Strengths and limitations
Strengths of this study include the natural setting in that the intervention was not externally prompted and therefore represented a real world context; the whole of office approach whereby the desks were the employees' own desks and not "hot desks" as in previous research; the ability to compare manual and electrical height adjustment; a substantial follow-up period (three months); and the qualitative methodology allowing detailed exploration of quantitative findings.
One limitation was the small number of participants, although this was somewhat due to the natural attrition and absences of staff members in the workplace. Therefore while tests on changes in sitting time were statistically significant, the confidence intervals were wide reflecting substantial variation in the data and results should therefore be interpreted with caution. We did not offer those who did not participate in the group interviews to complete a follow-up survey questionnaire. However, this would have added only one extra participant as the other two non-responders at follow-up requested to be removed from the study as a whole. Further, the sample may have been biased towards users, or at least triallers of the desk, as only one participant had not used the standing option at all, and 13 did not participate. Measurements of sitting were also self-report rather than objective and therefore future quantitative findings could be strengthened with objective monitoring such as accelerometers or by measuring cardiometabolic biomarkers although the latter entails substantial participant burden particularly for longitudinal studies. The self-report sitting measures used have, however, demonstrated good validity and reliability.