BMJ 1998;317:468-469 ( 15 August )

Education and debate

Statistics Notes

Time to event (survival) data

Douglas G Altman, head, ^a J Martin Bland, professor of medical statistics. ^b

^a ICRF Medical Statistics Group, Centre for Statistics in Medicine, Institute of Health Sciences, Oxford OX3 7LF, ^b Department of Public Health Sciences, St George's Hospital Medical School, London SW17 0RE

The first 150 words of the full text of this article appear below.

In many medical studies an outcome of interest is the time to an event. Such events may be adverse, such as death or recurrence of a tumour; positive, such as conception or discharge from hospital; or neutral, such as cessation of breast feeding. It is conventional to talk about survival data and survival analysis, regardless of the nature of the event. Similar data also arise when measuring the time to complete a task, such as walking 50 metres.

The distinguishing feature of survival data is that at the end of the follow up period the event will probably not have occurred for all patients. For these patients the survival time is said to be censored, indicating that the observation period was cut off before the event occurred. We do not know when (or, indeed, whether) the patient will experience the event, only that he or she has not done so . . . [Full text of this article]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    StumbleUpon    Technorati    What's this?

Relevant Article

Career progression and destinations, comparing men and women in the NHS: postal questionnaire surveys

Kathryn S Taylor, Trevor W Lambert, and Michael J Goldacre
BMJ 2009 338: b1735. [Abstract] [Full Text] [PDF]

This article has been cited by other articles:

• Boyle, P J (2009). Does occupational success influence longevity among England test cricketers?. Br. J. Sports. Med. 43: 851-855 [Abstract] [Full text]  
• Taylor, K. S, Lambert, T. W, Goldacre, M. J (2009). Career progression and destinations, comparing men and women in the NHS: postal questionnaire surveys. BMJ 338: b1735-b1735 [Abstract] [Full text]  
• Carter, R. E., Huang, P. (2009). Cautionary Note Regarding the Use of CIs Obtained From Kaplan-Meier Survival Curves. JCO 27: 174-175 [Full text]  
• Atkinson, M., Lakhanpaul, M., Smyth, A., Vyas, H., Weston, V., Sithole, J., Owen, V., Halliday, K., Sammons, H., Crane, J., Guntupalli, N., Walton, L., Ninan, T., Morjaria, A., Stephenson, T. (2007). Comparison of oral amoxicillin and intravenous benzyl penicillin for community acquired pneumonia in children (PIVOT trial): a multicentre pragmatic randomised controlled equivalence trial. Thorax 62: 1102-1106 [Abstract] [Full text]  
• Kilpatrick, E. S., Rigby, A. S., Atkin, S. L. (2007). Insulin Resistance, the Metabolic Syndrome, and Complication Risk in Type 1 Diabetes: "Double diabetes" in the Diabetes Control and Complications Trial. Diabetes Care 30: 707-712 [Abstract] [Full text]  
• Artes, P. H., Nicolela, M. T., LeBlanc, R. P., Chauhan, B. C. (2005). Visual Field Progression in Glaucoma: Total Versus Pattern Deviation Analyses. IOVS 46: 4600-4606 [Abstract] [Full text]  
• Bland, J M., Altman, D. G (2004). The logrank test. BMJ 328: 1073-1073 [Full text]  
• Sobolev, B., Mercer, D., Brown, P., FitzGerald, M., Jalink, D., Shaw, R. (2003). Risk of emergency admission while awaiting elective cholecystectomy. CMAJ 169: 662-665 [Abstract] [Full text]  
• Williams, D. G., Patel, A., Howard, R. F. (2002). Pharmacogenetics of codeine metabolism in an urban population of children and its implications for analgesic reliability. Br J Anaesth 89: 839-845 [Abstract] [Full text]  
• Sobolev, B, Brown, P, Zelt, D (2001). Potential for bias in waiting time studies: events between enrolment and admission. J. Epidemiol. Community Health 55: 891-894 [Abstract] [Full text]  
• Bland, J M., Altman, D. G (1998). Statistics Notes: Survival probabilities (the Kaplan-Meier method). BMJ 317: 1572-1580 [Full text]  

Online poll

Find out more here>> and here>>