Intraclass correlation

About: Intraclass correlation is a research topic. Over the lifetime, 4942 publications have been published within this topic receiving 224487 citations.

Reliability of gait performance tests in men and women with hemiparesis after stroke

Abstract: Objective: To assess the reliability of 6 gait performance tests in individuals with chronic mild to moderate post-stroke hemiparesis. Design: An intra-rater (between occasions) test-retest reliability study. Subjects: Fifty men and women (mean age 58 6.4 years) 6–46 months post-stroke. Methods: The Timed “Up & Go” test, the Comfortable and the Fast Gait Speed tests, the Stair Climbing ascend and descend tests and the 6-Minute Walk test were assessed 7 days apart. Reliability was evaluated with the intraclass correlation coefficient (ICC 2,1), the Bland & Altman analysis, the standard error of measurement (SEM and SEM%) and the smallest real difference (SRD and SRD%). Results: Test-retest agreements were high (ICC2,1 0.94–0.99) with no discernible systematic differences between the tests. The standard error of measurement (SEM%), representing the smallest change that indicates a real (clinical) improvement for a group of individuals, was small (9%). The smallest real difference (SRD%), representing the smallest change that indicates a real (clinical) improvement for a single individual, was also small (13–23%). Conclusion: These commonly used gait performance tests are highly reliable and can be recommended to evaluate improvements in various aspects of gait performance in individuals with chronic mild to moderate hemiparesis after stroke.

Systematic review of the validity and reliability of consumer-wearable activity trackers

Abstract: Consumer-wearable activity trackers are electronic devices used for monitoring fitness- and other health-related metrics. The purpose of this systematic review was to summarize the evidence for validity and reliability of popular consumer-wearable activity trackers (Fitbit and Jawbone) and their ability to estimate steps, distance, physical activity, energy expenditure, and sleep. Searches included only full-length English language studies published in PubMed, Embase, SPORTDiscus, and Google Scholar through July 31, 2015. Two people reviewed and abstracted each included study. In total, 22 studies were included in the review (20 on adults, 2 on youth). For laboratory-based studies using step counting or accelerometer steps, the correlation with tracker-assessed steps was high for both Fitbit and Jawbone (Pearson or intraclass correlation coefficients (CC) > =0.80). Only one study assessed distance for the Fitbit, finding an over-estimate at slower speeds and under-estimate at faster speeds. Two field-based studies compared accelerometry-assessed physical activity to the trackers, with one study finding higher correlation (Spearman CC 0.86, Fitbit) while another study found a wide range in correlation (intraclass CC 0.36–0.70, Fitbit and Jawbone). Using several different comparison measures (indirect and direct calorimetry, accelerometry, self-report), energy expenditure was more often under-estimated by either tracker. Total sleep time and sleep efficiency were over-estimated and wake after sleep onset was under-estimated comparing metrics from polysomnography to either tracker using a normal mode setting. No studies of intradevice reliability were found. Interdevice reliability was reported on seven studies using the Fitbit, but none for the Jawbone. Walking- and running-based Fitbit trials indicated consistently high interdevice reliability for steps (Pearson and intraclass CC 0.76–1.00), distance (intraclass CC 0.90–0.99), and energy expenditure (Pearson and intraclass CC 0.71–0.97). When wearing two Fitbits while sleeping, consistency between the devices was high. This systematic review indicated higher validity of steps, few studies on distance and physical activity, and lower validity for energy expenditure and sleep. The evidence reviewed indicated high interdevice reliability for steps, distance, energy expenditure, and sleep for certain Fitbit models. As new activity trackers and features are introduced to the market, documentation of the measurement properties can guide their use in research settings.

Reliability of assessment tools in rehabilitation: an illustration of appropriate statistical analyses

Abstract: Objective: To provide a practical guide to appropriate statistical analysis of a reliability study using real-time ultrasound for measuring muscle size as an example.Design: Inter-rater and intra-rater (between-scans and between-days) reliability.Subjects: Ten normal subjects (five male) aged 22–58 years.Method: The cross-sectional area (CSA) of the anterior tibial muscle group was measured using real-time ultrasonography.Main outcome measures: Intraclass correlation coefficients (ICCs) and the 95% confidence interval (CI) for the ICCs, and Bland and Altman method for assessing agreement, which includes calculation of the mean difference between measures (d), the 95% CI for d, the standard deviation of the differences (SD diff), the 95% limits of agreement and a reliability coefficient.Results: Inter-rater reliability was high, ICC (3,1) was 0.92 with a 95% CI of 0.72 → 0.98. There was reasonable agreement between measures on the Bland and Altman test, as d was -0.63 cm2, the 95% CI for d was -1.4 → 0.14 ...

How Many Subjects?: Statistical Power Analysis in Research

Abstract: CHAPTER 1 Introduction CHAPTER 2 General Concepts CHAPTER 3 The Pivotal Case Intraclass Correlation CHAPTER 4 Equality of News Z- and T- tests, Balanced ANOVA CHAPTER 5 Correlation Coefficients CHAPTER 6 Linear Regression CHAPTER 7 Homogeneity of Variance Tests CHAPTER 8 Binomial Tests CHAPTER 9 Contingency Table Analysis CHAPTER 10 Conclusions

A Physical Activity Screening Measure for Use With Adolescents in Primary Care

Abstract: Objective: To develop a reliable and valid physical activity screening measure for use with adolescents in primary care settings. Study Designs We conducted 2 studies to evaluate the test-retest reliability and concurrent validity of 6 single-item and 3 composite measures of physical activity. Modifications were based on the findings of the 2 studies, and a best measure was evaluated in study 3. Accelerometer data served as the criterion standard for tests of validity. Results: In study 1 (N=250; mean age, 15 years; 56% female; 36% white), reports on the composite measures were most reliable. In study 2 (N = 57; mean age, 14 years; 65% female; 37% white), 6 of the 9 screening measures correlated significantly with accelerometer data. Subjects, however, had great difficulty reporting bouts of activity and distinguishing between intensity levels. Instead, we developed a single measure assessing accumulation of 60 minutes of moderate to vigorous physical activity. Evaluated in study 3 (N=148; mean age, 12 years; 65% female; 27% white), the measure was reliable (intraclass correlation, 0.77) and correlated significantly (r=0.40, P<.001) with accelerometer data. Correct classification (63%), sensitivity (71%), and false-positive rates (40%) were reasonable. Conclusion: The moderate to vigorous physical activity screening measure is recommended for clinical practice with adolescents.