[YeGoblynQueenne]

The link changed since I posted my comment :)

The original article on Verge reported "87% accuracy" and 90% what sounded like TNR. The new link points to an FDA page that makes it more likely that ".87" is actually sensitivity:

Dx-DR was able to correctly identify the presence of more than mild diabetic retinopathy 87.4 percent of the time and was able to correctly identify those patients who did not have more than mild diabetic retinopathy 89.5 percent of the time.

So, I guess, something like this:

           Predicted + Predicted - Total
  Actual + 393         57          450
  Actual - 47          403         450
  -------------------------------------
  Total    440         460         900
  
  Accuracy:             0.8844
  Error:                0.1156
  True Positive Rate:   0.8733
  True Negative Rate:   0.8956
  Precision:            0.8932
  Recall (TPR):         0.8733
  F-Score:              0.8831

Closest I can get with exactly 900 cases :0

[ksolanki]

Thanks for this analysis. The balance in real world is more like 20-80, ie 20% of typically screened patients would have referable retinopathy (screen positive).