Combining regularization and logistic regression model to validate the Q-matrix for cognitive diagnosis model.

Q-matrix is an important component of most cognitive diagnosis models (CDMs); however, it mainly relies on subject matter experts' judgements in empirical studies, which introduces the possibility of misspecified q-entries. To address this, statistical Q-matrix validation methods have been proposed to aid experts' judgement. A few of these methods, including the multiple logistic regression-based (MLR-B) method and the Hull method, can be applied to general CDMs, but they are either time-consuming or lack accuracy under certain conditions. In this study, we combine the L1 regularization and MLR model to validate the Q-matrix. Specifically, an L1 penalty term is imposed on the log-likelihood of the MLR model to select the necessary attributes for each item. A simulation study with various factors was conducted to examine the performance of the new method against the two existing methods. The results show that the regularized MLR-B method (a) produces the highest Q-matrix recovery rate (QRR) and true positive rate (TPR) for most conditions, especially with a small sample size; (b) yields a slightly higher true negative rate (TNR) than either the MLR-B or the Hull method for most conditions; and (c) requires less computation time than the MLR-B method and similar computation time as the Hull method. A real data set is analysed for illustration purposes.

Using a Generalized Logistic Regression Method to Detect Differential Item Functioning With Multiple Groups in Cognitive Diagnostic Tests.

Items with the presence of differential item functioning (DIF) will compromise the validity and fairness of a test. Studies have investigated the DIF effect in the context of cognitive diagnostic assessment (CDA), and some DIF detection methods have been proposed. Most of these methods are mainly designed to perform the presence of DIF between two groups; however, empirical situations may contain more than two groups. To date, only a handful of studies have detected the DIF effect with multiple groups in the CDA context. This study uses the generalized logistic regression (GLR) method to detect DIF items by using the estimated attribute profile as matching criteria. A simulation study is conducted to examine the performance of the two GLR methods, GLR-based Wald test (GLR-Wald) and GLR-based likelihood ratio test (GLR-LRT), in detecting the DIF items, the results based on the ordinary Wald test are also reported. Results show that (1) both GLR-Wald and GLR-LRT have more reasonable performance in controlling Type I error rates than the ordinary Wald test in most conditions; (2) the GLR method also produces higher empirical rejection rates than the ordinary Wald test in most conditions; and (3) using the estimated attribute profile as the matching criteria can produce similar Type I error rates and empirical rejection rates for GLR-Wald and GLR-LRT. A real data example is also analyzed to illustrate the application of these DIF detection methods in multiple groups.

The Associations between Meeting 24-Hour Movement Guidelines (24-HMG) and Mental Health in Adolescents-Cross Sectional Evidence from China.

(1) Background: This study determined the prevalence of adolescents that meet 24-HMGs alone and in combination, and their association with the risk of developing adolescent anxiety and depression. (2) Methods: Participants were drawn from 9420 K8 grade adolescents (age 14.53 ± 0.69 years; 54.78% boys) from the China Education Tracking Survey (CEPS) 2014-2015 tracking data. Data on depression and anxiety were collected from the results of the questionnaire in the CEPS for the adolescent mental health test. Compliance with the 24-HMG was defined as: physical activity time (PA) ≥ 60 min/day was defined as meeting the PA. Screen time (ST) ≤ 120 min/day was defined as meeting the ST. Adolescents aged 13 years achieved 9-11 h of sleep per night and adolescents aged 14-17 years achieved 8-10 h of sleep per night, defined as meeting sleep. Logistic regression models were used to examine the association between meeting and not meeting the recommendations and the risk of depression and anxiety in adolescents. (3) Results: Of the sample studied, 0.71% of adolescents met all three recommendations, 13.54% met two recommendations and 57.05% met one recommendation. Meeting sleep, meeting PA+ sleep, meeting ST + sleep, and meeting PA + ST + sleep were associated with a significantly lower risk of anxiety and depression in adolescents. Logistic regression results showed that differences in the effects of gender on the odds ratio (ORs) for depression and anxiety in adolescents were not significant. (4) Conclusions: This study determined the risk of developing depression and anxiety in adolescents who met the recommendations for 24-HMG alone and in combination. Overall, meeting more of the recommendations in the 24-HMGs was associated with lower anxiety and depression risk outcomes in adolescents. For boys, reducing the risk of depression and anxiety can be prioritised by meeting PA + ST + sleep, meeting ST + sleep and meeting sleep in the 24-HMGs. For girls, reducing the risk of depression and anxiety may be preferred by meeting PA + ST + sleep or meeting PA+ sleep and meeting sleep in 24-HMGs. However, only a small proportion of adolescents met all recommendations, highlighting the need to promote and support adherence to these behaviours.

