determine if continuous ultrasound could predict whether subjects had a normal MRI, increased bone remodeling, or advanced bone remodeling consistent with a stress fracture. Results: Discriminant analysis on the visual analog scale correctly classified subjects into 1 of 3 clinical classification groups in 42.31 % of the cases. None of the subjects found to have a stress fracture by MRI were correctly identified by continuous ultrasound. This resulted in a predicted sensitivity of 0% and a predicted specificity of 100%. Conclusions: A protocol using visual analog scores after the application of 1 MHz continuous ultrasound is not sensitive for identifying subjects with tibial stress fractures. 1
Concerns about the definitions and identification criteria for special education categories, particularly learning disabilities, are a continuing subject of Abate in the profession. Vagueness in definitions and inconsistent criteria for learning disabilities have been said to hamper research and the delively of services, and to be partly responsible fm the tremenhus prevalence ratepwth of some categories. One measure considered by some to be an indication of these definition and identification problems is the variability of prevalence rates among states. Some have stated that prevalence rates are more variable fir the higher pvalence categories, such as learning disabilities, than for the low prevalence categories. This observation, however, h e s not take into account the effects of the size of the means on the variability. When this effect is contmlled for; the higher prevalence categories are no more variable as a pup than the lower ones; in fact the variability within some higher prevalence categories is the lowest of all. The possible reasons for and implications of these findings are discussed.
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