{"id":997,"date":"2014-10-20T21:01:56","date_gmt":"2014-10-20T20:01:56","guid":{"rendered":"https:\/\/blogs.bmj.com\/adc\/?p=997"},"modified":"2014-10-10T09:22:34","modified_gmt":"2014-10-10T08:22:34","slug":"guest-blog-sampling-bias-and-randomisation","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/adc\/2014\/10\/20\/guest-blog-sampling-bias-and-randomisation\/","title":{"rendered":"Guest Blog: Sampling bias and randomisation"},"content":{"rendered":"

\"\"The blog\u00a0series is expanding!\u00a0No doubt soley inspired by now running the magnificent @ADC_JC<\/a>, @davidking83<\/a> has taken up the challenge of exploring a critical appraisal nugget\/thorn in response to an appraisal session.<\/p>\n

You too could be part of our team\u00a0– tweet @ADC_BMJ<\/a> or find us on Faceboo<\/a>k to get in touch – but for now, let’s settle back, imaging the warm smell of pastries and coffee, switch off our pagers and enter the Journal Club…<\/p>\n

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We were recently discussing a paper in my local journal club at Sheffield Children\u2019s hospital<\/a>,which was a double-blind randomised controlled trial (RCT) examining the effect of pulse oximetry on the admission rate of infants with mild or moderate bronchiolitis. This is a fascinating paper<\/a> and well worth a read if you have not already. Essentially, it showed that in infants with mild to moderate bronchiolitis, clinicians are less likely to admit children if their oxygen saturations are artificially raised by 3%.<\/p>\n

However, one of the points raised from the journal club was the possible effect of selection bias on the results of the trial. The authors state that the parents of a large number of eligible infants refused to take part and this may have introduced selection bias.<\/p>\n

The question was raised as to if this made\u00a0the study less valid.<\/p>\n<\/a>\n

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