Number of clinical questions

We've just completed an analysis of clinical questions for the National Library for Health, principally based on the work of the NLH Q&A Service. One issue we addressed was the number of repeat questions. On a very crude level we have been able to map out the proportion of repeat questions based on the size of our answer bank (repository of previously answered questions). To repeat this is very crude, but still an interesting exercise.

When we had 2,000 previous answers the repeat rate was approximately 3.5%, when increased to 5,900 it increased to 9% and when it reached 6,900 it rose to 14.5 %. We've graphed this and it can be viewed below.













We've applied the MS-Excel trendline. If you extend the line, how many questions does an answer bank require to answer 100% of questions as repeat? 48,000.

I don't actually believe that figure. There will always be new interventions so new questions will be asked about these. However, an answer back of say 25,000 questions will possible answer 50% of questions. I look forward to our next analysis, with an even larger answer bank to see where the trendline goes!