The impact of students' mathematical attitudes on intentions, behavioral engagement, and mathematical performance in the China's context.

Referring to the theory of planned behavior (TPB), this study intends to investigate the impact of students' mathematical attitude determinants (i.e., attitude, subjective norms, and perceived behavioral control) on intentions, behavioral engagement, and mathematical performance. The data collected online in China's context and the research hypotheses are developed and then tested through structural equation modeling. It is found that attitude and subjective norms have effects, directly or indirectly, on intentions, behavioral engagement, and mathematical performance. In addition, the intentions have a significant effect on behavioral engagement, and behavioral engagement does likewise on mathematical performance. It has also been accepted that perceived behavioral control is not directly related to intentions but largely to behavior and indirectly to mathematical performance through behavior alone. In conclusion, this study's findings will contribute to the current literature on mathematical performance and will also inform the policymakers of the proposal on students' mathematics belief and attitude interventions as a means to improving students' mathematical performance.

Organizational support and job crafting with the new math teachers' well-being: The mediating effect of basic psychological needs.

Enhancement of the teacher well-being level has grown into a general, pressing problem to be solved in the domain of education worldwide. Based on the theoretical perspective of the multi-level dynamically formed mechanical model of occupational well-being, this study initially constructed a mechanism model with the occupational well-being role of organizational support, job crafting, and the occupational well-being of new math teachers at primary and junior high schools, and conducted empirical research using structural equation modeling. The study found out that organizational support, job crafting and basic psychological needs have prominent and positive effects on the occupational well-being of the new math teachers in primary up to junior high schools. It also argues that basic psychological needs may mediate the correlation between organizational support, job crafting, and the occupational well-being of the new math teachers. To sum up, the study findings reveal the mechanisms of the role in organizational support and job crafting on the occupational well-being of new primary up to junior high school math teachers. Also, the findings may be conducive to extending the research on the factors that influence the teacher well-being, notably fostering the study on that in the math teachers in the primary up to junior high schools of China.

The Associations between Meeting 24-Hour Movement Guidelines (24-HMG) and Self-Rated Physical and Mental Health in Older Adults-Cross Sectional Evidence from China.

BACKGROUND: This study determined the prevalence of older adults (aged 60-80 years) meeting the Canadian 24-HMG alone and in combination, and their association with the self-rated physical health and mental health of older adults. METHODS: Participants were drawn from 4134 older adults aged 60-80 years (age, 67.37 ± 0.08 years; 46.87% male) from the China Health and Nutrition Survey (CHNS) 2015 database. Mental health and physical health scores were obtained based on self-rated mental health questionnaires and physical health of older adults. The criteria for meeting the 24-HMG were: physical activity time ≥ 150 min/week, sedentary time ≤ 480 min/day, screen time ≤ 180 min/day, sleep time 7-9 h (60-64 years) and sleep time 7-8 h (65 years and above). Logistic regression models were used to examine the association between meeting the 24-HMG guidelines number and category and older adults' self-rated mental and physical health. RESULTS: The proportion of older people meeting three of the 24-HMG guidelines was 1.16%, the proportion meeting two guidelines was 38.19% and the proportion meeting one guideline was 49.14%. The number of people meeting 24-HMG was closely related to the self-rated physical health and mental health of older people. The category meeting 24-HMG was closely related to the self-rated physical health and mental health of older people. CONCLUSIONS: Meeting more guidelines in the 24-HMG was strongly associated with older people's self-rated mental health and physical health. However, only a small proportion of older people met all the recommendations, highlighting the need to promote and support adherence to these movement behaviours.

Evaluation of the validity of the physical exercise peer support questionnaire for college students.

