How big is the elephant in the room? Estimated and actual IT costs in an online behaviour change trial

Actual IT costs were approximately twice those that had been originally estimated by external contractors. These original estimates for IT costs allowed little scope for the identification of new needs, which was intrinsic to the iterative nature of the research enterprise.Making greater provision for the uncertain nature of these costs in future studies is a key practical lesson for the planning of future online behaviour change studies.Estimating research and intervention costs in the planning of any large study is a considerable practical challenge facing researchers. Overestimation may threaten the granting of research funding and underestimation can threaten the viability, quality and completion of the study. For most trials costs can be divided between those required to develop the intervention materials (both active and control) and the research evaluation. There is a particular need to take account of both the practical and methodological challenges inherent in online studies as the internet is increasingly used to both deliver healthcare and public health interventions, and to undertake research[1]. Here the uncertainties unavoidably encountered in any relatively new field of study are acute, and this raises additional technical and financial issues. We relate our experiences of estimating and managing information technology (IT) research and intervention costs in an ongoing internet trial in the hope that others will find this information useful.The Down Your Drink randomised controlled trial[2] was funded by the U.K. Medical Research Council on behalf of the National Prevention Research Initiative (see acknowledgements for further details). This ongoing study compares the effectiveness of an enhanced website in helping people concerned about their drinking to achieve behaviour change[3] in comparison with a standard alcohol website. The enhanced website was developed from an existing website which had been in operation for some years,[4] with demonstrated