[pymvpa] Calculation of TN(True Negative)
Jiang, Zhiguo
zhiguo.jiang at njit.edu
Sat Jan 18 04:47:14 UTC 2014
Hi, All
a bit confused by the output from tutorial Part 4:
so here is the output from the confusion matrix summary
----------.
predictions\targets bottle cat chair face
house scissors scrambledpix shoe
`------ ------------ ------------ ------------ ------------
------------ ------------ ------------ ------------ P' N' FP FN
PPV NPV TPR SPC FDR MCC F1
bottle 6 0 3 0
0 5 0 1 15 75 9 6
0.4 0.92 0.5 0.88 0.6 0.34 0.44
cat 0 10 0 0
0 0 0 0 10 67 0 2
1 0.97 0.83 1 0 0.79 0.91
chair 0 0 7 0
0 0 0 0 7 73 0 5
1 0.93 0.58 1 0 0.66 0.74
face 0 2 0 12
0 0 0 0 14 63 2 0
0.86 1 1 0.97 0.14 0.8 0.92
house 0 0 0 0
12 0 0 0 12 63 0 0
1 1 1 1 0 0.87 1
scissors 2 0 1 0
0 6 0 0 9 75 3 6
0.67 0.92 0.5 0.96 0.33 0.48 0.57
scrambledpix 2 0 1 0
0 0 12 1 16 63 4 0
0.75 1 1 0.94 0.25 0.75 0.86
shoe 2 0 0 0
0 1 0 10 13 67 3 2
0.77 0.97 0.83 0.96 0.23 0.69 0.8
Per target: ------------ ------------ ------------ ------------
------------ ------------ ------------ ------------
P 12 12 12 12
12 12 12 12
N 84 84 84 84
84 84 84 84
TP 6 10 7 12
12 6 12 10
TN 69 65 68 63
63 69 63 65
for example, in bottle category,
P=12, N=84;
True Positive= 6; False Positve=3+5+1; False Negative=2+2+2=6; that left us
with TN=84-9=75..
so where does the reported 69 comes from?
Best,
Tony
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