Peer support for physical exercise is defined as behaviors such as mutual or one-way provision of material help and/or emotional care and companionship between peers in the physical environment and/or physical behavior. The assessment of peer support is complex and based on reasoning. Trustworthy assessment processes need to provide sufficient evidence of validity. The purpose of this study was to organize, collect, and use Kane's validity framework to provide validity evidence for the identification of peer support for physical exercise among college students. The article describes the experience of using the framework in this study, considers data related to the four inferences (scoring, generalization, extrapolation, and implication) that emerge from the assessment process. The findings of the study are then interpreted through the four inferences to determine whether this evidence supports the purpose of this study. Based on Kane's framework to explain the validity process of this study, the study concludes that the evidence in terms of scoring, generalization, extrapolation, and implication supports the use of the PEPSQ for the identification of physical exercise peer support among college students.

Influencing Factors of Students Aged 10-20 Non-participating in Home Physical Exercise During the COVID-19 Isolation Policy Period: A Cross-Sectional Study From China.

Background: A number of public health measures are required during the COVID-19 pandemic. To stop the spread of COVID-19, the Chinese government has adopted isolation policies, including closing non-essential businesses, public transportation and schools, moving students' face-to-face learning to online, and recommending the cancellation of all non-essential activities and outdoor activities. However, while this isolation strategy has reduced human-to-human transmission of COVID-19, it has led to dramatic changes in students' daily lives and learning styles, including reduced physical activity and increased sedentary time. Considering the potentially harmful effects of physical inactivity, this study hoped to explore the incidence and influencing factors of non-participation in home physical exercise among Chinese students aged 10-20 during the implementation of the COVID-19 isolation policy. Methods: Through an online questionnaire platform, this study created an open-ended questionnaire (from March 1, 2020 to March 10, 2020) and distributed it to students in areas where isolation policies were enforced. The questionnaire was initially distributed by 10 recruited volunteers, and then the questionnaire was voluntarily forwarded and shared by the subjects or others, in a "snowball" way, to expand distribution. Finally, the survey data of 4,532 Chinese students aged 10-20 were collected. The incidence of respondents non-participating in home physical activity was determined using univariate analysis. Using odds ratios and 95% confidence intervals of a multivariate binary logistic regression model, factors influencing non-participation in home physical exercise were estimated. Results: Among the sample students, the incidence rate of non-participating in home physical exercise was 25.86% (24.06-27.15%). Exercise intentions, exercise habits, self-assessed health, beliefs in physical health, family exercise, family exercise recommendations, home exercise conditions, school exercise guidance, and health education programs had a negative impact on students non-participating in home physical exercise. Academic performance and electronic product use had a positive effect on non-participating in home physical exercise. Conclusions: A variety of forward leaning factors, enabling factors and demand factors have affected the occurrence of students" non-participating in home physical exercise. Future health isolation policies should take into account these influencing factors to reduce the occurrence of students" non-participating in home physical exercise and to promote students' independent participation in physical exercise.

Validity Evaluation of the College Student Physical Literacy Questionnaire.

Background: Physical literacy (PL) is an important tool to promote physical activity of individuals, and the level of physical literacy of individuals affects their physical activity behaviors. Currently, the physical fitness of college students in China is a prominent issue, and assessing physical literacy among college students may provide tools and directions to further promote physical fitness and precisely intervene in physical activity behaviors of college students in the future. This study aimed to develop a college student physical literacy questionnaire (CSPLQ) to address the lack of currently available physical literacy assessment tools for Chinese college students. We hoped to collect validity evidence of this questionnaire to measure the validity of the physical literacy self-assessment questionnaire among Chinese university students. Methods: An initial pool of items was obtained from existing research instruments, literature, and expert advice. An expert review panel evaluated its content. A subsequent validation process reduced the pool of items. We conducted a validation factor analysis of the CSPLQ using structural equation modeling. The relationship between physical literacy and other variables was also examined using correlation analysis. Results: The item content validity index (ICVI) of CSPLQ was 0.70-0.95. The CSPLQ was composed of a total of 38 items across 3 domains (physical and behavioral domain, affective domain, and cognitive domain) and 7 dimensions (motor skills, motor skills, physical activity, perceptions of healthy living, perceptions of physical activity, motivation to engage in physical activity, and confidence to engage in physical activity). The factor validity of the CSPLQ was determined by significant loading of all items on their expected factors, with good data model fit and good stability between two independent samples were demonstrated. Each subscale had a Cronbach α coefficient >0.9 and was strongly correlated with each other. The correlation coefficients between college students' physical literacy and other variables, including athletic ability, physical condition, physical attractiveness, physical fitness, frequency of physical activity, and length of physical activity, all reached a significance level of P < 0.05. Conclusion: The CSPLQ has sufficient evidence of validity. The development of the instrument showed evidence of validity for the content, response process, internal structure, and relationships with other variables.

