![\"\"](\"http:\/\/www.powerofthecrystals.com\/web_images\/amethyst_cluster2.jpg\" "\\"Amethyst\\"")
So, on hearing Matthew Thompson open up a mini-session with natural frequencies my mind turned to the healing power of crystals, and I become acutely concerned that the open-minds approach of the Teaching EBM Conference had gone too far.<\/p>\nSo, on hearing Matthew Thompson open up a mini-session with natural frequencies my mind turned to the healing power of crystals, and I become acutely concerned that the open-minds approach of the Teaching EBM Conference had gone too far.<\/p>\n
But this was quashed quickly by his description: ‘Natural frequencies’ means ‘real numbers’ … like 30 of 100 patients, not 30% or 0.3 … and this is easier for most people to deal with.<\/p>\n
He went on to show that a single box can crack the nut of turning diagnostic test information from meaningless prattle into something highly understandable:<\/p>\n
<\/p>\n
Using this approach means you can loose the faff of nomgrams, converting into odds or pocket calculating and work out, really quickly, what a test result means.<\/p>\n
It works like this: take a problem where 30% of the walk-ins will have it. The test you run has 50% sensitivity and 90% specificity. Of 100 people, 30 have the condition.\u00a0 50% sensitivity means half of the diseased have a +ve test (= 15). 90% specificity means 9\/10th of the undiseased will have a -ve test … so one-tenth (=7) will be test +ve.<\/p>\n
The result – 70% of the positive tests (15\/22) really do have the condition.<\/p>\n
Re-run it with a test prevalence of 60% :<\/p>\n
60 >>>>>\u00a0 30
\n\/\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0 .
\n\/disease\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 .
\n100\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 .
\n\\not disease\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 .
\n\\\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 \u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0 .
\n40 >>>>>\u00a0\u00a0\u00a0 4<\/p>\n
Now 30\/34 ~ 90% of +ve test results are in folk who really have the disease.<\/p>\n
Try it yourself with a prevalence of only 10% and see what the positive test really means …<\/p>\n
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<\/p>\n","protected":false},"excerpt":{"rendered":"
So, on hearing Matthew Thompson open up a mini-session with natural frequencies my mind turned to the healing power of crystals, and I become acutely concerned that the open-minds approach of the Teaching EBM Conference had gone too far. But this was quashed quickly by his description: […]<\/p>\n