Imputing accelerometer non-wear time when assessing children's moderate-to-vigorous physical activity

BACKGROUND: Moderate-to-vigorous physical activity (MVPA) is an important determinant of children’s physical health, and is commonly measured using accelerometers. A major limitation of accelerometers is non-wear time, which is the time the participant did not wear their device. Given that non-wear time is traditionally discarded from the dataset prior to estimating MVPA, final estimates of MVPA may be biased. Therefore, alternate approaches should be explored. OBJECTIVES: The objectives of this thesis were to 1) develop and describe an imputation approach that uses the socio-demographic, time, health, and behavioural data from participants to replace non-wear time accelerometer data, 2) determine the extent to which imputation of non-wear time data influences estimates of MVPA, and 3) determine if imputation of non-wear time data influences the associations between MVPA, body mass index (BMI), and systolic blood pressure (SBP). METHODS: Seven days of accelerometer data were collected using Actical accelerometers from 332 children aged 10-13. Three methods for handling missing accelerometer data were compared: 1) the “non-imputed” method wherein non-wear time was deleted from the dataset, 2) imputation dataset I, wherein the imputation of MVPA during non-wear time was based upon socio-demographic factors of the participant (e.g., age), health information (e.g., BMI), and time characteristics of the non-wear period (e.g., season), and 3) imputation dataset II wherein the imputation of MVPA was based upon the same variables as imputation dataset I, plus organized sport information. Associations between MVPA and health outcomes in each method were assessed using linear regression. RESULTS: Non-wear time accounted for 7.5% of epochs during waking hours. The average minutes/day of MVPA was 56.8 (95% CI: 54.2, 59.5) in the non-imputed dataset, 58.4 (95% CI: 55.8, 61.0) in imputed dataset I, and 59.0 (95% CI: 56.3, 61.5) in imputed dataset II. Estimates between datasets were not significantly different. The strength of the relationship between MVPA with BMI and SBP were comparable between all three datasets. CONCLUSION: These findings suggest that studies that achieve high accelerometer compliance with unsystematic patterns of missing data can use the traditional approach of deleting non-wear time from the dataset to obtain MVPA measures without substantial bias.

NON-FULL-TIME COLLEGE PROFESSORS: A NARRATIVE INQUIRY INTO THE NON-FULL-TIME FACULTY ROLE

The rate of non-full-time faculty members has increased rapidly over the last decade (Louis, 2009; MacKay, 2014; Meranze & Newfield, 2013), as the post-secondary landscape of fluctuating enrolment, fiscal and operational challenges, and the requirement to hire specialized skill sets have required institutions to rely heavily on this demographic. In the Ontario Colleges of Applied Arts and Technology (CAATs) system, institutions have tried to preserve and enhance educational quality with fewer resources through greater reliance on non-full-time faculty. The purpose of this study was to explore the perceptions and experiences of teaching and support of non-full-time faculty at one Eastern Ontario college. Employing a narrative inquiry methodology, data were collected from four participants through their writing three individual letters at the end of each month and participating in one interview at the end of the contract period. The data were analyzed and coded. This analysis revealed five themes: motivation, connection and engagement, compensation, teaching and development, and performance evaluation. Differences in the participants’ perceptions tended to reflect divergences across career stage: retired versus early career. The compensation package provided to non-full-time faculty was considered inadequate for those in the early career stage, especially comparing it to that of full-time faculty. In addition, the amount of previous teaching experience was an important indicator for the appropriate level of teaching resources and support provided by the institution. The newer faculty members required a higher level of support to combat feelings of role isolation. The temporary nature of the role made it difficult to establish a feeling of a strong connection to the institution and subsequently opportunities to engage further to deepen the relationship. Despite these differences across participants, autonomous motivators were consistent across all narratives, as participants expressed their desire to teach and share their knowledge to help students achieve their goals. Participants concluded their narratives by sharing future advice for faculty interested in pursuing the role. The narratives provided areas for improvement that would help increase the level of job satisfaction for non-full-time college faculty members: (a) establishing a more thorough performance evaluation process to align with institutional supports, (b) offering more diverse teaching resources to better prepare faculty and enhance teaching practices, (c) overhauling the compensation package to better recognize the amount of time and effort spent in the role and aligning with the compensation provided to full-time faculty, and (d) including rewards and incentives as part of the compensation package to enhance the level of commitment and availability for the role. These changes might well increase the job satisfaction and improve the retention of non-full-time faculty members.