Measurement Properties of Canadian Agility and Movement Skill Assessment for Children Aged 9-12 Years Using Rasch Analysis.

The Canadian Agility and Movement Skill Assessment (CAMSA) was recently widely used to assess fundamental motor skills in children. Although the CAMSA is reported to be reliable and valid, its measurement properties are not clear. This study aimed to examine the measurement properties of the CAMSA in a sample of Chinese children using Rasch analysis. The study sample was from 1,094 children aged 9-12 years in Zunyi City, Guizhou Province. Descriptive data were analyzed using SPSS 24.0 software, and the dichotomous data were analyzed by Winsteps version 4.5.4 and Facets 3.67.1 software performing Rasch analysis. The present study investigated CAMSA measurement characteristics by Rasch analysis, including the reliability of the rating instrument, unidimensionality, item-fit statistics, and differential item functioning (DIF). Inter-rater reliability and retest reliability showed that the CAMSA had a good internal consistency. Rasch analysis indicated that the CAMSA was unidimensional, locally independent, and had a good item-fit-statistic. Additionally, the CAMSA displayed a good fit for the item separation index (12.50 > 2.0), as well as for item reliability (0.99 > 0.90). However, the item difficulty of the CAMSA did not fit well with personal ability, and a significant DIF was found across genders. In the Chinese children sample test, the CAMSA demonstrated appropriate goodness-of-fit validity and rater reliability. Thus, future research will explore item difficulty and person ability fit, as well as DIF across genders.

Intervention Effect of Long-Term Aerobic Training on Anxiety, Depression, and Sleep Quality of Middle School Students With Depression After COVID-19.

Objective: To explore the effects of using RPE exercise intensity monitoring methods and 12-week mid- and low-intensity team aerobic training on anxiety, depression and sleep quality of depressed middle school students after the COVID-19 epidemic. Methods: All study participants were all from a boarding middle school in Chongqing, China. All study participants were screened by the self-rating depression scale and reached the diagnostic criteria for depression. The study subjects were divided into a control group (N = 35) and an exercise group (N = 34). The exercise group performed 30-min night aerobic running four times a week. Use the Borg 6-20 rating of perceived exertion scale (RPE) as a monitoring tool for exercise intensity, and control the exercise intensity at RPE = 11-14. And the control group studied and lived normally. The experiment lasted 12 weeks in total. After the experiment, there were 34 people in the control group and 23 people in the exercise group. The subjects' anxiety, depression and Pittsburgh sleep quality were scored before and after the experiment. Results: After intervention, the depression index (p < 0.01) of the exercise group was significantly lower than that of the control group. Conclusion: Using the RPE exercise intensity monitoring method for 12 weeks of mid- and low-intensity team aerobic training can improve the depressive symptoms of depressed middle school students, and it is beneficial to improve the students' mental health.

Binary Restrictive Threshold Method for Item Exposure Control in Cognitive Diagnostic Computerized Adaptive Testing.

Although classification accuracy is a critical issue in cognitive diagnostic computerized adaptive testing, attention has increasingly shifted to item exposure control to ensure test security. In this study, we developed the binary restrictive threshold (BRT) method to balance measurement accuracy and item exposure. In addition, a simulation study was conducted to evaluate its performance. The results indicated that the BRT method performed better than the restrictive progressive (RP) and stratified dynamic binary searching (SDBS) approaches but worse than the restrictive threshold (RT) method in terms of classification accuracy. With respect to item exposure control, the BRT method exhibited noticeably stronger performance compared with the RT method, even though its performance was not as high as that of the RP and SDBS methods.

Corrigendum: Spectral Clustering Algorithm for Cognitive Diagnostic Assessment.

[This corrects the article DOI: 10.3389/fpsyg.2020.00944.].

Psychometric Properties of the Exercise Orientation Questionnaire: A Confirmatory Study on Chinese University Students.

