Tuesday, 25 November 2014

Ebola Statistics - More Info Needed

I read the daily Ebola statistics for Sierra Leone released by the Ministry of Heath and Sanitation, and I appreciate the information they are sharing on a daily basis.
Like many others I watch the number of confirmed cases each day rise and fall and rise again. Yesterday it dawned on me that these numbers really aren't informative unless we also know the number of samples that are tested or the number of negative results each day also.
Yesterday there were 39 new confirmed cases - which is lower than it has been for some time.......but what I would really like to know is how many people were tested, or how many negative results were received for the same period. 39 sounds like an improvement......but what if it was a slow day in the labs and only 39 tests were performed......that would be a 100% infection rate on the samples tested........on the other hand if 400 tests were performed we would be looking at a less than 10% infection rate.
On the days we have 90 or more new confirmed cases, our hearts sink because the number is so high........but how many are tested on those days 100? 200? 1000? It could be that on those days there are more tests carried out making the infection rate seem higher.......perhaps the number of tests that return negative results is higher still........
We need more information so we can see the whole picture.

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