Bigger is better but medium is ok too

There is a clear need to bolster public confidence in breast screening programmes after recent (media sensationalised) errors and the most transparent way of doing this is to identify problems in the process and eliminate them, therefore improving performance. Bearing this in mind, researchers evaluated the performance of the current 95 breast screening programmes in the UK and found that the smaller programmes are less effective then their medium and large counterparts (

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The annual standard statistical returns of all programmes were analysed alongside extra information taken from supplementary questionnaires and demonstrated that smaller programmes (defined as the smallest 25%) detected fewer cancers and also had a lower positive predictive value (9.97 PPV compared with 12.06 PPV at 95% confidence intervals). Although the performance of smaller programmes was only marginally poorer than that of the medium and large programmes (which performed to similar standards), the inherent statistical instability associated with small numbers means that problems are harder to identify in these …