The Exercise Orientation Questionnaire (EOQ) is a method for evaluating individuals' exercise attitudes and behaviors associated with exercise motivation. A lack of exercise motivation can affect physical activity attitudes, behavior, and action among university students. Physical inactivity may lead to health risks. The purpose of this study was to assess the measurement of psychological properties in the EOQ and to determine the reliability and validity of the EOQ when applied to Chinese university students. A total of 368 university students (male 48.8%) aged between 17 and 23 years (M = 19.60, SD = 1.18) participated in the current study. Confirmatory factor analysis (CFA) and exploratory structural equation modeling (ESEM) were used to verify the factorial validity of the EOQ. The internal consistency coefficient (Cronbach's alpha and McDonald's omega) was used to determine reliability. Multiple regression analysis was used to test concurrent validity. The International Physical Activity Questionnaire (IPAQ) was used to determine the participants' level of physical activity. The range of the subscale coefficient was 0.80-0.89, and the total scale was 0.95, which indicated that the reliability of the EOQ was excellent. The research showed that the initial CFA model of the EOQ had poorly fitting indices. The corrected model after seven residual correlations achieved the setting standard, but the correlation coefficient between some factors exceeded the standard threshold, which indicated that the CFA fitting model was not ideal. ESEM is a combination of exploratory and verifiable analytical techniques. Using ESEM and abbreviated version CFA to analyze the data indicated that the model fitted well [ESEM: TLI = 0.97 > 0.90, CFI = 0.96 > 0.90, SRMR = 0.02 < 0.08, and RMSEA = 0.045 < 0.08 (90% CI 0.033-0.055); CFA: TLI = 0.92 > 0.90, CFI = 0.91 > 0.90, SRMR = 0.08, and RMSEA = 0.06 < 0.08 (90% CI 0.055-0.067)]. The results of multiple regression analysis suggested that the ESEM model was effective in distinguishing the differences between individuals with different levels of physical activity (PAL) and body mass index (BMI). Overall, the Chinese abbreviated version of the EOQ (EOQ-CA) was fond to be a reliable tool for monitoring the exercise attitudes and behaviors of Chinese University students.

The Impact of Item Calibration Error on Variable-Length Cognitive Diagnostic Computerized Adaptive Testing.

Calibration errors are inevitable and should not be ignored during the estimation of item parameters. Items with calibration error can affect the measurement results of tests. One of the purposes of the current study is to investigate the impacts of the calibration errors during the estimation of item parameters on the measurement accuracy, average test length, and test efficiency for variable-length cognitive diagnostic computerized adaptive testing. The other purpose is to examine the methods for reducing the adverse effects of calibration errors. Simulation results show that (1) calibration error has negative effect on the measurement accuracy for the deterministic input, noisy "and" gate (DINA) model, and the reduced reparameterized unified model; (2) the average test lengths is shorter, and the test efficiency is overestimated for items with calibration errors; (3) the compensatory reparameterized unified model (CRUM) is less affected by the calibration errors, and the classification accuracy, average test length, and test efficiency are slightly stable in the CRUM framework; (4) methods such as improving the quality of items, using large calibration sample to calibrate the parameters of items, as well as using cross-validation method can reduce the adverse effects of calibration errors on CD-CAT.

Assessment of Validity of Children's Movement Skill Quotient (CMSQ) Based on the Physical Education Classroom Environment.

The development of movement skills in children is a critical element in promoting physical activity and other positive health trajectories over their lifetime. A reliable and valid assessment tool is essential for evaluating children's movement skills in daily physical education environments. The purpose of this study was to examine the validity of Children's Motor Skills Quotient (CMSQ) used in the classroom setting. Six raters conducted evaluation to participants, and a total of 734 children completed all the test items and were included in the study. Descriptive statistics and Rasch analysis were used in this study. The descriptive statistics were mainly used for calculating the mean, standard deviation, percentage, and internal consistency coefficient. Rasch analysis was used to verify the fitting statistics, project difficulty, and functional differences of the items of the CMSQ. The findings showed that the CMSQ met the assumption of the Rasch model, including the unidimensionality, local independence, person measure, and item difficulty hierarchy. The CMSQ also demonstrated adequate interrater reliability and internal consistency. The differential item functioning (DIF) demonstrated a few items showing different probabilities across sex and age. To maintain the item difficulty hierarchy of the CMSQ, no items were deleted. Overall, the CMSQ seems to have appropriate test items with an appropriate rating scale structure for measuring 6-9-year-old children's movement skills in the physical education classroom environment.

Development and Validation of a Short Version Sport Orientation Questionnaire for Chinese Adolescents (SOQ-CA).

