Why do we need to collect additional data from other sources?

In some cases, our research may require us to collect additional data for the following reasons:

• To provide supplementary data that we may not have been able to obtain during the initial data collection stage because it was not available at that time.
• For validation of the quality of datasets i.e. to ensure that datasets are consistent and accurate, usually by cross-checking data from different sources.
• To enable research that follows the health outcomes of individuals over extended periods of time. For example, for the UK Flexible Sigmoidoscopy Trial (UKFSST), for which recruitment and screening started in November 1994 and was completed in March 1999, we are still collecting data for the purposes of this study to understand the duration of the protective effect of screening.
• To collect information on cancer diagnoses and deaths over the long term and combine this with clinical data collected from our studies. This enables us to use statistical methods to improve our understanding of bowel cancer prevention, screening and treatment strategies, which we anticipate will help improve bowel cancer survival.