A noted decrease in adolescent physical activity in the past decade has resulted in an increase in health risks. Sport orientation correlates closely with physical activity. A sufficient assessment scale that measures an individual's sport orientation is important to measure an adolescent's physical inactivity. The purpose of this study was to develop and validate a short version of the Sport Orientation Questionnaire for Chinese Adolescents (SOQ-CA). Based on Gill's SOQ and previous literature, an initial 30-item questionnaire was developed to create the original SOQ-CA. A five-point Likert scale was used to measure by self-report. In this study, three surveys were conducted. Volunteer participants completed 1,235 valid questionnaires. The data of the first collection sample (n = 486) were split randomly into two groups, sample 1 (n = 150) used for exploratory factor analysis (EFA) and sample 2 (n = 336) for confirmatory factor analysis (CFA). The data of the second (n = 377) and third (n = 372) collection samples were used to perform test-retest reliability, internal consistency, and CFA of the SOQ-CA. The SOQ-CA obtained good reliability and validity through both EFA and CFA. The development of the SOQ-CA provides an opportunity to develop further theories and practices regarding the assessment of both sport motivation and individual achievement orientation. The application of the SOQ-CA in China would be significant for monitoring the development of adolescent physical activity and aiding in the implementation of policies.

Spectral Clustering Algorithm for Cognitive Diagnostic Assessment.

In cognitive diagnostic assessment (CDA), clustering analysis is an efficient approach to classify examinees into attribute-homogeneous groups. Many researchers have proposed different methods, such as the nonparametric method with Hamming distance, K-means method, and hierarchical agglomerative cluster analysis, to achieve the classification goal. In this paper, according to their responses, we introduce a spectral clustering algorithm (SCA) to cluster examinees. Simulation studies are used to compare the classification accuracy of the SCA, K-means algorithm, G-DINA model and its related reduced cognitive diagnostic models. A real data analysis is also conducted to evaluate the feasibility of the SCA. Some research directions are discussed in the final section.

[Clinical application of intro-aortic balloon pump and centrifugal pump in low cardiac output syndrome after coronary artery bypass grafting].

OBJECTIVE: To explore the clinical application of Intra-aortic balloon pump (IABP) and centrifugal pump in low cardiac output syndrome (LCOS) after coronary artery bypass grafting (CABG). METHODS: From April 2000 to January 2004, 5 patients suffered serious LCOS after CABG in our department. Because maximum vasoactive agent had no significant effect, we supported these 5 patients with IABP and centrifugal pumps. The centrifugal pumps were connected with cannulas of right superior pulmonary vein and ascending aorta. The flow rate of the centrifugal pumps were increased to 3-4 L/min gradually. The dosage of vasoactive agent and flow rate of the centrifugal pumps were decreased gradually after hemodynamics stabilized. RESULTS: All 5 patients' hemodynamics were improved significantly after the left ventricular assist by IABP and centrifugal pumps. Five patients were weaned from the centrifugal pumps after 4 to 7 days successfully. But some degree damage to blood cells and renal function were detected. Renal function of 3 patients were recovered gradually after centrifugal pumps removed and discharged successfully, One patient died of acute renal failure, 1 patient died of multiple organ failure, 5 patients need transfusion of whole blood or concentrated erythrocytes and 4 patients need transfusion of platelets. CONCLUSIONS: There were significant improvements in hemodynamics after support with IABP and centrifugal pumps in the patients who suffered serious LCOS with less effect of maximum vasoactive agent after CABG. Some complications on blood cells and renal function should be paid more attention.

[Impact of intraoperative autotransfusion on RBC's in vivo half-life].

OBJECTIVE: To explore the changes of in vivo half-life of processed erythrocytes following intraoperative autotransfusion(IAT) in off-pump coronary artery bypass grafting(CABG). METHODS: From November 2003 to January 2004,20 consecutive patients undergoing scheduled off-pump CABG were randomly divided into experimental group and control group. Intra-operative autotransfusion was used in the experimental group. The samples were drawn immediately after the saving procedure in the experimental group and immediately after anesthesia introduction through central venous catheter in the control group. A single isotope technique ((51)Cr) was used to determine in vivo half-life of the RBCs in the two groups. RESULTS: There was no significant difference in in vivo half-life between the two groups. CONCLUSION: The in vivo half life of processed erythrocytes following intraoperative autotransfusion ZITI-3000 Cell saving system has not changed significantly in off-pump CABG.